Vacuum BrakeControllers

Aim - this section describes some common brake control positions, and how they can be modeled within the Open Rails ENG file.

The BrakeControllers are used to model the control valve positions on typical train or locomotive (engine) brake controllers.

Index

Introduction

Standard British Rail Brake Controller (Gresham & Craven - SSJ Controller)

Standard Great Western Railway (GWR) Brake Controller (Gresham & Craven - Dreadnought Ejector Controller)

Standard London North Eastern Railway (LNER) Brake Controller

Brake Controller Code Format

Sample Controller Code

Useful Links


Introduction

Over the years various brake systems have been developed. To control these brake systems various brake control valves were used to allow the locomotive driver to control the operation of the brakes. Older brakes tended to use air valves, whereas more modern systems have electrical (electronic) switches. The control valves or switches had multiple positions which allowed the driver to release or apply the brake under different scenarios.

Open Rails attempts to emmulate the operation of these valves or switches by providing a number of brake control tokens which can be defined in the ENG file. Each of these tokens may have a different function associated with them, and therefore the user should use the relevant tokens for the brake control being modelled. The order of the tokens when defined in the ENG file should be maintaind in the same sequence as the tokens are designed to operate. Out of sequence tokens may create incorrect brake control operations.

This page shows the brake control token that are thought to be used currently by Open Rails to define each of the relevant brake controller types. This is currently a work in progress, so any relevant feedback is welcomed through the contact page.

The brake system with an EQ reservoir has three timing components as follows, each of which will need some form of adjustment in OR:

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Standard British Rail Brake Control (Gresham & Craven SSJ Controller)

This type of brake system controller was typically fitted to British Rail steam locomotives, and used a Gresham & Craven SSJ Ejector with a standard BR control valve.

The control valve had two positions, "ON" and "OFF", and was "graduable", thus it could be moved to any position and the vacuum would be maintained at the level which corresponded to this position between the ON and OFF positions.

Automatic Brake Valve Controller () (Train Brake)
Brake Valve Position State OR BrakeContoller Type
Brake OFF The BP vacuum is "held at" 21 in Hg or increased to that value when the driver has the brake in this position due to the action of the ejectors.
Graduable between ON and OFF The brake valve is put in a position between the ON and OFF positions. TrainBrakesControllerVacuumContinuousServiceStart
Brake ON The BP vacuum is destroyed and the brakes are applied to stop the train.

Timing Parameters

The above train brake uses the following timing parameters in the ENG file:
Release - rate of release is the net sum of the following values = Large Ejector + Small Ejector - Brake Pipe Loss. The rate of vacuum creation will be dependent upon the settings in the ORTSBrakePipeChargingRate, VacuumBrakesLargeEjectorUsageRate, VacuumBrakesSmallEjectorUsageRate and VacuumBrakesMinBoilerPressureMaxVacuum parameters.
Application - rate of application is based upon the ratio of ORTSBrakePipeTimeFactor / ORTSBrakeServiceTimeFactor.

Independent Brake Valve Controller () (Engine Brake)

Typically a steam brake was applied to the locomotive and tender, which functioned as an Independent brake. This brake could be operated independently of the train brake. If a seperate locomotive brake is not fitted, then the EngineBrakeController parameters can be removed from the ENG file. This brake controller valve is based upon a 5 position notch control.

Brake Valve Position State OR BrakeContoller Type
Brake OFF The "Brake Off (Release)" position releases the brake.
Graduable between ON and OFF The steam pressure is maintained at the rate depending upon the valve position. EngineBrakesControllerBrakeNotchStart
Brake ON The "Brake On (Apply)" position applies the brake, independently of the train brake.

Timing Parameters

The above locomotive brake uses the following timing parameters in the ENG file:
EngineBrakesControllerMaxReleaseRate - rate of release, typically in InHg/s
EngineBrakesControllerMaxApplicationRate - rate of application, typically in InHg/s.

For an example of this type of brake configuration and operation see the DoG locomotive on the stock page.

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Standard Great Western Railway (GWR) Brake Controller (Gresham & Craven - Dreadnought Ejector Controller)

This type of brake system controller was typically fitted to Great Western Rail steam locomotives, and used a Gresham & Craven Dreadnought Ejector with a Dreadnought control valve.

The control valve had three positions, "ON", "RUNNING" and "OFF". thus it could be moved to any position and the vacuum would be maintained at the level which corresponded to this position between the ON and OFF positions.

Automatic Brake Valve Controller () (Train Brake)
Brake Valve Position State OR BrakeContoller Type
Brake OFF The BP vacuum is "held at" 25inHg or increased to that value when the driver has the brake in this position due to the action of the ejectors and vacuum pump. TrainBrakesControllerReleaseStart
Brakes ON The BP vacuum is destroyed at a variable rate depending upon how far that the controller valve is moved towards the ON position. TrainBrakesControllerVacuumApplyContinuousServiceStart

Timing Parameters

The above train brake uses the following timing parameters in the ENG file:
Release - rate of release is the net sum of the following values = Large Ejector + Small Ejector - Brake Pipe Loss. The rate of vacuum creation will be dependent upon the settings in the ORTSBrakePipeChargingRate, VacuumBrakesLargeEjectorUsageRate, VacuumBrakesSmallEjectorUsageRate and VacuumBrakesMinBoilerPressureMaxVacuum parameters.
Application - rate of application is based upon the ratio of ORTSBrakePipeTimeFactor / ORTSBrakeEmergencyTimeFactor.

