Testing and Stability of Rolling Stock

Need for Testing New Stock

● Safety of new design● Get natural frequency in various modes● Level of comfort ● Performance of locos ● Statutory requirements as per Policy Circular No

6 of Rly. Bd.

Policy Circular No 6

● No.92/CEDO/SR/4/0 dated 23/12/1999 issued by Member(Engg), Rly.Bd.

● Contains rules for certification of maximum permissible speeds for rolling stock

● Rly.Bd. is safety controlling authority for Indian Railways under Indian Railways Act

● Responsibility delegated to RDSO – Determine & recommend max permissible speed for

new design rolling stock

Policy Circular No 6(contd.)

● Zonal Rlys to apply for sanction through CRS to Rly Bd. for running new design stock on specific track taking into account– RDSO's recommendations of provisional/final speed– Condition and maintenance of

● Track structure● Fixed structures , incl bridges & OHE● Rolling stock

– Maximum Moving Dimensions

Policy Circular No 6(contd.)

● Definition of new rolling stock– Different principal dimensions– Different bogie design– New braking system– Change in axle load, track loading density, unsprung

mass– Minor changes in design,internal layout(with sanction

of CRS) only if leading to significant change in ● C.G.,Weight distribution, ride behaviour

Policy Circular No 6(contd.)● Movement of newly designed rolling stock

– From manufacturer/dock to destination/testing point– Not more than provisional speed– Determined by

● RDSO's EDs(MP, Bridges & Structures, Track)● Approved by CE,CME and CEE( for elect stock & OHE)

– CRS approval required for ● Attachment to passenger carrying vehicle ● Condonation for exceeding axle load

– Condonation by Rly Bd for exceeding max moving dimensions

Policy Circular No 6(contd.)● Provisional Speed by EDs (MP),(Bridge

&Structures),(Track) of RDSO before deciding final speed – < 80 for BG & < 60kmph for MG passenger stock ,

<65 for BG & < 45kmph for MG goods – With CRS sanction

● < 105 for BG & < 75 kmph for MG passenger stock ● < 75 for BG & < 50kmph for MG goods

– Determined from design features and data or similar stock already in service

– Valid for 5 years max

Policy Circular No 6(contd.)● Final speed of new stock decided by EDs (MP),

(Track),(Bridge&Structures)of RDSO– Based on experience with similar stock & detailed

oscillation trials– Detailed oscillation trials to be carried out by

ED(Testing) after consulting EDs (MP), (Track), (Bridge &Structure) & Design directorate RDSO

● After Jt safety certificate of zonal PHODs & CRS approval ● Evaluation based on Standing Criteria Committee

– Speed certificate includes max no of locos in multiple Unit

Policy Circular No 6(contd.)

● Types of trials -new stock● Detailed oscillation trials● Rating & performance trials of locos● EBD(speed >110 for passenger & 75 for goods) & Coupler

force trials of trains● Signal Interference trials for Elect locos● Confirmatory oscillgraph car run on tracks above

110Kmph ● Route Proving run between 105-110 Kmph by zonal rly

using portable accelerometers – Accel <.3 g or <.25 peaks/km for .3g < accel < .35g

Track and Related Issues

Indian Railway Track● Classified into two categories

– Main Line (speed <110)– High Speed

● For speed upto 140 Kmph● Based on Vol-I of Civil and Mechanical Engg Report No-I

(C&M-I) dated May 1969 for “Increase of Speed on DLI-HWH Route Feasibility Study”

● Track parameters– Unevenness of left & right rail– Twist over 3.6m– Gauge & Alignment

Indian Railway Track (Contd.)● Categorisation of track based on TRC data

– Peak based – Recorded every

● 3 months for Rajdhani routes● 4 months for A& B routes (1660 sleeper/km) ● 6 months for C & D routes (1440 sleeper/km)

– Separate category (i.e A,B,C,D) for each parameter● Twist – A < 1.39 < B < 2.08 < C < 2.78,D>2.78mm/m● Alignment – A < 3 < B< 5,C >5mm versine /7.2m● Unevenness - A < 6 < B <10 < C <15, D>15mm /3.6m● Gauge -A < 3 < B < 6, C> 6mm loose/tight

Indian Railway Track (Contd.)

● Categorisation of track based on TRC data(contd)– 10 peaks/km > limits set for each category allowed– No of peaks > B category limits is subscript e.g.

● Ten peaks of 3mm/m of twist => A10

● Eleven peaks of 3mm/m of twist => D11

● Track maintenance standards– NOT SAFETY standards– Peak based– Standard deviation based

Indian Railway Track (Contd.)

