indian railway final
TRANSCRIPT
TRAINING
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CERTIFICATE
This is to certify that _____________________________ (Name) pursuing
MECHANICAL ENGINEERING from DELHI TECHNOLOGICAL
UNIVERSITY (formerly DCE) having roll number 2K8/ME/____ has done his
winter training at Diesel Loco Shed Tughlakabad, DELHI from
____________to____________.
The project work entitled
“________________________________________________________”and
“________________________________________________________”, embodies
the original work done by him at the end of his winter training.
Mr. Hari Om
(C.I., D.T.C., Diesel Loco Shed)
Tughlakabad, Delhi
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ACKNOWLEDGEMENT
We take this opportunity to express our sincere gratitude to the people who have helped us in the
successful completion of our industrial training and the project. We would like to show our
greatest appreciation to the highly devoted technical staff, supervisors and officials of the Diesel
Locomotive Shed, Tughlakabad. We are highly indebted to them for their tremendous support
and help during the completion of our training and project.
In particular, we are grateful to Mr Hari Om, C.I. (D.T.C.) of Diesel Locomotive Shed,
Tughlakabad and the Principal of the Training School, who scheduled our training in the various
departments and cells of the shed and handed out this project to us. We would like to thank all
those people who directly or indirectly helped and guided us to complete our training and project
in the Diesel Training Centre and various sections.
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Contents CERTIFICATE ................................................................................................................................ i
ACKNOWLEDGEMENT .............................................................................................................. ii
List of Figures .............................................................................................................................. viii
List of Tables .................................................................................................................................. x
1 INDIAN RAILWAY HISTORY ............................................................................................ 1
2 DIESEL SHED TUGHLAKABAD ........................................................................................ 3
2.1 ABOUT DIESEL SHED TUGHLAKABAD .................................................................. 4
2.1.1 AT A GLANCE ........................................................................................................ 5
2.2 SPECIAL MACHINES & PLANT .................................................................................. 6
2.2.1 Pit wheel lathe machine ............................................................................................ 6
2.2.2 Effluent Treatment Plant:- ........................................................................................ 6
2.3 TECHNICAL INNOVATIONS ....................................................................................... 6
2.3.1 RTTM Test Stand ..................................................................................................... 6
2.3.2 Test Stand for Opening Pressure of on Line lube oil Centrifuge:............................. 7
2.3.3 Expresser Crank Shaft Bearing Extractor ................................................................. 8
2.4 FUEL SECTION .............................................................................................................. 9
2.5 CONTROL ROOM ........................................................................................................ 10
2.6 CTA (Chief Technical Assistance) CELL ..................................................................... 11
2.7 TURBO SUPERCHARGER .......................................................................................... 13
2.7.1 INTRODUCTION .................................................................................................. 13
2.7.2 TURBO SUPERCHARGER AND ITS WORKING PRINCIPLE ........................ 14
2.7.3 MAIN COMPONENTS OF TURBO-SUPERCHARGER .................................... 15
2.7.4 ROTOR ASSEMBLY ............................................................................................. 15
2.7.5 LUBRICATING, COOLING AND AIR CUSHIONING ...................................... 16
2.7.6 AFTER COOLER ................................................................................................... 16
2.7.7 Fitments of higher capacity Turbo Supercharger- .................................................. 17
2.7.8 TURBO RUN –DOWN TEST................................................................................ 18
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2.7.9 ROTOR BALANCING MACHINE ....................................................................... 18
2.7.10 ADVANTAGES OF SUPER CHARGED ENGINES ........................................... 18
2.7.11 Defect in Turbochargers ......................................................................................... 18
2.7.12 Must change components of Turbocharger. ............................................................ 19
2.8 FUEL OIL SYSTEM ..................................................................................................... 20
2.8.1 INTRODUCTION .................................................................................................. 20
2.8.2 FUEL OIL SYSTEM .............................................................................................. 20
2.8.3 CALIBRATION OF FUEL INJECTION PUMPS ................................................. 26
2.8.4 FUEL INJECTION NOZZLE TEST ...................................................................... 27
2.9 BOGIE ............................................................................................................................ 29
2.9.1 INTRODUCTION .................................................................................................. 29
2.9.2 Key Components Of a Bogie .................................................................................. 30
2.9.3 CLASSIFICATION OF BOGIE ............................................................................. 30
2.9.4 Failure and remedies in the bogie section:- ............................................................ 31
2.10 EXPRESSOR ................................................................................................................... 32
2.10.1 INTRODUCTION .................................................................................................. 32
2.10.2 WORKING OF EXHAUSTER .............................................................................. 33
2.10.3 Compressor ............................................................................................................. 33
2.11 SPEEDOMETER ........................................................................................................... 36
2.11.1 INTRODUCTION .................................................................................................. 36
2.11.2 WORKING MECHANISM .................................................................................... 36
2.11.3 Salient features ........................................................................................................ 37
2.11.4 Applications ............................................................................................................ 38
2.11.5 Technical Specifications ......................................................................................... 38
2.12 CYLINDER HEAD........................................................................................................ 40
2.12.1 INTRODUCTION .................................................................................................. 40
2.12.2 Components of cylinder head ................................................................................. 40
2.12.3 Benefits:- ................................................................................................................. 41
2.13 Maintenance and Inspection ........................................................................................... 42
2.13.1 Cleaning: ................................................................................................................. 42
2.13.2 Crack Inspection: .................................................................................................... 42
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2.13.3 Hydraulic Test:........................................................................................................ 42
2.13.4 Dimensional check : ................................................................................................ 42
2.13.5 Straightness of valve stem: ..................................................................................... 42
2.13.6 Checks during overhauling: .................................................................................... 43
2.13.7 Blow by test: ........................................................................................................... 43
2.14 PIT WHEEL LATHE ..................................................................................................... 44
2.14.1 INTRODUCTION .................................................................................................. 44
2.14.2 Wheel turning.......................................................................................................... 44
2.14.3 CAUSES OF WHEEL SKIDDING- ...................................................................... 45
2.15 FAILURE ANALYSIS .................................................................................................. 47
2.15.1 INTRODUCTION .................................................................................................. 47
2.15.2 Metallurgical lab. .................................................................................................... 48
2.15.3 Swelling test ............................................................................................................ 48
2.15.4 Procedure ................................................................................................................ 49
2.15.5 Rubber ..................................................................................................................... 49
2.15.6 ULTRASONIC TESTING...................................................................................... 50
2.15.7 ZYGLO TEST ........................................................................................................ 50
2.15.8 RED DYE PENETRATION TEST (RDP) ............................................................. 51
2.16 SCHEDULED EXAMINATION ................................................................................... 52
2.16.1 INTRODUCTION .................................................................................................. 52
2.16.2 MINOR SCHEDULES ........................................................................................... 53
2.16.3 MAJOR SCHEDULES ........................................................................................... 54
2.17 YEARLY/MECHANICAL ............................................................................................ 56
2.17.1 Examination while Engine is running. .................................................................... 58
2.17.2 (38). Additional items for WDP1:- ......................................................................... 59
2.17.3 (39). Additional items for WDP2 locos:- ................................................................ 59
3 Project Work ......................................................................................................................... 60
3.1 Introduction to bearing ................................................................................................... 61
3.2 Friction ........................................................................................................................... 62
3.3 Service life...................................................................................................................... 63
3.3.1 Fluid and magnetic bearings ................................................................................... 63
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3.3.2 Rolling element bearings ........................................................................................ 63
3.3.3 Plain bearings .......................................................................................................... 63
3.3.4 Flexure bearings ...................................................................................................... 63
3.3.5 Short-life bearings ................................................................................................... 64
3.3.6 L10 life .................................................................................................................... 64
3.3.7 External factors ....................................................................................................... 64
3.4 Classification of Bearings: ............................................................................................. 65
3.4.1 Fluid Film bearings: ................................................................................................ 65
3.4.2 Rolling contact bearings: ........................................................................................ 65
3.4.3 Comparison of bearing frictions: ............................................................................ 65
3.4.4 Sliding contact bearings - Advantages and Disadvantages: ................................... 66
3.5 Journal Bearing: ............................................................................................................. 67
3.5.1 Design parameters of journal bearing: .................................................................... 69
3.5.2 Selection of design zone: ........................................................................................ 69
3.6 Bearing Lubrication........................................................................................................ 71
3.6.1 Types of Lubrication ............................................................................................... 71
3.6.2 Stable Lubrication ................................................................................................... 72
3.7 General causes of bearing failure and Precautions......................................................... 74
3.7.1 DIRT: ...................................................................................................................... 74
3.7.2 INSUFFICIENT LUBRICATION.......................................................................... 75
3.7.3 MISASSEMBLY .................................................................................................... 77
3.7.4 IMPROPER MACHINING OF COMPONENTS. ................................................. 77
3.7.5 OVERLOADING ................................................................................................... 80
3.7.6 CORROSION ......................................................................................................... 80
3.7.7 CAVITATION ........................................................................................................ 81
3.8 Diesel Loco Specification .............................................................................................. 82
3.8.1 Diesel Locomotive Model: WDP3A ....................................................................... 82
3.8.2 Diesel Locomotive Model: WDP1.......................................................................... 83
3.9 Main Bearing Failure Cases ........................................................................................... 84
3.9.1 Loco No. 14004: ..................................................................................................... 84
3.9.2 Loco No. 15530: ..................................................................................................... 84
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3.9.3 Loco No. 15508: ..................................................................................................... 85
3.9.4 Loco No 15527: ...................................................................................................... 85
3.10 FINAL CONCLUSION of THE PROJECT .................................................................. 87
3.11 Ways to improve bearing life and performance ............................................................. 88
4 General Discipline ................................................................................................................ 90
4.1 Suggestions To Improve Performance of the Shed ........................................................ 90
4.2 Improvement in Working Conditions ............................................................................ 91
4.3 Reduction in Environmental Impact .............................................................................. 92
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List of Figures
Figure 1-1: Chhatrapati Shivaji Terminus, Mumbai. First Railway Station in India. Also a world
heritage site. .................................................................................................................................... 1
Figure 2-1: Diesel Shed Tughlakabad............................................................................................. 3
Figure 2-2: Diesel Shed Tughlakabad............................................................................................. 4
Figure 2-3: RTTM Test Stand......................................................................................................... 7
Figure 2-4: Test Stand for Opening Pressure of on Line lube oil Centrifuge ................................. 7
Figure 2-5: Closer look to test Stand for Opening Pressure of on Line lube oil Centrifuge .......... 8
Figure 2-6: Expresser Crank Shaft Bearing Extractor .................................................................... 8
Figure 2-7: Fuel tank ....................................................................................................................... 9
Figure 2-8: GE Turbocharger........................................................................................................ 17
Figure 2-9: Fuel Pump .................................................................................................................. 20
Figure 2-10: Fuel Injection Pump ................................................................................................. 21
Figure 2-11: Cut out section of assembled FIP ............................................................................. 23
Figure 2-12: Fuel Injection Nozzle ............................................................................................... 25
Figure 2-13: Diesel Engine Bogie................................................................................................. 29
Figure 2-14: Bo-Bo and Co-Co Bogies ........................................................................................ 30
Figure 2-15: Expressor .................................................................................................................. 32
Figure 2-16: Schematic Diagram of Expressor ............................................................................. 35
Figure 2-17: Speedometer and other gauges ................................................................................. 36
Figure 2-18: Block Diagram for speedometer Pulse ..................................................................... 37
Figure 2-19: Telpro Speedometer Circuit ..................................................................................... 38
Figure 2-20: Cylinder Head .......................................................................................................... 40
Figure 2-21: Inspection of an engine ............................................................................................ 42
Figure 2-22: Pit Wheel Lathe Machine ......................................................................................... 44
Figure 2-23: Wheel Specifications................................................................................................ 45
Figure 2-24: A Failure Detection Device...................................................................................... 47
Figure 2-25: A Crankshaft taken out for Scheduled Examination ................................................ 52
Figure 2-26: Engine block taken out for yearly maintanence ....................................................... 56
Figure 3-1: Introduction to Bearings............................................................................................. 61
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Figure 3-2: Different Motions supported by Bearing ................................................................... 62
Figure 3-3: Bearing Service Life .................................................................................................. 64
Figure 3-4: Friction in Different Bearings .................................................................................... 66
Figure 3-5: Different Types of Journal Bearings .......................................................................... 67
Figure 3-6: Operation of a Journal Bearing .................................................................................. 68
Figure 3-7: Friction variation with Bearing Characteristic number.............................................. 69
Figure 3-8: Regimes of Lubrication .............................................................................................. 72
Figure 3-9: DIRT IN THE LUBRICATION SYSTEM ............................................................... 74
Figure 3-10: Dirt on Bearing Back ............................................................................................... 75
Figure 3-11: Bearing Failure due to Malfunctioning Lubrication ................................................ 76
Figure 3-12: Bearing Seizure due to oil film failure ..................................................................... 76
Figure 3-13: Failure due to misplaced oil hole of the bearing ...................................................... 77
Figure 3-14: Failure Due to Improperly Ground Housing ............................................................ 78
Figure 3-15: Failure due to Fillet Ride ......................................................................................... 78
Figure 3-16: Misaligned Shaft leads to Bearing Failure ............................................................... 79
Figure 3-17: Failure due to Insufficient Crush ............................................................................. 79
Figure 3-18: Bearing Failure due to Overloading ......................................................................... 80
Figure 3-19: Metal Fatigue caused by Overloading ..................................................................... 80
Figure 3-20: Bearing Corrosion due to wrong Lube Oil............................................................... 81
Figure 3-21: Cavitation in Bearing ............................................................................................... 81
Figure 3-22: Hydraulic Bolt Tensioner ......................................................................................... 89
Figure 4-1: Earmuffs reduce External Noise ................................................................................ 92
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List of Tables
Table 1: List of Turbo Superchargers ........................................................................................... 17
Table 2: Calibration Value of different FIPs ................................................................................ 27
Table 3: Operating conditions ....................................................................................................... 39
Table 4: Analogue indication ........................................................................................................ 39
Table 5: Digital indication ............................................................................................................ 39
Table 6: General ............................................................................................................................ 39
Table 7: Functions of some Alloying Materials ........................................................................... 48
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1 INDIAN RAILWAY HISTORY
Figure 1-1: Chhatrapati Shivaji Terminus, Mumbai. First Railway Station in India. Also a world heritage
site.