Independent Brake Valve Controller () (Engine Brake)

No independent locomotive brake was fitted, so for this configuration parameters related to the locomotive brake can be left out of the ENG file.

For an example of this type of brake configuration and operation see the Hall locomotive on the stock page.

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Standard London North Eastern Railway (LNER) Brake Controller

This type of brake system controller was typically fitted to Great Western Rail steam locomotives, and used a Gresham & Craven Dreadnought Ejector with a Dreadnought control valve.

The control valve had three positions, "ON", "RUNNING" and "OFF". thus it could be moved to any position and the vacuum would be maintained at the level which corresponded to this position between the ON and OFF positions.

Automatic Brake Valve Controller () (Train Brake)
Brake Valve Position State OR BrakeContoller Type
Brake OFF The BP vacuum is "held at" 25inHg or increased to that value when the driver has the brake in this position due to the action of the ejectors and vacuum pump. TrainBrakesControllerReleaseStart
RUNNING The BP vacuum is held at the level that the BP has reached when the control valve is moved to the RUNNING position. TrainBrakesControllerRunningStart
Brakes ON The BP vacuum is destroyed at a variable rate depending upon how far that the controller valve is moved towards the ON position. TrainBrakesControllerVacuumApplyContinuousServiceStart

Timing Parameters

The above train brake uses the following timing parameters in the ENG file:
Release - rate of release is the net sum of the following values = Large Ejector + Small Ejector - Brake Pipe Loss. The rate of vacuum creation will be dependent upon the settings in the ORTSBrakePipeChargingRate, VacuumBrakesLargeEjectorUsageRate, VacuumBrakesSmallEjectorUsageRate and VacuumBrakesMinBoilerPressureMaxVacuum parameters.
Application - rate of application is based upon the ratio of ORTSBrakePipeTimeFactor / ORTSBrakeEmergencyTimeFactor.

Independent Brake Valve Controller () (Engine Brake)

An independent locomotive brake was fitted to steam braked locomotives, but omitted for vacuum braked units.

Brake Valve Position State OR BrakeContoller Type
Brake OFF The "Brake Off (Release)" position releases the brake.
Graduable between ON and OFF The steam pressure is maintained at the rate depending upon the valve position. EngineBrakesControllerVacuumContinuousServiceStart
Brake ON The "Brake On (Apply)" position applies the brake, independently of the train brake.

For an example of this type of brake configuration and operation see the V2 locomotive on the stock page.

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Brake Controller Code Format

The brake controller is defined with a range of positions that should match every position that the brake controller can be put into by the driver. It may have a smooth range of movement (ie graduated), notched movement or a combination of the two. The brake controller is defined by a block of code that has a typical format as follows:


ControllerName ( { min-val } { max-val } { step-val } { default-val }
      NumNotches ( { n }
            Notch ( { val } { smooth } { token-string } ) //one entry per notch
.................
      )
)

The individual lines of code are explained as follows:

i) ControllerName ( { min-val } { max-val } { step-val } { default-val }
Where -
ControllerName = name of the controller, for example it might be Brake_Train or Brake_Engine as appropriate
Min-val = minimum position of the controller, typically zero
Max-val = maximum position in the controller, typically one
Step-val = increment used when increasing /decreasing the control setting in OR for smooth ranges in notched controls, the smaller the number, the finer the adjustments in the control notch
Default-val = the position of the controller when OR starts, ie the brake can be ON, OFF, or in between.

ii) NumNotches ( { number }
Where -
Number = number of notches in the controller

iii) Notch ( { val } { smooth } { controller-token } )
Where -
Val = position between zero and one assigned to the notch
Smooth = allows smooth or notch movement, 0=notch, 1=smooth
Controller-token = the name of the brake token assigned to this notch. The token will assign relevant functionality or features to the notch position.

In particular, it is recommended that the "smooth" values not be set unless a continuous type brake token. Similarly attention should be paid to the "default-val" which will determine whether the position that the brake is in when OR starts.

For example, a typical train brake controller might look like the code block in the following section.

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Sample Controller Code

The following example shows the typical controller for a Standard BR brake control valve.

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

Comment ( *** Brake control equipment *** )
Brake_Train ( 0 1 0.3 0.4
    NumNotches ( 4
       Notch(0 0 TrainBrakesControllerReleaseStart )
       Notch(0.3 0 TrainBrakesControllerRunningStart )
       Notch(0.6 0 TrainBrakesControllerApplyStart )
       Notch(0.9 0 TrainBrakesControllerEmergencyStart )
       )
    )

SmallEjectorOrCompressor ( 0 1 0.1 0.5 )

If an Independent Brake Valve Controller (Engine Brake) is required then the following code should also be added to this section of the ENG file. Leave code out if no Engine brake fitted.

Brake_Engine ( 0 1 0.4 0.5
    NumNotches ( 3
       Notch(0 0 TrainBrakesControllerReleaseStart )
       Notch(0.5 0 TrainBrakesControllerRunningStart )
       Notch(0.9 0 TrainBrakesControllerApplyStart )
       )
    )

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Useful Links

Handbook For Railway Steam Locomotive Enginement - page 142 - Section 8 Brakes

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