● Separate standards for– New track/relaying– Planned maintenance– Urgent maintenance– Max speed above and below 105 kmph

Derailment ● Wheel climbing rail

– Tight gauge– Due to excessive angle of attack

● Sharp flange● Excessive wheel gauge(loose disc) ● Sharp curve -too much versine

– Excessive lateral force- Nadal's formula ● Hy/Q =(tanA-mu)/(1+mu tanA)= .997, where

A:flange angle wrt to horizontal=60degrees & mu=.27– Inadequate clearance between rail and check rail or

space between them filled with grit● Usually on level crossings

Derailment

● Wheel offloaded– Inadequate transition– Cant excessive– Uneven loading/empty between loaded wagons

● Bumping on sudden acceleration / retardation

– Excessive Twist -cause of derailments at● Low speed ● Straight track

Derailment

● Wheel offloaded due to resonance /excessive spring deflection– Due to inadequate ballast– Unevenness of track– Poor quality ballast -caked up– Poor damping– On multi-span bridges (more likely on steel girder

type)

Resonance

Derailment

● Wheel dropping between rails if track expands– Due to defective or inadequate fittings– Excessive track gauge

● Track buckling due to – Inadequate stress relieving– Inadequate ballast– Wrong shape of ballast packing– Usually in hot summer during high temperatures

Derailment

● Rail fractures due to– Inadequate stress relieving– Improper UFD – Inadequate ballast– Wheel flats?

● Shifting of sleepers– Prude Homme's Limit (wooden sleeper)– Wrong shape of ballast packing

Track Measurements After Derailment

● Type of Soil & Ballast● Drainage● Sleeper & Rails● Fastenings & Joints● Location of Point of mount● Measurements from -90m +45m from zero

station if cause of derailment is disputed else from zero station

Track Measurements After Derailment

● Under load & without load– Gauge– Cross Level

● Versine on 20m cord● Transition

– Length– Rate of change of superelevation

● Unevenness in case of sags

Effect of Vibration on Human Body

Sperling's Ride Index

● Human sensation of comfort proportional to – Displacement (sinusoidal)– Acceleration– Rate of change of acceleration

● RI=.896(g(f)*b3/f)0.1, b= acceleration amp● Ride comfort correction factor g(f) =kf2

– k=.325 for vertical RI (0.5-5.4Hz)– k= .8 for lateral RI (0.5-5.4 Hz)– k=1 for goods stock

Oscillation trials of Rolling Stock

3rd Report of Standing Criteria Committee dated January 2000

● To evolve criteria for assessment of stability of rolling stock on IR,

● Composition– Ed Testing, Convener– EDs (MP), (Carriage),(Wagon),(Research)– EDs (Track Design), (Track Machines)– ED Electric loco

● Formulates oscillation trial procedure and Evaluation criteria

3rd Report of Standing Criteria Committee dated January 2000

● Need for Oscillation trials– Establish vehicle is safe at desired speed– Stability of vehicle at that speed– Check vehicle oscillation behaviour– Check vehicle ride comfort

● Test track should include– Straight 1 Km X 2– Station yard– 700-800 m Curve of about 2 degree

3rd Report of Standing Criteria Committee dated January 2000

● Test track– Rundown track worse than 90% of IR track– On main line track

● Include high speed (C&M I vol I) for speed >110kmph

– Track geometry peak based track category● Main line “B or C” Unevenness & Gauge, “C or D” Twist,

“C” Alignment● C&M Vol-I “A or B” Unevenness & Gauge, “B or C”

Twist, “C” Alignment

– Long confirmatory run for 10-50kms with resonance check hard spots like L-Xing, Culverts, Bridges

3rd Report of Standing Criteria Committee dated January 2000

● Test Speed (Loaded & Empty)– Start with low speed (60kmph/80kmph)– Increase speed in increments of 5/10Kmph

● Stop if any limit is exceeded

– Max speed 10% higher than the proposed speed

● Test vehicle to be last vehicle (except loco)● Free end bogie (leading bogie for loco) usually

instrumented● Data acquisition system usually in oscillograph car

3rd Report of Standing Criteria Committee dated January 2000

● Recording in both empty and loaded conditions● Transducer

– Accelerometers kept at floor level above bogie pivot– Linear Variable Differential Transformer for

● Spring deflections● Bogie rotation● Bolster Swing

– Load cell for lateral force measurement at axle box level

– (Pressure transducers for braking tests)

Data Acquisition System● Transducers● Signal Conditioners

– Excitation to transducer (2.5 Khz, ~5V AC)– Amplification – Frequency filtration (.5 to 15 Hz)

● 5 Hz for coaches● 10 Hz for Wagons

● Data recording– Chart Recorders– Computerised -using PCI/PXI DAQ card

3rd Report of Standing Criteria Committee dated January 2000

● Criteria for locos

– Hy2m

<.85(1+P/3), P= axle load (Prud Homme's limit)

– Hy/Q (for >1/20 sec) <1– <.3g accelerations in vertical & lateral directions

(isolated peak upto .35g if no resonance)– Ride index < 4, preferred 3.75

● Criteria for carriage– Ride index <3.5,preferred 3.25 (upto 4 for EMU/DMU)– <.3g accelerations in vertical & lateral directions

(isolated peak upto .35g if no resonance)

3rd Report of Standing Criteria Committee dated January 2000

● Criteria for Wagons

– Hy2m

<.85(1+P/3),P= axle load (Prude Homme's limit)

– Hy/Q (for >1/20 sec) <1– In case Hy cannot be measured,

● Ride index < 4.5, preferred 4.25

– General stable running characteristics based on ● Accelerations● Spring deflections

Thank You!!!