rdso training report -navin dixit
TRANSCRIPT
RDSO Summer Training 2014
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S.no. Page no
1. Acknowledgement 02
2. Introduction 03
3. Testing Directorate 06
4. Test cell laboratory 07
(a Quality of ride 08
(b Stability & Dynamic forces 10
(c Drailment coefficient 13
(d Instrumentation 14
5. Fatigue testing laboratory 17
(a 100 ton system 17
(b 500 ton system 19
(c Stress measurements 24
6. Brake dynamometer laboratory 27
(a Test procedure and particulars 29
7. Air brake laboratory 32
(a Types of AB system 34
(b Working principle 35
(c Salient features 38
(d AB system test rig 41
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Creation of this report is influenced by numerous persons working
under the esteemed organization established by Indian Government
, RDSO. It is an archetype of best research center of India. As
engineers the training experience have explored an another
dimension and platform for our thinking .
I would like to express our sincere gratitude to Mr. D. K. Srivastav
(Testing Directorate Head of RDSO) for providing administrative
permission for my summer training and Also igniting curiosity and
emancipating our thinking from the boundary of engineering .
I am thankful to all the lab in-charge and superintendents and
with whose support and guidance the creation of report came to
existence .
I duly express my indebtness to Mr. Rajesh Gupta (Incharge
Training) for their kind support in helping me get settled in an
entirely new space to work and gain.
I am very thankful to Mr. H.N. Gupta(visiting faculty) for
enhancing my technical knowledge which made the understanding
of practical concepts easy.
Last , but not the least our gratitude and indebtness are also due to
some unnamed persons who remained unexpressed in words.
-Navin Dixit
B.tech (ME)
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Indian railways is a mammoth organization with a budget
running in to the thousands of crores and with a employee rtrength
of 1.6 million much more than the strength of Indian army.Such a
big organization like the IR can not run efficiently without
adequate R&D and design support. This is provided by RDSO at
lucknow.
Railways were introduced in India in 1853 and as their
development progressed through to the twentieth century, several
companies managed and state-owned railway systems grew up. To
enforce standardization and co-ordination amongst various
railway systems, the Indian Railway Conference Association (IRCA)
was set up in 1903, followed by the Central Standards Office (CSO) in
1930, for preparation of designs, standards and specifications.
However, till independence, most of the designs and manufacture of
railway equipments was entrusted to foreign consultants. With
Independence and the resultant phenomenal increase in country‟s
industrial and economic activity, which increased the demand of
rail transportation- a new organization called Railway Testing
and Research Centre (RTRC) was setup in 1952 at Lucknow, for
testing and conducting applied research for development of railway
rolling stock, permanent way etc.
Central Standards office (CSO) and the Railway Testing and
Research Centre (RTRC) were integrated into a single unit named
Research Designs and Standards Organization (RDSO) in 1957,
under Ministry of Railways at Lucknow.
The status of RDSO has been changed from an „Attached Office‟ to
„Zonal Railway‟ since 01.01.2003.
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ORGANISATION
RDSO is headed by a Director General. The Director General is
assisted by additional Director General, Sr. Executive Directors and
Executive Directors, heading different directorates. RDSO has
various directorates for smooth functioning:
Bridges and Structures , Carriage , Defense Research , Electrical
Loco , EMU & Power supply , Engine Development , Finance &
Accounts ,Geo-technical Engineering ,Quality Assurance,
Metallurgical & Chemical,Motive Power, Psycho-technical , Research
,Signal , Telecommunication ,Track ,Testing,Track Machines &
monitoring, Traction Installation, Traffic, Wagon
All the directorates of RDSO except Defense Research are located at
Lucknow. Cells for Railway Production Units and industries, which
look after liaison, inspection and development work, are located at
Bangalore, Bharatpur, Bhopal, Mumbai, Burnpur, Kolkata,
Chittaranjan, Kapurthala, Jhansi, Chennai, Sahibabad, Bhilai and
New Delhi.
QUALITY POLICY
To develop safe, modern and cost effective Railway technology
complying with Statutory and Regulatory requirements, through
excellence in Research, Designs and Standards and Continual
improvements in Quality Management System to cater to growing
demand of passenger and freight traffic on the railways.
FUNCTIONS
RDSO is the sole R&D organization of Indian Railways and
functions as the Technical advisor to Railway Board, Zonal
Railways and Production Units and performs the following
important functions:
Development of new and improved designs.
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Development, adoption, absorption of new technology for use
on Indian Railways.
Development of standards for materials and products specially
needed by Indian Railways.
Technical investigation, statutory clearances, testing and
providing consultancy services.
Inspection of critical and safety items of rolling stock,
locomotives, signaling & telecommunication equipment and
track components.
RDSO‟s multifarious activities have also attracted attention of
railway and non-railway organizations in India and abroad.
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Testing Directorate is the premier directorate of RDSO undertaking
design validations of all newly designed/modified rolling stock
developed in-house or imported, employing the latest state-of-the-
art data acquisition and analysis tools and techniques. Besides
undertaking actual field trials, this directorate has three
laboratories for conducting stationary tests as well.
In the year 1989 the present Testing directorate was created for
carrying out all dynamic and static mechanical testing activities of
all type Railway Rolling stocks. This directorate is looked after by
Executive Director Research Testing.
The various tests and trials done by Testing Directorate can be
broadly classified into Field Trials and Laboratory Tests. Field Trials
are those trials which are conducted on newly designed prototypes
and modified rolling stock, for assessing ride quality and ride
comfort apart from Route proving runs, Brake trials and Coupler
force trials to assess their behavior in actual operating conditions.
Testing Directorate has also been entrusted with carrying out
periodic track monitoring runs on Rajdhani and Shatabdi routes.
Laboratory Tests are conducted on newly designed sub-assemblies
and Rolling Stocks components as well as quality audit check for
assessing the suitability by simulating service condition /field
condition in three well equipped and modernized laboratories.
Well-qualified, fully trained and vastly experienced dedicated team
of 11 officers and 52 mechanical and instrumentation supervisors of
the Directorate are geared to meet the challenges posed in the field
of testing of railway vehicles and their components.
