acknowledgement

Summer Training Report

ACKNOWLEDGEMENT

I am thankful to all my faculty members of electrical & electronics engineering department for their valuable teaching in their subjects. From the knowledge which gained up to the sixth semester helped me allot to understand the various aspects which came across me under training.

Also I am very grateful all the employees of the electric loco shed who helped & guided constantly to understand the various operations & components of the loco.

Also to my fellow trainees who coordinated with me to explore various ideas about loco.

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PREFACE

This Training Report Is Based On Four Weeks Training I Performed In The Electric Loco Shed, Ghaziabad. The Training is in loco shed which is responsible for the maintenance of the of electric loco in Delhi region. In Ghaziabad shed there are two types of loco i.e. Conventional loco & 3-Ф loco.

In conventional loco category there is WAP 1, WAP 4, WAG 5 and WAG 7.

In 3-Ф loco category are WAP 5, WAP 7 and WAG 9.

In this overall training of four weeks I put my greatest effort to understand & explore more & more about the loco. But the loco is such a complex machine which has so many function & components which need so much time to understand. But I try my best to utilize this short span of time to bring out the valuable knowledge about the loco.

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ABOUT RDSO( RESEARCH, DEVELOPMENT, AND STANDARDS ORGANIZATION )

RDSO is IR's premier R&D facility. It is located at Manaknagar, Lucknow. RDSO is tasked with controlling and standardizing all equipment used by IR, and coming up with new designs for equipment in line with IR's projected needs. RDSO's originated with the merger of two different organizations. The Central Standards Office (CSO) was established in 1930, and the Railway Testing and Research Centre (RTRC) was established in 1952. In 1957 these two were combined to form RDSO.

Since then, RDSO has come to be in charge of all R&D work for IR. RDSO is responsible for setting out design specifications for all rolling stock, including locomotives, wagons, and coaches, as well as traction systems, track structure, and pretty much everything within the IR system. RDSO is also in charge of technical approval of all imported technology and equipment or materials, and it undertakes trials and testing of all such items before they are brought into regular service by IR. Additionally, RDSO also continuously carries out various kinds of testing and monitoring of existing IR equipment, including speed and oscillation tests, track monitoring, traction system monitoring, adherence to safety and technical specifications, etc.

RDSO is organizationally divided into several directorates, one each for a specific technical area such as signalling, telecommunication, track technology, bridges and other permanent way structures, coaching stock, wagons, etc. RDSO laboratories include: Air Brake Laboratory, Brake Dynamometer Laboratory, Beam & Slab Laboratory for work on structural mechanics, Diesel Engine Development Laboratory capable of testing diesel engines from 100hp to 6000hp with computerized systems to record 128 system parameters at once, Psycho-technical and Ergonomics Laboratory for issues concerning psychological assessments and stress management for IR staff, Fatigue Testing Laboratory, Metallurgical & Chemical Laboratory, Signal Testing Laboratory for testing all kinds of signal equipment, block instruments, etc., Track Laboratory, and a Vehicle Characterization Laboratory. RDSO has recently been given the administrative status of a zonal railway to give it some independence in its projects and operations.

RDSO has a test track near Tundla that is used for carrying out real-world tests and trials of rolling stock. Current work at RDSO is focused on the development of lighter wagons capable of higher speeds, and high-speed passenger coaches, along with numerous projects for incremental improvements to existing equipment designs.

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TABLE OF CONTENTS

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S.NO CONTENT PAGE NO.1. INTRODUCTION 052. TYPES OF ELECTRIC LOCO 063. CATEGORY OF LOCO 064. CODING OF LOCO 085. LAYOUT OF LOCOMOTIVE 096. WAP 1 107. WAP 4 128. WAG 5 149. WAG 7 1610. WAP 5 1811. WAP 7 2112. WAG 9 2313. WAG 9H 2514. MOTOR RATING OF 3-Ф LOCO 2715. MOTOR RATING OF CONVENTIONAL LOCO 2816. RATING OF ARNO 2917. RATING OF STATIC CONVERTER 2918. RATING OF CONVENTIONAL LOCO TRANSFORMER 3019. NUMBER OF AUXILIARY MOTOR IN CONVENTIONAL LOCO 3120. NUMBER OF AUXILIARY MOTOR IN 3 PHASE LOCO 3221. 3-Ф LOCO 3322. AUTO EMERGENCY BRAKE 3723. AIR BRAKE 3924. WHEEL SLIP IN LOCO 4025. ELECTRIC LOCO TAP CHANGER 4326. BLOCK DIAGRAM OF CONVENTIONAL LOCO 4827. REGENERATIVE BRAKING 4928. GEAR OF TRACTION MOTOR 5029. COUPLING 5230. ENERGIZING A DEAD OR STABLED LOCO 5631. WHEELSET 59


INTRODUCTION

An electric locomotive is a locomotive powered by electricity from an external source. Sources include overhead lines, third rail, or an on-board electricity storage device such as a battery, flywheel system, or fuel cell.

One advantage of electrification is the lack of pollution from the locomotives themselves. Electrification also results in higher performance, lower maintenance costs, and lower energy costs for electric locomotives.

Power plants, even if they burn fossil fuels, are far cleaner than mobile sources such as locomotive engines. Also the power for electric locomotives can come from clean and/or renewable sources, including geothermal power, hydroelectric power, nuclear power, solar power, and wind turbines. Electric locomotives are also quiet compared to diesel locomotives since there is no engine and exhaust noise and less mechanical noise. The lack of reciprocating parts means that electric locomotives are easier on the track, reducing track maintenance.

Power plant capacity is far greater than what any individual locomotive uses, so electric locomotives can have a higher power output than diesel locomotives and they can produce even higher short-term surge power for fast acceleration. Electric locomotives are ideal for commuter rail service with frequent stops. They are used on high-speed lines, such as ICE in Germany, Acela in the US, Shinkansen in Japan and TGV in France. Electric locomotives are also used on freight routes that have a consistently high traffic volume, or in areas with advanced rail networks.

Electric locomotives benefit from the high efficiency of electric motors, often above 90%. Additional efficiency can be gained from regenerative braking, which allows kinetic energy to be recovered during braking to put some power back on the line. Newer electric locomotives use AC motor-inverter drive systems that provide for regenerative braking.

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TYPES OF ELECTRIC LOCO

Conventional loco

3 Phase loco

CATEGORY OF LOCO

Passenger train loco

Goods train loco

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CONVENTIONAL LOCO

WAP 1

WAP 4

WAG 5

WAG 7

THREE PHASE LOCO

WAP 5

WAP 7

WAG 9

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WHAT THE CODING OF LOCO SIGNIFY

W = WIDE A = A.C. G = GOODS P = PASSENGER M = MIXED ( GOODS + PASSENGER)

NUMBER OF ROLLING STOCK IN GHAZIABAD SHED

Total Loco = 175

WAP 5 = 27

WAP 7 = 51

WAP 1 = 40

WAP 4 = 42

WAG 5 = 14

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LAYOUT OF LOCOMOTIVE

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CONVENTIONAL LOCO

WAP 1

WAP–1 Built by CLW to RDSO specifications. First in the dedicated electric passenger loco series. Production began in 1980 and the locos were at first used solely for the Howrah-Delhi Rajdhani. A single WAP-1 (#22001) was all that was needed to haul the 18-coach Rajdhani at a max. speed of 120 km/h. and an average speed of around 82km/h. Continuous power 3760hp; starting TE 22.2t, continuous TE 13.8t. Loco weight is 112.8t.

