Operations Manual - Open Rails

29
Fadh. MAX
? A ?
? weather _ coeff ? M ? 9,
81?
?
? C?
? B ? Speed?
kmph?
?
This means that the maximum is related to the speed of the train, or to the weather conditions.
“D” parameter is used in advanced adhesion model and should be always 0.7.
There are some additional parameters in the “Force Information” HUD view. The axle/wheel is
driven by the “Axle drive force” and braked by the “Axle brake force”. The “Axle out force” is the
output force of the adhesion model (used to pull the train). To compute the model correctly the
FPS rate needs to be divided by “Solver dividing” value in a range from 1 to 50. By default, the
Runge-Kutta4 solver is used to get the best results. When the “Solver dividing” value is higher
than 40, the Euler-modified solver is used instead to reduce CPU load.
Anyway, in some cases when the CPU load is higher, the time step for the computation may
become very high and the simulation may start to oscillate (the “Wheel slip” rate of change (in the
brackets) becomes very high). There is a stability correction feature that modifies the dynamics of
the adhesion characteristics. Higher instability can cause a huge wheel slip. You can use
“DebugResetWheelSlip” (“Ctrl+X” by default) command to reset the adhesion model. If you
experience such behavior for most of time, please use the basic adhesion model instead by
pressing “DebugToggleAdvancedAdhesion” ( “Ctrl+Alt+X” by default).
To match some of the real world features, the “Wheel slip” event can cause automatic zero throttle
setting. Use the “Engine (ORTS (WheelSlipCausesThrottleDown ))” Boolean value of the ENG file.
Engines – Multiple Units in Same Consist or AI Engines
Locomotives can either be controlled by a player, or controlled by the train's MU signals for
braking and throttle position, etc. The player-controlled loco generates the MU signals which
pass along to every unit in the train. For AI trains, the AI software directly generates the MU
signals - there is no player-controlled loco. In this way, all engines use the same physics code
for power and friction.
This software model will ensure that non-player controlled engines will
behave exactly the same way as player controlled ones.
Open Rails Braking
Open Rails software has implemented its own braking physics in the current release. It is based
on the Westinghouse 26C and 26F air brake and controller system. Open Rails braking will
parse the type of braking from the ENG file to determine if the braking physics uses passenger
or freight standards, self-lapping or not. This is controlled within the Options menu as shown
below.