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FIELD TRIALS OF ROLLING STOCK
Whenever a railway vehicle undergoes a modification or a new
vehicle design is sought to be introduced, Field Trials are
mandatory before the Commissioner of Railway Safety permits their
introduction into the Railway system.
Testing Directorate has five field units to conduct various Field
trials like Oscillation trials, Confirmatory oscillograph car runs,
Track Monitoring runs, Brake trials of passenger & goods trains,
Jerk trials, Emergency Brake trials, Coupler force measurement and
Rating & Performance trials of locomotives.
It includes following trials:
• Oscillation trial
• Emergency Braking Distance trials
• Coupler Force and controllability
• Rating and Performance of locomotives
• Stress investigation of prototype shell of coach/wagon
• Regular track monitoring run
• Confirmatory oscillograph car run of loco/coach
Oscillation trial is conducted on a new or modified design of
rolling stock, which is proposed to be cleared for running on IR
track. The purpose of oscillation trial is, thus, an acceptance of a
railway vehicle by conducting dynamic behaviour tests in
connection with safety, track fatigue and quality of ride.
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An oscillation trial can be commenced only after receipt of CRS
sanction. CRS sanction is accompanied by Joint Safety Certificate
from the Railway and Speed Certificate issued by RDSO. In addition,
documents like, „List of curves and bridges‟, „Permanent and
temporary speed restrictions‟ on the route from the railway
applicable on the day of run, „Test scheme‟ from the
sponsoring/design directorate and latest summarised „TRC results‟
for selected detailed test stretches are needed to conduct the trials.
The „test scheme‟ includes objective of trial, background of trial,
various trial conditions, measurements and parameters to be
recorded, design particulars of the test vehicle, load vs. deflection
charts for individual and nested springs, necessary drawings of
bogie, axle box etc for load-cell fitment, instrumentation etc.
The oscillation trial is carried out either on „Main line‟ for
operation at less than 110 kmph on 52 kg rail or on 90R rail track
and/or on „High-speed line‟ for operation at 110 kmph or above and
up to 140 kmph on track maintained to C&M1-Vol.1 standard.
Quality of Ride
Human sensation of comfort is dependent on displacement,
acceleration and the rate of change of acceleration. In other words,
the product of displacement, acceleration and the rate of change of
acceleration could be used as a measure of discomfort during
travel.
For sinusoidal vibration with β as the amplitude and as its
periodicity, the formula, developed by Dr. Sperling, hence known as
Sperling‟s Ride Index, can be derived as under:
Displacement: s = * sin t
Velocity: v = ds/dt = * cost
Acceleration: adv/dt = * * sin t
Impulse: I = da/dt = - * * cos t
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Thus, level of discomfort a * I * s
Taking the maximum value of parameters over the half wave of
displacement,
The level of discomfort (- )* (- )* (
or, 3
Defining the RI as a measure of discomfort,
RI 3
or, RI = k* 3 *
If „b‟ is the amplitude of acceleration, then, b = * and also, = 2f
where, f is the frequency of vibration. Substituting and in
equation (1) above,
RI = k * (-b/2)3 * 5
= - k * b3 /
= K * b3 / f
For an individual, the sensation of vibration varies according to an
exponential law and thus,
RI = 0.896 * (b3 / f )0.1 --------- (2) (for ride quality)
In order to take human reactions, the formula is modified taking
into a correction factor and thus,
RI = 0.896 * [b3 * (f) /f ]0.1 -------- (3) (for ride comfort)
The term Ride quality means that the vehicle itself is to be judged.
Ride comfort means that the vehicle is to be assessed according to
the effect of mechanical vibrations on people in the vehicle.
RIDE QUALITY
Ride Index Appreciation
1 very good
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2 good
3 satisfactory
4 accepted for running
4.5 not accepted for running
5 dangerous
RIDE COMFORT
Ride Index Appreciation
1 just noticeable
2 clearly noticeable
2.5 more pronounced but not unpleasant
3 strong, irregular but still tolerable
3.25 very irregular
3.5 extremely irregular, unpleasant, annoying, prolonged
exposure intolerable
4 extremely unpleasant, prolonged exposure harmful
Stability & Dynamic Forces
Vertical and lateral forces are developed between the rail and the
wheel as a result of dynamic interplay of track and vehicle
characteristics. It is important to understand these forces because of
their role in vehicle stability and track stresses. Generally these
forces can be classified into three categories, namely, static forces,
quasi-static forces and dynamic forces.
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Static forces arise due to static wheel load applied on the rail.
Quasi-static forces are developed due to one or several factors, which
are independent of the parasitic oscillations of the vehicle and do
not vary in a periodical manner. Centrifugal forces caused by cant
excess or deficiency, curving action on points and crossings and
forces due to cross winds fall in this category.
Dynamic forces are caused by track geometry and stiffness
irregularities, discontinuities like rail joints and crossings, wheel set
hunting and vehicle defects like wheel flats. Dynamic forces are the
most significant ones in the study of vehicle stability and rail
stresses and are also the most difficult to mathematically determine
or to experimentally measure.
According to Esveld, the frequency ranges for the vertical dynamic
forces are 0-20 Hz for sprung mass, 20-125 Hz for un-sprung mass
and 0-2000 Hz for corrugations, welds and wheel flats. The vertical
forces in the lower frequency range are produced due to vehicle
response to changes in the vertical track geometry like unevenness
and twist whereas forces in the higher frequency range are caused
by discontinuities like rail joints, crossings, rail and wheel surface
irregularities. A wheel flat produces high frequency peaks at regular
intervals, which is easily distinguishable from other surface
irregularities.
QSL
2B QSR
H C
YL
A B YR
QL
2G QR
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The net lateral forces acting on the track by the wheel set can lead
to the distortion of track laterally, causing derailment. In other
words, this force is a measure of lateral strength of the track. This
force is equal to the lateral force at axle box level as a result of
reaction of the wheel set with the vehicle body/bogie. This force,
usually denoted by the symbol Hy
, can be measured with the help of a
load-cell placed between the journal face and the axle box cover or
the bogie frame and the axle box.
In the given diagram, QR
or QL
is vertical wheel load at rail level, QSR
or QSL
is vertical wheel load measured at axle box level, 2B is
distance between springs, 2G is track gauge, C is axle height from
rail level and H is net compressive force measured at axle box level.
