### Open Rails Units of Measure

**Aim -** this section describes the standard units of measure (UoM) available in Open Rails Train Simulator. These are the UoM used to input values from the

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**Note:**

- The default UoM shown in the "Default" column is the UoM value that OR assumes if no UoM value is included in the parameter statement.
**(However it is always good practice to include the relevant UoM)** - The "Alternative UoMs" column shows alternate UoM currently supported by OR.
- The UoM should directly follow the numerical value in the parameter with any spacing, otherwise it will not be correctly interpreted.

Unit of Measure | Description | Default UoM | Alternative UoMs | Typical Examples |
---|---|---|---|---|

Mass | Describes the weight of an object | kg | lb, t (metric tonne), t-uk (imperial ton), t-us (us ton) | Mass ( 106t-us ) |

Distance | Describes the length or distance between two points or locations. | m | cm, mm, km, ft, in | WheelRadius ( 21.5in ) |

Area | Describes the area of an object. | m^2 | ft^2 | ORTSSuperheatArea ( 295ft^2 ) |

Volume (of a space) | Describes the volume of an object. | m^3 | ft^3, in^3 | BoilerVolume ( 340ft^3 ) |

Volume (fluid quantity) | Describes the fluid quantity contained by an object. | l | g-uk (gallons - uk), g-us (gals - us) | MaxDieselLevel ( 800g-uk ) |

Time | Describes the elapsed time between two events. | s | m, h | |

Current | Describes the current flow in a circuit. | A | MaxCurrent ( 2700A ) | |

Voltage | Describes the voltage of a circuit. | V | kV | |

Speed | Describes the speed of an object. | m/s | mph, km/h | Sanding ( 20mph ) |

Mass Rate of Change | Describes the rate of change in mass for an object. | lb/h | kg/h | |

Frequency | Describes the frequency of movement of an object. | hz | rpm, rps | |

Force | Describes the force applied to an object. | N | kN, lbf | MaxForce ( 227kN ) |

Power | Describes the power of an object. | W | kW, hp | MaxPower ( 2650hp ) |

Pressure | Describes the pressure of an object. | psi | bar, kpa, inhg | MaxBoilerPressure ( 250psi ) |

Pressure rate of change | Describes the rate of change in pressure of an object. | psi/s | bar/s, kpa/s, inhg/s | TrainPipeLeakRate ( 0.01inhg/s ) |

Energy Density | Describes the energy density of an object. | kj/kg | btu/lb | ORTSFuelCalorific ( 13700btu/lb ) |

Temperature | Describes the temperature of an object. | degc | degf | |

Davis B Coefficient | Describes the UoM for the Davis B value. | ns/m | lbf/mph | |

Davis C Coefficient | Describes the UoM for the Davis C value. | Nm/s^2 | lbf/mph^2 | |

Stiffness | Describes the stiffness. | n/m | Stiffness ( 1e6N/m 2e6N/m ) | |

Rotational Inertia | Describes the inertia due to the rotation of an object. | kgm^2 | ||

Angle | Describes the angle of an object. | rad | deg | ORTSMaximumWheelFlangeAngle ( 75deg ) |