Open Rails Steam Locomotive Advanced Physics Parameters

Aim - this section describes the advanced physics parameters required to correctly define a steam locomotive in Open Rails Train Simulator. For standard physics parameters see the Standard Steam Setting Parameters.

It is recommended that these settings are changed with great care only, as they may significantly impact the performance of the locomotive.

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Note: The default unit of measure (UoM) shown in the "Recommended Input Units" column is the UoM value that OR assumes if no UoM is included in the parameter statement.

ParameterENG or WAGDescriptionRecommended Input UnitsSuggested settingsNew or ExistingTypical Examples
ORTSBoilerEvaporationRate ( x )ENGAmount of steam generated by locomotiveValueAs per locomotive specifications.
Typically Steam Gnererated (lbs/hr) = Evap Rate x Grate Area (ft^2)
Value can be between 10 and 15.
NewORTSBoilerEvaporationRate ( 15.0 )
ORTSMaxIndicatedHorsepower ( x )ENGMaximum IHP of locomotivePower - W, kW, HP
Default - W
As per locomotive specifications.NewORTSMaxIndicatedHorsepower ( 2500.0hp )
ORTSMaxSuperheatTemperature ( x )ENGMaximum superheat temperature of locomotiveDefault - FahrenheitAs per locomotive specifications.NewORTSMaxSuperheatTemperature ( 280.0 )
ORTSSuperheatCutoffPressureFactor ( x )ENGFactor to vary cutoff pressure (wiredrawing) with speed.
Superheated locomotives only
valueAs per locomotive MEP specifications.NewORTSSuperheatCutoffPressureFactor ( 55.0 )
ORTSCylinderPortOpening ( x )ENGFactor to vary cutoff pressure (wiredrawing) with speed.
Saturated locomotives only
valueAs per locomotive MEP specifications.NewORTSCylinderPortOpening ( 0.05 )
ORTSCylinderExhaustOpen ( x )ENGPoint in steam cycle at which the cylinder exhausts.valueAs per locomotive specifications.
This value must not be set below maximum cutoff value.
NewORTSCylinderExhaustOpen ( 0.9 )
ORTSBoilerEfficiency ( x y)ENGEfficiency of boiler.valueAs per loco specs:
x = Dry Coal (lbs/sq ft/hr)
y = Dry coal (lbs/hr)
NewORTSBoilerEfficiency ( x y )
ORTSBurnRate ( x y )ENGIndicates the rate of coal usage against steam generation.valueAs per loco specs:
x = Actual evaporation (lb/hr)
y = Boiler Efficiency
NewORTSBurnRate ( x y )
ORTSCylinderInitialPressureDrop ( x y )ENGIndicates the drop in pressure between the boiler and the cylinder.valueAs per loco specs:
x = Wheel revolutions (rpm)
y = Initial to boiler pressure drop factor
NewORTSCylinderInitialPressureDrop ( x y )
ORTSCylinderBackPressure ( x y )ENGIndicates the back pressure in the steam cylinder as the indicated horsepower rises.valueAs per loco specs:
x = Indicated Horsepower (hp)
y = Back pressure in psi (atmospheric)
NewORTSCylinderBackPressure ( x y )

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