Brake Settings

Aim - this section provides an overview of the typical operation of the Westinghouse air brake system, and describes the "best" brake settings for Open Rails (OR) WAG and ENG files. Settings are based upon NSWGR standards, which mostly used a single air pipe system.

To convert tons to kN = tons x 9.964 kN.

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

Introduction

Brake Code - Structure and layout in Open Rails

No Brake Systems

         Sample Brake Code - Wagon Section

Manual Brake Systems

         Sample Brake Code - Wagon Section

         Sample Brake Code - Locomotive system

         Sample Brake Code - Train and Locomotive Control Valve

Air Brake Systems

         Sample Brake Code - Wagon Section

         Sample Brake Code - Locomotive - Compressor, Reservoir and Train system

         Sample Brake Code - Train and Locomotive Control Valve

Vacuum Brake Systems

         Sample Brake Code - Wagon Section

         Sample Brake Code - Locomotive and Train system

         Sample Brake Code - Train and Locomotive Control Valve

Brake Calculators

         Vehicle Maximum Brake and Handbrake Force

         Brake Cylinder Size Calculator

         Brake Pipe Volume

         Reservoir Charging Rate

Useful References


Introduction

This page will describe some typical brake configurations that can be configured within Open Rails. It will be assumed that the reader is familiar with some of physics and terminology associated with brake operation. If not, read the Train Brakes page first.

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Brake Code - Structure and layout in Open Rails

In OR, code to define the braking capabilities of the rolling stock is defined in a number of separate locations as follows:

  • WAG files (Non-powered stock) - contain all the braking parameters relevant to the braking equipment usually located on the wagon.
  • ENG files (Powered or Locomotive Stock) - contains all the relevant braking information for the locomotive and train as follows:
    • Wagon sub-section - contains the parameters for the locomotives "own" brake equipment
    • Engine sub-section - train & engine brake operation - contains the parameters for the compressor, general brake system, train and engine brake operation.
    • Engine sub-section - control levers - contains information for the control levers that operate the various brakes.

For consistency of overall operation, braking parameters should be set the same between all common types of rolling stock and only a small number of stock specific parameters should need to be changed.

More Info

Note: It is good practice to put notes into the WAG and ENG files to act as reminder for any assumptions made. These notes can be made with comment statements as shown below:

Comment (Assume Main Reservoir of 9.549 cu ft and air compressor of 8in)

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

Standard Brake Parameters for WAG and ENG files (updated Sept 2020)

The Brake Calculators can be used to calculate some of the relevant values that are required for entry in the WAG files.

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No Brake Systems

Sample Brake Code - Wagon Section

The brake configuration in this section represents the brake configuration for a wagon or locomotive with no brakes fitted. No other code is required.

This type of code goes into the WAG file or the wagon section of the ENG file.

WAG File or wagon section of ENG file

Comment ( *************** Brakes - Wagon Section - General ********************** )
    BrakeSystemType ( "Manual_Braking" )

Make sure that you test your settings with the brake tests described on the testing page.

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Manual Brake Systems

Sample Brake Code - Wagon Section

The brake configuration in this section represents a manual brake scenario, whereby a brakeman operates brakes along a train, and steam brakes are fitted to the locomotive.

This type of code goes into the WAG file or the wagon section of the ENG file.

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

Use the
Brake Calculators to calculate some of the relevant values that are required for entry in the WAG files. Additional information is also available in the Generic Brake Design Section.

WAG File or wagon section of ENG file

Comment ( *************** Brakes - Wagon Section - General ********************** )
    BrakeEquipmentType ( "Manual_brake, Handbrake" )
    BrakeSystemType ( "Manual_Braking" )
    MaxBrakeForce ( 24.95kN )      Comment ( Empty weight - 6.5t-uk, NBR - 0.6, Friction - 0.5 )
    MaxHandbrakeForce ( 12.45kN )
    MaxReleaseRate ( 50.0 )
    MaxApplicationRate ( 50.0 )

A sample configuration for this type of brake system can be found in the XYZ locomotive found on the test stock page.

Make sure that you test your settings with the brake tests described on the testing page.

