Elvas Tower: Vacuum Braking Update - Elvas Tower

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Vacuum Braking Update

#11 User is offline   steamer_ctn 

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Posted 17 November 2019 - 03:50 PM

To allow simple operation of some of the vacuum brake configurations, a simple control mode has been implemented. This will allow operation of the vacuum brakes without the need for the user to use all the ejector valves.

#12 User is offline   darwins 

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Posted 14 January 2020 - 10:52 PM

It is now possible to have a separate large ejector on steam locomotives.

It is also now possible to have functional independent "steam brakes" on vacuum braked steam locos.
There is an example activity on the Coals to Newcastle website: https://www.coalstonewcastle.com.au/physics/demo-activity/#act7
The example is based on the Gresham & Craven type SSJ brake controller used on BR standard locos.

Thanks Peter for adding this to the OpenRails code.

This will allow more realistic braking control for BR, GWR, LMS and MR locos.

In the near future I will be releasing, via UKTS, some OpenRails updates to some of the excellent MSTS cab views by Hans Nooyen and Lew Price to include a large ejector control and high resolution gauges.

The details for this required in the eng section of the file are:
Comment ( ************************** Brake System *********************************************
Included in this section - Compressor, Reservoir, Application rates, etc
************************************************************************************* )

Comment (*** Braking systems ***)
BrakesTrainBrakeType( vacuum_single_pipe )
TrainPipeLeakRate ( 0.05inHg/s )

Comment (*** Ejectors ***)
Comment (* Estimate for Gresham & Craven SSJ type P ejector *)
VacuumBrakesHasVacuumPump ( 0 )
ORTSBrakePipeChargingRate ( 0.38inHg/s )
VacuumBrakesLargeEjectorUsageRate ( 690lb/hr )
VacuumBrakesSmallEjectorUsageRate ( 210lb/hr )
VacuumBrakesMinBoilerPressureMaxVacuum ( 110psi )

Comment (*** Brake Valve ***)
TrainBrakesControllerMaxSystemPressure ( 21InHg )
ORTSBrakePipeTimeFactor ( 0.02s )
ORTSBrakeServiceTimeFactor ( 10.0s )

Comment ( == Independent Brake valve - Engine & Tender == )
EngineBrakesControllerMaxReleaseRate ( 2.0inHg/s )
EngineBrakesControllerMaxApplicationRate ( 2.0inHg/s )

and in the EngineControllers section:
Comment ( Locomotive brake based upon Gresham & Craven MkIV Steam Brake Valve )
Brake_Engine ( 0 1 0.25 0.0
NumNotches( 5
Notch( 0 0 EngineBrakesControllerBrakeNotchStart )
Notch( 0.25 0 EngineBrakesControllerBrakeNotchStart )
Notch( 0.5 0 EngineBrakesControllerBrakeNotchStart )
Notch( 0.75 0 EngineBrakesControllerBrakeNotchStart )
Notch( 1 0 EngineBrakesControllerBrakeNotchStart ) ) )

Comment ( Based upon Gresham & Craven SSJ Ejector and control valve )
Brake_Train ( 0 1 0.1 0.1
NumNotches( 1
Notch( 0 1 TrainBrakesControllerVacuumContinuousServiceStart ) ) )

ORTSLargeEjector ( 0 1 0.1 0.0 NumNotches ( 0 ) )

ORTSSmallEjector ( 0 1 0.1 1.0 NumNotches ( 0 ) )








#13 User is offline   darwins 

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Posted 21 January 2020 - 12:22 AM

There is now a second tutorial on the Coals to Newcastle website. This one uses a locomotive (LNER V2) with a combination ejector of the type that was common on the LNER, SR and many of the pre-grouping companies.

https://www.coalston...-activity/#act8

Another example will shortly be provided as a tutorial for GWR brakes.

The latest round of developments mean that brake valves in Open Rails now behave in a much more appropriate way for vacuum brakes.

These changes do not automatically work with old MSTS files, but a simple cut and paste can significantly improve the functionality of vacuum brakes in old MSTS steam locomotive models.

If you still wish to use MSTS as well as OR you will need to make a copy of the MSTS eng file and put it into an OpenRails sub folder.

Open the copy in the OpenRails sub folder and find the train brake part in the file - this is from the default Flying Scotsman

Brake_Train ( 0 1 0.01 0.65
NumNotches( 3
Notch(0 1 TrainBrakesControllerReleaseStart )
Notch(0.4 1 TrainBrakesControllerRunningStart )
Notch(0.5 1 TrainBrakesControllerApplyStart )
)
)


Replace the entire of the section with:

Brake_Train ( 0 1 0.2 0.2
NumNotches( 3
Notch( 0.0 0 TrainBrakesControllerReleaseStart )
Notch( 0.2 0 TrainBrakesControllerRunningStart )
Notch( 0.4 1 TrainBrakesControllerVacuumApplyContinuousServiceStart ) ) )


and you should find that vacuum brakes on your steam loco work in a similar way to how they used to work with MSTS and probably even better!

Any feedback on progress so far would be welcomed.

#14 User is offline   darwins 

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Posted 22 January 2020 - 10:36 PM

The GWR demonstration is now available:

https://www.coalston...-activity/#act9

The demonstration uses a Hall class locomotive, with both large and small ejector controls as well as the driver's brake valve.

For those who like the GWR there it is now possible to include the brake controls as well as the vacuum pump for most types of GWR locos.

The same features will also allow improved brake models for MR/LMS and LNWR/LYR vacuum brake systems.

Together with the models above this gives fairly comprehensive coverage of vacuum brake systems for steam locomotives.

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