The original WAP-1 locos were modified and regeared versions of the WAM-4, originally classified WAM-4R. Rated max. speed is 130km/h (some documents suggest 140km/h). Some (5?) with Flexicoil Mark II bogies were classified WAP-1 FM II and later WAP-3. Two WAP-1 units were also converted to WAP-6. [10/02] One of them, #22212, the first prototype WAP-6, was then converted to a WAP-4 and was based at Jhansi (now [8/03] at Mughalsarai).

Many remaining WAP-1's are being converted to WAP-4's by a complete retrofit including new traction motors, new transformers, etc. These upgrades do not result in the 'R' suffix in the road number that is typical for rebuilt locos. Ghaziabad shed locos are currently [1/05] the only ones not scheduled for such upgrades and are expected to remain as 'pure' WAP-1 units. The WAP-1E has only air brakes. Earlier WAP-1's had loco air brakes and vacuum train brakes but were retrofitted for dual train brakes. Motors are grouped in 2S-3P combination and weak field operation is available. Elgi compressors, Northey exhausters, S F India blowers. The locos were originally not designed for MU operation but were later modified to allow MU'ing.

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WAP 1

Manufacturers CLW Traction Motors Alstom/CLW - TAO 659 (575kW (770hp),

750V, 1095 rpm) Axle-hung, nose-suspended, force-ventilated.

Gear Ratio 58:21Transformer BHEL type HETT-3900, 3900 kVA. 32 taps.Rectifiers Two silicon rectifiers, with S18FN35 cells (by

Hind Rectifier) with 64 cells per unit. 2700A/1050V.

Axle load 18.8t.Bogies Co-Co Flexicoil (cast steel bogies); primary

and secondary wheel springs with bolstersPantographs Two Faiveley AM-12.Current Ratings 900A/10min

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WAP 4

I WAP-4

This 5000 HP locomotive was evolved to meet the requirement of hauling longer trains of 24 coaches at higher speed up to 130 kmph over Indian railways. This loco is presently hauling important high-speed trains on Indian Railways. These are six axles loco with axle and nose suspended drive.

5000 HP 25 KV AC WAP 4 Passenger Electric Locomotive.

Need :-

Due to advanced mechanical design especially those of bogies, the locomotive has low unsprung masses and is truly track friendly. Presently WAP-5 is the only passenger locomotive with fully suspended drive. Anti-collision posts give locomotive superior crash worthiness. The fleet of WAP-5 class locomotives is now being geared up for the proposed 150 kmph services

Salient Details :-

system 25 KV, AC, 50 Hz.

Class of Loco WAP-4

Track Gauge 1676 mm (Broad Gauge)

Axle arrangement Co-Co

Brake System Air and Rheostatic

Total weight 112.8 + 1% t.`

Wheel Diameter 1092 mm (New) , 1016 mm (Full worn)

Length over buffers 18794 mm

Panto locked down height 4232.5 mm

Traction Motor type HS 15250A, DC Series Motor

Continuous Power at Wheel Rim 5000 HP

Starting Tractive Effort 30.8 t

Control System Voltage 110 V DC

WAP 4

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Manufacturers CLW Traction Motors Hitachi HS15250 (630kW, 750V, 900A.

895rpm. Weight 3500kg). Axle-hung, nose-suspended, force ventilated, taper roller bearings.

Gear Ratio 23:58 (One loco, #22559, is said to have a 23:59 ratio.)

Transformer 5400kVA, 32 tapsRectifiers Two silicon rectifiers, (ratings?). Axle load 18.8t.Bogies Co-Co Flexicoil Mark 1 cast bogies; primary

and secondary wheel springs with bolstersPantographs Two Stone India (Calcutta) AM-12.Current Ratings 1000A/10min, 900A continuousTractive Effort 30.8t

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WAG 5

WAG–5Introduced in 1984. Power 3850hp (some documents say 3900hp, which may be a later modification), 6-axled (Co-Co). Starting TE 382kN (33500kgf); continuous TE 202kN (20600kgf). Adhesion 29%. A very successful class, and probably the one with the most numbers produced. There are many variants of these, starting with the plain WAG-5. WAG-5A locos have Alsthom motors. Later versions were WAG-5H and variants with Hitachi motors: WAG-5HA by CLW, with high-adhesion bogies, and WAG-5HB built by BHEL to RDSO's specifications. (Note: Lallaguda shed uses the simple code 'WAG-5' for locos that would normally be denoted 'WAG-5HA'.) Newer versions have been spotted: WAG-5HG, WAG-5HR, WAG-5RH (here the 'R' is believed to denote rheostatic braking, but not all WAG-5 class locos that have rheostatic braking use this suffix), WAG-5D, WAG-5P for fast passenger traffic (mail and express trains) with gear ratio 21:85. etc,. WAG-5HE variants are believed to have Hitachi traction motors and only air brakes.

The detailed differences among these variants are not precisely known. Specifications for the base WAG-5 model are given below. Some of the variants are known to have different gearing and equipment, and different rated speeds. The original WAG-5 units had a top speed of 80km/h. Many variants have a gear ratio of 21:58, the same as that of the WAM-4 6P, which allows these WAG-5 locos to be used for mixed applications including hauling passenger trains at 100km/h.

Auxiliaries are from many sources: typically Elgi compressors, Northey exhausters, and other equipment from S F India, but many variations exist. Speed control by parallel combinations of motors and weak field operation. Air brakes for loco, dual train brakes are original equipment.

In the external appearance of WAG-5 locos, it can be seen that locomotives with road numbers up until 23293 have side louvres and round glass windows like the WAM-4 locos showing the legacy of the WAM-4 design. From number 23294 onwards the locos have the newer WAP-4/WAG-7 style of louvres, thought to be for better ventilation.

More recently WAG-5 locos of all types have been retrofitted with data loggers, flasher lights, train parting alarms, etc.

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WAG 5

Traction Motors Alstom TAO 659 (575kW, 750V, 1070 rpm) or TAO 656; or Hitachi HS 15250A (See description under WAP-4.) Axle-hung, nose-suspended. Six motors.

Gear Ratio 62:16 or 62:15 with Alstom motors, some 64:18 (Hitachi motors), many now 58:21 for mixed use.

Transformer BHEL, type HETT-3900. 3900kVA, 22.5kV, 182A. 32 taps.

Rectifiers Silicon rectifiers (two) using 64 S-18FN-350 diodes each from Hind Rectifier. 2700A / 1050V per cubicle.

Bogies Co-Co cast bogies (Alco asymmetric trimount -- shared with WDM-2, WAM-4).

Axle load 20t Max. Haulage 2375tPantographs Two Faiveley AM-12Current Ratings 1100A/10min, 750A continuous

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WAG 7

WAG-7

With the ever increasing freight traffic and the need for hauling heavier loads in 1 in 200 grade at increased balancing speeds, CLW went into for the design of an uprated version of WAG-5 locomotive with high capacity transformer, rectifier, traction motor, compressor and other matching associated equipments. These are six axles loco with axle and nose suspended drive. DC series motors, controlled by a tap changer are used in this locomotive. Indian Railway is going to achieve 7,00 million tonnes of traffic, WAG-7 is the main stay of loco. In the locomotive vehicle market WAG -7 is more economical option and one of the cheapest in the world.