Indian Railways is the departmental undertaking of the Government of India. It comes under the
Ministry of Railways, Government of India. Indian Railways has one of the largest and busiest
rail networks in the world, transporting over 30 million passengers and more than 2.8 million
tonnes of freight daily. Its net income (2009-10) was over Rs. 9500 crore. It is the world's largest
commercial employer, with more than 1.36 million employees. It operates rail transport on 7,500
stations over a total route length of more than 65,000 kilometres (40,389 miles). About 40% of
the total track kilometre is electrified & almost all electrified sections use 25,000 V AC. The
fleet of Indian railway includes over 240,000 (freight) wagons, 60,000 coaches and 9,000
locomotives. It also owns locomotive and coach production facilities. It was founded in 1853
under the East India Company.
Indian Railways is administered by the Railway Board. Indian Railways is divided into 16 zones.
Each zone railway is made up of a certain number of divisions. There are a total of sixty-seven
divisions. It also operates the Kolkata metro. There are six manufacturing plants of the Indian
Railways. Indian Railways use four rail track gauges:-
1. The broad gauge (1670 mm)
2. The meter gauge (1000 mm)
3. Narrow gauge (762 mm)
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4. Narrow gauge (610 mm).
CLASSIFICATION
Standard “Gauge” designations and dimensions:-
W = Broad gauge (1.67 m)
Y = Medium gauge ( 1 m)
Z = Narrow gauge (0.762 m)
N = Narrow gauge (0.610 m)
“Type of Traction” designations:-
D = Diesel-electric traction
C = DC traction
A = AC traction
CA=Dual power AC/DC traction
The “type of load” or “Service” designations:-
M= Mixed service
P = Passenger
G= Goods
S = Shunting
“Horse power” designations from June 2002 (except WDP-1 & WDM-2 LOCOS)
‘3’ For 3000 horsepower
‘4’ For 4000 horsepower
‘5’ For 5000 horsepower
‘A’ For extra 100 horsepower
‘B’ For extra 200 horsepower and so on.
Hence „WDM-3A‟ indicates a broad gauge loco with diesel-electric traction. It is for mixed
services and has 3100 horsepower.
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2 DIESEL SHED TUGHLAKABAD
Figure 2-1: Diesel Shed Tughlakabad
Diesel locomotive shed is an industrial-technical setup, where repair and maintenance works of
diesel locomotives is carried out, so as to keep the loco working properly. It contributes to
increase the operational life of diesel locomotives and tries to minimize the line failures. The
technical manpower of a shed also increases the efficiency of the loco and remedies the failures
of loco.
The shed consists of the infrastructure to berth, dismantle, repair and test the loco
and subsystems. The shed working is heavily based on the manual methods of
doing the maintenance job and very less automation processes are used in sheds,
especially in India.
The diesel shed usually has:-
Berths and platforms for loco maintenance.
Pits for under frame maintenance
Heavy lift cranes and lifting jacks
Fuel storage and lube oil storage, water treatment plant and testing labs etc.
Sub-assembly overhauling and repairing sections
Machine shop and welding facilities.
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2.1 ABOUT DIESEL SHED TUGHLAKABAD
Figure 2-2: Diesel Shed Tughlakabad
Diesel Shed, Tughlakabad of Northern Railway is located in NEW DELHI. The shed was
established on 22nd
April 1970. It was initially planned to home 75 locomotives. The shed cater
the needs of Northern railway. This shed mainly provides locomotive to run the mail, goods and
passenger services. No doubt the reliability, safety through preventive and predictive
maintenance is high priority of the shed. To meet out the quality standard shed has taken various
steps and obtaining of the ISO-9001-200O& ISO 14001 OHSAS CERTIFICATION is among of
them. The Diesel Shed is equipped with modern machines and plant required for Maintenance of
Diesel Locomotives and has an attached store depot. To provide pollution free atmosphere,
Diesel Shed has constructed Effluent Treatment Plant. The morale of supervisors and staff of the
shed is very high and whole shed works like a well-knit team.
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2.1.1 AT A GLANCE
Inception: 22nd
April1970
Present Holding: 147 Locomotives
19 WDM2
37 WDM3A
08 WDM3D
11 WDG3A
46 WDP1
26 WDP3A
Accreditation ISO-9001-2000 & ISO 14001
Covered area of shed 10858 SQ. MTR
Total Area of shed 1, 10,000 SQ. MTR
Staff strength Sanctioned – 1357
On roll - 1201
Berthing capacity 17 locomotives
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2.2 SPECIAL MACHINES & PLANT
2.2.1 Pit wheel lathe machine
This machine is suitable for turn & re-profiles the wheels of locomotives.
2.2.2 Effluent Treatment Plant:-
In order to provide pollution free environment, an ETP PLANT is installed. Various effluents
emitted from diesel shed are passed through the Plant. The water thus collected is pollution free
and is used for non-drinking purposes such as gardening and washing of the locomotives.
2.3 TECHNICAL INNOVATIONS
Based on day-to-day maintenance problems a large number of innovations/modifications have
been conceived and implemented in Diesel Shed, TKD during 2003-2004 which have improved
the reliability and downtime of locomotives. Some of them are as below:
2.3.1 RTTM Test Stand
Rear Truck Traction Motor Blower has been an area of concern due to a number of failures
because of bearing seizure or belt breakage. A test stand has been developed in house by using
available material for running the RTTM blower after assembly on load for a few hours so that
both the bearing and the belts can be checked before the blower is fitted on the locomotive. A
photograph of the test stand is reproduced below:
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Figure 2-3: RTTM Test Stand
2.3.2 Test Stand for Opening Pressure of on Line lube oil Centrifuge:
TKD shed has developed a “Test stand” for testing the opening pressure of the online lube oil
centrifuge fitted in the Diesel Locomotive. This will ensure that online centrifuge does not open
till adequate pressure is developed in system. This test stand shall also improve overall health of
the system components such as main bearing, Connecting Rod, bearings, Camshafts, Valve lever
mechanism, Piston & Liners etc.
Figure 2-4: Test Stand for Opening Pressure of on Line lube oil Centrifuge
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Figure 2-5: Closer look to test Stand for Opening Pressure of on Line lube oil Centrifuge
2.3.3 Expresser Crank Shaft Bearing Extractor
Diesel Shed, TKD has fabricated one Expresser Crankshaft main ball bearing puller for
extracting serviceable ball bearings in good conditions from the condemned C/Shaft as well as
old unserviceable ball bearings from serviceable C/shaft without damaging any of the items.
Prior to this, ball bearings were removed either by gas cutting or with the use of sledge hammers.
Figure 2-6: Expresser Crank Shaft Bearing Extractor
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2.4 FUEL SECTION
Figure 2-7: Fuel tank
The section is concern with receiving, storage and refilling of diesel and lube oil. It has 3 large
storage tanks and one underground tank for diesel storage which have a combined
storage capacity of 10,60, 000 litres. This stock is enough to end for 15-16 days The fuel
is supplied by truck from IOC - Panipat refinery. Each truck diesel sample is treated in
diesel lab and after it in unloaded. Sample check is necessary to avoid water, kerosene
mixing diesel. Two fuel filling points are established near the control room It also
handles the Cardiam compound , lube oil. diesel is only for loco use if the diesel samples
are not according to the standard , the delivery of the fuel is rejected. Viscosity of lube oil
should be 100-1435 CST. Water mixing reduces the viscosity.
Statement of diesel storage and received is made after every 10 days and the report is send to the
Division headquarter. The record of each truck, wagons etc. are included in it. The record of
issued oil is also sending to headquarter. After each 4 months. A survey is conducted by high
level team about the storage, records etc. 0.1% of total stored fuel oil is given for handling losses
by the HQ. The test reports of diesel includes the type of diesel (high speed diesel- Euro-3 with
0.035 % S), reason for test, inspection lot no, store tank no, batch no. etc.
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2.5 CONTROL ROOM
It controls and regulates the complete movement, schedules, duty of each loco of the shed.
Division level communications and contacts with each loco on the line are also handled by the
control room. Full record of loco fleet, failures, duty, overdue and availability of locos are kept
by the control room. It applies the outage target of loco for the shed, as decided by the HQ. It
decides the locomotives mail and goods link that which loco will be deployed on which train. It
operates 116 Mail and 11Goods link from the shed locos. For 0-0 outage total 127 loco should be
on line.
The schedule of duty, trains and link is decided by the control room according to the type of
trains. If the loco does not return on scheduled time in the shed then the loco is termed as
„overdue‟ and control room can use the loco of another shed if that is available.
The lube oil consumption is also calculated by the control room for each loco:-
Lube Oil Consumption (LOC) = Lube oil consumed in litres/ total kms travelled ×100
New and better operational loco have less LOC.
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2.6 CTA (Chief Technical Assistance) CELL
This cell performs the following functions:-
Failure analysis of diesel locos
Finding the causes of sub system failures and material failures
Formation of inquiry panels of Mechanical and Electrical engineers and to help the
special inquiry teams
Material failures complains, warnings and replacement of stock communications with
the component manufacturers
Issues the preventive instructions to the technical workers and engineers
Preparation of full detailed failure reports of each loco and sub systems, components
after detailed analysis. The reports are then sent to the Divisional HQ.
Correspondence with the headquarters is also done by the CTA Cell.
The failures analysed are:-
Category 1 failures:- If the VIP trains loco fails or the train is delayed by the failure of another
trains loco failure. Failure of the single loco may delay a no of trains.
Non- reported failures:- the failure or delay of the local passenger trains for 2-3 hours is taken in
this category. They are not reported to the higher levels and can be adjusted in the section
operations.
Foreign Railway-FR failures:- If the loco of one division fails in the other division and affects
the traffic seriously in that division. The correspondence in this case is done by the cell.
Other failures are:-
1. Material failure: - may be due to poor quality, defective material and defects in the
manufacturing of the component. Component is replaced if fails frequently.
2. Maintenance failures: - if lapse is by the maintenance workers. Inquiry is done and
punishment is set by CTA Cell on behalf of Sr. DME or instructions are issued for better
maintenance.
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3. Crew lapse: - proper actions are take or instructions issued to the crew of locos.
After every 4 years IOH of loco is done in the shed. After 8years POH of loco is done at the
Charbag loco shed –Lucknow. After 18 years rebuilding of loco is done at DMW-Patiala. Total
life of a loco is 36 years.
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2.7 TURBO SUPERCHARGER
2.7.1 INTRODUCTION
The diesel engine produces mechanical energy by converting heat energy derived from burning
of fuel inside the cylinder. For efficient burning of fuel, availability of sufficient air in proper
ratio is a prerequisite.
In a naturally aspirated engine, during the suction stroke, air is being sucked into the cylinder
from the atmosphere. The volume of air thus drawn into the cylinder through restricted inlet
valve passage, within a limited time would also be limited and at a pressure slightly less than the
atmosphere. The availability of less quantity of air of low density inside the cylinder would limit
the scope of burning of fuel. Hence mechanical power produced in the cylinder is also limited.
An improvement in the naturally aspirated engines is the super-charged or pressure charged
engines. During the suction stroke, pressurised stroke of high density is being charged into the
cylinder through the open suction valve. Air of higher density containing more oxygen will make
it possible to inject more fuel into the same size of cylinders and produce more power, by
effectively burning it.
A turbocharger, or turbo, is a gas compressor used for forced-induction of an internal
combustion engine. Like a supercharger, the purpose of a turbocharger is to increase the density
of air entering the engine to create more power. However, a turbocharger differs in that the
compressor is powered by a turbine driven by the engine's own exhaust gases.