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Sample Brake Code - Locomotive system

This type of code describes the configuration locomotive braking system, and is located in the engine section of the ENG file.

Comment ( *** Braking system *** )

Comment ( == Compressor, Reservoir and General == )
    BrakesEngineBrakeType( "Steam_brake" )
    EngineBrakesControllerMaxReleaseRate( 1.0 )
    EngineBrakesControllerMaxApplicationRate( 1.0 )

Make sure that you test your settings with the brake tests described on the testing page.

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Sample Brake Code - Train and Locomotive Control Valve

This type of code describes the controller (brake valves) in the locomotive.

Comment ( *** Brake control equipment *** )
Brake_Engine ( 0 1 0.2 0.3
    NumNotches ( 1
       Notch( 0.0 1 EngineBrakesControllerContinuousServiceStart )
       )
    )

Brake_Brakeman ( 0 1 0.2 0.3
    NumNotches ( 1
       Notch( 0 1 BrakemanBrakesControllerManualBrakingStart )
       )
    )

Brake_Hand ( 0 1 0.0125 0        Comment ( Note: some locomotives were not fitted with handbrakes. )
       NumNotches( 0 )
    )

A sample configuration for this type of brake system can be found in the XYZ locomotive found on the test stock page.

Make sure that you test your settings with the brake tests described on the testing page.

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Air Brake Systems

Sample Brake Code - Wagon Section

The brake configuration in this section represents the brake configuration (A-6-ET type) generally used by the NSWGR pre-1950, which did not have emergency or supplementary reservoirs on the wagons.

This type of code goes into the WAG file or the wagon section of the ENG file.

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

Use the
Brake Calculators to calculate some of the relevant values that are required for entry in the WAG files. Additional information is also available in the Generic Brake Design Section.

WAG File or wagon section of ENG file

Comment ( *************** Brakes - Wagon Section - General ********************** )
    BrakeEquipmentType ( "Triple_valve, Auxilary_reservoir, Handbrake" )
    BrakeSystemType ( "Air_single_pipe" )
    MaxBrakeForce ( 24.95kN )      Comment ( Empty weight - 6.5t-uk, NBR - 0.6, Friction - 0.5 )
    MaxHandbrakeForce ( 12.45kN )
    EmergencyResVolumeMultiplier ( 1.0 )
    TripleValveRatio ( 2.5 )
    MaxReleaseRate ( 50.0 )
    MaxApplicationRate ( 50.0 )
    MaxAuxilaryChargingRate ( 20.0 )
    EmergencyResChargingRate ( 20.0 )
    BrakeCylinderPressureForMaxBrakeBrakeForce ( 50.0 )
    EmergencyResCapacity ( 2.064ft^3 )
    BrakePipeVolume ( 0.386ft^3 )
    ORTSBrakeShoeFriction ( 0.0 0.49 8.0 0.436 16.1 0.4 24.1 0.371 32.2 0.35 40.2 0.336 48.3 0.325 56.3 0.318 64.4 0.309 72.2 0.304 80.5 0.298 88.5 0.295 96.6 0.289 104.6 0.288)      Comment ( == COBRA Brakeshoes == )

Non-Air Rolling Stock

Non-air rolling stock can be modelled by using the following 'abbreviated' code instead of the full code above. For vehicles not fitted with air brakes set the BrakeSystemType to "Air-piped".

Comment ( *************** Brakes - Wagon Section - General ********************** )
    BrakeEquipmentType ( "Triple_valve, Auxilary_reservoir, Handbrake" )
    BrakeSystemType ( "Air_piped" ) Comment (Wagons not fitted with air brakes)
    MaxHandbrakeForce ( 7.971kN )      Comment ( Empty weight - 6.5t-uk, NBR - 0.6, Friction - 0.5 )
    BrakePipeVolume ( 0.145ft^3 )

Typically these types of wagons had handbrakes fitted. It was also normal operating practice to 'pin' down (or apply) a number of handbrakes on non-air trains when they were descending steep gradients to maintain control of the train. Once at the bottom of the grade the handbrakes were released.