5000 HP 25 KV AC WAG-7 Freight Electric Locomotive.

Need :-


Salient Details :-

Gauge 1676 mm

System Voltage 25 KV AC

Continuous H. P 5000

Max. Speed 100 kmph

Starting Tractive Effort 402 KN. (41t)

Continuous Tractive Effort 235 KN (24t)

Wheel Arrangement 25KV AC, 50 Hz.

Weight of loco Co-Co

Type of Bogie Fabricated

Gear Ratio 16: 65

Adhesion 34.5%

Brake System Dual brake-rheostatic and air.

Total weight of locomotive 123 t.

.

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WAG 7

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Traction Motors Hitachi HS15250-G (a variant of the standard HS15250 with higher current rating (thicker wire gauge, better insulation); see description under WAP-4.) Motors built by CLW and BHEL.

Gear Ratio 65:18 Transformer CCL India, type CGTT-5400, 5400kVA, 32

taps.Rectifiers Two silicon rectifiers, cell type S18FN350

(from Hind Rectifier), 64 per bridge, 2700A / 1050V per cubicle.

Axle load 20.5t Bogies Alco High-Adhesion bogies, fabricated bogie

frame assembly, with unidirectional mounting of traction motors, primary and secondary suspension.

Hauling Capacity 3010tPantographs Two Stone India (Calcutta) type AN-12.Current Ratings 1350A/2min, 1200A/10min, 960A/hr, 900A

continuous


WAP 5 WAP - 5 : 5400 hp,25 kV ac, B.G. 160 km/hr. speed,3-phase driveWAP-5 class locomotives employ advanced control and propulsion technology and are capable to deliver 5400 hp on rail. The locomotive has all the hallmarks of a high-speed propulsion unit viz. light weight, fully suspended drive and disc brake. Though presently, it has been certified for 160 kmph operation, the locomotive has been designed to give a service speed of 200 kmph with test speed potential of 225 kmph. Since IR is currently facing severe competition in Premium Passenger business market from commercial airlines, sooner or later, IR will have to introduce medium high speed intercity Passenger Services. This emerging market will call for powerful Electric locos with 150 kmph plus speed potential to be deployed in the immediate future and WAP-5 is the locomotive of choice for this Passenger Services market of IR.

5400 HP 25 KV 3 phase Passenger Electric Locomotive WAP-5

Need :-


Salient Details :-

Horse Power 5400

Supply system 25 kV, AC, 50 Hz.


Axle Arrangement Bo-Bo

Total weight 78+ 1%t

Axle Load 19.5 + 2%t.

Wheel Diameter 1092 mm (new ),1016 mm (Full Worn)


Panto locked down height 4237 mm

Max. Service Speed 160 kmph

Type of Traction motors FXA 7059, 3-phase Squirrel Cage Induction Motors

Traction Motor Mounting Fully suspended

Continuous Power at wheel rim 4000 kW (5450 hp)

Starting Tractive Effort 258 KN

Control System Voltage 110 V dc

Drive System 3 phase Drive with GTO Thyristors and microprocessor based VVVF Control.

Multiple Unit operation Maximum 2 locos.

Hauling Capacity 26 coaches at 140 km/ hr on level.

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Brake System Air, Regenerative & parking

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WAP 5

Manufacturers ABB / CLW Traction Motors ABB's 6FXA 7059 3-phase squirrel cage

induction motors (1150kW, 2180V, 370/450A, 1583/3147 rpm) Weight 2050kg. Forced-air ventilation, fully suspended. Torque 6930/10000Nm. 96% efficiency.

Gear Ratio 67:35:17. (3-stage gears)Transformer ABB's LOT-7500. 7475kVA primary,

4x1450kVA secondary.Power Drive Power convertor from ABB, type UW-2423-

2810 with SG 3000G X H24 GTO thyristors (D 921S45 T diodes), 14 thyristors per unit (two units). Line convertor rated at 2 x 1269V @ 50Hz, with DC link voltage of 2180V. Drive convertor rated at 2180V phase to phase, 953A output current per phase, motor frequency from 0 to 160Hz.

Axle load 19.5tBogies Bo-Bo Henschel Flexifloat; bogie centre

distance 10200mm; bogie wheel base 2800mmUnsprung mass per axle 2.69tPantographs Two Stone India (Calcutta) AN-12.Wheel diameter 1092mm new, 1016mm wornWheel base 13000mmLength over buffers 18162mmLength over headstocks 19280mmBody width 3142mmnCab length 2434mmPantograph locked down height 4537mmTractive Effort 26.3t

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WAP 7

WAP-7 - The “Heavy Haul” Passenger locomotives of IR:-

Intercity and interstate fare friendly Passenger market has of late shown a strong and sustained growth in recent times. This market needs very powerful Electric locos which can haul 24 to 26 coaches at speeds in the range of 130/ 140 kmph. To meet the surging demands of this amazingly exploding Passenger market segment, CLW has come out with a 6000 H.P loco premium Electric loco product – WAP-7.WAP-7 class loco is based on WAG-9 platform and differs from WAG-9 in gear ratio and the control software. Locomotive rated at 6000 hp is design to the starting tractive effort of 323 KN and maximum braking effort is 260 KN.

6000 HP 25 KV 3-phase Passenger Electric Locomotive WAP-7

Need :-

This loco also is capable to give 6000 hp on rail upto its rated speed of 100 kmph which gives superior section clearing capability especially in handling speed restriction.

Salient Details :-

Horse Power 6000

Supply System 25kV, AC, 50 Hz.


Total weight 123.0 + 1%t.

Wheel Diameter 1092 mm (New ), 1016 mm (Full Worn)


Panto locked down height 4255 mm

Type of Traction motors 6FRA 6068, 3-phase Squirrel Cage Induction MotorsContinuous Power at wheel rim

4500 kW (6000 hp)

Starting Tractive effort 323 kN

Max. Service Speed 140 kmph

Brake System Air, Regenerative & parking

Drive System 3 phase Drive with GTO Thristors and microprocessor based VVVF Control.

WAP 7

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Manufacturers CLW Traction Motors 6FRA 6068 3-phase squirrel-cage induction

motors (850kW, 2180V, 1283/2484 rpm, 270/310A. Weight 2100kg, forced-air ventilation, axle-hung, nose-suspended. Torque 6330/7140Nm. 95% efficiency.)

Gear Ratio 72:20 Axle load 20.5t Wheel diameter 1092mm new, 1016mm wornWheel base 15700mmBogies Co-Co, ABB bogies; bogie wheel base 1850mm

+ 1850mmUnsprung mass per axle 3.984tLength over buffers 20562mmLength over headstocks 19280mmBody width 3152mmnCab length 2434mmPantograph locked down height 4525mmTractive Effort 36.0t

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WAG 9

WAG-9 - The “Heavy Haul” Freight locomotive of IR:-Rail Freight market which is registering a remarkable growth since 2000, has also triggered a buoyancy in demand for Electric Freight locomotives. Almost 60 – 65 % of IR’s freight handling takes place over IR’s Electrified Golden Quadrilaterals and Diagonals , though it accounts for only 25 % of its route kilometrage . Golden Quadrilateral and Diagonals being saturated routes, need heavy throughput and faster sectional clearance. This is where these heavy haul and speedier WAG-9 locos play a significant role. This Gem of a loco is indeed a rail operator’s delight.This six axle loco with axle and nose suspended drive is designed to give a starting tractive effort of 460 KN and maximum braking effort of 260 KN. Rated 6000 hp, the loco has also been successfully adapted to give 508 KN of starting tractive effort with additional ballast. This loco also is capable to give 6000 hp on rail upto its rated speed of 100 kmph which gives superior section clearing capability especially in handling speed restriction.