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2.7.2 TURBO SUPERCHARGER AND ITS WORKING PRINCIPLE
The exhaust gas discharge from all the cylinders accumulate in the common exhaust manifold at
the end of which, turbo- supercharger is fitted. The gas under pressure there after enters the
turbo- supercharger through the torpedo shaped bell mouth connector and then passes through
the fixed nozzle ring. Then it is directed on the turbine blades at increased pressure and at the
most suitable angle to achieve rotary motion of the turbine at maximum efficiency. After rotating
the turbine, the exhaust gas goes out to the atmosphere through the exhaust chimney. The turbine
has a centrifugal blower mounted at the other end of the same shaft and the rotation of the
turbine drives the blower at the same speed. The blower connected to the atmosphere through a
set of oil bath filters, sucks air from atmosphere, and delivers at higher velocity. The air then
passes through the diffuser inside the turbo- supercharger, where the velocity is diffused to
increase the pressure of air before it is delivered from the turbo- supercharger.
Pressurising air increases its density, but due to compression heat develops. It causes expansion
and reduces the density. This affects supply of high-density air to the engine. To take care of this,
air is passed through a heat exchanger known as after cooler. The after cooler is a radiator, where
cooling water of lower temperature is circulated through the tubes and around the tubes air
passes. The heat in the air is thus transferred to the cooling water and air regains its lost density.
From the after cooler air goes to a common inlet manifold connected to each cylinder head. In
the suction stroke as soon as the inlet valve opens the booster air of higher pressure density
rushes into the cylinder completing the process of super charging.
The engine initially starts as naturally aspirated engine. With the increased quantity of fuel
injection increases the exhaust gas pressure on the turbine. Thus the self-adjusting system
maintains a proper air and fuel ratio under all speed and load conditions of the engine on its own.
The maximum rotational speed of the turbine is 18000/22000 rpm for the Turbo supercharger
and creates max. Of 1.8 kg/cm2 air pressure in air manifold of diesel engine, known as Booster
Air Pressure (BAP). Low booster pressure causes black smoke due to incomplete combustion of
fuel. High exhaust gas temperature due to after burning of fuel may result in considerable
damage to the turbo supercharger and other component in the engine.
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2.7.3 MAIN COMPONENTS OF TURBO-SUPERCHARGER
Turbo- supercharger consists of following main components.
Gas inlet casing.
Turbine casing.
Intermediate casing
Blower casing with diffuser
Rotor assembly with turbine and rotor on the same shaft.
2.7.4 ROTOR ASSEMBLY
The rotor assembly consists of rotor shaft, rotor blades, thrust collar, impeller, inducer, centre
studs, nosepiece, locknut etc. assembled together. The rotor blades are fitted into fir tree slots,
and locked by tab lock washers. This is a dynamically balanced component, as this has a very
high rotational speed.
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2.7.5 LUBRICATING, COOLING AND AIR CUSHIONING
2.7.5.1 LUBRICATING SYSTEM
One branch line from the lubricating system of the engine is connected to the turbo-
supercharger. Oil from the lube oils system circulated through the turbo- supercharger for
lubrication of its bearings. After the lubrication is over, the oil returns back to the lube oil
system, through a return pipe. Oil seals are provided on both the turbine and blower ends of the
bearings to prevent oil leakage to the blower or the turbine housing.
2.7.5.2 COOLING SYSTEM
The cooling system is integral to the water cooling system of the engine. Circulation of water
takes place through the intermediate casing and the turbine casing, which are in contact with hot
exhaust gases. The cooling water after being circulated through the turbo- supercharger returns
back again to the cooling system of the locomotive.
2.7.5.3 AIR CUSHIONING
There is an arrangement for air cushioning between the rotor disc and the intermediate casing
face to reduce thrust load on the thrust face of the bearing which also solve the following
purposes.
It prevents hot gases from coming in contact with the lube oil.
It prevents leakage of lube oil through oil seals.
It cools the hot turbine disc.
Pressurised air from the blower casing is taken through a pipe inserted in the turbo- supercharger
to the space between the rotor disc and the intermediate casing. It serves the purpose as described
above.
2.7.6 AFTER COOLER
It is a simple radiator, which cools the air to increase its density. Scales formation on the tubes,
both internally and externally, or choking of the tubes can reduce heat transfer capacity. This can
also reduce the flow of air through it. This reduces the efficiency of the diesel engine. This is
evident from black exhaust smoke emissions and a fall in booster pressure.
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2.7.7 Fitments of higher capacity Turbo Supercharger-
Following new generation Turbo Superchargers have been identified by diesel shed TKD for
2600/3100HP diesel engine and tabulated in table 1.
Table 1: List of Turbo Superchargers
TYPE POWER COOLING
1.ALCO 2600HP Water cooled
2.ABB TPL61 3100HP Air cooled
3.HISPANO SUIZA HS 5800 NG 3100HP Air cooled
4. GE 7S1716 3100HP Water cooled
5. NAPIER NA-295 2300,2600&3100HP Water cooled
6. ABB VTC 304 2300,2600&3100HP Water cooled
Figure 2-8: GE Turbocharger
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2.7.8 TURBO RUN –DOWN TEST
Turbo run-down test is a very common type of test done to check the free running time of turbo
rotor. It indicates whether there is any abnormal sound in the turbo, seizer/ partial seizer of
bearing, physical damages to the turbine, or any other abnormality inside it. The engine is started
and warmed up to normal working conditions and running at fourth notch speed. Engine is then
shut down through the over speed trip mechanism. When the rotation of the crank shaft stops, the
free running time of the turbine is watched through the chimney and recorded by a stop watch.
The time limit for free running is 90 to 180 seconds. Low or high turbo run down time are both
considered to be harmful for the engine.
2.7.9 ROTOR BALANCING MACHINE
A balancing machine is a measuring tool used for balancing rotating machine parts such as
rotors of turbo supercharger, electric motors, fans, turbines etc. The machine usually consists of
two rigid pedestals, with suspension and bearings on top. The unit under test is placed on the
bearings and is rotated with a belt. As the part is rotated, the vibration in the suspension is
detected with sensors and that information is used to determine the amount of unbalance in the
part. Along with phase information, the machine can determine how much and where to add or
remove weights to balance the part.
2.7.10 ADVANTAGES OF SUPER CHARGED ENGINES
A super charged engine can produce 50 percent or more power than a naturally
aspirated engine. The power to weight ratio in such a case is much more favorable.
Better scavenging in the cylinders. This ensures carbon free cylinders and valves, and
better health for the engine also.
Better ignition due to higher temperature developed by higher compression in the
cylinder.
It increases breathing capacity of engine
Better fuel efficiency due to complete combustion of fuel.
2.7.11 Defect in Turbochargers
1. Low Booster Air Pressure (BAP).
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2. Oil throwing from Turbocharger because of seal damage or out of clearance.
3. Surging- Back Pressure due to uneven gap in Nozzle Ring or Diffuser Ring.
2.7.12 Must change components of Turbocharger.
1. Intermediate casing gasket.
2. Water outlet pipe flange gasket.
3. Water inlet pipe flange gasket.
4. Lube Oil inlet pipe rubber ‘o’ ring.
5. Turbine end Bearing.
6. Blower end Bearing.
7. Chimney gasket.
8. Rubber ‘o’ Ring kit.
9. Spring Washers.
10. Lock Washer Rotor Stud.
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2.8 FUEL OIL SYSTEM
Figure 2-9: Fuel Pump
2.8.1 INTRODUCTION
All locomotive have individual fuel oil system. The fuel oil system is designed to introduce fuel
oil into the engine cylinders at the correct time, at correct pressure, at correct quantity and
correctly atomized. The system injects into the cylinder correctly metered amount of fuel in
highly atomized form. High pressure of fuel is required to lift the nozzle valve and for better
penetration of fuel into the combustion chamber. High pressure also helps in proper atomization
so that the small droplets come in better contact with the compressed air in the combustion
chamber, resulting in better combustion. Metering of fuel quantity is important because the
locomotive engine is a variable speed and variable load engine with variable requirement of fuel.
Time of fuel injection is also important for better combustion.
2.8.2 FUEL OIL SYSTEM
The fuel oil system consists of two integrated systems. These are -
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FUEL INJECTION PUMP (F.I.P).
FUEL INJECTION SYSTEM.
2.8.2.1 FUEL INJECTION PUMP
Figure 2-10: Fuel Injection Pump
It is a constant stroke plunger type pump with variable quantity of fuel delivery to suit the
demands of the engine. The fuel cam controls the pumping stroke of the plunger. The length of
the stroke of the plunger and the time of the stroke is dependent on the cam angle and cam
profile, and the plunger spring controls the return stroke of the plunger. The plunger moves
inside the barrel, which has very close tolerances with the plunger. When the plunger reaches to
the BDC, spill ports in the barrel, which are connected to the fuel feed system, open up. Oil then
fills up the empty space inside the barrel. At the correct time in the diesel cycle, the fuel cam
pushes the plunger forward, and the moving plunger covers the spill ports. Thus, the oil trapped
in the barrel is forced out through the delivery valve to be injected into the combustion chamber
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through the injection nozzle. The plunger has two identical helical grooves or helix cut at the top
edge with the relief slot. At the bottom of the plunger, there is a lug to fit into the slot of the
control sleeve. When the rotation of the engine moves the camshaft, the fuel cam moves the
plunger to make the upward stroke.
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Figure 2-11: Cut out section of assembled FIP
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It may also rotate slightly, if necessary through the engine governor, control shaft, control rack,
and control sleeve. This rotary movement of the plunger along with reciprocating stroke changes
the position of the helical relief in respect to the spill port and oil, instead of being delivered
through the pump outlet, escapes back to the low pressure feed system. The governor for engine
speed control, on sensing the requirement of fuel, controls the rotary motion of the plunger,
while it also has reciprocating pumping strokes. Thus, the alignment of helix relief with the spill
ports will determine the effectiveness of the stroke. If the helix is constantly in alignment with
the spill ports, it bypasses the entire amount of oil, and nothing is delivered by the pump.
The engine stops because of no fuel injected, and this is known as „NO-FUEL‟ position. When
alignment of helix relief with spill port is delayed, it results in a partly effective stroke and
engine runs at low speed and power output is not the maximum. When the helix is not in
alignment with the spill port throughout the stroke, this is known as „FULL FUEL POSITION‟,
because the entire stroke is effective.
Oil is then passed through the delivery valve, which is spring loaded. It opens at the oil pressure
developed by the pump plunger. This helps in increasing the delivery pressure of oil. It functions
as a non-return valve, retaining oil in the high pressure line. This also helps in snap termination
of fuel injection, to arrest the tendency of dribbling during the fuel injection. The specially
designed delivery valve opens up due to the pressure built up by the pumping stroke of plunger.
When the oil pressure drops inside the barrel, the landing on the valve moves backward to
increase the space available in the high-pressure line. Thus, the pressure inside the high-pressure
line collapses, helping in snap termination of fuel injection. This reduces the chances of dribbling
at the beginning or end of fuel injection through the fuel injection nozzles.
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2.8.2.2 FUEL INJECTION NOZZLE
Figure 2-12: Fuel Injection Nozzle
The fuel injection nozzle or the fuel injector is fitted in the cylinder head with its tip projected
inside the combustion chamber. It remains connected to the respective fuel injection pump with a
steel tube known as fuel high pressure line. The fuel injection nozzle is of multi-hole needle
valve type operating against spring tension. The needle valve closes the oil holes by blocking the
oil holes due to spring pressure. Proper angle on the valve and the valve seat, and perfect bearing
ensures proper closing of the valve.
Due to the delivery stroke of the fuel injection pump, pressure of fuel oil in the fuel duct and the
pressure chamber inside the nozzle increases. When the pressure of oil is higher than the valve
spring pressure, valve moves away from its seat, which uncovers the small holes in the nozzle
tip. High-pressure oil is then injected into the combustion chamber through these holes in a
highly atomised form. Due to injection, hydraulic pressure drops, and the valve returns back to
its seat terminating the fuel injection, termination of fuel injection may also be due to the
bypassing of fuel injection through the helix in the fuel injection pump causing a sudden drop in
pressure.
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2.8.3 CALIBRATION OF FUEL INJECTION PUMPS
Each fuel injection pump is subject to test and calibration after repair or overhaul to ensure that
they deliver the same and stipulated amount of fuel at a particular rack position. Every pump
must deliver regulated and equal quantity of fuel at the same time so that the engine output is
optimum and at the same time running is smooth with minimum vibration.
The calibration and testing of fuel pumps are done on a specially designed machine. The
machine has a 5 HP reversible motor to drive a cam shaft through V belt. The blended test oil of
recommended viscosity under controlled temperature is circulated through a pump at a
specified pressure for feeding the pump under test. It is very much necessary to follow the laid
down standard procedure of testing to obtain standard test results. The pump under test is fixed
on top of the cam box and its rack set at a particular position to find out the quantum of fuel
delivery at that position. The machine is then switched on and the cam starts making delivery
strokes. A revolution counter attached to it is set to trip at 500 RPM or 100 RPM as required.
