[abschlammventil]

Stijn D.C., on 28 April 2019 - 12:14 PM, said:

Mg = Magnetic brakes
But you mean selection brakeregime P/R/G...

This is a picture of a german double deck passenger coach. Pictured is indeed the selection lever to change brake regimes. In Germany there are 4 different brake regimes for conventional air brakes:

• "G" ("Güterzug" = freight train): Freight operation, slow applying and releasing to avoid strain on couplers in long trains.
  
• "P" ("Personenzug" = passenger train): Mostly used on older (slower) passenger equipment and shorter freight trains. Faster reaction times.
  
• "R" ("Rapid" no translation needed...): Used on faster passenger trains, fast reaction times. Coaches are often equipped with "electro-pneumatic" ("ep") brakes allowing for very fast brake application and release.
  
• "R+Mg" ("Mg" = magnet): Same as "R" but with added magnetic brakes (used only on passenger trains). When brake valves are in emergency position, electro magnets are lowered on the rails, allowing for short stopping distances in emergencies (and causing chaos in the dining car...).

The maximum permitted speed of a train is dependend on the brake regime it's under: "G" allows only for slow speeds. For high speeds (140 km/h and over) "R+Mg" is needed. The pictured lever has no "G" option, because it's not needed on passenger trains. First option on top is "P", followed by "R" in the middle and "R+Mg" currently activated at the bottom. Most passenger trains run in "R+Mg" nowadays. The numbers on the scale inform the train's conductor about the braking abilities of each coach for each brake regime (higher number = better braking ability). Based on that the braking ability for the whole train is calculated and information is given to the driver so he (or she) can adjust his (her) braking accordingly.

[mrmosky]

Looking at a couple of diesel locomotives and the braking steup.

In the HUD with the braking parameters, the main Reservoir pressure is showing 135 psi, whereas the .eng file specifies a maximum of 90 psi ( AirBrakesMainMaxAirPressure( 90 ). Can anyone tell mw where the HUD gets the reservoir pressure from?

Geoff

[darwins]

They seem to work for me. (Using MG anyway) With:

Comment ( == Compressor, Reservoir and General == )
AirBrakesMainMaxAirPressure( 140 )
AirBrakesCompressorRestartPressure( 118 )
The result is

https://imgur.com/VAzh8xq.jpg
Changing that to:
Comment ( == Compressor, Reservoir and General == )
AirBrakesMainMaxAirPressure( 90 )
AirBrakesCompressorRestartPressure( 80 )
I then gethttps://imgur.com/VAzh8xq.jpg
Might I ask why you want to go so low anyway? BR diesel and electric locos generally had main reservoir between 118 and 140 psi AFAIK.

https://imgur.com/VAzh8xq

[mrmosky]

These pictures look the same to me. The main res pressure at 138.

The reason I ask is that I am currently making a 3d cab for a class 73, and it has a combined pressure gauge for min res and brake pipe (two needles on the same scale ). The maximum pressure on the gauge scale is 120 psi, so I assume that the max pressure for this loco is a little below that value. However, I have not been able to make it any lower than 138.

Geoff

[darwins]

You are quite right about the gauge in the class 73, you are now making me wonder about other Southern Region classes.The 73s and some 33s were equipped for working with EP braked multiple unit stock.
Possibly they had the same reservoir pressure in order to work with them. This may have also applied to class 71 which was built with air brakes (almost a decade before they started fitting air brakes on diesel and electric elsewhere in UK).
Sorry to say that I have little information to go on. I have been unable to locate any manuals for any of classes 33, 71, 73, 74 or the SR EP braked multiple unit stock.
My best guess in the absence of hard fact would be 100 psi - this was the reservoir pressure of the older SR EMU stock as noted in this accident report. (I am finding accident reports to be a very useful source of information about brakes - providing a lot of information that is not readily available elsewhere.)
Also today found a very informative video about the original EP braked BR(S) units.
That then brings me on to think about the air brake controller - Class 73 you have a single controller for EP brakes, air brakes and vacuum brake - do you know any more about this?
Again without hard information I would guess it to be the same as the one described on the EMU in the video - that is OFF / EP continuous service / LAP / APPLY / EMERGENCY - which (apart from the EP bit) is kind of possible in OR at the moment - as LAP / APPLY and EMERGENCY definitely work with twin pipe air brakes, and should work with vacuum_single_pipe_EQ brakes as well.
OFF is more of an issue as there are problems at the moment with RUNNING for vacuum brakes on diesel and electric and questions around the choice of RUNNING, RELEASE and FULL QUICK RELEASE with regards to air brakes.
The 73 did have an exhauster speed up button - the equivalent of RELEASE for vacuum brakes, but I am not sure if this was also a RELEASE button for air brakes that allowed the train pipe to be overcharged.
So many unknowns... unless someone can come up with more detail on these.