6000 HP, 25 KV, 3- phase Freight Electric Locomotive WAG-9

Need :-

Due to advanced mechanical design especially those of bogies, the locomotive has low unsprung masses and is truly track friendly. Presently WAP-5 is the only passenger locomotive with fully suspended drive. Anti-collision posts give locomotive superior crash worthiness. The fleet of WAP-5 class locomotives is now being geared up for the proposed 150 kmph services Salient Details :-Gauge 1676 mm

Continuous HP 6000

Starting Tractive effort 460KN (47t)

Max, Speed 100 kmph

Breaking Air, Regenerative

Wheel Aggangement Co-Co.

System Voltage 25KV AC, 50 Hz.

Weight of loco 123t.

Type Freight

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WAG 9

Manufacturers ABB, CLW Traction Motors ABB's 6FRA 6068 (850kW, 2180V, 1283/2484

rpm, 270/310A. Weight 2100kg) Axle-hung, nose-suspended.

Gear Ratio 77:15 / 64:18Transformer ABB's LOT 6500, 4x1450kVA.Power Drive Power convertor from ABB, type UW-2423-

2810 with SG 3000G X H24 GTO thyristors (D 921S45 T diodes), 14 thyristors per unit (two units). Line convertor rated at 2 x 1269V @ 50Hz, with DC link voltage of 2800V. Motor/drive convertor rated at 2180V phase to phase, 971A output current per phase, motor frequency from 0 to 132Hz.

Hauling capacity 4250t Bogies Co-Co, ABB bogies; bogie wheel base 1850mm

+ 1850mmWheel base 15700mmAxle load 20.5tUnsprung mass per axle 3.984tLength over buffers 20562mmLength over headstocks 19280mmBody width 3152mmnCab length 2434mmPantographs Two Secheron ES10 1Q3-2500.Pantograph locked down height 4525mm

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WAG 9H

WAG–9HA heavier variant of the WAG-9 (12t extra ballast, welded at four locations in the machine room behind the cabs -- a design proposed by CLW and approved by AdTranz) and consequently higher TE. Everything else was just as in the WAG-9 class, except for some application software changes. This was expected to be used in haul heavy freights (58 BOXN wagons, 4700t) without the need for multiple units even on incline sections of 1:150. The ballasting raised the starting TE from 460kN to 520kN. Continuous TE 325kN. The first (and only, as it turned out) of this class was was commissioned on June 30, 2000. This locomotive, #30130, 'Navshakti', then homed at Gomoh, cleared trials but because of concerns about the weight, did not enter regular service. It was deballasted and converted to a plain WAG-9 by mid-2002. That was the only unit of this class ever tried out. The class was intended for MU operation (2 units). Trivia: This reclassified loco, now at the Ajni shed, still sports its variant livery with two white stripes instead of the single yellow stripe characteristic of other WAG-9 locos.

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WAG 9H

Manufacturers ABB, CLW Traction Motors ABB's 6FRA 6068 3-phase squirrel-cage

induction motors (850kW, 2180V, 1283/2484 rpm, 270/310A. Weight 2100kg) Axle-hung, nose-suspended.

Gear Ratio 77:15 / 64:18Transformer ABB's LOT 6500, 4x1450kVA.Power Drive Power convertor from ABB, type UW-2423-

2810 with SG 3000G X H24 GTO thyristors (D 921S45 T diodes), 14 thyristors per unit (two units). Line convertor rated at 2 x 1269V @ 50Hz, with DC link voltage of 2800V. Motor/drive convertor rated at 2180V phase to phase, 971A output current per phase, motor frequency from 0 to 132Hz.

Axle load 22.5tHauling capacity 4700t Bogies Co-CoPantographs Two Secheron ES10 1Q3-2500

.

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MOTOR RATING OF WAP5 & WAP7

TYPE-6FXA 7059[WAP-5]

TYPE 6FRA 6068[WAP-7]

POWER CONT. 850KW 850KW(MAX)SPEED 1283 RPM 2584 RPM WEIGHT 2150KGVOLTAGE 2180V 2180VCURRENT 270A 393AFREQUENCY 65HZ 132HZ

RATING OF DC TRACTION MOTOR

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POWER CONT. 1150KW 1150KW

SPEED 1585RPM

3174.1RPM WEIGHT 1990KG

VOLTAGE 2180V 2180V COOLED AIR 108M3/MINCURRENT 370A 543AFREQUENCY 80HZ 161HZ


HITATCHI TRACTION MOTOR

CAPACITY 630KW RATING CONT.

VOLTAGE 750V EXCITATION SERIES

CURRENT 900A COOLING AIR 80M3/MIN

TAO TRACTION MOTOR

RPM VOLTS AMPS SHAFT O/PCONT. RATING

1090 750 840 575KW

MAX. VALUES 2500 900 1350

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RATING OF JYOTI ARNO CONVERTER 1-Ф INPUT 3- Ф OUTPUT

KVA 160 120VOLTS 386 380AMPS 396 190FRAME VA330 CONN. : STARRPM 1495 CYCLES 50

RATING OF STATIC CONVERTER

180 KVA 1- Ф TO 3- Ф STATIC CONVERTER

INPUT VOLT AC 645-1115VOUTPUT VOLT 415±5%V

FREQUENCY 50 HZ±3%PHASE 3-ФTYPE PWM SINE WAVE

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RATING OF LOCOMOTIVE TRANSFORMER (CONVENTIONAL)

WINDING PRIMARY SECONDARY AUXILIARY

KVA 4170 3900 270

VOLTS (NO LOAD) 22500 0-865(TAP 0-32) 389

25000 0-862(TAP 0-29) 432

27500 0-859(TAP 0-26) 476

AMPS 185.3 2250 694

166.8 2250 625

151.6 2250 567

A33-A0 a6-a5 and a4-a3 a1-a0

TEMP. RISE OIL/WINDING 45°C/55°C

TYPE HETT 3900

WEIGHT 4170 PHASE SINGLE

FREQUENCY 50 HZ

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TOTAL NO. OF AUXILIARY MOTORS IN CONVENTIONAL LOCOS

S.No. Name Of Auxiliary Motor

No. Of Motors In Loco

HP Rating

1 Traction Motor Blower(MVMT)

02 35 HP/26 KW

2 Transformer Oil Cooling Blower Motor(MVRH)

01 30 HP/22 KW

3 Blower Motor For Rectifier BLOCK Cooling(MVSI)

02 4 HP/3 KW

4 Blower Motor For Reactor Cooling(MVSL)

02 2.7 HP/2.2 KW

5 Pump Motor For Transformer Oil Circulation(MPH)

01 4.3 HP/3.0 KW

6 Main Compressor Motor(MCP)

02 12.6 HP/ 9.5 KW

7 Auxiliary Compressor Motor(MCPA)

01 1 HP/.75 KW

8 Crew Cab Fan 04 .04 HP/32 W9 ARNO

CONVERTER01 1-Ф I/P 150 KVA

3-Ф O/P 120 KVA

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TOTAL NO. OF AUXILIARY MOTORS IN 3- Ф LOCOS

S.No. Name Of Auxiliary Motor

No. Of Motors In Loco

HP Rating

1 Traction Motor Blower

02 34 HP/25 KW

2 Motor For Traction Motor Scavenger Blower

02 4 HP/3 KW

3 Transformer Oil Cooling Blower Motor

02 34 HP/25 KW

4 Motor For Machine Room Blower

02 4 HP/3 KW

5 Motor For Machine Room Blower

02 1 HP/.75 KW

6 Pump Motor For Converter Oil Circulation

02 15 HP/11 KW

7 Main Compressor Motor

02 20 HP/ 15 KW

8 Auxiliary Compressor Motor

01 1 HP/.75 KW

9 Crew Cab Fan 04 .04 HP/32 W10 Pump Motor For

Transformer Oil Circulation

02 6.3 HP/4.7 KW

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THREE PHASE LOCOMOTIVES

Q. How do the new 3-phase AC locos (WAP-5, etc.) work, and how do they compare with the earlier locos?

Three-phase AC locos such as WAP-5 use some fairly new technology as compared to the earlier generations of diesel-electrics and electrics. In most of the earlier locos, the traction motors driving the axles are DC motors. DC motors were used because they afforded (in those days) far superior speed and torque control compared to AC motors — the latter require variation of input frequency and voltage for effective control, which was not an easy matter earlier.

