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)
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
Brake Code - Structure and layout in Open Rails
Sample Brake Code - Wagon Section
Sample Brake Code - Wagon Section
Sample Brake Code - Locomotive system
Sample Brake Code - Train and Locomotive Control Valve
Sample Brake Code - Wagon Section
Sample Brake Code - Locomotive - Compressor, Reservoir and Train system
Sample Brake Code - Train and Locomotive Control Valve
Sample Brake Code - Wheel Slipe Protection
Automatic Vacuum Brake Systems
Sample Brake Code - Wagon Section
Sample Brake Code - Locomotive and Train system
Sample Brake Code - Train and Locomotive Control Valve
Non-Automatic (Straight) Vacuum Brake Systems
Sample Brake Code - Wagon Section
Sample Brake Code - Locomotive and Train system
Sample Brake Code - Train and Locomotive Control Valve
Vehicle Maximum Brake and Handbrake Force
Brake Cylinder Size Calculator
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.
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.
Note: It is good practice to put notes into the
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 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 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.
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
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 theWAG File or wagon section of ENG file
Comment ( *************** Brakes - Wagon Section - General ********************** )
BrakeEquipmentType ( "Manual_brake, Handbrake" )
BrakeSystemType ( "Manual_Braking" )
ORTSBrakeShoeType ( "Cast_Iron" )
ORTSMaxBrakeShoeForce ( 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 locomotives found on the test stock page.
Make sure that you test your settings with the brake tests described on the testing page.
Sample Brake Code - Locomotive system
This type of code describes the configuration locomotive braking system, and is located in the engine section of the
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.
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 locomotives found on the test stock page.
Make sure that you test your settings with the brake tests described on the testing page.
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
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 theWAG File or wagon section of ENG file
Comment ( *************** Brakes - Wagon Section - General ********************** )
BrakeEquipmentType ( "Triple_valve, Auxilary_reservoir, Handbrake" )
BrakeSystemType ( "Air_single_pipe" )
ORTSBrakeShoeType ( "Cast_Iron" )
ORTSMaxBrakeShoeForce ( 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.
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
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.
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 locomotives found on the test stock page.
Make sure that you test your settings with the brake tests described on the testing page.
Sample Brake Code - Wheel Slipe Protection
Wheel Slide Protection (WSP) can be added to various cars by adding the following parameters.
To activate it,
Under normal operation WSP is disabled if the BP pressure drops below 250kPa. However this limit can be disabled on some trains if required by inserting
Automatic 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
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 theWAG File or wagon section of ENG file
Comment ( *************** Brakes - Wagon Section - General ********************** )
BrakeEquipmentType ( "Vacuum_brake, Auxilary_reservoir" )
BrakeSystemType ( "Vacuum_Single_Pipe" )
ORTSBrakeShoeType ( "Cast_Iron" )
ORTSMaxBrakeShoeForce ( 24.95kN ) Comment ( Empty weight - 6.5t-uk, NBR - 0.6, Friction - 0.5 )
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.
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
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.
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 locomotives found on the test stock page.
Make sure that you test your settings with the brake tests described on the testing page.
Non-Automatic (Straight) Vacuum Brake Systems
Sample Brake Code - Wagon Section
Open Rails allows the modelling of both the Eames and hardy Brake Systems. Sample models are provided on the CTN Stock Page. The sample brake code below is from a Eames brake system and was used on steam trams in Sydney.