Taking moment of forces about point A or B, we get,
QR
= [(B+G)/2G]*QSR
– [(B-G)/2G]*QSL
+ [C/2G]*H
QL
= [(B+G)/2G]*QSL
– [(B-G)/2G]*QSR
- [C/2G]*H
Thus, measuring H and spring deflection can compute Q at rail
level computed by above formula.
„Off-loading‟ and „On-loading‟ of the test vehicle is represented in
percentage. It is calculated as % off-loading = 2*k*(-/P and % on-
loading = 2*k*(+ /P, where, is the spring deflection in mm, P is axle
load in tonnes and k is spring stiffness in tonnes/mm for springs
fitted on the wheel. To calculate maximum off-loading and on-
loading max is used, where, -max is maximum spring deflection in
expansion and +max is maximum spring deflection in compression.
The concerned Design Directorate furnishes the primary and
secondary spring heights at different axle loads, in a tabular form,
at increments of 0.5 tonnes along with the test scheme. The above
treatment assumes that the vertical forces due to the unsprung
masses remain at their static value. When a measuring wheel is
used, the maximum and minimum values of QL
and QR
are
determined. These values, when divided by the static wheel load,
indicate the true On-loading and Off-loading of the wheels.
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Derailment Coefficient
Derailment can happen when the values of lateral and vertical
forces acting at the rail-wheel contact point assume a critical
combination leading to mounting of the flange on the rail. This
phenomenon is known as derailment by flange mounting
All the theories that have been evolved to explain the phenomena of
derailment have tried to establish a suitable ratio between the
instantaneous values of lateral force and vertical force at the rail-
wheel contact point beyond which derailment may occur.
Mr J.Nadal, Chief Mechanical Engineer of French State Railway
propounded the earliest of these theories of derailment by wheel
flange mounting the rail in 1908.
Consider a flanged wheel supporting a load Q and subjected to a
lateral thrust Y passing round a curve. It is seen that the point of
contact between the flange and the rail will be slightly ahead of the
wheel center line so that at the point of contact the flange will have
a small movement downwards, producing a frictional reaction Y in
an almost vertical direction.
Q wheel
µY
wheel
Rail Y Rail
QR
µQR
The flange will begin to climb the rail as soon as the frictional force
µY exceeds the load Q. Let the flange make contact with the rail at
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some angle and the lateral force Y produce a reaction QR
from the
rail at the point of contact.
Then, resolving the forces, it is seen that if the wheel is not to derail,
Q Sin – Y Cos – QR > 0 --------------- (1)
QR = Y Sin + Q Cos --------------- (2)
Substituting QR
in equation (1),
Q Sin - Y Cos - [ Y Sin + Q Cos ] > 0
Or, Q [ Sin - Cos ] – Y [ Cos + Sin ] > 0
Or, Q [ Sin - Cos ] > Y [ Cos + Sin ]
Or, Y/Q < [ Sin - Cos ] / [ Cos + Sin ]
Or, Y/Q < [ tan - ] / [ 1 + tan ]
Where, Y and Q are the instantaneous values of the lateral and
vertical forces at the rail-wheel contact pointis the angle of
flange with horizontal plane and is the coefficient of static
friction between wheel tread and rail. It can be seen from Nadal‟s
formula that for =0.27 and =600
, Y/Q =0.997 or 1. This is the
limiting value beyond which the wheel flange will tend to mount on
the rail table. The other question is that of the duration for which
this ratio can exceed the value of 1. It is well known that derailment
by flange mounting is not an instantaneous, but a gradual process.
In Japanese Railways, the limiting value of Y/Q is taken as 0.04/t if t
is less than 1/20 seconds and 0.8 if exceeds 1/20 seconds.
Instrumentation
The instrumentation is done as per test scheme. Normally,
instrumentation used for recording data is transducers as input
device, signal conditioners as processing device and chart recorders
and/or computerised data acquisition system as output device.
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Power supply unit is used to provide power supply to signal
conditioners and recorders and excitation to passive transducers.
Transducers are used to measure acceleration, deflection and force.
Signal picked up from transducer is fed into signal conditioner for
processing. The processed output from signal conditioner can be
recorded on chart recorder and/or acquired on computer (PC or
laptop) through data acquisition cards.
Transducers normally used are passive types either resistive or
inductive. Transducer used for measurement of acceleration in x, y
and z directions is also called accelerometer and can be either
„strain gauge type‟ or „piezo electric‟. Transducer used for
measurement of deflection of spring, bolster, bogie movement etc
can be either LVDT, i.e., linear voltage differential transformer or
string-pot. Transducer used for measurement of force or load at axle
box level is normally a load-cell. Measuring wheel measures lateral
and vertical forces at rail wheel level. Transducers are excited either
by 5V rms 2.5 kHz AC or DC voltage to provide output signal.
Load cell assembly is used for recording lateral forces at axle box
level. Load cell of strut type is manufactured in-house suiting to the
axle box arrangement with range of measurement from 0 to 10t
compressive load only. Load cell is of full bridge resistance type and
calibrated with excitation voltage from 5 to 10V AC and under pre-
calibrated hydraulic jack. Its output is about 90 mV/V/tonnes. A
load cell calibration chart is prepared with load in tonnes on x-axis
and mV output on y-axis. The excitation voltage used during
calibration is mentioned in the chart. Care should be taken to use
the same excitation voltage during trial.
Measuring wheel is used for measuring vertical and lateral forces at
rail wheel level. FEM analysis of wheel conforming to s-shape web
profile is carried out to determine the strain gage locations sensitive
to vertical and lateral force. The strain gage locations used for
measurement of lateral force are having minimal effect of vertical
wheel load and similarly, strain gages for vertical wheel load are
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having minimal influence of lateral load. The cross talk between
vertical and lateral forces is kept to the barest minimum while
selecting the locations.