[darwins]

Oh no... I posted the same picture twice!!! This should be the second one

https://imgur.com/TDWmFQQ.jpg

[darwins]

The document on setting brakes is very useful indeed. It has enabled me to set up blended dynamic braking in such a way that the air brake does not apply unless the dynamic brake force is less than the the air brake force would have been.
I should also take the advice to adjust some values for EmergencyResVolumeMultiplier ( ) and EmergencyResCapacity ( )
To add to the discussion on suitable values for MaxReleaseRate ( ) and MaxApplicationRate ( ) the standards given in GMRT 2045 should be very useful for present day trains in UK and the rest of Europe.
To summarise these:
For Air_Twin_Pipe ( Figures for OR assuming Max BC pressure 5.0 bar or 72.5 psi )

For passenger carriages time for BC to go from 0 to 95% max pressure is 2 to 3 seconds and time to release from max pressure to 0.4 bar is 15 to 20 seconds.That approximates to having MaxApplicationRate between ( 23 ) and ( 34 ) and MaxReleaseRate between ( 3.3 ) and ( 4.4 )
For locomotives hauling or propelling passenger carriages time for BC to go from 0 to 95% max pressure is 2 to 3 seconds and time to release from max pressure to 0.4 bar is 9 to 12 seconds.That approximates to having MaxApplicationRate between ( 23 ) and ( 34 ) and MaxReleaseRate between ( 5.6 ) and ( 7.4 )
For goods wagons time for BC to go from 0 to 95% max pressure is 9 to 15 seconds and time to release from max pressure to 0.4 bar is 30 to 45 seconds.That approximates to having MaxApplicationRate between ( 4.6 ) and ( 7.6 ) and MaxReleaseRate between ( 1.5 ) and ( 2.2 )
For locomotives hauling goods wagons time for BC to go from 0 to 95% max pressure is 20 to 28 seconds and time to release from max pressure to 0.4 bar is 30 to 45 seconds.That approximates to having MaxApplicationRate between ( 2.5 ) and ( 3.4 ) and MaxReleaseRate between ( 1.5 ) and ( 2.2 )

For Air_Single_Pipe ( Figures for OR assuming Max BC pressure 5.0 bar or 72.5 psi )

For passenger carriages time for BC to go from 0 to 95% max pressure is 3 to 5 seconds and time to release from max pressure to 0.4 bar is 15 to 20 seconds.That approximates to having MaxApplicationRate between ( 14 ) and ( 23 ) and MaxReleaseRate between ( 3.3 ) and ( 4.4 )
For locomotives hauling or propelling passenger carriages time for BC to go from 0 to 95% max pressure is 3 to 5 seconds and time to release from max pressure to 0.4 bar is 9 to 12 seconds.That approximates to having MaxApplicationRate between ( 14 ) and ( 23 ) and MaxReleaseRate between ( 5.6 ) and ( 7.4 )
For goods wagons time for BC to go from 0 to 95% max pressure is 18 to 30 seconds and time to release from max pressure to 0.4 bar is 30 to 45 seconds.That approximates to having MaxApplicationRate between ( 2.3 ) and ( 3.8 ) and MaxReleaseRate between ( 1.5 ) and ( 2.2 )
For locomotives hauling goods wagons time for BC to go from 0 to 95% max pressure is 20 to 28 seconds and time to release from max pressure to 0.4 bar is 30 to 45 seconds.That approximates to having MaxApplicationRate between ( 2.5 ) and ( 3.4 ) and MaxReleaseRate between ( 1.5 ) and ( 2.2 )
For vehicles with Electro-Pneumatic (EP) braking, the standards are


The brake force build up time is 4 - 5 secs and release time is 5 - 6 secs.

Which in OR approximates to MaxApplicationRate ( 14 ) to ( 17 ) and MaxReleaseRate ( 11 ) to ( 13 )




For independent locomotive brakes (straight air brakes)

The brake force build up time is 2.5 - 5 secs and release time is 7 secs.


Which in OR approximates to MaxApplicationRate ( 17 ) to ( 27 ) and MaxReleaseRate ( 9.5 )





An older UK document that I have found (from the 1960s when air brakes were starting to replace vacuum brakes) gives the following numbers for tests with an Air_Twin_Pipe on locomotives ( 70 psi max pressure for train pipe and BC, 140 psi for MR and 100 psi for MR pipe )

In 'Passenger' braking mode for application train pipe 70 to 0 psi in 3.5 s and BC from 0 to 65 psi in 3.8 s and for release train pipe 0 to 70 psi in 1.5 s and BC from 70 to 5 psi in 7.8 s.