With the cam making strokes, if the pump delivers any oil, it returns back to the reservoir in
normal state. A manually operated solenoid switch is switched on and the oil is diverted to a
measure glass till 300 strokes are completed after operation of the solenoid switch. Thus the oil
discharged at 300 working strokes of the pump is measured which should normally be within the
stipulated limit. The purpose of measuring the output in 300 strokes is to take an average to
avoid errors. The pump is tested at idling and full fuel positions to make sure that they deliver
the correct amount of fuel for maintaining the idling speed and so also deliver full HP at full
load. A counter check of the result at idling is done on the reverse position of the motor which
simulates slow running of the engine.
If the test results are not within the stipulated limits as indicated by the makers then adjustment
of the fuel rack position may be required by moving the rack pointer, by addition or removal of
shims behind it. The thickness of shims used should be punched on the pump body. The
adjustment of rack is done at the full fuel position to ensure that the engine would deliver full
horse power. Once the adjustment is done at full fuel position other adjustment should come
automatically. In the event of inconsistency in results between full fuel and idling fuel, it may
call for change of plunger and barrel assembly.
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The calibration value of fuel injection pump as supplied by the makers is tabulated in table 2 at
300 working strokes, rpm -500, temp.-100 to 120 0F & pressure 40 PSI:
Table 2: Calibration Value of different FIPs
Dia. of element(mm) Rack(mm) Required volume of
fuel(cc)
15 mm 30 mm(full load)
9 mm(Idling)
351 cc +5/-10
34 cc +1/-5
17 mm 28 mm (full load)
9 mm (Idling)
401 cc +4/-11
45 cc +1/-5
Errors are likely to develop on the calibration machine in course of time and it is necessary to
check the machine at times with master pumps supplied by the makers. These pumps are
perfectly calibrated and meant for use as reference to test the calibration machine itself. Two
master pumps, one for full fuel and the other for idling fuel are there and they have to be very
carefully preserved only for the said purpose.
2.8.4 FUEL INJECTION NOZZLE TEST
The criteria of a good nozzle are good atomization, correct spray pattern and no leakage or
dribbling. Before a nozzle is put to test the assembly must be rinsed in fuel oil, nozzle holes
cleaned with wire brush and spray holes cleaned with steel wire of correct thickness.
The fuel injection nozzles are tested on a specially designed test stand, where the following tests
are conducted.
2.8.4.1 SPRAY PATTERN
Spray of fuel should take place through all the holes uniformly and properly atomized. While the
atomization can be seen through the glass jar, an impression taken on a sheet of blotting paper at
a distance of 1 to 1 1/2 inch also gives a clear impression of the spray pattern.
2.8.4.2 SPRAY PRESSURE
The stipulated correct pressure at which the spray should take place is 3900-4050 psi for new and
3700-3800 psi for reconditioned nozzles. If the pressure is down to 3600 psi the nozzle needs
replacement. The spray pressure is indicated in the gauge provided in the test machine. Shims
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are being used to increase or decrease the tension of nozzle spring which increases or decreases
the spray pressure.
2.8.4.3 DRIBBLING
There should be no loose drops of fuel coming out of the nozzle before or after the injections. In
fact the nozzle tip of a good nozzle should always remain dry. The process of checking dribbling
during testing is by having injections manually done couple of times quickly and checks the
nozzle tip whether leaky.
Raising the pressure within 100 psi of set injection pressure and holding it for about 10 seconds
may also give a clear idea of the leakage.
The reasons of nozzle dribbling are (1) Improper pressure setting (2) Dirt stuck up between the
valve and the valve seat (3) Improper contact between the valve and valve seat (4) Valve sticking
inside the valve body.
2.8.4.4 NOZZLE CHATTER
The chattering sound is a sort of cracking noise created due to free movement of the nozzle valve
inside the valve body. If it is not proper then chances are that the valve is not moving freely
inside the nozzle.
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2.9 BOGIE
Figure 2-13: Diesel Engine Bogie
2.9.1 INTRODUCTION
A bogie is a wheeled wagon or trolley. In mechanics terms, a bogie is a chassis or framework
carrying wheels, attached to a vehicle. It can be fixed in place, as on a cargo truck, mounted on a
swivel, as on a railway carriage or locomotive, or sprung as in the suspension of a caterpillar
tracked vehicle. Bogies serve a number of purposes:-
To support the rail vehicle body
To run stably on both straight and curved track
To ensure ride comfort by absorbing vibration, and minimizing centrifugal forces when
the train runs on curves at high speed.
To minimize generation of track irregularities and rail abrasion.
Usually two bogies are fitted to each carriage, wagon or locomotive, one at each end.
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2.9.2 Key Components Of a Bogie
The bogie frame itself.
Suspension to absorb shocks between the bogie frame and the rail vehicle body.
Common types are coil springs, or rubber airbags.
At least two wheel set, composed of axle with a bearings and wheel at each end.
Axle box suspension to absorb shocks between the axle bearings and the bogie frame.
The axle box suspension usually consists of a spring between the bogie frame and axle
bearings to permit up and down movement, and sliders to prevent lateral movement. A
more modern design uses solid rubber springs.
Brake equipment:-Brake shoes are used that are pressed against the tread of the
wheels.
Traction motors for transmission on each axle.
2.9.3 CLASSIFICATION OF BOGIE
Bogie is classified into the various types described below according to their configuration in
terms of the number of axle, and the design and structure of the
suspension. According to UIC classification two types of bogie in Indian Railway are:-
Bo-Bo
Co-Co
Figure 2-14: Bo-Bo and Co-Co Bogies
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A Bo-Bo is a locomotive with two independent four-wheeled bogies with all axles powered by
individual traction motors. Bo-Bo is mostly suited for express passenger or medium-sized
locomotives.
Co-Co is a code for a locomotive wheel arrangement with two six-wheeled bogies with all axles
powered, with a separate motor per axle. Co-Co is most suited to freight work as the extra
wheels give them good adhesion. They are also popular because the greater number of axles
results in a lower axle load to the track.
2.9.4 Failure and remedies in the bogie section:-
Breakage of coiled springs due to heavy shocks or more weight or defective material.
They are tested time to time to check the compression limit. Broken springs are
replaced.
14 to 60 thou clearance is maintained between the axle and suspension bearing. Lateral
clearance is maintained between 60 and 312 thou. Less clearance will burn the oil and
will cause the seizure of axle. Condemned parts are replaced.
RDP tests are done on the frame parts, welded parts, corners, guide links and rigid
structures of bogie and minor cracks can be repaired by welding.
Axle suspension bearings may seizure due to oil leakage, cracks etc. If axle box bearing’s
roller is damaged then replaced it completely.
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2.10 EXPRESSOR
Figure 2-15: Expressor
2.10.1 INTRODUCTION
In Indian Railways, the trains normally work on vacuum brakes and the diesel locos on air
brakes. As such provision has been made on every diesel loco for both vacuum and compressed
air for operation of the system as a combination brake system for simultaneous application on
locomotive and train.
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In ALCO locos the exhauster and the compressor are combined into one unit and it is known as
EXPRESSOR. It creates 23" of vacuum in the train pipe and 140 PSI air pressure in the reservoir
for operating the brake system and use in the control system etc.
The expressor is located at the free end of the engine block and driven through the extension
shaft attached to the engine crank shaft. The two are coupled together by fast coupling (Kopper's
coupling). Naturally the expressor crank shaft has eight speeds like the engine crank shaft. There
are two types of expressor are, 6CD, 4UC & 6CD, 3UC. In 6CD, 4UC expressor there are six
cylinder and four exhauster whereas 6CD, 3UC contain six cylinder and three exhauster.
2.10.2 WORKING OF EXHAUSTER
Air from vacuum train pipe is drawn into the exhauster cylinders through the open inlet valves in
the cylinder heads during its suction stroke. Each of the exhauster cylinders has one or two inlet
valves and two discharge valves in the cylinder head. A study of the inlet and discharge valves as
given in a separate diagram would indicate that individual components like (1) plate valve outer
(2) plate valve inner (3) spring outer (4) spring inner etc. are all interchangeable parts. Only
basic difference is that they are arranged in the reverse manner in the valve assemblies which
may also have different size and shape. The retainer stud in both the assemblies must project
upward to avoid hitting the piston.
The pressure differential between the available pressure in the vacuum train pipe and inside the
exhauster cylinder opens the inlet valve and air is drawn into the cylinder from train pipe during
suction stroke. In the next stroke of the piston the air is compressed and forced out through the
discharge valve while the inlet valve remains closed. The differential air pressure also
automatically opens or closes the discharge valves, the same way as the inlet valves operate.
This process of suction of air from the train pipe continues to create required amount of vacuum
and discharge the same air to atmosphere. The VA-1 control valve helps in maintaining the
vacuum to requisite level despite continued working of the exhauster.
2.10.3 Compressor
The compressor is a two stage compressor with one low pressure cylinder and one high pressure
cylinder. During the first stage of compression it is done in the low pressure cylinder
where suction is through a wire mesh filter. After compression in the LP cylinder air is
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delivered into the discharge manifold at a pressure of 30 / 35 PSI. Workings of the inlet and
exhaust valves are similar to that of exhauster which automatically open or close under
differential air pressure. For inter-cooling air is then passed through a radiator known as inter-
cooler. This is an air to air cooler where compressed air passes through the element tubes and
cool atmospheric air is blown on the outside fins by a fan fitted on the expressor crank shaft.
Cooling of air at this stage increases the volumetric efficiency of air before it enters the high-
pressure cylinder. A safety valve known as inter cooler safety valve set at 60 PSI is provided
after the inter cooler as a protection against high pressure developing in the after cooler due to
defect of valves.
After the first stage of compression and after-cooling the air is again compressed in a cylinder of
smaller diameter to increase the pressure to 135-140 PSI in the same way. This is the second
stage of compression in the HP cylinder. Air again needs cooling before it is finally sent to the
air reservoir and this is done while the air passes through a set of coiled tubes after cooler.
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Figure 2-16: Schematic Diagram of Expressor
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2.11 SPEEDOMETER
Figure 2-17: Speedometer and other gauges
2.11.1 INTRODUCTION
The electronic speedometer is intended to measure traveling speed and to record the status of
selected locomotive engine parameters every second. It comprises a central processing unit that
performs the basic functions, two monitors that are used for displaying the measured speed
values and entering locomotive driver‟s identification data and drive parameters and a speed
transducer. The speedometer can be fitted into any of railway traction vehicles. The monitor is
mounted on every driver‟s place in a locomotive. It is connected to the CPU by a serial link.
Monitor transmits a driver, locomotive and train identifications data to the CPU and receives
data on travel speed, partial distance traveled, real time and speedometer status from the CPU A
locomotive driver communicates with the speedometer using the monitor: a keyboard and
alphanumeric displays are used for authorization purposes, travel speed values are monitored on
analog and digital displays, whereas alphanumeric displays, LEDs and a buzzer signal provide
information on speedometer and vehicle status.
2.11.2 WORKING MECHANISM
Speedometer is a closed loop system in which opto-electronic pulse generator is used to convert
the speed of locomotive wheel into the corresponding pulses. Pulses thus generated are then
converted into the corresponding steps for stepper motor. These steps then decide the movement
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of stepper motor which rotates the pointer up to the desired position. A feedback potentiometer is
also used with pointer that provides a signal corresponding to actual position of the pointer,
which then compared with the step of stepper motor by measuring and control section. If any
error is observed, it corrected by moving the pointer to corresponding position.
Presently a new version of speed-time-distance recorder cum indicator unit TELPRO is used in
the most of the locomotive. Features and other technical specification of this speedometer are
given below.
Figure 2-18: Block Diagram for speedometer Pulse
2.11.3 Salient features
Light weight and compact in size
Adequate journey data recording capacity
Both analog and digital displays for speed
Both internal and external memories for data storage
Memory freeze facility
Step less wheel wear compensation
Dual sensor opto electronic pulse generator for speed sensing
Over speed audio visual alarm
7-digit odometer
User friendly Windows-based data extraction and analysis software
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Graphical and tabular reports generation for easy analyzing of recorded data
Cumulative, Trip-wise, Train-wise, Driver-wise and Date-wise report generation
Master-Slave configuration
2.11.4 Applications
Speed indication for driver.
Administrative control of traction vehicle for traffic scheduling.
Vehicle trend analysis in case of derailment/accident.
Analysis of driver’s operational performance to provide training, if required.
Figure 2-19: Telpro Speedometer Circuit
2.11.5 Technical Specifications
The system requires a wide operating voltage of 50 V DC to 140 V DC.
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Table 3: Operating conditions
Conditions Values
Temperature -5°C to +70°C
Relative humidity 95% (max)
Accuracy of Master & Slave ±1.0% of full scale deflection
Table 4: Analogue indication
Factors Values
Scale spread over 240°
Illumination 12 equally spaced LEDs on dial circumference
Brightness control 0-100% in 10 steps
Dial size 120 mm
Dial colour White with black pointer & numerals
Max speed range 0-150, 0-160 & 0-180 Kmph (can be made as per
customer‟s request)
Table 5: Digital indication
Features Values
LCD display 16x2 character alphanumeric LCD with backlit control
Time display HH:MM:SS on 24-hour scale
Table 6: General
Factors Values
Size 145x215x160 mm (typical)
Weight: Master & Slave (approx) 3.5 kg (Master); 3.15 kg (Slave)
Odometer 7 digit with 1km resolution
Input speed sensing 2 inputs for opto-electronic pulse generator 200 or
100 pulses/rev (configurable)
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2.12 CYLINDER HEAD
Figure 2-20: Cylinder Head
2.12.1 INTRODUCTION
The cylinder head is held on to the cylinder liner by seven hold down studs or bolts provided on
the cylinder block. It is subjected to high shock stress and combustion temperature at the lower
face, which forms a part of combustion chamber. It is a complicated casting where cooling
passages are cored for holding water for cooling the cylinder head. In addition to this provision is
made for providing passage of inlet air and exhaust gas. Further, space has been provided for
holding fuel injection nozzles, valve guides and valve seat inserts also.