Wheatstone bridges are formed for vertical and lateral force
measurement channels. Measuring wheel supplied by Swede Rail has
two vertical and one lateral load sensing bridges per wheel. Sixteen
strain gage locations have been selected for vertical bridge with two
gages per arm and twelve locations for lateral bridge with three
gages per arm. This means that in one revolution of the wheel two
vertical and one lateral value would be obtained. Measuring wheel
supplied by AAR has one position channel in addition to above,
which indicates the rail wheel contact point.
Output of channels is taken from slip-ring device fitted on axle end
cap. AAR measuring wheel-set has slip-ring device on both ends of
the axle. Swede Rail measuring wheel-set has slip-ring device on one
end of the axle. Output signal lead from left wheel to right wheel is
transferred through a hole drilled in the axle. This has been done to
save the cost of slip-ring device.
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1) 100 TON CAPACITY FATIGUE TESTING SYSTEM
Introduction: To conduct general fatigue test on full scale
structures a closed loop electro-hydraulic servo controlled fatigue
testing system of 44 tone capacity with facility of testing full size
structures simulated service condition was installed in the fatigue
lab of RDSO in year 1972. This system was procured from MTS/USA.
Then because of the capacity and design constraint a new 100 tone
capacity fatigue system was procured from M/s Instorn U.K. and
installed in fatigue lab in 1997.
Salient Feature of the system: The test system basically consists of
closed loop electro-hydraulic computerized fatigue testing
equipment. It is provided with two hydraulic power supplies for
generating high hydraulic pressure required for producing the
desire forces. The high pressure hydraulic fluid at 210 Kg/cm2 is fed
to the hydraulic actuator to the maximum rate of 500 LPM, through
a servo-value. The actuator, which is a cylinder piston
arrangement, applies the compressive/tensile forces to the specimen
mounted on the test bed. The desired level of loading is achieved by
the controller in computerized control equipment of the system. A
command signal is fed to the input module which passes it on to a
servo controller. The desired dynamic wave form is provided by a
function generator. The controller sends electronic signal to the
servo valve to regulate its port opening in such a manner as to
achieve the desired load level. A feedback transducer introduced in
the system, sense the load applied to the specimen and sends a
proportional signal to the input module. Here, the feedback is
compared with the command and any difference in their
magnitudes or polarity is corrected through an electronic signal to
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the controller. With this arrangement any continuously varying
command is reproduced faith fully.
The desire load is achieved through under mentioned set of
dynamic actuators, one 50 tone and three 35 tone capacity reaction
frames mounted on rail type slotted bed of 7.5m*14m size.
Capabilities of system: System can provide dynamic and static
loadings on two axes simultaneously up to a maximum load of 100
tones in combination of above mentioned actuators. System has
facility to provide sine, square, haver-sine and triangle waveforms
of loading in dynamic mode.
Benefits: Rolling stock components like bogie frame and bolster of
Box- N wagons, Coaches and locomotives, Side bearer pads, friction
snubbers, brake beams, buffer springs, elastomeric pads, upper and
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lower spring pads, bridge stringers Composite material sleepers etc.
are regularly being tested on this machine.
S/No.
Type of
actuators
Quantity
Capacity
Stroke
Frequency w.r.t.
Displacement
Remarks Displacement
in mm
Frequency
in Hz
1.
Dynamic
Actuator
04Nos.
25 tones
+-
50mm
2.5 10 Actuators can work in
compressive as well
as in tensile mode
also
50 0.3
2. Dynamic
Actuator
02Nos.
10 tones
+-
50mm
2 10 Actuators can work in
compressive as well
as in tensile mode
also
50 0.5
2) 500 TONES CAPACITY STRUCTURAL
FATIGUE TESTING SYSTEM
Introduction:
Before Sep-2010, Fatigue testing lab of Testing Directorate was
equipped with 100 tones capacity fatigue testing system with a
maximum of 25 tones load actuators. This system was capable to
cater the general fatigue testing requirements of bogie frame and
bolster of existing wagon with maximum axle load of 22.82 tones.
Towards the process of development of high axle load wagons, RDSO
now is in process to develop the higher axle load wagons as per the
AAR standards. The bogies and bolsters of higher axle load wagons
are supposed to clear the accelerated fatigue testing on 453 tones
static and dynamic loadings as per the AAR test criteria. Hence this
system has been procured to cater the future testing requirements for
higher axle load wagons as per the AAR testing parameters.
Salient Feature of the system:
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This system is very high capacity equipment which can test the
specimen up to a load of 500 tones in static and dynamic modes.
But it has been designed in such a way that this huge system can be
utilized for testing of smallest components of rolling stock under 0.5
tone also, for its optimum utilization. The system is equipped with
two hydraulic power units with six pumps of 100 LPM in each HPU to
generate 3000 PSI hydraulic pressure on 1200 LPM discharge rate to
achieve the desire load through under mentioned set of dynamic
and static actuators and 500 tone capacity reaction frame on 10*10
meter “T” slotted bed plate, which can bear 600tones load.
The test system basically consists of closed loop electro-hydraulic
computerized fatigue testing equipment. It is provided with a
hydraulic power supply for generating high hydraulic pressure
required for producing the desired forces.
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The high pressure hydraulic fluid at 3000 PSI is fed to the hydraulic
actuator through a servo-value. The actuator, which is a cylinder
piston arrangement, applies the compressive/tensile forces to the
specimen mounted on the test bed. The desired level of loading is
achieved by the controller in computerized control equipment of the
system. A command signal is fed to the input module which passes it
on to a servo controller. The desired dynamic wave form is provided
by a function generator. The controller sends electronic signal to
the servo valve to regulate its port opening in such a manner as to
achieve the desired load level. A feedback transducer introduced in
the system, sense the load applied to the specimen and sends a
proportional signal to the input module. Here, the feedback is
compared with the command and any difference in their
magnitudes or polarity is corrected through an electronic signal to
the controller. With this arrangement any continuously varying
command is reproduced faithfully.
S/No.
Type of
actuators
Quantity
Capacity
Stroke
Frequency w.r.t.
Displacement
Remarks Displacement
in mm
Frequency
in Hz
1.
Dynamic
Actuator
04Nos.
25 tones
+-
50mm
2.5 10 Actuators can work
in compressive as
well as in tensile
mode also
50 0.3
2. Dynamic
Actuator
02Nos.