Modern microprocessor technology and the availability of efficient and compact power components have changed that picture. In 3-phase AC locos, the input (single-phase AC) from the OHE is rectified and then 3-phase AC is generated from it, whose voltage, phase, and frequency can be manipulated widely, without regard to the voltage, phase, frequency of the input power from the OHE. AC traction motors can thus be driven with a great degree of control over a wide range of speed and torque.

AC traction motors are also used on diesel-electrics nowadays. The WDP4 & WDG4 are examples of this.

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DETAILS : THERE ARE 3 MAIN STAGES IN THE POWER CIRCUIT OF A 3-PHASE AC LOCO.

Input Converter : This rectifies the AC from the catenary to a specified DC voltage using GTO (gate turn-off) thyristors. A transformer section steps down the voltage from the 25kV input. It has filters and circuitry to provide a fairly smooth (ripple-free) and stable DC output, at the same time attempting to ensure that a good power factor presented to the electric supply. There may also be additional mechanisms such as transformers, inductors, or capacitor assemblies to improve the power factor further.

The transformer section is designed with high leakage impedance and other characteristics, which together with the fine control possible with the GTO switching, allow the loco to present nearly unity power factor, a very desirable situation from the point of view of the electricity suppliers (the grid). The main transformer also has some filter windings which are designed to further attenuate harmonics from the loco's traction motors which may pass through the filtering in the DC link.

The input converters can be configured to present different power factors (lagging or leading) to the power supply, as desired. IR's WAP-5 and other 3-phase AC locos are generally configured to present a unity power factor (UPF). (Note: the power factor cannot be changed on the run.)

DC Link : This is essentially a bank of capacitors and inductors, or active filter circuitry, to further smooth the DC from the previous stage, and also to trap harmonics generated by the drive

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converter and traction motors. Since the traction motors and drive converters present non-linear loads, they generate reactive power in the form of undesirable harmonics; the DC link acts as a reservoir for the reactive power so that the OHE supply itself is not affected.

During regenerative braking this section also has to transfer power back to the input converter to be fed back to the catenary. The capacitor bank in this section can also provide a small amount of reserve power in transient situations (e.g., pantograph bounce) if needed by the traction motors.

Drive Converter : This is basically an inverter which consists of three thyristor-based components that switch on and off at precise times under the control of a microprocessor (pulse-width modulation). The three components produce 3 phases of AC (120 degrees out of phase with one another). Additional circuitry shapes the waveforms so that they are suitable for feeding to the traction motors. The microprocessor controller can vary the switching of the thyristors and thereby produce AC of a wide range of frequencies and voltages and at any phase relationship with respect to the traction motors. Various kinds of thyristor devices are used to perform the switching.

Currently produced modern locos generally use GTO thyristors (Gate Turn-Off thyristors), but it is expected that soon insulated-gate bipolar transistors (IGBTs), which offer extremely high switching speeds allowing for finer control over the waveforms generated, will be the switching technology of choice. The WAP-5, WAP-7, WAG-9, and WAG-9H models all use GTOs. At present no Indian loco uses IGBTs; some trial locos such as the 12X from Adtranz do use this technology, as do many light-rail and metro

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locomotives or EMUs around the world.The new AC-DC EMUs in the Mumbai area (introduced on WR) use IGBTs.

The 3-phase AC is fed to the AC traction motors, which are induction motors. As the voltage and the frequency can be modified easily, the motors can be driven with fine control over their speed and torque. By making the slip frequency of the motors negative (i.e., generated AC is 'behind' the rotors of the motors), the motors act as generators and feed energy back to the OHE — this is how regenerative braking is performed. There are various modes of operation of the motors, including constant torque and constant power modes, balancing speed mode, etc. depending on whether their input voltage is changed, or the input frequency, or both.

AC motors have numerous advantages over DC motors. DC motors use commutators which are prone to failure because of vibration and shock, and which also result in a lot of sparking and corrosion. Induction AC motors do not use commutators at all. It is hard to use a DC motor for regenerative braking, and the extra switchgear for this adds to the bulk and complexity of the loco. AC motors can fairly easily be used to generate power during regenerative braking. In addition, DC motors tend to draw power from the OHE poorly, with a bad power factor and injecting a lot of undesirable harmonics into the power system. AC motors suffer less from these problems, and in addition have the advantage of a simpler construction.

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AUTO-EMERGENCY BRAKES (AEB)

Introduction

Auto-Emergency Brakes (AEB) refers to a special system of braking employed on some ghat sections with steep gradients, notably the Braganza ghat between Kulem and Castle Rock. With this system, the loco's speed is limited to 30km/h and the brakes are automatically applied if the loco moves faster than that at any time on the AEB section.

Procedures

The AEB system is activated by means of a key obtained at the top of the descending grade (at Castle Rock for the Braganza ghat). The key, which is specific to each loco, is engaged and turned in the loco, and then removed and handed to the guard of the train (except for light locos where there is no guard). While the AEB system is activated, the loco cannot run faster than 30km/h; the brakes are applied immediately if the speed rises above that.

When the loco reaches the bottom of the down grade (Kulem at the foothills of the Braganza ghat), the AEB system is deactivated and the key is handed over to the Station Master of the station at the bottom of the ghat section (Kulem). From there onwards, the loco can proceed at normal permissible speeds.

The AEB key specific to a loco is handed over to the loco pilot by the Station Master of the station at the bottom (Kulem) when the loco is above to ascend the ghat section.

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Operation

The AEB system depends on a speed sensor attached to the axle generator (tachometer generator) of the locomotive. The speed sensor controls the Emergency Brake Relay (EBR). The EBR gets energized when the speed sensor detects that the loco is moving faster than 30km/h (or other programmed speed limit).

When the EBR is energized, two emergency brake valves, EBV1 and EBV2 get activated.

The first emergency brake valve EBV1 cuts off pilot air from A9 to C2, with the additional C2 relay then causing the Brake Pipe to exhaust, while the second emergency brake valve EBV2 also exhausts the Brake Pipe pressure and causes application of the brakes.

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AIR BRAKE

A comparatively simple brake linkage

In the air brake's simplest form, called the straight air system, compressed air pushes on a piston in a cylinder. The piston is connected through mechanical linkage to brake shoes that can rub on the train wheels, using the resulting friction to slow the train. The mechanical linkage can become quite elaborate, as it evenly distributes force from one pressurized air cylinder to 8 or 12 wheels.