2.12.2 Components of cylinder head
In cylinder heads valve seat inserts with lock rings are used as replaceable wearing part. The
inserts are made of stellite or weltite. To provide interference fit, inserts are frozen in ice and
cylinder head is heated to bring about a temperature differential of 250F and the insert is pushed
into recess in cylinder head. The valve seat inserts are ground to an angle of 44.5 whereas the
valve is ground to 45 to ensure line contact. (In the latest engines the inlet valves are ground at
30° and seats are ground at 29.5°). Each cylinder has 2 exhaust and 2 inlet valves of 2.85" in dia.
The valves have stem of alloy steel and valve head of austenitic stainless steel, butt-welded
together into a composite unit. The valve head material being austenitic steel has high level of
stretch resistance and is capable of hardening above Rockwell- 34 to resist deformation due to
continuous pounding action.
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The valve guides are interference fit to the cylinder head with an interference of 0.0008" to
0.0018". After attention to the cylinder heads the same is hydraulically tested at 70 psi and
190F. The fitment of cylinder heads is done in ALCO engines with a torque value of 550 Ft. lbs.
The cylinder head is a metal-to-metal joint on to cylinder.
ALCO 251+ cylinder heads are the latest generation cylinder heads, used in updated engines,
with the following feature:
Fire deck thickness reduced for better heat transmission.
Middle deck modified by increasing number of ribs (supports) to increase its mechanical
strength. The flying buttress fashion of middle deck improves the flow pattern of water
eliminating water stagnation at the corners inside cylinder head.
Water holding capacity increased by increasing number of cores (14 instead of 11)
Use of frost core plugs instead of threaded plugs, arrest tendency of leakage.
Made lighter by 8 kgs (Al spacer is used to make good the gap between rubber grommet
and cylinder head.)
Retaining rings of valve seat inserts eliminated.
2.12.3 Benefits:-
Better heat dissipation
Failure reduced by reducing crack and eliminating sagging effect of fire deck area.
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2.13 Maintenance and Inspection
Figure 2-21: Inspection of an engine
2.13.1 Cleaning:
By dipping in a tank containing caustic solution or ORION-355 solution with water (1:5)
supported by air agitation and heating.
2.13.2 Crack Inspection:
Check face cracks and inserts cracks by dye penetration test.
2.13.3 Hydraulic Test:
Conduct hyd. test (at 70 psi, 200°F for 30 min.) for checking water leakage at nozzle sleeve,
ferrule, core plugs and combustion face.
2.13.4 Dimensional check :
Face seat thickness: within 0.005" to 0.020"
2.13.5 Straightness of valve stem:
Run out should not exceed 0.0005"
Free & Compressed height (at 118 lbs.) of springs: 3 13/16" & 4 13/16"
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2.13.6 Checks during overhauling:
Ground the valve seat insert to 44.5°/29.5°, maintain run out of insert within 0.002" with respect
to valve guide while grinding.
Grind the valves to 45°/30° and ensure continuous hair line contact with valve guide by checking
colour match.
Ensure no crack has developed to inserts after grinding, checked by dye penetration test.
Make pairing of springs and check proper draw on valve locks and proper condition of groove
and locks while assembling of valves.
Lap the face joint to ensure leak proof joint with liner.
2.13.7 Blow by test:
On bench blow by test is conducted to ensure the sealing effect of cylinder head.
Blow by test is also conducted to check the sealing efficiency of the combustion chamber on a
running engine, as per the following procedure:
Run the engine to attain normal operating temperature (65°C)
Stop running after attaining normal operating temperature.
Bring the piston of the corresponding cylinder at TDC in compression stroke.
Fit blow-by gadget (Consists of compressed air line with the provision of a pressure
gauge and stopcock) removing decompression plug.
Charge the combustion chamber with compressed air.
Cut off air supply at 70 psi. Through stop cock and record the time when it comes down
to zero.7 to 10 secs is OK.
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2.14 PIT WHEEL LATHE
Figure 2-22: Pit Wheel Lathe Machine
2.14.1 INTRODUCTION
Various type of wear may occur on wheal tread and flange due to wheel skidding and emergency
breaking. Four type of wear may occur as follows:-
Tread wear
Root wear
Skid wear and
Flange wear
For maintaining the required profile pit wheel lathe are used. This lathe is installed in the pit so
that wheel turning is without disassembling the axle and lifting the loco and hence the name “pit
wheel lathe”
2.14.2 Wheel turning Wheel turning on this lathe is done by rotating the wheels, both wheels of an axle are placed on
the four rollers, two for each wheel. Rollers rotate the wheel and a fixed turning tool is used for
turning the wheel.
Different gages are used in this section to check the tread profile. Name of these gages are:-
Star gage
Root wear gage
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Flange wear gage
J gage
j-gage is used to calculate the app. Dia of wheel.
Dia. Of wheel = 962 + 2 × (j-gage reading) mm
Figure 2-23: Wheel Specifications
2.14.3 CAUSES OF WHEEL SKIDDING-
On excessive brake cylinder pressure (more than 2.5 kg/cm²).
Using dynamic braking at higher speeds.
When at the time of application of dynamic braking, the brakes of loco would have
already been applied (in case of failure of D-1 Pilot valve).
Continue working, when C-3-W Distributor valve P/G handle is in wrong position.
Due to shunting of coaches with loco without connecting their B.P./vacuum pipe.
Shunting at higher speeds.
Continue working when any of the brake cylinders of loco has gotten jammed.
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The time of application/release of brakes of any of the brake cylinder being larger than
the others.
When any of the axles gets locked during on the line.
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2.15 FAILURE ANALYSIS
Figure 2-24: A Failure Detection Device
2.15.1 INTRODUCTION A part or assembly is said to have failed under one of the three conditions:-
1. When it becomes completely inoperable-occurs when the component breaks into two
or more pieces. When it is still inoperable but is no longer able to perform its intended
function satisfactorily- due to wearing and minor damages.
2. When serious deterioration has made it unreliable or unsafe for continuous use, thus
necessitating its complete removal from service for repair or replacement-due to
presence of cracks such as thermal cracks, fatigue crack, hydrogen flaking.
In this section we will study about:-
Metallurgical lab.
Ultrasonic test
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Zyglo test and
RDP test.
2.15.2 Metallurgical lab.
Metallurgical lab concerns with the study of material composition and its properties. Specimens
are checked for its desired composition. In this section various tests are conducted like hardness
test, composition test e.g determination of percentage of carbon, swelling test etc.
Table 7: Functions of some Alloying Materials
S. No. Compound Function
1. Phosphorous Increase the fluidity property
2. Graphite Increase machinability
3. Cementite Increase hardness
4. Chromium Used for corrosion prevention
5. Nickel Used for heat resistance
6. Nitride rubber Oil resistance in touch of „O‟ ring
7. Neoprene Air resistance & oil resistance in fast coupling in
rubber block.
8. Silicon Heat resistance and wear resistance (up to 600 ºC) use
at top and bottom pore of liner.
2.15.3 Swelling test
Swelling test is performed for rubber in this test percentage increase in weight of the rubber after
immersing in solution is measured and increase in weight should not be more than 20%. Two
type of swelling test viz low swelling and high swelling are performed in the lab. Three type of
oil solution are used for this purpose listed below:-
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ASTM 1
ASTM 2
ASTM 3
2.15.4 Procedure
1. Select specimen for swelling test.
2. Note the weight of the specimen.
3. Put in the vessel containing ASTM 1 or ASTM 3.
4. Put the oven at 100 ºC.
5. Put the vessel in the oven for 72 hrs.
6. After 72 hrs. Weigh the specimen.
2.15.5 Rubber
Broadly there are two types of rubber:
1. Natural rubber- this has very limited applications. It is used in windows and has a life of
1 year.
2. Synthetic rubber- this is further subdivided into five types.
VUNA-N (2 year life)
Polychloroprene or Neoprene (2 year life)
SBR (3 year life)
Betel (3 year life)
Silicone (3 year life).
VUNA-N rubber is used in oily or watery area; neoprene is used in areas surrounded by oil and
air while betel and silicone are used in areas subjected to high temperatures such as in pistons.
When the fresh supply of rubber comes from the suppliers it is tested to know its type. The test
consists of two solutions, solution 1 and solution 2, which are subjected to the vapors of the
rubber under test and then the color change in solution is used for determination of the type of
rubber. The various color changes are as follows:
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Violet- natural rubber
Pink- nitrile
Green-SBR
When no color change is observed the vapours are passed through solution 2. The colour change
in solution 2 is: Pink- neoprene.
Silicone produces white powder on burning. If there is no result on burning then the rubber is
surely betel.
2.15.6 ULTRASONIC TESTING
In ultrasonic testing, very short ultrasonic pulse-waves with center frequencies ranging from 0.1-
15 MHz and occasionally up to 50 MHz are launched into materials to detect internal flaws or to
characterize materials.
Ultrasonic testing is often performed on steel and other metals and alloys, though it can also be
used on concrete, wood and composites, albeit with less resolution. It is a form of non-
destructive testing.
2.15.7 ZYGLO TEST
The zyglo test is a nondestructive testing (NTD) method that helps to locate and identify surface
defects in order to screen out potential failure-producing defects. It is quick and accurate process
for locating surface flaws such as shrinkage cracks, porosity, cold shuts, fatigue cracks, grinding
cracks etc. The ZYGLO test works effectively in a variety of porous and non-porous materials:
aluminum, magnesium, brass, copper, titanium, bronze, stainless steel, sintered carbide, non-
magnetic alloys, ceramics, plastic and glass. Various steps of this test are given below:-
Step 1 – pre-clean parts.
Step 2 – apply penetrant
Step 3 – remove penetrant
Step 4 – dry parts
Step 5 – apply developer
Step 6 – inspection
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2.15.8 RED DYE PENETRATION TEST (RDP)
Dye penetrant inspection (DPI), also called liquid penetrant inspection (LPI), is a widely applied
and low-cost inspection method used to locate surface-breaking defects in all non-porous
materials (metals, plastics, or ceramics). Penetrant may be applied to all non-ferrous materials,
but for inspection of ferrous components magnetic particle inspection is preferred for its
subsurface detection capability. LPI is used to detect casting and forging defects, cracks, and
leaks in new products, and fatigue cracks on in-service components.
2.15.8.1 Principles
DPI is based upon capillary action, where low surface tension fluid penetrates into clean and dry
surface-breaking discontinuities. Penetrant may be applied to the test component by dipping,
spraying, or brushing. After adequate penetration time has been allowed, the excess penetrant is
removed, a developer is applied. The developer helps to draw penetrant out of the flaw where a
visible indication becomes visible to the inspector.
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2.16 SCHEDULED EXAMINATION
Figure 2-25: A Crankshaft taken out for Scheduled Examination
2.16.1 INTRODUCTION
The railway traffic requires safety and reliability of service of all railway vehicles. Suitable
technical systems and working methods adapted to it, which meet the requirements on safety and
good order of traffic should be maintained. For detection of defects, non-destructive testing
methods - which should be quick, reliable and cost-effective - are most often used. Inspection of
characteristic parts is carried out periodically in accordance with internal standards or
regulations; inspections may be both regular and extraordinary; the latter should be carried out
after collisions, derailment or grazing of railway vehicles.
Maintenance of railway vehicles is scheduled in accordance with periodic inspections and
regular repairs. Inspections and repairs are prescribed according to the criteria of operational life,
limited by the time of operation of a locomotive in traffic or according to the criteria of
operational life including the path traveled.
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For the proper functioning of diesel shed and to reduce the number of failures of diesel locos,
there is a fixed plan for every loco, at the end of which the loco is checked and repaired. This
process is called scheduling. There are two types of schedules which are as follows:-
Major schedules
Minor schedule
2.16.2 MINOR SCHEDULES
Schedule is done by the technicians when the loco enters the shed.
After 15 days there is a minor schedule. The following steps are done every minor
schedule & known as SUPER CHECKING.
The lube oil level & pressure in the sump is checked.
The coolant water level & pressure in the reservoir is checked.
The joints of pipes & fittings are checked for leakage.
Check super charger, compressor & its working.
The engine is checked thoroughly for the abnormal sounds if there is any.
F.I.P. is checked properly by adjusting different rack movements.