10 tones
+-
50mm
2 10 Actuators can work
in compressive as
well as in tensile
mode also
50 0.5
3. Static
Actuator
04Nos.
75 tones
300mm
Not applicable
Actuators can work
in compressive mode
only
The other important features are as under:
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1. Automotive test controller for controlling 8 actuators
upgradable up to 32 actuators.
2. 96 channel data acquisition system for on line stress
recording.
3. T-slot bed plate of 10m*10m size which can bear dynamic load
of 500 tones.
4. Four column portal frame of 500 tones capacity.
5. 6-point concentrator of 600 tones capacity and 3 point force
concentrator for combined load application of multiple
actuators.
6. Manual movement of ram of actuators through pendant.
7. Hydrostatic bearings have been provided in all the actuators
to bear maximum angular thrust.
8. Height of transverse beam can be adjusted through motorized
lifting device with laser beam safety monitoring system.
9. Heavy duty spring loaded roller clamp for easy sliding of cross
beam and actuators.
FOLLOWING FEATURES MAKE‟S THIS SYSTEM DIFFERENT FORM THE 100
TONE INSTRON MAKE OLD FATIGUE TESTING SYSTEM
1. This system can test the specimen up to 500 tones static and
dynamic load whereas old Instron machine is capable to test
up to 100 tones only.
2. A wide range of testing can be accomplished on these heavy
load actuators with +-125mm stroke whereas max. stroke of
Instron make actuators are +-50mm.
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3. Automotive test controller for controlling 8 actuators with
smart wave software capable of sequential loading between two
to all eight actuators on different load, different frequency
and different phase.
4. Facility to provide different waveforms of loading: sine, square,
ramp, rounded ramp, haver-sine and triangle.
5. Facility to provide vertical loading, lateral loading and
longitudinal loading simultaneously in different phase,
frequency and amplitude.
6. System can run in automatic mode on pre-programmed
loading test scheme.
7. 96 channel data acquisition system for on line stress recording
with auto channel balancing and auto calibration.
8. Facility of simultaneous acquisition and real time display of
feedback channels (position & load) of actuators with stress
value.
9. System to measure deflection up to 1 inch with accuracy of
0.001 inch.
10. Continuous running of the machine with feedback system
through SMS in case of any breakdown in the machine. This
facility will reduce testing time and manpower in other than
general shifts.
Capabilities:
1. This system can test the specimen upto 500 tones static and
dynamic loads.
2. Future heavy axle load wagons bogie, bolster and other
components can be tested as per AAR standards.
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3. Load deflection test and energy characteristics test can be done
on helical springs and rubber buffer springs through the machine,
since stroke of the actuators are 250mm.
4. Calibration of CBC can be done in tensile and compression mode
at 150 tones.
5. With the help of 96 channel data acquisition system on line stress
recording with auto channel balancing and auto calibration
which shows directly stress value. This reduces the testing time and
analysis time of data.
6. T-slot bed plate provides lot of flexibility while mounting the test
sample under the actuators.
7. Two hydraulic power supply units each provided with six pumps
with automatic flow control to save the power i.e. No of motors in use
will automatic are selected by the system depending upon the oil
flow requirement
Benefits: Accelerated Fatigue Testing of Bogies & Bolster of high axle
load wagons as per AAR specifications. This Fatigue Testing Machine
will help for design validation of high axle load wagons i.e. 25t
wagon & 32.5t etc. & other rolling stocks (coach & locos) also by
simulating field load conditions. This will also help to improve the
reliability of wagon bogie, bolster and other structure by assessing
the fatigue life of sub assembly.
STRESS MEASUREMENTS
The bogie is strain gauged at locations specified in the test scheme,
which are mostly linear gauges and a few three-directional Rossette
gauges. Each gauge (the arm in the case of Rossette gauges) fixed
on the bogies frame, functions as an active arm of Wheatstone
bridge for monitoring the strain / stress. The remaining three
gauges required to form the Wheatstone bridge, called the dummy
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gauges, are cemented on steel strips mounted on a junction box,
kept close to the bogie frame during the course of the tests.
Terminals of the bridge, thus formed, are connected to the recorder
(visicorder). During the stress recording in static condition, the
bogie is subjected to the desired load combinations and three sets of
readings are taken for every load combination. It is generally
noticed that the difference between the three readings is practically
negligible. Before conducting the dynamic stress measurement, the
bogie frame is subjected to the desired load combinations for at
least for 3 to 5 minutes and thereafter, the readings are taken.
FATIGUE TEST
The bogie frame is subjected to fatigue test by applying dynamic
load combinations as per test scheme. The load application is of
sinusoidal nature, which is achieved with the help of the function
generator available with control panel of the fatigue testing
equipment. Fatigue tests are carried out upto 10 million cycles. The
test frequency, with the stablised test set up, is achieved as 3 to 4 Hz.
All the dynamic load actuators are applying load at the same
frequency and in the same phase.
VERTICAL LOAD APPLICATION AND REACTION
The bogie frame is placed on the four vertical stools clamped with
the test bed. The loading is done with the help of load actuators,
each with the capacity of +10 or 25 t mounted on the two separate
main reaction frames capable of bearing 30 or 50 t force and
located longitudinally on both the sides of test bed, through two
loading beams placed at the ends of bolster which, in fact, is kept on
two specially designed steel tubes (in place of secondary springs)
placed in the spring seat guide located in the middle of the side
frames.
Reaction of the vertical load at axle box location is attained
through fabricated steel tubes placed between the bogie frame and
vertical stool at all the four locations. Specially designed load cells,
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one each at all the four axle box locations, are inserted between the
stool and the steel tubes for equalizing the load distribution.
TRANSVERSE LOAD APPLICATION AND REACTION
A U-type clamp is mounted in the middle of the one of the side
frames on the existing bracket welded to the bogie frame. The
transverse load is applied centrally with the help of the +10 t
capacity dynamic actuators, held horizontally on the specially
designed brackets mounted on the test bed.
Transverse reaction is taken at all the axle box locations by suitable
reaction brackets clamped on the test bed.