The pressurized air comes from an air compressor in the locomotive and is sent from car to car by a train line made up of pipes beneath each car and hoses between cars. The principal problem with the straight air braking system is that any separation between hoses and pipes causes loss of air pressure and hence the loss of the force applying the brakes.

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http://en.wikipedia.org/wiki/File:Brake_Diagram.png

http://en.wikipedia.org/wiki/File:Brake_Diagram.png


WHEEL SLIP IN LOCOMOTIVES

Wheel slip on locos such as the WAG-5/WAG-7,WAM-4,WCAM-1/2/3, is detected by a relay designated 'QD' which is a current differential relay. It detects the difference in the current flow between two traction motors. If all the traction motors are running at uniform and equal speeds, the armature of the relay remains balanced. However, if any of the axles are slipping, the current to this motor is slightly reduced producing a current imbalance in relay QD which is then triggered. QD gives a repeat to a relay 'Q48' which in turn may activate some automatic wheel-slip reduction procedures as detailed below, depending on the configuration in the particular locomotive. Operation of relay Q48 also lights the LSP (Signal lamp to indicate Wheel-Slip) on the driver's desk.

WAG-5/7,WAM-4,WCAM-1/2/3, etc., have been provided with mainly three methods to minimise wheel slip:

Sanders to improve adhesion: Sanders can be operated automatically by relay Q48 or manually by pressing a foot switch 'PSA' below the driver's desk.

Auto-Regression of the Tap-Changer to reduce tractive effort: Q-48 also gives an impulse to relay Q-51 (Relay for Auto-Regression of Tap-Changer) to reduce the notches which in turn lowers the voltage to the traction motors thereby reducing the tractive effort.

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Field Weakening (Weak Field Operation) : The DC series motors have their fields wound in series with the armature winding. Normally,the current through the field and the armature is equal but if the current through the field is partially bypassed, the torque of the motor is reduced. Hence, by shunting the field, the tractive effort of the motor is reduced. During wheel slipping, weak field is usually introduced on the leading axles of both the bogies because these are usually the ones to slip first due to dynamic weight transfer which tends to reduce the weight on the leading axles and proportionately increases weight on the trailing axles. (The same field shunting device is used to increase the speed of the loco above 21 notches but in that case it's applied to all the traction motors.) In WCAM-1 locos, a special switch 'ZQWC' has been provided in front of the driver the introduce weak field manually.

The above methods of detection and prevention also suffer from various drawbacks.

Relay QD has to have a built-in bias. It has to compensate for slight differences in the wheel diameters which also tend to introduce wheel slipping and skidding and may cause spurious operation of the relay.

Another problem is that on many locos, sanders are only partially operational and can't be relied upon.

Auto-Regression of the tap-changer is a mixed blessing. Repeated attempts by the driver to start the load may fail due to lack of progression of the tap-changer. This may result in the load being failed. In practice, many locos have the wire providing the impulse to relay Q51 disconnected by the sheds to minimise such failures on the line. In desperation, some drivers also tend to temporarily

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wedge the relay Q51 to prevent its operation and thereby prevent auto-regression.

Field-weakening is also not too reliable a method because it may reduce the power too much and may prevent the loco from starting altogether.

Microprocessor controlled locos: Microcontrollers on the newer generation of locos use a tachometer generator (tachogenerator) on all the axles which gives a precise output voltage for each axle, all of which are fed into a comparator. If all the voltages tally, the motors are running at the same speed but if an axle is slipping, it speeds up which increases the voltage measured. When the comparator detects such a difference, it can take the requisite action such as applying brakes slightly on the on the individual wheels or reduce the frequency of power supply to that motor.

In sections where wheel-slipping is a persistent and chronic problem, MU'ed (multiple unit) locos often give better results. This is because although a single loco may be sufficient to start and haul the formation, during the starting phase, wheel slipping may cause undue problems. In the case of a MU'ed consist, although the gross tractive effort is enough to start the load, the individual axles by themselves do not generate sufficient torque to induce wheel-slipping.

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ELECTRIC LOCO TAP-CHANGER On the Indian Railways, a large number of electric locomotives are in operation today. Many different models of these locos have been manufactured, many of which have now been scrapped. However, many of those models which are still in service such as the WAM-4, WAP-4, WCAM-1, WCAM-2, WCAM-3, WCAG-1, WAG-5, WAG-7, etc., use almost the same electrical setup (excepting the newer 3-phase AC locos such as the WAP-5 and WAG-9).

In traction duty,the basic characteristics of the traction Vehicle should be such that it can exert a high torque during the starting phase and gradually the torque should decrease and the speed of the vehicle should increase.

These characteristics are obtained in electric locos on the Indian Railways by the use of the series-wound DC traction motor which has an inherent characteristic of exerting a high torque during its starting phase and a high speed during the running phase when the train resistance is minimal.

However in order to have proper speed control over these traction motors the voltage supplied to these motors must be varied. Increasing the voltage to the motor increases its torque and speed and vice-versa.

This variation of voltage is obtained by the use of an on-load tap-changer in the locos.

This is a picture of the tap-changer of a electric locomotive.

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TRACTION MOTOR POWER SUPPLY OVERVIEW

Before explaining the working of the tap-changer provided in these locos, it will better if the broad outline of the power circuit of these locos is understood properly.

These locos operate on a nominal voltage of 25,000V AC (single phase). The power is supplied from the overhead equipment (OHE). This power is collected from the OHE by the pantograph which then passes it to the main circuit breaker (DJ). From the DJ the supply is fed into the main transformer through a high tension bushing. The transformer is actually composed of two different transformers which are wound on the same steel core. This reduces space requirement and also provides better magnetic coupling.

The first transformer is an autotransformer with around thirty one tappings which are brought out to the tap-changer. The output voltage of the autotransformer depends on the tap at which the selector of the tap-changer is resting. Hence,by changing the position of the tap-changer selector the output voltage of the auto-transformer can be varied conveniently. The Tap-Changer is provided on the high-tension side of the transformer which reduces its size due to the lower current. Insulation is enhanced by filling the selector casing with oil.

The output of the autotransformer is fed to the second transformer which has a fixed ratio and steps down the voltage to a fixed fraction. The output of this second transformer is then fed to the rectifier blocks (RSI 1 and RST 2). These convert the AC into DC. In turn the DC output is fed into a pair of chokes known as smoothing reactors (SL 1 and SL 2). The smoothing reactors are provided to remove the AC ripple which is left over from the rectification cycle.

This smoothened DC is then handed over to the DC switchgear for the line and combination control of the traction motors and then finally to the traction motors themselves.

The subject of this article is the detailed manner in which the above mentioned tap-changer works.

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TAP-CHANGERS Before going into the details of the actual tap-changer which is used in the Indian Railways locos, it will better to understand in general what tap-changers are.

The output voltage of a transformer varies according to the turns ratio of the primary and the secondary windings of the transformer. It can appreciated that at any point of the primary or the secondary winding the voltage is different from any other point on the same winding because these points are at different ratios with respect to the other winding.

Hence each and every tap brought out from the winding gives a different voltage.

Broadly tap-changers can be divided into two categories-namely off-load and on-load.

Off-load tap-changers cannot be operated while current is flowing in the circuit. Off-load tap-changers are used mainly for non-critical applications where a momentary interruption in the current can be tolerated. Hence, such tap-changers have no use in traction duty.

In traction only on-load tap-changers (OLTC) are used. They are capable of changing the taps rapidly without interrupting the flow of current.