This process should be done nearly four hour only. After this the engine is sent in the mail/goods
running repairs for repairs. There are following types of minor schedules:-
T-1 SHEDULE AFTER 15 DAYS
T-2 SHEDULE AFTER 30 DAYS
T-1 SHEDULE AFTER 45 DAYS
M-2 SHEDULE AFTER 60 DAYS
T-1 SHEDULE AFTER 75 DAYS
T-2 SHEDULE AFTER 90 DAYS
T-1 SHEDULE AFTER 105 DAYS
2.16.2.1 TRIP-1
Fuel oil & lube check.
Expressor discharge valve.
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Flexible coupling’s bubbles.
Turbo run down test.
Record condition of wheels by star gauge.
Record oil level in the axle caps for suspension bearing.
2.16.2.2 TRIP-2
All the valves of the expressor are checked.
Primary and secondary fuel oil filters are checked.
Turbo super charger is checked.
Under frame are checked.
Lube oil of under frame checked.
2.16.2.3 MONTHLY-2 SEHEDULE
All the works done in T-2 schedule.
All cylinder head valve loch check.
Sump examination.
Main bearing temperature checked.
Expressor valve checked.
Wick pad changed.
Lube oil filter changed.
Strainer cleaned.
Expressor oil changed.
2.16.3 MAJOR SCHEDULES
These schedules include M-4, M-8 M-12 and M-24. The M-4 schedule is carried out for 4
months and repeated after 20 months. The M-8 schedule is carried out for 8 months and repeated
after 16 months. The M-12 is an annual schedule whereas the M-24 is two years.
Besides all of these schedules for the works that are not handled by the schedules there is an out
of course section, which performs woks that are found in inspection and are necessary. As any
Locomotive arrives in the running section first of all the driver diary is checked which contains
information about the locomotive parameters and problem faced during operation. The
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parameters are Booster air pressure (BAP), Fuel oil pressure (FOP), Lubricating oil pressure
(LOP) and Lubricating oil consumption (LOC). After getting an idea of the initial problems from
the driver‟s diary the T-1 schedule is made for inspection and minor repairs.
2.16.3.1 M-4 Schedule
1. Run engine; check operation of air system safety valves and expressor crankcase lube oil
pressure.
2. Stop engine; carry out dry run operational test, check FIP timing and uniformity of rack
setting and correct if necessary.
3. Engine cylinder head:-Tighten all air and exhaust elbow bolts, check valve clearance,
exhaust manifold elbow etc.
4. Engine crankcase cover:-Remove crankcase cover and check for any foreign material.
Renew gaskets.
5. Clean Strainer and filters, replace paper elements.
6. Compressed air and vacuum system:-Check, clean and recondition rings, piston, Intake
strainers, and inlet and exhaust valve, lube oil relief valve, unloading valve. Drain, clean
and refill crankcase.
7. Radiator fan- tightens bolts and top up oil if necessary.
8. Roller bearing axle boxes. Check for loose bolts, loss of grease, sign of overheating.
Remove covers, clean and examine roller races and cages for defects. Carry out
ultrasonic test of axles.
9. Clean cyclonic filters, bag filters and check the condition of rubber bellows of air intake
system.
10. Renew airflow indicator valve.
11. Carry out blow bye test and gauge wheel wears.
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2.17 YEARLY/MECHANICAL
Figure 2-26: Engine block taken out for yearly maintanence
In this section, major schedules such as M-24, M48 and M-72 are carried out. Here, complete
overhauling of the locomotives is done and all the parts are sent to the respective section and
new parts are installed after which load test is done to check proper working of the parts. The
work done in these sections are as follows:
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1) Repeating of all items of trip, quarterly and monthly schedule.
2) Testing of all valves of vacuum/compressed air system. Repair if necessary.
3) Replacement of coalesce element of air dryer.
4) Reconditioning, calibration and checking of timing of FIP is done. Injector is overhauled.
5) Cleaning of Bull gear and overhauling of gear-case is done.
6) RDP testing of radiator fan, greasing of bearing, checking of shaft and keyway.
Examination of coupling and backlash checking of gear unit is done.
7) Checking of push rod and rocker arm assembly. Replacement is done if bent or broken.
Checking of clearance of inlet and exhaust valve is also done.
8) Examination of piston for cracks, renew bearing shell of connecting rod fitment.
Checking of connecting rod elongation is done.
9) Checking of crankshaft thrust and deflection. Shims are added if deflection is more than
the tolerance limit.
10) Main bearing is discarded if it has embedded dust, or gives evidence of fatigue failure or
has worn.
11) Checking of cracks in water header and elbow. Install new gaskets in the air intake
manifold. Overhauling of exhaust manifold is done.
12) Checking of cracks in crankcase, lube oil header, jumper and tube leakage in lube oil
cooler. Replace or dummy of tubes is done.
13) Lube oil system- Overhauling of pressure regulating valves, by pass valve, lube oil filters
and strainers is done.
14) Fuel oil system- Overhauling of pressure regulating valve, pressure relief valve, primary
and secondary filters.
15) Checking of rack setting, governor to rack linkage, fuel oil high-pressure line is done.
16) Cooling water system- draining of the cooling water from system and cleaning with new
water carrying 4 kg tri-phosphate is done. All water system gaskets are replaced. Water
drain cock is sealed. Copper vent pipes are changed and water hoses are renewed.
17) Complete overhauling of water pump is done. Checking of impeller shaft for wear and
lubrication of ball bearing. Water and oil seal renewal.
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18) Complete overhauling of expressor/compressor, pistons rings and oil seal renewed.
Expressor orifice test is carried out.
19) Complete overhauling of Turbo supercharger is done. Dynamic balancing and Zyglo test
of the turbine/impeller is done. Also, hydraulic test of complete Turbo supercharger is
done.
20) Overhauling of after-cooler is done. Telltale hole is checked for water leak.
21) Inspection of the crankcase cover gasket and diaphragm is done. It is renewed if
necessary.
22) Rear T/Motor blower bearing are checked and changed. Greasing of bearing is done.
23) Cyclonic filter rubber bellows and rubber hoses are changed. Air intake filter and
vacuum oil bath filter are cleaned and oiled.
24) Radiators are reconditioned; fins are straightened by hydraulic test to detect leakage
and cleaning by approved chemical.
25) Bogie- Checking of frame links, spring, equalizing beam locating roller pins for free
movement, buffer height, equalizer beam for cracks, rail guard distance is done. Refilling
of center plate and loading pads is done. Journal bearings are reconditioned.
26) Axle box- cleaning of axle box housing is done.
27) Wheels- inspection for fracture or flat spot. Wheel are turned and gauged.
28) Checking of wear on horn cheek liners and T/M snubber wear plates.
29) Checking of brake parts for wear, lubrication of slack adjusters is done. Inspection for
fatigue, crack and distortion of center buffers couplers, side buffers are done.
30) Traction motor suspension bearing- cleaning of wick assembly, checking of wear in
motor nose suspension. Correct fitment of felt wick lubricators is ensured. Axle boxes
are refilled with fresh oil. Testing of all pressure vessels is carried out.
2.17.1 Examination while Engine is running.
31) Expressor orifice test is performed. Engine over speed trip assembly operation, LWS
operation are checked. Checking of following items is done:
Water and oil leakage at telltale hole of water pump, turbo return pipes for leakage and
crack, air system for leakage, fuel pump and pipes for leakage, exhaust manifold for
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leaks, engine lube oil pressure at idle, turbo for smooth run down as engine is stopped.
Difference in vacuum between vacuum reservoir pipe and expressor crankcase & and
pressure difference across lube oil filters at idle and full engine speed are recorded.
32) Brakes at all application positions are checked. Checking of fast and flexible coupling is
done and the expressor is properly aligned. Inspection of camshaft, lubrication of hand
brake lever and chain.
33) Speedometer- Overhaul, testing of speed recorder and indicator, pulse generator is
done.
2.17.2 (38). Additional items for WDP1:-
Overhauling and operation of TBU is done, center pivot pin is checked, and CPP bush housing
liners are checked for wear, inspection of vibration dampers for oil leakage and their operation.
RDP test is done to check for cracks at critical location in the bogie frame. Checking of coil
springs for free height.
2.17.3 (39). Additional items for WDP2 locos:-
Check for cracks in bogie frame and bolster. Checking of hydraulic dampers for oil leakage.
Check coil spring for free height. Zyglo test of guide link bolts is performed. Examination of
taper roller bearing for their condition and clearance is done. Check and change center pivot
liners. Checking of tightness of nuts on brake head pin. Disassembly, cleaning, greasing,
repairing, replacement of brake cylinder parts is done. Ultrasonic test of axles is performed.
Visual Examination of suspension springs for crack and breakage. Checking of free and working
height of spring. Inspection of bull gear for any visible damage is done and the teeth profile is
checked. Test loco on load box as per RDSO standards.
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3 Project Work
To do analysis of main bearing seizures loco type-wise/make wise during the past 5 years
leading to damage of crankshaft/engine block and to study cause of main bearing seizure and
suggest remedies to overcome fail of main bearing/cs/engine block.
The main bearings are the bearings in which the crankshaft rotates. Hence, for an engine to work
properly it should have very good main bearings. Moreover, better is the quality of main bearing,
lesser the frictional force encountered by the crankshaft while rotating, which results in lesser
energy being wasted to overcome the frictional resistance and thereby resulting in improved
overall engine efficiency.
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3.1 Introduction to bearing
Figure 3-1: Introduction to Bearings
A bearing is a device to allow constrained relative motion between two or more parts, typically
rotation or linear movement. Bearings may be classified broadly according to the motions they
allow and according to their principle of operation as well as by the directions of applied loads
they can handle.
There are at least six common principles of operation:
plain bearing, also known by the specific styles: bushings, journal bearings, sleeve
bearings, rifle bearings
rolling-element bearings such as ball bearings and roller bearings
jewel bearings, in which the load is carried by rolling the axle slightly off-centre
fluid bearings, in which the load is carried by a gas or liquid
magnetic bearings, in which the load is carried by a magnetic field
flexure bearings, in which the motion is supported by a load element which bends
Common motions permitted by bearings are:
Axial rotation e.g. shaft rotation
Linear motion e.g. drawer
spherical rotation e.g. ball and socket joint
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hinge motion e.g. door, elbow, knee
Figure 3-2: Different Motions supported by Bearing
3.2 Friction
Reducing friction in bearings is often important for efficiency, to reduce wear and to facilitate
extended use at high speeds and to avoid overheating and premature failure of the bearing.
Essentially, a bearing can reduce friction by virtue of its shape, by its material, or by introducing
and containing a fluid between surfaces or by separating the surfaces with an electromagnetic
field.
By shape, gains advantage usually by using spheres or rollers, or by forming flexure
bearings.
By material, exploits the nature of the bearing material used. (An example would be
using plastics that have low surface friction.)
By fluid, exploits the low viscosity of a layer of fluid, such as a lubricant or as a
pressurized medium to keep the two solid parts from touching, or by reducing the
normal force between them.
By fields, exploits electromagnetic fields, such as magnetic fields, to keep solid parts
from touching.
Combinations of these can even be employed within the same bearing. An example of this is
where the cage is made of plastic, and it separates the rollers/balls, which reduce friction by their
shape and finish.
Bearings vary greatly over the size and directions of forces that they can support.
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Forces can be predominately radial, axial or bending moments perpendicular to the main axis.
3.3 Service life
3.3.1 Fluid and magnetic bearings
Fluid and magnetic bearings can have practically indefinite service lives. In practice, there are
fluid bearings supporting high loads in hydroelectric plants that have been in nearly continuous
service since about 1900 and which show no signs of wear.
3.3.2 Rolling element bearings
Rolling element bearing life is determined by load, temperature, maintenance, lubrication,
material defects, contamination, handling, installation and other factors. These factors can all
have a significant effect on bearing life. For example, the service life of bearings in one
application was extended dramatically by changing how the bearings were stored before
installation and use, as vibrations during storage caused lubricant failure even when the only load
on the bearing was its own weight, the resulting damage is often false brinelling. Bearing life is
statistical: several samples of a given bearing will often exhibit a bell curve of service life, with a
few samples showing significantly better or worse life. Bearing life varies because microscopic
structure and contamination vary greatly even where macroscopically they seem identical.
3.3.3 Plain bearings
For plain bearings some materials give much longer life than others.
3.3.4 Flexure bearings
Flexure bearings rely on elastic properties of material. Flexure bearings bend a piece of material
repeatedly. Some materials fail after repeated bending, even at low loads, but careful material
selection and bearing design can make flexure bearing life indefinite.
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3.3.5 Short-life bearings
Although long bearing life is often desirable, it is sometimes not necessary. Harris describes a
bearing for a rocket motor oxygen pump that gave several hours life, far in excess of the several
tens of minutes life needed.
3.3.6 L10 life
Bearings are often specified to give an "L10". This is the life at which ten percent of the bearings
in that application can be expected to have failed due to classical fatigue failure (and not any
other mode of failure like lubrication starvation, wrong mounting etc.), or, alternatively, the life
at which ninety percent will still be operating. The L10 life of the bearing is theoretical life and
may not represent service life of the bearing.