TRACTIVE LOAD / BRAKING FORCE AND REACTION
Longitudinal loads, simulating tractive / braking load and their
reactions, are applied on the bogie frame separately. For the
purpose of braking force, loads are applied simultaneously at four
brake hanger locations, through two static jacks in the upward
direction, and through two pre-calibrated helical springs in the
downward direction. The tractive / braking loads are applied on
the two anchor links in the same direction through two static jacks
mounted horizontally on the two brackets, and their reactions are
taken in the opposite direction at the end of each side frame.
VISUAL EXAMINATION
Visual examination of the bogie frame is to be done regularly
throughout the test to check if any crack or deterioration in the
bogie frame, has got developed.
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Gyrating Mass Brake Dynamometer
Brake Dynamometer Laboratory of RDSO has a dynamometer
supplied by M/s MAN, Germany.It was commissioned in 1974 for
study of brake material characteristics, development of new brake
materials, study of braking effect on wheels and quality control of
brake block.
The dynamometer has facilities for simulation of maximum road
speed of 245kmph with a one meter dia wheel. An axle load up to
25t. And maximum brake force of 6000kg pr brake block can also be
simulated. In addition to dry rail condition, spraying water
continuously on the wheel surface can also simulate wet rail
conditions.
For simulation of air impinging on the wheel, while the train is
running, blower fan having speeds of 750,1000 and 1500rpm has
been provided with the equipment and for extracting smoke, fumes
and dust of the brake blocks from the test space, exhaust fan having
3speeds of 750,1000 and 1500rpm is also provided.
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The control room has a control desk, which accommodates, control
and indicator switches and a data acquisition system .A dial meter
displays the brake cylinder pressure Rotation speed of wheel and
braking time is digitally displayed.
Various brake characteristics e.g. speed, braking time, run out
revolution, brake torque, brake horse power, brake energy are
recorded by the data acquisition system. The temperature of the
Brake Block is also recorded in the data acquisition system, and the
temperature of the wheel is digitally displayed separately. The value
of mean coefficient of friction for individual brake applications is
also recorded in DAS.A graph of instantaneous µ versus speed is also
drawn for each brake application.
BRAKE BLOCK SAMPLES
FOR TESTING
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Test Procedure And Allied Particulars:
Physical Check:
After the receipt of the brake block samples in the laboratory, these
are registered and identification numbers are stamped on each
brake block. These brake blocks are physically checked to ensure that
they match the wheel profile of the rolling stock for which testing is
to be done.
Bedding:
The brake blocks are then fitted on the dynamometer for bedding to
achieve about 80% of the block contact area .This exercise is
necessary to have a uniform distribution of brake block force over
the full brake block area during the tests. Bedding of the brake
block is done at a speed of 60km/hr and with a brake block force of
2000kg .During bedding a wheel temperature up to 100 degree
centigrade is maintained. After the contact area of the brake block
is needed to about 80%, tests are started.
Dry Tests:
1. Brake block are tested under dry condition at speeds of 40, 60,
80,100,110,120kmph with a brake block force of 3575kg.
2. After switching on the system with DC motor is first run at slow
speed. The motor is then accelerated to the desired rpm
corresponding to the required speed. The motor rpm is kept slightly
higher than the required braking speed. After attainment of the
slightly higher rpm, motor is switched off and brakes are applied at
corresponding speed with the help of „brake on‟ switch provided on
the control desk. Blower fan at a speed of 750 rpm and Exhauster
fan at a speed of 1000 rpm is normally kept running during the
tests.
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3. Various parameters e.g. braking speed, braking time, run out
revolution, brake energy and mean coefficient of friction are
recorded on the data acquisition system.
4. Iron-Constantan thermocouples are embedded on the brake
blocks to monitor the brake block temperature.
5.Wheel temperature is, however, measured with a highly sensitive
contact less sensor mounted at the wheel rim very close to the
rubbing surface. This temperature is digitally displayed.
6.At the end of the each test series, the brake blocks are inspected in
respect of grooving, metallic inclusion, burning, non-uniform wear,
over heating etc. and surface condition of wheel tyre in respect of
polishing, pitting, flacking, cracking and other defects.
7.Brake blocks are weighed for wear as per test schemes.
Wet Tests:
1.As laid down in the ORE report No. B-64/RP10, continuous flow of
water at the rate of 14 liters per hour is allowed to fall on the top of
the wheel through small nozzles of 1-mm dia during wet tests. It
simulates the rainy season conditions.
2. During wet tests, blower is not used. This is to avoid flying away of
water falling on the top of the wheel.
3. Acceleration, running and braking at desired force are done in
the same manner as the dry tests.
4. During the wet tests, also inspection of both wheel and brake
blocks is done for any abnormally as per para 6 of dry test.
Drag Test:
1. After dry and wet tests on the brake blocks are over, the samples
are subjected to most severe type of braking, simulating controlling
of train on ghat section by applications of continuous brake.
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2. The brakes are kept applied on the wheel for 20 minutes without
switching off the motor at a constant speed of 60 kmph. During drag
tests, torque equivalent to about 45 BHP is maintained. For
maintaining of constant torque, the brake force on the brake block
is recorded at every 60 sec. At the end of 20 minutes maximum
temperature attained by the wheel and brake blocks are recorded.
In case of brake blocks catching fire or any abnormality observed in
course of testing, further drag testing is stopped.
3. Immediately after above test, motor is shut off & brake block force
is increased to 2400 Kg and brakes are applied and various brake
characteristics are studied. During drag tests phenomena like,
emission of smoke and spark, formation of red band and flaming
etc. are recorded. At the end of the test, inspection of the wheel and
brake block is done to see any abnormality on the wheel and brake
blocks.
4. A WDM2 locomotive wheel having a diameter of 1092 mm was
used for these tests.
5. Gyrating masses having a moment of inertia of 286 kgfms2.
Excluding that of revolving wheel and sub-axle were engaged to
simulate an axle load of 18.8t.
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The laboratory is equipped with a Test Rig having the complete
pneumatic circuits of 192 wagons and 30 coaches with twin pipe air
brake system. Three locomotive control stands can be used anywhere
in the formation, with varying compressed airflow rate up to 16 kl
per minute with the help of 7 compressors. Data acquisition and
analysis is completely computerised. The laboratory is equipped with
a single car test rig and an endurance test rig for distributor valves.