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RELAYS ASSOCIATED WITH THE TAP-CHANGER

The main relays associated with the tap-changer are Q46, Q49, Q51, Q52, Q44 and QV62.

Q46-Relay GR protection during regression. When the driver puts the MP to 0 position the tap-changer (GR) starts regressing to 0 notch. However, the driver once having put the MP to 0 may not be monitoring the notch indicator and due to some reason the GR may have stopped midway. In such a case relay Q46 acts. It trips the DJ after a time delay of around 5 seconds. It should be noted that although Q46, by itself is not a Time Delay Relay but it acts through relay Q118 which has a time delay of 5 seconds.

Q49-Relay GR Synchronization during MU working -- In order to ensure that all the Tap-Changers work in tandem during MU working Relay Q49 is provided.

Q51-Auto Regression relay -- This relay is used to give regression impulse to the GR in case of wheel-slipping, load-parting, emergency braking, traction supply failure, etc.

Q52-Notch-to-Notch relay -- During progression, this relay ensures that the driver can take only one notch at a time. Even if he keeps the MP at '+' continuously he gets only one notch and must return the MP to 'N' before taking the next notch.

QV62 -- Relay to monitor GR reaching '0'position.This relay lights the LSGR lamp on the driver's desk when GR reaches 0 position.

Q44 -- I've kept the explanation of Q44 till the very last because this is probably the most important protective relay related to the tap-changer. Also Q44 relay is a not an ordinary relay but it is a time delay relay. It releases after a delay of 0.6 seconds after the supply to its energizing coil is cut off. In older versions the Q44 was a mechanical relay with a clock mechanism used to bring about the time delay. But newer versions are electronic. Older locos are also being retrofitted with electronic Q44 relays.

Another important feature of the Q44 is that it can be 'wedged' in the closed position, that is in case the Q44 itself becomes defective it can be temporarily wedged so that the DJ can be closed and the section can be cleared.

Coming back to its function with respect to the Tap-Changer, as I've explained above, the transition between two notches must be as fast as possible because the shorting of two taps through the RGR gives rise to almost short-circuit level current which can damage the RGR and the Transformer. Hence, during transition if the tap-changer

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becomes stuck between notches and the taps remain shorted for a long duration, it can destroy the RGR and the transformer.

In order to prevent such an occurrence there is a contact on the ASMGR which opens between notches, that is during transition. This contact is connected in series with relay Q44. Hence, during transition, supply to relay Q44 coil is interrupted which initiates the de-energizing time delay. However, if during such delay the transition is completed successfully, then the ASMGR contact closes, thereby restoring supply to Q44 and keeps it energised but if the tap-changer gets stuck mid-notch then Q44 drops out and trips the DJ. As such the tap-changer must complete its transition in 0.6 second which is the maximum time which Q44 gives it.

From the above the importance of Q44 can be judged and it should also be ensured drivers do not indulge in wedging the Q44 lightly. Many drivers, for the sake of expediency may wedge Q44 without verifying that nothing is wrong with the tap-changer or some other equipment that the relay protects such as the RSI blocks.

.

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BLOCK DIAGRAM OF OPERATION OF CONVENTIONAL LOCO

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Q. HOW DOES REGENERATIVE BRAKING WORK?

Regenerative braking works on the principle of converting the kinetic energy of the locomotive (and train) back to electricity by using the traction motors in reverse (as generators) and feeding the electricity back to the OHE. This is somewhat easier with DC than with AC traction as with the latter the phase and frequency of the generated electricity have to be matched to that of the OHE. On the other hand, regeneration with DC motors adds to their bulk and complexity.

The newer AC locos have microprocessor control which helps enormously as the waveform and phase of the regenerated power can be adjusted precisely. The regenerated voltage is in effect the loco presenting a negative load to the OHE system, which manifests itself as a slight rise in the system voltage. This results in a corresponding reduction in energy supplied by the generating units on the grid, and the regenerated energy can, in principle, even go back to the supplying grid and be used elsewhere.

The OHE is said to be receptive if it is in a state where the loco can use regenerative braking. If there is no other loco on the section that can absorb the power, and if the substation is not set up to send power back to the supply grid, regeneration results in the OHE voltage rising more than a certain threshold -- this is how the control systems on board the loco can detect the (non-)receptivity of the line. If the line is not receptive the loco has to resort to using frictional or rheostatic braking.

Even if the line is receptive, feeding power back to the supply grid may not always be possible, though, because of practical constraints in the design of the substation equipment, reverse flow detection relays in the supply grid (provided as protection in case of a fault in the 132kV supply system), improper phase match by the loco resulting in relays blocking the regenerated power, etc. The regenerated power therefore often gets used just by circulating in the OHE system and thereby getting used by other locomotives in the section. Because of this, regenerative braking bears fruit in busy sections where there are always some live locos. (In other railway systems, e.g., in Japan, although not in India, sometimes the regenerated power is just dissipated using large resistive loads at the substation or elsewhere.) Conversely when the system voltage starts dropping, it is an indication that the locomotive(s) on the section is/are not generating power and are instead consuming power (the normal case) in which case the normal power supply feeds energy back in to the OHE.

Apart from saving a fraction of the electricity costs for the railways, regenerative braking in practice also offers the driver finer control over braking a train, and the savings in brake pads and other equipment used in normal frictional braking is also significant. It has been claimed that regnerative braking in busy sections can save up to 10% or more of the electricity costs.

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GEAR OF TRACTION MOTOR

SPUR GEAR = CONVENTIONAL LOCO

HELICAL GEAR = 3-Ф LOCO

SPUR GEARS

Spur gears or straight-cut gears are the simplest type of gear. They consist of a cylinder or disk, and with the teeth projecting radially, and although they are not straight-sided in form, the edge of each tooth thus is straight and aligned parallel to the axis of rotation. These gears can be meshed together correctly only if they are fitted to parallel axles.

HELICAL GEARS

Helical gears offer a refinement over spur gears. The leading edges of the teeth are not parallel to the axis of rotation, but are set at an angle. Since the gear is curved, this angling causes the tooth shape to be a segment of a helix. Helical gears can be meshed in a parallel or crossed orientations. The former refers to when the shafts are parallel to each other; this is the most common orientation. In the latter, the shafts are non-parallel.

The angled teeth engage more gradually than do spur gear teeth causing them to run more smoothly and quietly. With parallel helical gears, each pair of teeth first make

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contact at a single point at one side of the gear wheel; a moving curve of contact then grows gradually across the tooth face to a maximum then recedes until the teeth break contact at a single point on the opposite side. In spur gears teeth suddenly meet at a line contact across their entire width causing stress and noise. Spur gears make a characteristic whine at high speeds and can not take as much torque as helical gears. Whereas spur gears are used for low speed applications and those situations where noise control is not a problem, the use of helical gears is indicated when the application involves high speeds, large power transmission, or where noise abatement is important. The speed is considered to be high when the pitch line velocity exceeds 25 m/s.

A disadvantage of helical gears is a resultant thrust along the axis of the gear, which needs to be accommodated by appropriate thrust bearings, and a greater degree of sliding friction between the meshing teeth, often addressed with additives in the lubricant.