Make sure that you test your settings with the brake tests described on the testing page.

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Sample Brake Code - Locomotive - Compressor, Reservoir and Train system

This type of code describes the configuration and operation of the compressor, train reservoir and the train braking system, and is located in the engine section of the ENG file.

Use the
Brake Calculators to calculate some of the relevant values that are required for entry in the ENG file. Additional information is also available in the Generic Brake Design Section.

Comment ( *** Braking system *** )

Comment ( == Compressor, Reservoir and General == )
    AirBrakesMainMaxAirPressure( 107.0 )
    AirBrakesCompressorRestartPressure( 90.0 )
    ORTSBrakePipeChargingRate ( 40.0 )
    AirBrakesMainResVolume( 11.0ft^3 )
    ORTSMainResChargingRate ( 0.575 )
    TrainPipeLeakRate ( 0.0833 )

Comment ( == Automatic Brake valve - Train == )
    TrainBrakesControllerMaxSystemPressure( 70 )
    TrainBrakesControllerMaxReleaseRate( 1.0 )
    TrainBrakesControllerMaxQuickReleaseRate( 20.0 )
    TrainBrakesControllerMaxApplicationRate( 1.0 )
    TrainBrakesControllerEmergencyApplicationRate( 30.0 )
    TrainBrakesControllerFullServicePressureDrop( 25.0 )
    TrainBrakesControllerMinPressureReduction( 7.0 )

Comment ( == Independent Brake valve - Engine & Tender == )
    EngineBrakesControllerMaxSystemPressure( 70 )
    EngineBrakesControllerMaxReleaseRate( 1.0 )
    EngineBrakesControllerMaxQuickReleaseRate( 20.0 )
    EngineBrakesControllerMaxApplicationRate( 1.0 )
    EngineBrakesControllerEmergencyApplicationRate( 30.0 )
    EngineBrakesControllerFullServicePressureDrop( 25.0 )
    EngineBrakesControllerMinPressureReduction( 7.0 )

Make sure that you test your settings with the brake tests described on the testing page.

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Sample Brake Code - Train and Locomotive Control Valve

Note: It is recommended that graduation operation be selected with this brake configuration. For graduated operation of the brakes, it will be necessary to select the relevant menu option tickbox in Open Rails before starting. For more information on the BrakeController tokens used by Open Rails to model the different types of vacuum brake valves, see Air BrakeControllers page.

This type of code describes the controller (brake valves) in the locomotive.

Comment ( *** Brake control equipment *** )
Brake_Engine ( 0 1 0.01 0.25
    NumNotches ( 5
       Notch( 0.0 0 TrainBrakesControllerFullQuickReleaseStart )
       Notch( 0.25 0 TrainBrakesControllerRunningStart )
       Notch( 0.50 0 TrainBrakesControllerHoldStart )
       Notch( 0.75 0 TrainBrakesControllerFullServiceStart )
       Notch( 1.0 0 TrainBrakesControllerEmergencyStart )
       )
    )

Brake_Train ( 0 1 0.01 0.25
    NumNotches ( 5
       Notch( 0.0 0 TrainBrakesControllerReleaseStart )
       Notch( 0.25 0 TrainBrakesControllerRunningStart )
       Notch( 0.50 0 TrainBrakesControllerHoldStart )
       Notch( 0.75 0 TrainBrakesControllerFullServiceStart )
       Notch( 1.0 0 TrainBrakesControllerEmergencyStart )
       )
    )

Brake_Hand ( 0 1 0.0125 0        Comment ( Note: some locomotives were not fitted with handbrakes. )
       NumNotches( 0 )
    )

A sample configuration for this type of brake system can be found in the XYZ locomotive found on the test stock page.

Make sure that you test your settings with the brake tests described on the testing page.

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Vacuum Brake Systems

Sample Brake Code - Wagon Section

The sample brake code below is from a typical British railway carriage of the early twentieth century. Most passenger carriages in Britain did not have handbrakes. Brake carriages and fitted goods wagons would also have a handbrake. Carriages built from the 1940s onwards (or after 1906 on the GWR) would also have Direct Action valves fitted. During the 20th century the maximum vacuum specified by most railway companies was increased from 20 InHg to 21 InHg. The Great Western Railway used a vacuum of 25 InHg. Bogie vehicles generally had two brake cylinders, whereas four and six wheeled vehicles usually only had one brake cylinder.

