Aim - this section describes an "optimal" coupler setting based upon the current setup for Open Rails wag and eng files.

At the time of writing (November 2014), Open Rails only appears to implement a simplified version of the MSTS coupler, and only uses the following parameters in the configuration of the coupler:

  • CouplingHasRigidConnection
  • Spring - Stifness
  • Spring - Break
  • Spring - r0

Break Force

Is the breaking force of the coupler. If the force on the coupler exceeds this force then the coupler will break (requires "Break" option to be selected in OR Option Menu). The force on each of the couplers in the train can be identified in the extended HUD. The coupler force will vary depending upon the number of wagons connected to the coupler, ie the load, and will also vary as the train negiotiates hills or curves, etc which increase the load force. In driving the train the driver needs to be conscious of not putting excessive loads (forces) on the coupler.

For NSW operational practice, typical coupler breaking forces (or Draw Capacity) are somewhere between 0.15MN (150kN) and 4.45MN (4500kN), as summarised in the table below, which shows a selection of the wagons, and locomotives from the documents in the Useful Links section below. Refer to the Draw Capacity column. Similarly values for UK practice are shown in one of the other document, including screw and draw hook couplings.

Coupler Type

Draw Capacity (MN)


Coal wagons - modern permanently coupled (Eg PHEH)


Bar type connection

Coal wagons - bogie (Eg BCH)


autocoupler, metal body

Water Gin (Eg L229)


Rail Car - Modern style (Eg XPT)


Diesel - Modern (Eg 5000 Class)


Special coal haulage locomotive

Diesel - Branch Line (Eg 48 Class)



Diesel - Mainline (Eg 442 Class)



Passenger - Modern style (Eg ARL)


Steel body

Passenger - Modern style (Eg SBN)


Steel body

Passenger - Older style (Eg FO)


Wooden body

Steam locomotive - Modern (Eg 3801)


Steam locomotive - Older style (Eg 2705)


To view the coupler forces in Open Rails, refer to the extended HUD, by pressing the Shft-F5 key until the following screen is found. Refer to the column called "Coupler".

Forces HuD - Break Force


Sample Coupler Code

Typically the lines shown in red text are the only ones that would need to be changed on individual wagons.

Comment( Coupling Information )
Coupling (
Spring (
Stiffness ( 1e6N/m 5e6N/m )
Break ( 500kN 500kN )
r0 ( 20cm 30cm )
CouplingHasRigidConnection (1)


Force Conversion

Convert long tons (UK) to Newtons.

tonsf (UK) to N:
Force (tonf):       
Force (N):     Force (kN): Force (MN):


Useful Links

NSW Locomotive and Rolling Stock Data

The Evolving Coal Wagon by Ross Peter Golotta

Structural Requirements for Drawgear and Buffers on Railway Vehicles (Superseded UK standard)