In 'Goods' braking mode for application train pipe 70 to 0 psi in 3.0 s and BC from 0 to 65 psi in 21 s and for release train pipe 0 to 70 psi in 1.5 s and BC from 70 to 5 psi in 29.6 s.
These timings can be achieved in OR using ORTSBrakePipeChargingRate ( 300 ) , TrainBrakesControllerMaxReleaseRate( 46psi/s ) , TrainBrakesControllerMaxApplicationRate( 4.2psi/s ) and TrainBrakesControllerEmergencyApplicationRate( 60psi/s ) together with
For passenger braking MaxReleaseRate ( 9.0psi/s ) and MaxApplicationRate ( 10.0psi/s )
For goods braking MaxReleaseRate ( 2.4psi/s ) and MaxApplicationRate ( 3.4psi/s )

[darwins]

What Rob posted in April is very much a case for having options in eng files.
In that case for a present day wagon (or locomotive) in Europe we have a choice of four braking regimes:
G - GoodsP - Passenger (conventional)R - Rapid PassengerM - Magnetic Emergency Brake
I am not sure if it is necessary for all vehicles to have this choice. It would probably be sufficient to choose from the locomotive the most suitable regime for the vehicles in the train. (Although no vehicle would be able to brake more rapidly than using the fastest system specified in its own wag file.)
From the 1960s to the 1990s most locomotives offered a choice of 5 braking regimes
Vacuum Unbraked - slow application and release of vacuum brake for trains where only a few wagons or none at all had vacuum brakes.Vacuum Braked - faster application and release of vacuum brake for trains where most or all vehicles have working vacuum brakes.Off - train brakes not in use - the independent locomotive brake generally had a different speed of operation when in this position.Air Passenger - used for close coupled trains with twin pipe air brake throughout - including passenger and container trains.Air Goods - used for other air braked goods trains which generally worked on the single pipe system.
Another thread from the US has mentioned the choice of graduated release air brakes or not being in the eng file. It seems in US and possibly elsewhere that graduated release was used for passenger trains but not for goods trains.
Recent tests with OR suggest this is not a problem for British models. With the options box not checked then there is no graduated release with air single pipe, but graduated release is possible with twin pipe and EP brakes - so this is exactly like the prototype - there was AFAIK never any graduated release single pipe system in this country.

Now to add to the list of things that need choices, I have found some cases that relate to the throttle rather than the brake.
All new London Underground stock built after 1927 (and some built earlier) has had some form of automatic acceleration. (Early on either electro-magnetic or electro-pneumatic contacters, later pneumatic cam and more recently solid state).I have found that it is possible to approximate these using ORTSMaxTractiveForceCurves.A throttle can be set up to give four notches equivalent to OFF / Shunt / SERIES / PARALLEL.

Options that changed the behaviour of the throttle were (1) The Rate Switch, (2) The Weak Field Flag Switch and on some District line trains (3) The Coasting Control flag switch

The rate switch can not easily be included in OR.The rate switch offered two different rates of acceleration - normal and slow. The slower one would be used in conditions of low adhesion.
These would require two different sets of ORTSMaxTractiveForceCurves.At present if an eng file is set up for the normal rate it would slip constantly in snow - so perhaps better by default to set the slower rate and provide an optional alternative eng file with the faster rate.
When the weak field flag is down the PARALLEL position causes acceleration until full parallel is reached.When the weak field flag is up and the throttle is moved to the PARALLEL position then field weakening follows on from full parallel to give faster running.At present the workaround for this is to add a fourth notch to the throttle in the eng file to give OFF / Shunt / SERIES / PARALLEL / WEAK FIELD.
When the coasting flag is raised it has the effect of cutting off power when a speed of 30 mph is reached (if the weak field flag is down!). Again this can be included in the throttle but not changed by a separate switch.
Thinking about choices for both brakes and throttles - they are choices generally made at the start of a journey and not often changed when the train is in motion. Hence in Open Rails keystrokes might not be needed -we are running out of keystrokes available!A pull up menu that can be clicked with a mouse would do the job - a bit like the present F9 train operations menu. Having said that it would also be desirable with new 3-D cabs to have the various switches work with a click or the mouse.
The same could perhaps be used to make other choices such as diesel or electric operation for bi-mode trains or for selection of the correct pantograph for dual or multiple voltage electric trains (or TGV which have different performance on regular 25kV or on the 25kV LGV where they are allowed to draw a higher current).

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