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COUPLING

A coupling (or a coupler) is a mechanism for connecting rolling stock in a train. The design of the coupler is standard, and is almost as important as the railway gauge, since flexibility and convenience are maximised if all rolling together.stock can be coupled

BUFFERS AND CHAIN

Two cars coupled

Traditional buffer-and-chain coupler

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http://en.wikipedia.org/wiki/File:Mh_eisenbahn_schraubenkupplung.jpeg

http://en.wikipedia.org/wiki/File:Eisenbahn_Schraubenkupplung_1.jpeg


Chain coupler detail (train in shunting mode)

Cars coupled in ride mode

The standard type of coupling on railways following the British tradition is the buffer and chain coupling used on the pioneering Liverpool and Manchester Railway of 1830. These couplings followed earlier tramway practice but were made more regular. The vehicles are coupled by hand using a hook and links with a turnbuckle-like device that draws the vehicles together. In Britain, this is called a screw coupling. Vehicles have buffers, one at each corner on the ends, which are pulled together and compressed by the coupling device. This arrangement limits the slack in trains and lessens shocks. In contrast, Janney couplers encourage comparatively violent encounters in order to engage the coupling fully. The earliest buffers were fixed extensions of the wagon frames, but later spring buffers were introduced.

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http://en.wikipedia.org/wiki/File:Chain_coupler_detail.jpg

http://en.wikipedia.org/wiki/File:Coupler_ride_mode.jpg


AUTOMATIC COUPLER

JANNEY COUPLER

Later Master Car Builders Association coupler, now AAR (Association of American Railroads) coupler; also known as knuckle coupler and alliance coupler.

Diagram of the top view of Janney's coupler design as published in his patent application in 1873.

The knuckle coupler or Janney coupler was invented by Eli H. Janney, who received a patent in 1873 (U.S. Patent 138,405) [2]. It is also known as a "buckeye coupler", notably in the United Kingdom, where some rolling stock (mostly for passenger trains) is fitted with it. Janney was a dry goods clerk and former Confederate Army officer from Alexandria, Virginia, who used his lunch hours to whittle from wood an alternative to the link and pin coupler.

In 1893, satisfied that an automatic coupler could meet the demands of commercial railroad operations and, at the same time, be manipulated safely, the United States Congress passed the Safety Appliance Act. Its success in promoting switchyard safety was stunning. Between 1877 and 1887, approximately 38% of all railworker accidents involved coupling. That percentage fell as the railroads began to replace link and pin couplers with automatic couplers. By 1902, only two years after the SAA's effective date, coupling accidents constituted only 4% of all employee accidents.

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http://en.wikipedia.org/wiki/File:Railroad_coupler_diagram.jpg

http://en.wikipedia.org/wiki/File:Railroad_coupler_diagram.jpg


Coupler-related accidents dropped from nearly 11,000 in 1892 to just over 2,000 in 1902, even though the number of railroad employees steadily increased during that decade.

When the Janney coupling was chosen to be the American standard, there were 8,000 patented alternatives to choose from. The only significant disadvantage of using the AAR (Janney) design is that sometimes the drawheads need to be manually aligned.

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ENERGIZING A DEAD OR STABLED ELECTRIC LOCO Whenever the locomotive is not required for the use, the locomotive is switched off and its pantograph lowered, and it is stabled on a suitable line in dead condition. While energizing such a dead or stabled locomotive, certain precautions are to be followed. These are explained below.

1. Locomotive log book inspection

This should be gone through minutely and information if any regarding defects or any special working instructions for the locomotive are to be found out. If the locomotive has been made dead for attention of some defects, etc., the locomotive must not be energized before these defects are dealt with. After the logbook is inspected to satisfaction and it is certain that there is nothing wrong in energizing the locomotive the following procedure is to be followed.

2. Checking of the safety fittings of the locomotive

All the safety fittings of the locomotive should be checked. If the locomotive is stabled on the pit, the underframe safety fittings must be checked and must be ensured that all the safety fittings are intact.

3. up the emergency reservoir pressure and raising the pantograph Building

After checking the safety fittings, the battery should be switched 'ON' with HBA switch and baby compressor (MCPA) should be started. During the process RAL cock which connects the emergency reservoir to the air circuit of the locomotive should be closed. When the emergency reservoir pressure builds upto 7 to 8 kg/cm^2. The RAL cock should be opened. After building up the pressure, it must be ensured that locomotive is under the OHE. After this Panto should be raised with the help of ZPT key. A sound of an transient arc or spark will be heard when the pantograph touches the OHE, which gives an indication that the OHE is live. The BL key and MPJ should be fitted in its position.

4. Putting the isolation cocks of brakes in proper position

The isolating cocks of the locomotive brake and train brake in the working cab should be in open position and in the rear cab they should be in closed position. This should be ensured before closing DJ.

5. Inspection of switch board/relay boards

5a. Program switches

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This board is provided behind cab No 2. All the program switches should be at '1' position. If any of the switches is not in '1' position the reason for the isolation of respective relay or equipment should be ascertained and action taken accordingly.

5b. Condition of Relays

The condition of the relay targets should be inspected. No relay target should be in a dropped condition. If the target of any relay is dropped, it should checked for any defects and action taken accordingly.

6. H.T. Compartment Tour

A walk-through of the locomotive corridor is necessary for visual inspection of the condition of the H.T. compartment. There should not be any abnormalities like leakage of TFP/GR oil, etc.

7. Closing of DJ

Now the DJ of the locomotive can be closed by depressing the BLDJ and then depressing BLRDJ. The DJ will then close and this will result in a change in the voltmeter which should now show a reading of approximately 25kV. The BLCP switch should then be turned ON immediately to start the compressor to build up main reservoir pressure of 8 to 10 kg/cm^2.

8. Testing of locomotive brake

After building up the MR pressure and releasing the hand brake of the locomotive (if in applied condition), the locomotive brake must be tested and it should be ensured that the brake power is adequate. Any skids or wheel blocks placed under the wheels of the locomotive, should now be removed.

9. Traction testing of the locomotive

After moving the MPJ to the forward and reverse positions, the pilot lamp LSB should now extinguish itself. If it does not extinguish itself even with the MPJ in forward or reverse position, the necessary trouble-shooting procedure has to be followed, such as verifying the reverse and Q 50 relays.

Following this, the MPJ should be kept in the forward position and with the help of MP two or three notches should be taken by keeping locomotive brakes applied so that locomotive does not move. As soon as one notch is taken the LSGR lamp should extinguish itself. The same testing should be done by keeping the MPJ in reverse position.

10. Checking of emergency brake

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After taking two to three notches as above, the vacuum or air pressure should be destroyed by applying the emergency brake. The brake should now be applied on the locom

otive and at the same time the notches should come to zero automatically.

11. Checking the work of EEC

The ZEMS switch should be kept at the '1' position and the MP on the 'N' position; the push-button switch for operation of EEC should now be depressed. The notches should come down one by one with each push of EEC push button.

12. Checking of Headlight, Marker light, Flasher light

The working of the headlight, marker lights and flasher light should be checked from both the cabs. After carrying out these checks and inspection the locomotive is ready to be worked.

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WHEELSET

A wheelset is the wheel-axle assembly of a railroad car. The frame assembly beneath each end of a car, railcar or locomotive that holds the wheelsets is called the bogie

CONICAL SHAPE

Most wheels have a conical shape of about 1 in 20. The conical shape has the effect of steering the wheelset around curves, so that the flanges rarely come into play. The rails generally slant in at the same rate as the wheel conicity. As the wheels approach a curve, they will tend to follow a straighter path. This causes the wheelset to shift sideways on the track so that the effective diameter of the outer wheels is greater than that of the inner ones. Since the wheels are joined rigidly by the axle, the outer wheels will travel further, causing the train to naturally follow the curve.

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