Open Rails Basic Diesel Parameters

Aim - this section describes the basic "optimal" settings for diesel related parameters in Open Rails (OR) ENG files.

This page references information for the British Rail Class D16/2 (#10203) diesel electric locomotive which has been used as a demonstration and test model. The documents indicated in the Useful References at the bottom of this page were used as the principal reference sources. A diesel test model based upon this locomotive has been configured for use in Open Rails.

For realistic performance it is important to set the Open Rails diesel parameters to calculate the correct values.

If you wish to provide any feedback on this page, please use the contact page. It would br great to have some feedback as this helps to ensure the accuracy of the information and models.

Index

Key Open Rails Parameters for Diesel Locomotives

Setting Prime Mover (Diesel Engine) Section

Setting Traction Motor Section (Diesel Electric)

Setting Gear Box Section

Sample Diesel Code

Useful References

Key Open Rails Parameters for Diesel Locomotives

The key parameters that impact upon the performance of a diesel locomotive are described on the following web page.

Standard Parameters for Diesel ENG and WAG Files (updated Sept 2021)

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Setting Prime Mover (Diesel Engine) Section

In a BASIC ENG file configuration some simple information can be entered to specify the operation of the locomotives prime mover or diesel engine. Alternatively if desired, an ADVANCED configuration can be created by building a series of tables, and specifing some parameters. The BASIC configuration assumes constant equal incremental changes as the prime mover power is increased or decreased. An ADVANCED configuration allows the user to configure different incremental changes into the prime movers operation. It also supports the configuration of multiple prime movers for locomotives with more then one prime mover.

An example of a BASIC prime mover configuration is shown in the Sample Diesel Code below.

For a description of how to set up an ADVANCED configuration refer to the Advanced Prime Mover Setup page.

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Setting Traction Motor Section (Diesel Electric)

In a BASIC ENG file configuration some simple information can be entered to specify the rail forces used by the locomotive. Alternatively if desired, an ADVANCED configuration can be created by building a Tractive Force Curve Table. This advanced table allows the creation of special shaped traction curves to be configured for the diesel.

The traction motor information contains information about the forces applied to the rails by the diesel locomotive. Typically a locomotive will be specified by the tractive forces as indicated in this example:

Maximum Force (typically Starting Force) = 50,000lbf
Maximum Continuous Force = 30,000lbf
Speed of Maximum Continuous Force = 19.5mph

The Rail HP can then be calculated as described by re-arranging the terms in one of the formulas on the Diesel Physics page (though it is suggested that the metric formula be used, as it doesn't include a mathematical constant in it).

Using the above values, and the formula we can calculate the Rail Hp as 1560hp. These values can then be entered into the traction motor section of the ENG file, as demonstrated below.

If a value of adhesion is quoted with the above values, that is different to 0.33, it maybe necessary to create and add a Curtius-Kniffler Adhesion Table. This will typically the case when configuring a modern locomotive with AC traction motors, as they could have adhesive coefficients up to around 0.45.

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Setting Gear Box Section

Typically a Diesel Mechanic locomotive will have a gear box to connect the diesel engine to the wheels. Different ratios will be applied in the different gears, and this will change the tractive force curves for each gear.

For a more detailed description of how tractive force will vary for a geared locomotive compared to a diesel electric locomotive, see the description here.

Currently a geared diesel can only be configured in the BASIC mode of configuration.

Refer to the Key Open Rails Parameters for Diesel Locomotives above for a list of the parameters to be set for a gearbox.

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Sample Diesel Code

The code parameters shown below are those that are required to define a diesel locomotive within Open Rails. They should be set using known parameters so that the optimal accuracy of operation can be obtained.

A diesel test model with sample ENG files can be downloaded from the CTN test stock page.

When inserting values in these parameters it is recommended that you use the appropraite units of measure.

Comment ( *** General Information *** )
WheelRadius ( 0.5461m )
Sanding ( 25mph )
NumWheels ( 6 )
ORTSDriveWheelWeight ( 109.5t-uk )

Comment ( *** Diesel Prime Mover (Engine) *** )
Type ( Diesel )
ORTSDieselEngineMaxPower ( 1260kW )
MaxDieselLevel( 1180g-uk )
MaxTemperature ( 120degF )
MaxOilPressure ( 90 )
DieselUsedPerHourAtMaxPower ( 75.2g-uk )
DieselUsedPerHourAtIdle ( 25.5g-uk )
DieselEngineIdleRPM( 450 )
DieselEngineMaxRPM( 850 )
DieselEngineMaxRPMChangeRate( 40 )

Comment ( *** Diesel Engine - Exhaust Effects *** )
DieselSmokeEffectInitialMagnitude( 1.7 )
DieselSmokeEffectMaxMagnitude( 2.2 )
DieselSmokeEffectInitialSmokeRate( 0.2 )
DieselSmokeEffectMaxSmokeRate( 10 )

Comment ( *** Traction Motor *** )
MaxPower ( 1560hp )
MaxForce ( 50000lb )
MaxContinuousForce ( 30000lb )
ORTSSpeedOfMaxContinuousForce ( 19.5mph )
MaxVelocity ( 90mph )
MaxCurrent ( 2600A )

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Useful References

British Railways Test Report 2000 HP Diesel Electric Locomotive #10203

British Railways Class D16/2 Diesel Electric Locomotive #10203

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