This type of code goes into the WAG file or the wagon section of the ENG file.

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

Use the
Brake Calculators to calculate some of the relevant values that are required for entry in the WAG files.

WAG File or wagon section of ENG file

Comment ( *************** Brakes - Wagon Section - General ********************** )
    BrakeEquipmentType ( "Vacuum_brake, Auxilary_reservoir" )
    BrakeSystemType ( "Vacuum_single_pipe" )
    MaxBrakeForce ( 74.0kN )      Comment ( == Braked at 70% tare mass, coefficient of friction 0.50 == )
    ORTSNumberBrakeCylinders ( 2 )
    ORTSBrakeCylinderSize ( 15in )
    ORTSAuxilaryResCapacity ( 2.25ft^3 )
    MaxReleaseRate ( 5.0InHg/s )
    MaxApplicationRate ( 5.0InHg/s )
    BrakeCylinderPressureForMaxBrakeBrakeForce ( 20.0InHg )
    BrakePipeVolume ( 1.45ft^3 )      Comment ( == Based on length of carriage plus 16 feet for bends etc == )
    ORTSBrakeShoeFriction ( 0.0 0.50 8.0 0.288 16.1 0.241 24.1 0.211 32.2 0.187 40.2 0.173 48.3 0.161 56.3 0.150 64.4 0.142 72.2 0.139 80.5 0.134 88.5 0.129 96.6 0.125 104.6 0.123 112.7 0.121)      Comment ( == Cast Iron Brakeshoes == )

Piped Stock

The code for a wagon that has a through vacuum pipe looks like this

Comment ( *************** Brakes - Wagon Section - General ********************** )
    BrakeEquipmentType ( "Handbrake" )
    BrakeSystemType ( "Vacuum_piped " ) Comment (Wagons not fitted with vacuum brakes)
    MaxHandbrakeForce ( 2.5kN )      Comment ( Empty weight - 6.5t-uk, NBR - 0.6, Friction - 0.5 )
    BrakePipeVolume ( 0.82ft^3 )      Comment ( == Based on length of wagon plus 16 feet for bends, stands and hoses == )

Typically these types of wagons had handbrakes fitted. It was also normal operating practice to 'pin' down (or apply) a number of handbrakes on non-air trains when they were descending steep gradients to maintain control of the train. Once at the bottom of the grade the handbrakes were released.

Make sure that you test your settings with the brake tests described on the testing page.

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Sample Brake Code - Locomotive and Train system

This type of code describes the configuration and operation of the ejector(s) or exhausters and the train braking system, and is located in the engine section of the ENG file.

Use the
Brake Calculators to calculate some of the relevant values that are required for entry in the ENG files.

Comment (*************************** Brake System *********************************************
             Included in this section - Compressor, Reservoir, Application rates, etc
             **************************************************************************************)


Comment ( == Reservoir and General == )
    BrakesTrainBrakeType( "vacuum_single_pipe" )
    ORTSBrakeServiceTimeFactor ( 10 )
    ORTSBrakeEmergencyTimeFactor ( 10 )
    ORTSBrakePipeTimeFactor ( 0.36 )
    TrainPipeLeakRate ( 0.04InHg/s )
Comment (== Ejectors/Exhauster ==)
VacuumBrakesHasVacuumPump ( 0 )
    ORTSBrakePipeChargingRate ( 0.21InHg/s ) Comment (* Estimate for Gresham & Craven Dreadnought 25/20 ejector: BrakePipeChargingRateLargeEjector = 0.13 / BrakePipeChargingRateSmallEjector = 0.08 *)
    VacuumBrakesLargeEjectorUsageRate ( 600lb/h )
    VacuumBrakesSmallEjectorUsageRate ( 240lb/h )
    VacuumBrakesMinBoilerPressureMaxVacuum ( 90psi )
Comment ( == Automatic Brake valve - Train == )
    TrainBrakesControllerMaxSystemPressure ( 21InHg )

Make sure that you test your settings with the brake tests described on the testing page.