This type of code goes into the WAG file or the wagon section of the
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 theWAG File or wagon section of ENG file
Comment ( *************** Brakes - Wagon Section - General ********************** )
BrakeEquipmentType ( "Handbrake" )
BrakeSystemType ( "Straight_Vacuum_Single_Pipe" )
ORTSBrakeShoeType ( "Cast_Iron" )
ORTSMaxBrakeShoeForce ( 24.95kN ) Comment ( Empty weight - 6.5t-uk, NBR - 0.6, Friction - 0.5 )
MaxHandbrakeForce ( 5kN )
ORTSNumberBrakeCylinders ( 2 )
ORTSBrakeCylinderSize ( 10.5in ) Comment ( Gives approx volume of Eames brake 'cylinder' of 15in diameter = 0.22ft^3 )
ORTSAuxilaryResCapacity ( 2.25ft^3 )
MaxReleaseRate ( 10.0InHg/s )
MaxApplicationRate ( 10.0InHg/s )
BrakeCylinderPressureForMaxBrakeBrakeForce ( 19.0InHg )
BrakePipeVolume ( 2.14ft^3 ) Comment ( == Based on length of carriage plus 16 feet for bends etc == )
ORTSBrakeShoeFriction ( 0 0.31 1 0.30 2 0.28 3 0.27 4 0.26 5 0.25 7 0.24 8 0.23 9 0.22 12 0.21 14 0.20 17 0.19 20 0.18 24 0.17 29 0.16 34 0.15 40 0.14 47 0.13 55 0.12 66 0.11 84 0.10 115 0.09 160 0.09 ) Comment ( == Cast Iron Brakeshoes == )
During the changeover from straight vacuum brakes to automatic vacuum brakes, in Austria, at the end of the 19th century, some vehicles were converted to operate on either system (Auto or Non-Auto). This was done by the addition of an auxiliary reservoir and a valve that could allow it to be connected or disconnected from the brake system. In OR, if an auxiliary reservoir is added to a vehicle, that is given BrakeSystemType ( "Straight_Vacuum_Single_Pipe" ) then OR will automatically detect if the vehicle is part of a straight vacuum braked train or an automatic vacuum braked train and switch the auxiliary reservoir into or out of use accordingly. So if the cars are connected to a "Vacuum_Single_Pipe" system locomotive then they will operate as "Automatic" vacuum braked train.
Make sure that you test your settings with the brake tests described on the testing page.
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
Comment (*************************** Brake System *********************************************
Included in this section - Compressor, Reservoir, Application rates, etc
**************************************************************************************)
Comment ( == General == )
ORTSBrakeServiceTimeFactor ( 0.002s )
ORTSBrakePipeTimeFactor ( 0.08 )
TrainPipeLeakRate ( 0.20InHg/s )
Comment (== Ejectors/Exhauster ==)
ORTSBrakePipeChargingRate ( 0.0667InHg/s ) Comment ( evacuation rate of 40 cfm - based on volume of 200ft^3 )
VacuumBrakesLargeEjectorUsageRate ( 250lb/h )
VacuumBrakesMinBoilerPressureMaxVacuum ( 100psi )
Comment ( == Automatic Brake valve - Train == )
TrainBrakesControllerMaxSystemPressure ( 20InHg )
Make sure that you test your settings with the brake tests described on the testing page.
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 Eames Vacuum Brake Controllers and Hardy Vacuum Brake Controllers - Single Ejector, Hardy Vacuum Brake Controllers - Twin Ejector page.
A sample configuration for this type of brake system can be found in the locomotives found on the test stock page.
Make sure that you test your settings with the brake tests described on the testing page.
Brake Calculators
Vehicle Maximum Brake and Handbrake Force
To use this calculator:
- Step 1 - Insert the empty weight of the vehicle. If the vehicle has Load Compensation fitted to it, then the loaded version may be set up with a separate Brake Force.
- Step 2 - Select the Units of Measure that the weight is in.
- Step 3 - The calculator calculates the Brake Shoe Force based upon the appropriate NBR. Adjustments may need to be made if you are not entering the Brake Shoe Force in OR.
- Step 4 - Adjust the default Net Braking Ratio (NBR) as appropriate. Refer to the Net Braking Ratio section for more information on possible values.
- Step 5 - Press the 'Calculate' button, and copy the relevant values into the appropriate
WAG file parameters shown above.
If you need to convert any numbers on this page for input into the following calculators, then use the conversions page.
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.
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:
- Main Reservoir - The charging rate for the main reservoir. In this instance the reservoir volume will be the capacity of the main reservoir, and the free air capacity limit will be the output of the locomotive air compressor, which can be read from the table of air compressors information at the bottom of this page.
- Brake Cylinder - When the triple valve opens to apply the brakes the brake cylinder and auxiliary reservoir will equalise at the rate calculated in this formula. In this instance the reservoir volume will be the capacity of the brake cylinder, and the free air capacity limit will be the pipe connecting the brake cylinder and the auxiliary reservoir together. The charging rate for the brake cylinder will provide the max application rate in Open Rails terms. Typical free air capacity of the connecting pipe can be can be read from this table.
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.
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.
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.