Figure 3-3: Bearing Service Life
3.3.7 External factors
The service life of the bearing is affected by many parameters that are not controlled by the
bearing manufactures. For example, bearing mounting, temperature, exposure to external
environment, lubricant cleanliness and electrical currents through bearings etc.
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3.4 Classification of Bearings:
Bearings are broadly categorized into two types:
a) Fluid film
b) Rolling contact type.
3.4.1 Fluid Film bearings:
In fluid film bearing the entire load of the shaft is carried by a thin film of fluid present between
the rotating and non-rotating elements. The types of fluid film bearings are as follows:
a) Sliding contact type
b) Journal bearing
c) Thrust bearing
d) Slider bearing
3.4.2 Rolling contact bearings:
In rolling contact bearings, the rotating shaft load is carried by a series of balls or rollers placed
between rotating and non-rotating elements. The rolling contact type bearings are of two types,
namely:
a) Ball bearing
b) Roller bearing
3.4.3 Comparison of bearing frictions:
The Fig. shows a plot of Friction vs. Shaft speed for three bearings. It is observed that for the
lower shaft speeds the journal bearing have more friction than roller and ball bearing and ball
bearing friction being the lowest. For this reason, the ball bearings and roller bearings are also
called as anti-friction bearings. However, with the increase of shaft speed the friction in the ball
and roller bearing phenomenally increases but the journal bearing friction is relatively lower than
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both of them. Hence, it is advantageous to use ball bearing and roller bearing at low speeds.
Journal bearings are mostly suited for high speeds and high loads.
Figure 3-4: Friction in Different Bearings
The ball and roller bearings require less axial space but more diametrical space during
installation and low maintenance cost compared to journal bearings. Ball bearings and roller
bearing are relatively costly compared to a journal bearing. The reliability of journal bearing is
more compared to that of ball and roller bearings.
3.4.4 Sliding contact bearings - Advantages and Disadvantages:
These bearings have certain advantages over the rolling contact bearings. They are:
1) The design of the bearing and housing is simple.
2) They occupy less radial space and are more compact.
3) They cost less.
4) The design of shaft is simple.
5) They operate more silently.
6) They have good shock load capacity.
7) They are ideally suited for medium and high speed operation.
The disadvantages are:
1) The frictional power loss is more.
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2) They required good attention to lubrication.
3) They are normally designed to carry radial load or axial load only.
3.5 Journal Bearing:
Among the sliding contact bearings, radial bearings find wide applications in industries and
hence these bearings are dealt in more detail here.
The radial bearings are also called journal or sleeve bearings. The portion of the shaft inside the
bearing is called the journal and this portion needs better finish and specific property. Depending
on the extent to which the bearing envelops the journal, these bearings are classified as full,
partial and fitted bearings. As shown in Fig.
Figure 3-5: Different Types of Journal Bearings
Fig. 3-6 describes the operation of a journal bearing. The black annulus represents the bush and
grey circle represents the shaft placed within an oil film shown by the shaded region. The shaft,
called journal, carries a load P on it. The journal being smaller in diameter than the bush, it will
always rotate with an eccentricity.
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Figure 3-6: Operation of a Journal Bearing
When the journal is at rest, it is seen from the figure that due to bearing load P, the journal is in
contact with the bush at the lower most position and there is no oil film between the bush and the
journal. Now when the journal starts rotating, then at low speed condition, with the load P acting,
it has a tendency to shift to its sides as shown in the figure. At this equilibrium position, the
frictional force will balance the component of bearing load. In order to achieve the equilibrium,
the journal orients itself with respect to the bush as shown in figure. The angle θ, shown for low
speed condition, is the angle of friction. Normally at this condition either a metal to metal contact
or an almost negligible oil film thickness will prevail. At the higher speed, the equilibrium
position shifts and a continuous oil film will be created as indicated in the third figure above.
This continuous fluid film has a converging zone, which is shown in the magnified view. It has
been established that due to presence of the converging zone or wedge, the fluid film is capable
of carrying huge load. If a wedge is taken in isolation, the pressure profile generated due to
wedge action will be as shown in the magnified view.
Hence, to build-up a positive pressure in a continuous fluid film, to support a load, a converging
zone is necessary. Moreover, simultaneous presence of the converging and diverging zones
ensures a fluid film continuity and flow of fluid. The journal bearings operate as per the above
stated principle.
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3.5.1 Design parameters of journal bearing:
The first step for journal bearing design is determination of bearing pressure for the given design
parameters:
a) Operating conditions (temperature, speed and load)
b) Geometrical parameters (length and diameter)
c) Type of lubricant (viscosity)
The design parameters, mentioned above, are to be selected for initiation of the design. The
bearing pressure is known from the given load capacity and preliminary choice of bearing
dimensions. After the bearing pressure is determined, a check for proper selection of design zone
is required. The selection of design zone is explained below.
3.5.2 Selection of design zone:
Figure 3-7: Friction variation with Bearing Characteristic number
The Fig. shows the results of test of friction by McKee brothers. Figure shows a plot of variation
of coefficient of friction with bearing characteristic number. Bearing characteristic number is
defined as:
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It is a non-dimensional number, where:
is the viscosity,
N is the speed of the bearing and
p is the pressure given by
, d and l being diameter and length of the journal respectively.
The plot shows that from B with the increase in bearing characteristic number the friction
increases and from B to A with reduction in bearing characteristic number the friction again
increases. So B is the limit and the zone between A to B is known as boundary lubrication or
sometimes termed as imperfect lubrication.
Imperfect lubrication means that metal – metal contact is possible or some form of oiliness will
be present. The portion from B to D is known as the hydrodynamic lubrication. The calculated
value of bearing characteristic number should be somewhere in the zone of C to D. This zone is
characterized as design zone.
For any operating point between C and D due to fluid friction certain amount of temperature
generation takes place. Due to the rise in temperature the viscosity of the lubricant will decrease,
thereby, the bearing characteristic number also decreases. Hence, the operating point will shift
towards C, resulting in lowering of the friction and the temperature. As a consequence, the
viscosity will again increase and will pull the bearing characteristic number towards the initial
operating point. Thus a self-control phenomenon always exists. For this reason the design zone is
considered between C and D. The lower limit of design zone is roughly five times the value at B.
On the contrary, if the bearing characteristic number decreases beyond B then friction goes on
increasing and temperature also increases and the operation becomes unstable.
Therefore, it is observed that, bearing characteristic number controls the design of journal
bearing and it is dependent of design parameters like, operating conditions (temperature, speed
and load), geometrical parameters ( length and diameter) and viscosity of the lubricant.
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3.6 Bearing Lubrication
The object of lubrication is to reduce friction, wear and heating of machine parts that move
relative to each other. A lubricant is any substance that when inserted between the moving
surfaces, accomplishes these purposes.
3.6.1 Types of Lubrication
Five distinct forms of lubrication may be identified:
1. Hydrodynamic
2. Hydrostatic
3. Elastohydrodynamic
4. Boundary
5. Solid film
Hydrodynamic lubrication means that the load-carrying surfaces of the bearing are separated by
a relatively thick film of lubricant, so as to prevent metal-to-metal contact. Hydrodynamic
lubrication does not depend upon the introduction of the lubricant under pressure. The film
pressure is created by the moving surface itself pulling the lubricant into a wedge-shaped zone at
a velocity sufficiently high to create the pressure necessary to separate the surfaces against the
load on the bearing.
Hydrostatic lubrication is obtained by introducing the lubricant, which is sometimes air or
water, into the load-bearing area at a pressure high enough to separate the surfaces with a
relatively thick film of lubricant. This should be considered in designing bearings where the
velocities are small or zero and where the frictional resistance is to be an absolute minimum.
Elastohydrodynamic lubrication is the phenomenon that occurs when a lubricant is introduced
between surfaces that are in rolling contact.
Insufficient surface area, a drop in the velocity of the moving surface, a lessening in the quantity
of lubricant delivered to a bearing, an increase in the bearing load, or an increase in lubricant
temperature resulting in a decrease in viscosity – any one of these – may prevent the buildup of a
film thick enough for full-film lubrication. When this happens, the highest asperities may be
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separated by lubricant films only several molecular dimensions in thickness. This is called
Boundary lubrication.
When bearings must be operated at extreme temperatures, a solid-film lubricant such as graphite
or molybdenum disulfide must be used because the ordinary mineral oils are not satisfactory.
3.6.2 Stable Lubrication
The difference between boundary and hydrodynamic lubrication can be explained by reference to
the following figure.
Figure 3-8: Regimes of Lubrication
The plot is important because it defines stability of lubrication and helps us to understand
hydrodynamic and boundary lubrication.
A design constraint to keep thick film lubrication is to be sure that,
)10(7.1 6P
N
Suppose we are operating to the right of line BA (at 1.0P
N) and something happens, say, an
increase in lubricant temperature. This results in a lower viscosity and hence a smaller value of
P
N. The coefficient of friction decreases, not as much heat is generated in shearing the
lubricant, and consequently the lubricant temperature drops. Thus the region to the right of line
BA defines stable lubrication because variations are self-correcting.
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To the left of the line BA, a decrease in viscosity would increase the friction. A temperature rise
would ensue, and the viscosity would be reduced still more. Thus the region to the left of line BA
represents unstable lubrication.
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3.7 General causes of bearing failure and Precautions
3.7.1 DIRT:
3.7.1.1 DIRT IN THE LUBRICATION SYSTEM
The presence of dirt particles entrained in the lubrication system is one of the most frequent
causes of bearing damage. The root of the problem is usually that the engine is not sufficiently
clean. In line with the nature and size of the foreign particles, the bearing will exhibit a
correspondingly lesser or greater degree of circumferential scratching and, usually, any debris
that may have become embedded in the lining.
Figure 3-9: DIRT IN THE LUBRICATION SYSTEM
Recommendation: Ensure that all housings, in which bearings are to be seated, are carefully
cleaned prior to assembly.
3.7.1.2 DIRT ON BEARING BACK
The presence of a foreign particle trapped between the bearing back and its housing will lead to a
raised area, with the ensuing risk of contact between this protruding high-spot and the journal.
Signs of this will be seen in the area opposite the particle, along the inner surface of the bearing,
where there will be evidence of marked localized wear.
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Figure 3-10: Dirt on Bearing Back
Recommendation: The lubrication system must be thoroughly checked in order to
pinpoint the cause of failure, which may be a blocked oil passage, an improperly
installed bearing, an oil pump malfunction, etc.
3.7.2 INSUFFICIENT LUBRICATION
3.7.2.1 MALFUNCTION IN THE LUBRICATION SYSTEM
A total absence of lubrication of the journal-bearing system leads to bearing seizure and,
normally, to total destruction of the part. However an altogether more frequent phenomenon is
fatigue due to oil starvation, whereby the amount of oil reaching the journal-bearing system is
insufficient to maintain the oil film, leading to metal-to-metal contact between the two parts.
Prolonged operation under such conditions will also result in total destruction of the whole.
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Figure 3-11: Bearing Failure due to Malfunctioning Lubrication
Recommendation: The lubrication system must be thoroughly checked in order to pinpoint the
cause of failure, which may be a blocked oil passage, an improperly installed bearing, an oil
pump malfunction, etc.
3.7.2.2 OIL SEAL FAILURE
In the example shown in the photograph, the failure of the crankshaft seal led to oil escaping at
this point. The track of the pair of bearing shells nearest the seal exhibits symptoms of seizure,
due to the oil film rupturing as a result of loss of oil pressure. The circumferential oil groove
acted as a barrier to the defect, so that the other track of the bearing shells, as well as the two
remaining pairs in the set, only exhibit shiny areas, a sign of oil starvation.
Figure 3-12: Bearing Seizure due to oil film failure
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Recommendation: Check for possible loss of oil at the seals and replace these wherever
necessary.
3.7.3 MISASSEMBLY
3.7.3.1 BEARING REVERSED
Where a bearing having no oil hole is mistakenly fitted in a position in which it ought to have
one, e.g., in a case where the upper and lower seats of a pair of main bearing shells are
inadvertently switched, this effectively prevents that particular main journal receiving
lubrication. As a consequence, no lubrication can reach the crankpin via such oil holes,
eventually leading to seizure of the bearing in question. From the bearing back, it will be evident
that the oil passage hole has been blocked off.
Figure 3-13: Failure due to misplaced oil hole of the bearing
Recommendation: Ensure that the utmost precaution is taken during the installation of new
bearings and that the correct positioning of each is double checked.
3.7.4 IMPROPER MACHINING OF COMPONENTS.
3.7.4.1 IMPROPERLY GROUND HOUSING (FACETED OR POLYGONAL)
Where a housing bore becomes flawed due to engine vibration or some other cause that gives
rise to marked out-of-roundness, the bearing will tend to conform to the defective shape of its
housing. It will display alternating bands of heavy and normal wear. This defect can lead to
metal fatigue.
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Figure 3-14: Failure Due to Improperly Ground Housing
Recommendation: Check for correct grinding of shaft and housing.
3.7.4.2 FILLET RIDE
If the radius of the fillet is increased during the course of a repair to the crankpin, the edge of the
bearing may make metal-to-metal contact with the fillet, and will also hinder oil flow. In the
photograph, the bearing exhibits signs of incipient damage, with its edge rounded from rubbing
against the fillet.