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Sample Brake Code - Train and Locomotive Control Valve

This type of code describes the controller (brake valves) in the locomotive. For more information on the BrakeController tokens used by Open Rails to model the different types of vacuum brake valves, see Vacuum BrakeControllers page.

A sample configuration for this type of brake system can be found in the XYZ locomotive found on the test stock page.

Make sure that you test your settings with the brake tests described on the testing page.

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Brake Calculators

Vehicle Maximum Brake and Handbrake Force

To use this calculator:


More Info If you need to convert any numbers on this page for input into the following calculators, then use the conversions page.


Tare (Empty) Weight:

Select input units:
tons (UK) tons (US) tonnes (Metric)

Note: In most instances where a CoF curve similar to the above has been entered into the WAG file this value will be 0.5 - see Implementation for more details.
Coefficient of friction (Automatic Brake): Coefficient of friction (Handbrake):

NBR - Passenger: NBR - Goods: NBR - Locomotive: NBR - Tender: NBR - Handbrake:

Results

The following values represent the force applied to the brake shoes, and are the values used in OR to calculate a wagon's braking force. Naturally the actual force applied to the wheels of the wagon will be further reduced by the relevant factor from the CoF curve used in the WAG file, based upon the speed of the train.

Weight (Tons UK):    Weight (Tons US):     Weight (Tonne Metric):

Goods - Brake Force (kN):     Handbrake Force (kN):    

Passenger - Brake Force (kN):     Handbrake Force (kN):

Locomotive - Brake Force (kN):    

Tender - Brake Force (kN):     Handbrake Force (kN):

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Brake Pipe Volume

The appropriate values can then be entered into the relevant input boxes below. The calculator makes allowance for the brake hose connection between the cars (two per car). The exterior length of the car (excluding the couplers) should be entered into the calculator.

The train brake pipes vary depending upon whether the braking system is Air or Vacuum. Air systems typically use 1.25" pipes, whilst Vacuum systems use 2.0" pipes. Select the correct brake system type.

If you need to convert any numbers on this page for input into the following calculators, then please use the conversions page.

Car Length (ft):

Select car brake type:

Vacuum Air

Results

Pipe Volume (cu ft):

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Reservoir Charging Rate

The charging rate for a reservoir can be determined by the following formula:

Charging time (min) = [ Reservoir Vol (cu ft) * (Max Press (psi) - Min Press (psi)) ] / [(Free air (scfm) * Atm Press (psi) ]

Where scfm = Standard cubic feet per minute

The outcome of this formula is then converted to a charging rate per sec for inclusion into open Rails.

This calculator can be used to determine the charging rates for various air reservoir type devices as follows:

The appropriate values can then be entered into the relevant input boxes below.

If you need to convert any numbers on thsi page for input into the following calculators, then please use the conversions page.

Starting Pressure (psi):     Max Resevoir Pressure (psi):     Main Resevoir Volume (cu ft):     Compressor Free Air (cu ft / min):    

Results

Charging Time (mins):     Charging Rate (psi/sec):    

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Brake Cylinder Size Calculator

To calculate the size of the necessary brake cylinder size for the stock in question the following equation can be used as a rule of thumb.

Brake Cylinder Force (lbf) = {Max Brake Force (kN) / Leverage ratio} (kN)

Leverage ratio - The connection from the brake cylinder to the brake-shoes is made by beams and levers, or their equivalents. Leverage ratio is a measure of the mechanical leverage of the levers in the braking system. Typically it will be somewhere between 7 and 9.

These values can then be entered into the appropriate code lines below.

If you need to convert any numbers on this page for input into the following calculators, then please use the conversions page.

Max Brake Force (kN):     Leverage ratio:    

Results

Brake Cylinder Force (kN):    

Once the required brake Brake Cylinder Forece is determined, then the appropriate brake cylinder size can be found, and then the corresponding auxiliary cylinder size selected.

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Useful References

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