Brakes are essentially meant for controlling the speed and stopping
of train. Different brake systems are prevailing in the requirements
laid down by each Railway Administration. However, whatever may
be the brake system it should have the following basic requirements :
Should be automatic and continuous i.e., at the event of train
parting brake should apply.
Shortest possible emergency braking distance.
Maximum possible brake force.
Shortest brake application time.
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Shortest brake release time.
Low exhaustibility of brake power under continuous or repeated
brake application.
Minimum run-in and snatch action during braking.
TYPES OF BRAKE SYSTEM
Vacuum brake
Single or Twin pipe graduated Air brake system
Electro-Pneumatic brake
AIR BRAKE SYSTEM
Single pipe graduated release air brake system is used in air braked
wagons. The main components of this system are :-
Distributor valve
Brake Cylinder
Auxiliary reservoir
control reservoir
Brake pipe and feed pipe
Flexible House Coupling
Rubber House pipe
Brake pipe which runs throughout the length of the train has air
pressure at 5 kg/sq.cm. The compressed air is supplied by compressor
/expresser in the locomotive and the brake pipes of adjacent wagons
are joined by using flexible coupling. For application of brakes, the
air pressure is reduced. The drop in pressure being proportional to
the braking effort required. The drop in pressure is sensed by the
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distributor valve (DV) which allows compressed air from the
auxiliary reservoir into the brake cylinder and results in brake
application through brake shoes,release of brake taking place by
normalizing by A-9and air from the brake cylinder released
symlatenaus brake pipe pressure increased up to 5 kg. The brake
cylinder develops a maximum air pressure of 3.8kg/sq.cm.
During application of brakes the auxiliary reservoir gets
disconnected from the brake pipe. The auxiliary reservoir has
capacity of 100 liters capacity whereas control reservoir is of 6 liters
capacity. A fig of Single pipe graduated release air brake system is
given below-
TYPES OF AIR BRAKE SYSTEM
1. Direct Release Air Brake System – AAR Standard
In direct release air brake system, the release of brakes depends
upon complete buildup of BP pressure. Since the pressure differential
between brake pipe and the Auxiliary reservoir controls the both
application and release, the release pressure once initiated cannot
be stopped except by reduction in brake pipe pressure below AR
pressure, which if resorted to frequently before the Auxiliary
Reservoir is charged fully, will results in the exhaustibility of the
brake system.
The main advantage of direct releaser system is that it has faster
release compared with the graduated release system. The addition
of emergency valve to the triple valve in the direct release system
permits, a very rapid application by venting the train pipe locally at
every vehicle.
2. Graduated Release Air Brake System – UIC Standard
In graduated release system, the Brake cylinder pressure varies
according to brake pipe pressure. The brakes are fully released when
the BP pressure is fully charged. The graduated release system is
inexhaustible as the BC pressure is related all times to the pressure in
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brake pipe, full release of the brakes being obtained when brake pipe
have been fully charged.
The main advantage of Graduated release system is quick release of
brake system and reduced release time.
The graduated release brakes are considered more suitable for
passenger stock because of inherent smooth release function
promoting riding comfort. The graduated release system conforms to
UIC regulation, which lays down a release time of 45-60 seconds.
In the graduated release system the application of the brake can be
accelerated with brake accelerator valves which can be attached to
the main control valve.
WORKING PRINCIPLE OF AIR BRAKE SYSTEM
In air brake system compressed air is used for operating the brake
system. The locomotive compressor charges the Feed pipe and Brake
pipe throughout the length of the train. The feed pipe is connected to
the Auxiliary reservoir and the brake pipe is connected to the
distributor valve. AR is also connected to the BC through DV. The
brake application takes place by dropping the air pressure in the
brake pipe by the driver from locomotive by the application of A-9
valve. Following three activities involved in this system:
1. Charging
Brake pipe throughout the length of the train is charged with the
compressed air at 5 Kg/cm2
.
Feed pipe throughout the length of the train is charged with
compressed air at 6 Kg/cm2
.
Control reservoir is charged to 5 Kg/cm2
.
Auxiliary reservoir is charged to 6 Kg/cm2
.in case of twin pipe and
5 Kg/cm2
in case of single pipe
2. Brake Application
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For brake application, the brake pipe pressure is dropped by venting
air from driver‟s brake valve subsequently the following action takes
place:
The control reservoir is disconnected from the brake pipe.
The DV connects the AR to the brake cylinder and the brake
cylinder piston is pushed outwards for application of brakes
The AR is towards continuously charged from the feed pipe at 6
Kg/cm2
air pressure.
3. Brake Release Stage
Brakes are released by recharging brake pipe to 5 Kg/cm2
through
the driver‟s A-9 brake valve.
The DV isolate the BC from AR.
The BC pressure is vented to atmosphere through DV and the BC
piston moves inwards.
Description Reduction in BP Pressure
Full Service Brake application 1.3 to 1.6 Kg/cm2
Emergency Brake application Brake pipe is fully exhausted to
zero pressure
BASIC REQUIREMENTS TO DESIGN THE BRAKE SYSTEM
While designing the brake system, the following are the basic
requirements, which kept in the mind:
Brake system should be in operation and reliable.
Should be continuous and being applied to each vehicle
in the train.
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Should be instantaneous in action and capable of being
applied from the driver‟s CAB.
Should be self-employing in case of train parting.
Should have minimum number of parts.
Should apply equal forces on each wheel.
Should have maximum possible braking force.
Should have shortest possible emergency braking
distance.
Should have shorter brake application time.
Should have shorter brake release time.
Low exhaustibility of brake power under continuous
repeated brake application.
Ease in maintenance.
ADVANTAGES OF AIR BRAKE SYSTEM
It has higher rate of propagation.
It has shorter brake application and release time.
Brake fade does not take place, therefore, the train can
be held on down grade without any difficulty for a
considerably longer period.
It has higher degree of reliability, controllability and
maintainability.
Rigging is simple and entire equipment‟s are lighter and
required less space.
Simple maintenance through calling for a higher degree
of skill.
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Provide for higher operating speed.
Caters for smaller emergency braking distance.
Compressed air can be stored to higher-pressure
differential.