Figure 3-15: Failure due to Fillet Ride
Recommendation: Use a grindstone in perfect condition to achieve correct crankshaft geometry.
3.7.4.3 MISALIGNMENT OF SHAFT AND HOUSING
There are a number of causes that give rise to misalignment of the crankshaft and cylinder-block
housings, such as improper machining, bent crankshaft, distorted cylinder block, etc. These
defects result in localized wear, which tends to be greatest on some of the main bearings and less
pronounced on others.
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Figure 3-16: Misaligned Shaft leads to Bearing Failure
Recommendation: Ensure that cylinder-block and crankshaft machining tolerances are in
accordance with the engine manufacturer‟s specifications.
3.7.4.4 INSUFFICIENT CRUSH
Total contact between the bearing back and housing is fundamental to ensure good heat transfer
and a correct seating of the part. If crush is insufficient, the bearing will move back and forth
within the housing and shiny areas will be visible on the bearing back due to friction with the
housing. On other occasions, discolorations or stains may appear evidence of burnt oil that has
worked its way into the space between the two surfaces.
Figure 3-17: Failure due to Insufficient Crush
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Recommendation: Ensure that the size of the housing bore and torquing are in accordance with
the manufacturer‟s recommendations.
3.7.5 OVERLOADING
Where operating conditions cause excessive load to be exerted upon the bearings, this leads to
damage due to metal fatigue
Figure 3-18: Bearing Failure due to Overloading
Figure 3-19: Metal Fatigue caused by Overloading
Recommendation: Check that the assembly clearances and bearing material are as specified for
the application in question. Similarly, ensure that engine-tuning conditions are respected.
3.7.6 CORROSION
Oil in poor condition can damage the bearing surface. This effect is due to dilution of the lead in
the alloy by certain of the compounds produced by oil degradation.
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Figure 3-20: Bearing Corrosion due to wrong Lube Oil
Recommendation: Always use the oil recommended by the manufacturer, and perform the
scheduled oil changes as indicated in the vehicle maintenance manual.
3.7.7 CAVITATION
Under certain operating conditions, oil pressure drops locally, producing vapour bubbles that
cause damage to the bearing surface. This damage will be evident in certain bearing areas, such
as oil grooves or holes, which are affected by discontinuities in the oil flow.
Figure 3-21: Cavitation in Bearing
Recommendation: Check that lubrication conditions, such as oil pressure, flow rate and type,
are as stipulated by the vehicle manufacturer.
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3.8 Diesel Loco Specification
3.8.1 Diesel Locomotive Model: WDP3A
Service Type: Passenger service
Track Type: Broad Gauge
Engine name: Upgraded fuel efficient 251B engine
Number of Cylinders: 16
Horse Power: 3100 hp gross power
Axle load: 19.5 tonne
Maximum operating speed: 160 km/h
Bogie Type: Co-Co 2-stage 3-axle flexi coil bogie
Number of bearings: 9
Bearing Material:
No. of bolts:
Bolt Diameter:
Bearing Diameter:
Journal Diameter:
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3.8.2 Diesel Locomotive Model: WDP1
Service Type: Passenger service
Track Type: Broad Gauge
Engine name: Upgraded fuel efficient 251B engine
Number of Cylinders: 12
Horse Power: 2300 hp gross power
Axle load: 20.0 tonne
Maximum operating speed: 120 km/h
Bogie Type: Two stage flexi-coil suspension Bo-Bo bogie
Number of bearings: 7
Bearing Material:
No. of bolts:
Bolt Diameter:
Bearing Diameter:
Journal Diameter:
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3.9 Main Bearing Failure Cases
3.9.1 Loco No. 14004:
Arrived in shed on 04.03.2011 as dead with empty water tank. On examination its water pump
gear was found lying in engine sump after breakage of water pump shaft. On further checking
few metallic chips were found in engine crank case No.1 to 5. On removal of Cylinder Head and
Main bearing, all power assemblies & Main Bearing were found seized. Water pump SS Shaft
was found broken which caused overheating of power pack due to non-circulation of water.
Engine oil could not sustain its property and lead to seizure of all power assemblies & main
bearings along with draining out of water through pressure cap after boiling.
CONCLUSION
After breakage of water pump shaft, temperature of power pack had increased above 100°C due
to non-circulation of water. Due to the resulting high temperature, engine oil could not sustain
its lubricating properly and lead to seizure of all power assemblies and main bearing along with
draining out of all water after boiling.
3.9.2 Loco No. 15530:
On examination, metal chips were found in No.2 crank case. On further checking, its crank shaft
was found broken from Expresser side web portion at No.2 journal. No.2 main bearing also
seems to have been seized. This crank shaft and engine block were fitted at CB Shop/LKO
during POH+SR in Sept‟2006.There was no water in expansion tank. It is observed that crank
shaft developed cracks internally and on the surface later with seizure of No.2 main bearing
leaving behind crank shaft broken at No.2 crank pin web portion. Due to the seizure of main
bearing no.2, both power assemblies seized consequently and caused cracking of liner at top
which lead to draining out of water. Crank shaft was broken first with initiation from inner
texture and lead to breakage of crank shaft at web portion.
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CONCLUSION
This crank shaft was removed from loco No.17906 & fitted on this loco during its POH schedule
in Sept. 2006 .It is observed that crank shaft was already distorted internally and surfaced in the
form of this breakage during service of locomotive.
3.9.3 Loco No. 15508:
Arrived in the shed on 12.01.2010 in working condition. During examination in the shed, metal
chips were found in No.7 crank case sump. On further examination its No.7 Main Bearing was
found seized. R-6 & L-6 Connecting Rod bearing shells were also observed to have scoring
marks. Main Bearing No.7 was found badly metal flaked and this caused the consequential effect
on both L-6 & R-6 Connecting Rod bearing shell in the form of deep scoring mark. Fine chips of
bearing shell material were also found on lube oil strainer and filter elements.
CONCLUSION
The main bearing was last fitted in POH in Oct’2007 when this loco was taken in M24 schedule
in the month of December’2009. The location 7 Main Bearing had scored mark. Crank shaft &
saddle were polished and fitted during M24 schedule in shed. But again this bearing seized on
12.01.2010. During Yearly schedule, the main bearing temperature difference across consecutive
bearing was also within the permissible range. Reverse elongation was also within the range. It
appears that during overhauling of bearing, the contact area of bearing with saddle was less
(70%) which lead to breakage of hydro-dynamic film at higher temperature and seizure of main
bearings.
3.9.4 Loco No 15527:
Was detained for M-24 schedule in normal working condition. During stripping, its Main
Bearing No.8 shell was found broken after overheating and working out of bearing material,
though its spectrographic report was normal and there was no sign of any abnormality either on
No.7 crank pins or Power assemblies.
The history sheet of this loco also indicated that this loco was not involved either in main bearing
or power assembly‟s seizure or any hydraulic locking. It was observed in the last moment of its
working before being detaining for M-24 schedule, the main bearing breakage had caused
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distortion of the crank pin internally which surfaced only along with the seizure of the
connecting rod within short period of service after M24 schedule.
CONCLUSION
Breakage of crank pin No.7 occurred at an angle of 45° started from Radial fillet at Main
Journal No.8. It is a case of fatigue failure which progressed fast. There must be any notch
which acted as stress raiser and fatigue developed from there.
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3.10 FINAL CONCLUSION of THE PROJECT
From the available main bearing failure cases from the CTA Cell it is apparent that of the 4
bearing failure reports, only one was caused due to the improper fitting of the main bearing, rest
all were initiated by some other defect or malfunctioning in the Loco Engine. Moreover, there is
no repetitive pattern or cause of main bearing failure.
On the basis of study of above cases, we can safely conclude that the maintenance work carried
out by the technicians at various diesel sheds across India are generally following correct
procedures for servicing, since the major cause of failure is not dust, rather some other defect or
malfunctioning of Diesel Loco‟s engine component.
In order to prevent or reduce the rate of failure of main bearing/crankshaft and engine in the
future, we have suggested a few steps which can be further implemented to further reduce the
rate of engine failures.
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3.11 Ways to improve bearing life and performance
The following precautions can be taken while servicing the main bearing to increase its life:-
1) Bearing should be properly cleaned before assembly, as dirt is the primary cause of
bearing failure. Moreover, any clogged holes for lubrication, will starve the bearing of
the lubricating oils, thereby resulting in pre mature failure of bearing.
2) The bearing should be assembled properly and the holding screws shouldn’t be
tightened above or below the required stresses, as faulty assembly and overloading of
engine bearing results in near imminent failure of the same.
3) Use of hydraulic bolt tensioner for tightening the holding bolts on the main bearing and
other engine assembly. Since, the use improper tools and processes to carry out this
operation correctly in bolted assemblies is a major cause of failure. Hence the use of
hydraulic bolt tensioner may be used for tightening the bolts in the engine assembly.
The added benefits of the same are:-
a) No torsion stress
b) Good accuracy
c) Easy implementation
d) No damage to components
e) Process automation possible
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Figure 3-22: Hydraulic Bolt Tensioner
4) In case the capital investment for hydraulic bolt tensioner can’t be made a torque
wrench can be used. A torque wrench is a tool used to precisely apply a
specific torque to a fastener such as a nut or bolt. It was designed to prevent over
tightening bolts.
5) The bearing should be aligned properly while the crank is being fitted in the crank case,
as misalignment is also one of the most prominent causes of failure.
6) Digital gauges can be used for measurement of re-machined bearing rather than
analogue, so as to ensure the correct reading is taken into account.
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4 General Discipline
Parameters influencing performance of the diesel shed are as follows:
1) Outage or Target (target is fixed by Railway board)
If more, then outage = +ve
If less, then outage = -ve
2) Total number of failure/ Total number of setouts
3) Reliability of locos (between Periodicity, it should not fail)
4) Punctuality (if 3 trains get late due to failure of loco)
5) Lube oil Consumption (Average)
6) Specific Fuel Consumption
7) Environment and health of employee
8) Number of employees available in diesel shed
9) Infrastructure of shed
10) Quantity of diesel used within the shed
During our training at the Tughlakabad Diesel Locomotive shed, we were able to observe the
work culture and the general attitude of the shed in detail. On the basis of our observation we
were impressed and humbled by the quality of workmanship and dedication of the workers and
staff at the shed. Even though the shed is operating and maintaining very high quality of service,
we believe if the following suggestions if implemented will further improve the performance of
the shed.
4.1 Suggestions To Improve Performance of the Shed
The suggestions are as stated below:-
Upgradation of equipments and tools, so that not only the quality of repair and work improves
but also the stress on the technicians and impact on environment is reduced.
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Some of the equipments we do like to see changed are:-
1) Adoption of Hydraulic Bolt Tensioner or Torque Wrench to tighten all bolts. The use of
any of the two above mentioned tools will result in the bolts being tightened to
appropriate tension only, thereby reducing or eliminating the chance of the bolts being
under or over tightened. If budget is not an issue we would like the shed to use
Hydraulic Bolt Tensioner for tightening bolt, as its use will not only result in better
workmanship but also in reduced fatigue in workers, which shall also improve the
amount work done in a day and the quality of work.
2) Use of MIG welding to perform the welding operations wherever necessary. The
advantage of MIG welding is that it has higher penetration and lower chance of weld
contamination compared to arc welding, thereby resulting in stronger welds.
3) Whenever the measuring instruments are replaced, they be replaced with digital
measuring instruments, so that measuring time is reduced.
4) Establishment of a proper paint shop, where painting is carried out using a spray gun
rather than brush. The use of a spray gun reduces the time of painting.
We would also like to suggest that, all the locomotives arriving at the shed and the repair work
being carried out on them needs to be also maintained in a computer database. This shall help in
identifying the locomotive or component that is most likely to fail and hence special attention to
the same can be given during scheduled maintenance. Moreover, this data can be sent to the
designers at RDSO and Diesel Loco Factories of Indian Railways, which shall help them in
improving the design of the failure prone component and also help in designing better
locomotives in the future.
4.2 Improvement in Working Conditions
We were not impressed by the amount of facilities provided for the worker comfort. We request
the concerned authority to consider the following suggestions:-
1) The number of fans in the loco shed should be increased considerably, so as to increase
the comfort for workers.
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2) Wearing of earplugs/earmuffs. Since the working environment is very noisy and which
may lead to hearing loss of workers. Also all workers should be asked to undergo
audiometry test every year.
Figure 4-1: Earmuffs reduce External Noise
3) The cleanliness of the canteen needs to be increased.
4) All workers should be provided with gloves for handling hazardous chemicals and sharp
objects. They should also be provided with safety glasses.
5) The quality and cleanliness of the restrooms needs to be improved considerably.
4.3 Reduction in Environmental Impact
Steps that can be considered for making the Tughlakabad Diesel Loco Shed more
environmentally friendly are:
1) All the existing lighting can be replaced systematically with LED lights.
2) Lubricating oils need to be used carefully, as any spillage of the same results in
environmental degradation.