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 valve positions on typical train or locomotive (engine) brake controllers.

For more information on the types of control valves used by each brake system refer to here.

Index

Introduction

Standard British Rail Brake Control

Gresham & Craven SSJ Controller

Diesel and Electric - EQ System Vacuum

Diesel and Electric - No EQ System

Diesel and Electric - Dual Vacuum and Air Brakes - Vacuum System

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

This type of brake system was typically fitted to British Rail steam locomotives.

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 and vacuum pump. TrainBrakesControllerReleaseStart
Running The brake is put into a "neutral" position whereby the BP will lose vacuum due to leakage over time. This leakage can be compensated by adjusting the small ejector or "automatically" by the vacuum pump if fitted. TrainBrakesControllerRunningStart
Brake On The BP vacuum is destroyed and the brakes are applied to stop the train. TrainBrakesControllerApplyStart
Emergency The BP vacuum is destroyed as fast as possible. TrainBrakesControllerEmergencyStart
Independent Brake Valve Controller () (Engine Brake)

On some locomotives the Independent brake was not fitted, and in this instance it can be left out of the ENG file.

Brake Valve Position State OR BrakeContoller Type
Brake Off The "Brake Off (Release)" position releases the brake. EngineBrakesControllerReleaseStart
Running The air pressure is maintained at the rate when position changed. EngineBrakesControllerRunningStart
Brake On The "Brake On (Apply)" position applies the brake. EngineBrakesControllerApplyStart

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Gresham & Craven SSJ Controller

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 and vacuum pump. TrainBrakesControllerReleaseStart
Brake On The BP vacuum is increased or decreased is "graduated" by moving this control up or down. TrainBrakesControllerVacuumContinuousServiceStart
Emergency The BP vacuum is destroyed as fast as possible. TrainBrakesControllerEmergencyStart
Independent Brake Valve Controller () (Engine Brake)

On some locomotives the Independent brake was not fitted, and in this instance it can be left out of the ENG file.

Brake Valve Position State OR BrakeContoller Type
Brake Off The "Brake Off (Release)" position releases the brake. EngineBrakesControllerReleaseStart
Running The air pressure is maintained at the rate when position changed. EngineBrakesControllerRunningStart
Brake On The "Brake On (Apply)" position applies the brake. EngineBrakesControllerApplyStart

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Diesel and Electric - EQ System Vacuum

Automatic Brake Valve Controller () (Train Brake)
Brake Valve Position State OR BrakeContoller Type
Running The RUNNING position connects the exhauster to the brake pipe. A separate exhauster speeder button is provided for the driver to switch the exhauster to full speed. This raises the vacuum in the brake pipe as quickly as possible to get a release. TrainBrakesControllerFullQuickReleaseStart
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 and vacuum pump. TrainBrakesControllerReleaseStart
Service (Self-lapping) In the SERVICE range, the automatic brake valve adjusts the vacuum in the EQ, which, in turn, operates the application valve within the locomotive. The application valve admits air into the brake pipe. The EQ system therefore enables the driver to use his brake valve in a similar fashion, irrespective of the length of the train. The EQ brake is of a self-lapping type, and when the valve is moved a position in the SERVICE range the vacuum will fall to the required value and then remain constant. Further movement of the handle will cause the vacuum to "lap" at a different value. TrainBrakesControllerVacuumContinuousServiceStart
Emergency The BP vacuum is destroyed as fast as possible. TrainBrakesControllerEmergencyStart
Independent Brake Valve Controller () (Engine Brake)

On some locomotives the Independent brake was not fitted, and in this instance it can be left out of the ENG file.

Brake Valve Position State OR BrakeContoller Type
Brake Off The "Brake Off (Release)" position releases the brake. EngineBrakesControllerReleaseStart
Running The air pressure is maintained at the rate when position changed. EngineBrakesControllerRunningStart
Brake On The "Brake On (Apply)" position applies the brake. EngineBrakesControllerApplyStart

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Diesel and Electric - No EQ System

No equalising reservoir is fitted to brakes, so braking release/application rates are not impacted by the EQ Reservoir timing values

Automatic Brake Valve Controller () (Train Brake)
Brake Valve Position State OR BrakeContoller Type
Running The RUNNING position connects the exhauster to the brake pipe. A separate exhauster speeder button is provided for the driver to switch the exhauster to full speed. This raises the vacuum in the brake pipe as quickly as possible to get a release. TrainBrakesControllerFullQuickReleaseStart
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 and vacuum pump. TrainBrakesControllerReleaseStart
Lap BP Vacuum is held at present vacuum, but isolated from exhauster, so some BP leakage will occur. TrainBrakesControllerHoldLappedStart
Service (Self-lapping) In the SERVICE range, the brake is of a self-lapping type, and when the valve is moved a position in the SERVICE range the vacuum will fall to the required value and then remain constant. Further movement of the handle will cause the vacuum to "lap" at a different value. TrainBrakesControllerVacuumContinuousServiceStart
Emergency The BP vacuum is destroyed as fast as possible. TrainBrakesControllerEmergencyStart
Independent Brake Valve Controller () (Engine Brake)

On some locomotives the Independent brake was not fitted, and in this instance it can be left out of the ENG file.

Brake Valve Position State OR BrakeContoller Type
Brake Off The "Brake Off (Release)" position releases the brake. EngineBrakesControllerReleaseStart
Running The air pressure is maintained at the rate when position changed. EngineBrakesControllerRunningStart
Brake On The "Brake On (Apply)" position applies the brake. EngineBrakesControllerApplyStart

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Diesel and Electric - Dual Vacuum and Air Brakes - Vacuum System

No equalising reservoir is fitted to brakes, so braking release/application rates are not impacted by the EQ Reservoir timing values

Automatic Brake Valve Controller () (Train Brake)
Brake Valve Position State OR BrakeContoller Type
Brake Off The "Brake Off (Release)" position connects the exhauster to the brake pipe and switches the exhauster to full speed. This raises the vacuum in the brake pipe as quickly as possible to get a release. TrainBrakesControllerReleaseStart
Running The exhauster keeps running but at its slow speed. This ensures that the vacuum is maintained against any small leaks or losses in the brake pipe, connections and hoses. TrainBrakesControllerRunningStart
Lap Lap is used to shut off the connection between the exhauster and the brake pipe to close off the connection to atmosphere after a brake application has been made. This position is not used on more modern brakes. TrainBrakesControllerHoldLappedStart
Brake On The "Brake On (Apply)" position closes off the connection to the exhauster and opens the brake pipe to atmosphere. The vacuum is reduced as air rushes in. TrainBrakesControllerApplyStart
Emergency The BP vacuum is destroyed as fast as possible. TrainBrakesControllerEmergencyStart
Independent Brake Valve Controller () (Engine Brake)

On some locomotives the Independent brake was not fitted, and in this instance it can be left out of the ENG file.

Brake Valve Position State OR BrakeContoller Type
Brake Off The "Brake Off (Release)" position releases the brake. EngineBrakesControllerReleaseStart
Running The air pressure is maintained at the rate when position changed. EngineBrakesControllerRunningStart
Brake On The "Brake On (Apply)" position applies the brake. EngineBrakesControllerApplyStart

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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

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