Salient Features of Air Brake System (BMBS)
The brake system provided on the wagons is single pipe graduated
release system with automatic two stage braking. Its operating
principle is as follows: -
Schematic layout of single pipe graduated release air brake system
as provided on the wagons is shown in sketch below. Brake pipe runs
through the length of wagon. Brake pipe on consecutive wagons in
a train are coupled to one another by means of hose coupling to
form a continuous air passage from the locomotive to the rear end
of the train. Brake pipe is charged to 5 kg/cm2
through the
compressor of the locomotive.
The wagons are provided with automatic two-stage Automatic
Brake Cylinder Pressure Modification Device to cater for higher
brake power in loaded condition instead of the conventional
manual empty load device. With the provision of this, brake
cylinder pressure of 2.2 kg/cm2
is obtained in empty condition and
3.8 kg/cm2
is obtained in the loaded condition. To obtain this a
change over mechanism, “Automatic Brake Cylinder Pressure
Modification Device” (APM) is interposed between the under-frame
and side frame of the bogie. The mechanisms gets actuated at a
pre-determined change over weight and change the pressure going
to the brake cylinder from 2.2 kg/cm2
to 3.8 kg/cm2.
and vice-versa
For application of brake, air pressure in the brake pipe is reduced by
venting it to the atmosphere from drives brake valve in the
locomotive. The reduction of the brake pipe pressure, positions the
distributor valve in such a way that the auxiliary reservoir is
connected to the brake cylinder through APM device and thereby
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applying the brake. During full service brake application, a
reduction of 1.4 to 1.6 kg/cm2
takes, a maximum brake cylinder
pressure of 3.8 kg/cm2
in loaded condition and 2.2 kg/cm2
in empty
condition is developed. Any further reduction of brake pipe pressure
has no effect on the brake cylinder pressure. During emergency
brake application, the brake pipe is vented to atmosphere very
quickly; as a result the distributor valve acquires the full application
position also at a faster rate. This result in quicker built up of brake
cylinder pressure but the maximum brake cylinder pressure will be
the same as that obtained during a full service brake application.
For release of brakes, air pressure in the brake pipe is increased
through driver‟s brake valve. The increase in the brake pipe pressure
results in exhausting the brake cylinder pressure through the
Distributor valve. The decrease in the brake cylinder pressure
corresponds to the increase in the brake pipe pressure. When the
brake pipe pressure reaches 5kg/cm2
, the brake cylinder pressure
exhausts completely and the brakes are completely released.
Brake Cylinder with built-in Double acting Slack Adjuster
The brake cylinder receives pneumatic pressure from auxiliary
reservoir after being regulated through the distributor valve and
Automatic Brake Cylinder Pressure Modification Device develops
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mechanical brake power by outward movement of its piston and
ram assembly.
The piston rod assembly is connected to the brake shoes
through a system of rigging levers to amplify and transmit the brake
power. The compression spring provided in the brake cylinder brings
back the rigging to its original position when brake is released.
Automatic Brake Cylinder Pressure Modification Device (APM)
Load sensing device is interposed between bogie side frame of casnub
bogie and the under frame of wagons. It is fitted on one of the
bogies of the wagon. It is fitted for achieving 2-stage load braking
with automatic changeover of brake power.
Salient feature of BMBC
External slack adjuster is removed/eliminated.
Higher composition brake blocks of „K‟ type have been
used.
Advantage of BMBS
Higher service life of brake block.
Elimination of slack adjuster shall result in lesser cases of
brake binding and consequent from detention.
Simplified brake rigging shall reduce maintenance
inputs in carriage maintenance depots.
Reduce level of noise during braking.
Saving in energy in haulage on account of weight
reduction of coaches.
Due to elimination of levers the brake rigging efficiency
increased to 90% against 80% in U/F mounted brake
system.
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AIR BRAKE SYSTEM TEST RIG:
INTRODUCTION:
Air brake test rig is, with a facility for simulation of field condition
for 132 wagon freight train & 30 coach passenger train with single
and twin pipe air brake system with data acquisition facility on 234
channels only. This test rig has also facility to acquire data of BP,
BC at every wagons on 58 wagon‟s freight train and for 30 coach‟s
passenger train with BP, FP, BC, & MR on three locomotive along
with facility to measure air flow at four points on whole test rig.
The test rig is designed to measure real time pressure in brake pipe,
Feed pipe, brake cylinders in coaches and wagons and BP,FP,BC,MR,
and air flow in three multiple locomotives on 234 channels data
acquisition system with a sampling rate of 100 sample per second
during initial charging of brake system and application and
release of brakes.
The application software is in LABVIEW and Data Acquisition system
is also of National Instrument. The software is such that it can
calculate the application and release time of any intermediate
coach/wagon with the help of 0.08% accuracy (very high accuracy)
GE Druck /Germany make pressure transmitters. The exact flow of air
is cross checked by flow meter connected in BP and MR line. It can
check the application and release time with flexible number of
coach/wagon connected with loco within the maximum limit.
CAPABILITIES OF TEST RIG:
This test rig is being used to test the performance of brake valves and
equipments on the simulated train consist in stable condition to
study on under mentioned scopes.
1. Braking characteristics of freight train up to 132 BOXN
wagon with single and twin pipe system.
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2. Passenger train up to 30 coaches with twin pipe system.
3. Effect of change in design of loco brake system on braking
characteristics of passenger and freight train.
4. Brake characteristics of freight and passenger train with
multiple loco operation.
5. Optimum location of locos in long freight train.
6. Effect of changes in design of distributor valve on brake
characteristic of freight & passenger train.
7. Brake characteristic in case of train parting.
8. Effect of leakage rate on brake system.
9. Effect of over charge feature on train operation.
10. Optimum compressor & reservoir capacity for various
train lengths.
11. Indication to driver in case of train parting.
12. Performance test of distributor valves.
13. Performance test of all valves and equipments of loco,
coaches and freight brake system.
14. Effect of EOTT on train brake operation.
15. Effect of Automatic Brake Unit of Anti-Collision device of
locomotive on Brake operation.
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Twin Pipe Air Brake System For Coaches
Single Pipe Air Brake system For Wagons