Effects of Buffer Friction on the

Vehicle Behavior in Switch Series

Dipl.-Ing. Claudia Kossmann

Stadler Altenrhein AG (Switzerland)

Dipl.-Ing. Karl Tillmetz

Stadler Bussnang AG (Switzerland)

SIMPACK User Meeting 2014

Claudia Kossmann SIMPACK User Meeting 2011 2

Shunting Locomotive Eem 923 – On Track soon

Claudia Kossmann, Karl Tillmetz SIMPACK User Meeting 2014 3

Shunting Locomotive Eem 923 – Introduction

• 2-frequency – Hybrid – Locomotive BUTLER

with Electric and Diesel power

• Ordered by SBB Cargo for Cargo- and Shunting-Services

• Maximum speed 120 km/h

• Weight 40 – 45 t

Shunting Locomotive Eem 923

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Switch Series – Simulation and Measurement

• Requirement: Tests in Switch Series (SBB Infra R I-50007)

• Evaluation of ΣY forces (also Ymax, Qmax and Y/Q)

• Comparison with s-variable limit value for – Standard Switches (Rmin = 185 m)

– Double-Slip Switches (Rmin = 160 m)

Sophisticated

Coupling and Buffer

model

Switch Series – Simulation of S-curves

• Loco Eem 923 in combination with standard coach EW IV on reference track ‘Lausanne Main Station’

• Effect of traction forces (Push/Pull: -150 / 0 / +150 kN)

– leading loco v=const.

– trailing loco with max. traction force

Claudia Kossmann, Karl Tillmetz SIMPACK User Meeting 2014 6

2x R160

2x R185

Coupling and Buffer

• Real Screw Coupling built up of

several elements

• Buffer Contact as convex Plate (R ~ 1.5 m)

with Slip Surface

– Steel (greased)

– Plastic inlay (low friction)

• Coupler absorber elements

– Elastomer pads

e.g. ‘Miner ST-9-2/170’, ...

• Buffer absorber elements

– Steel friction (conical rings)

e.g. ‘Ringfeder BLS110’, ...

– Elastomer pads

e.g. ‘Miner T-63-10/417’, ...

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Coupler

absorber

End Stop

Hook

Buffer

absorber

End Stops

convex

Buffer Plate

with

Slip Surface

Hook Buffer

Link

Nut L Nut R

Spindle

(+Lever)

Rod

Bern

Rectangle*

Buffer Plate

Contact+Friction

Coupling and Buffer model

• Buffer surface modelled as

‘Spherical Buffer Contact’ (MM-100, FE-018)

with friction (FE-100)

• Both Coupler and Buffer Absorber

modelled as Hysteresis Elements (FE-104+FE-018)

– Measured characteristics for

compression and expansion (could be improved

with more capable force element)

– Mechanical end stops (Buffer) (additional damping needed

due to high ratio of stiffness to mass)

– Pre-stressed initial state

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Coupling characteristic

(tension) Buffer characteristic

(pressure)

end stop

* Minimal space for shunter (in German: Berner Raum)

no end stop (dip)

Coupling

Spindle

Coupling

Bush

Buffer Plate

Bush

Coupling and Buffer substructure: Pre-stressed initial state

• Initial screw-in of Coupling Spindle normally ~ 3 turns* (dx = 42 mm)

Pressure forces on all 4 Buffer Plate Bushes

Tension forces on both Coupling Bushes

Screw Coupling assumed to be stretched and stiff

• Pre-calculation of initial displacements to get the correct working point in between both hysteresis curves (depending on combination of Buffer and Coupling Bush characteristics)

Claudia Kossmann, Karl Tillmetz SIMPACK User Meeting 2014 9

* in Swiss German ‘drü Chäs’ [drɥ xæs] (literal interpretation: ‘three cheeses’)

• Compensation of the initial displacement inside the substructure

to keep nominal car lengths of the connected wagons (wagons can be placed on track in a nominal s-position)

Switch Series – Simulation / Buffer Model – Animation

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2x R185 2x R160

Switch Series – Measurements in Lausanne

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(SBB I-AT-FBI-IA-TNZ)

2+2 = Y, Q Rad-Schiene-Kräfte (Messradsatz)

2+1 = ypp0 Beschl. am Radsatz (Radlager)

3+3 = ypp*,zpp* Beschl. auf Wagenfussboden

2+2 = ypp*,zpp* Beschl. auf Tilger

4+2+4 = dx+, dy+, dz+ Wege in der Primärstufe

2 = dy* Wege in der "Sekundär"stufe

1 Messradsatz

4 Beschleunigungsgeber

10 Weggeber

1 Zugkraft (ab FLG)

1 Geschwindigkeit (ab FLG)

Fahrtrichtung vorwärts 1 Strecke (Kilometrierung) - optional

1 Kreiselgeschwindigkeit um Hochachse

• Measured quantities for evaluation of running safety in

switches

– Sum Y-Forces: measured by

instrumented wheelset

– Lateral displacements of

primary suspension

dy ~ ΣY

Switch Series – Measurements

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Switch Series – Measurement Results

• Comparison of measured and simulated lateral displacement

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trailing wheelset

leading wheelset

Switch Series – Measurement Results

• Consideration of friction between buffers

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trailing wheelset

leading wheelset

Switch Series – Measurement Results

• Asymmetric behaviour caused by different surface material of

Coach EW IV:

- one buffer with steel

- one buffer with plastic plate

• Consideration of different

friction coefficients in model

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Switch Series – Measurement Results

• Consideration of different friction coefficients

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trailing wheelset

leading wheelset

Switch Series – Buffer surfaces

• High friction effects with steel to steel contact

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Switch Series – Buffer surfaces

• Friction reduction with plastic plates

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Conclusions

• Sophisticated buffer model used for simulation of running

behaviour in switch series

• Comparison of simulation and measurement showed that

wheel-rail-forces highly depend on friction between buffers

• SIMPACK simulation helped to evaluate the friction coefficient

and to optimise the buffer surface of the shunting locomotive

Eem 923

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