Reputable ORTS users, develorers of the Program and a Rolling stock,
Let's discuss the brake system modeling problems. Preamble
Spoiler
Since I started using MSTS nearly 20 years ago, I encountered some odd things in brake systems reproducing.
When the models of native rolling stock started to appear, this lacks became much more evident.
I certainly started to learn and try, how to bring the brakes behavior as close to prototype as it possible, so here's the time to say "Great thanks" to Rudolf Richter and authors of the real railroad literature as well as people, who had carefully scanned and uploaded that valuable documents to the Internet.
As far as I see, most of the world's braking systems are based on the invention of Westinghouse, and even now their operating principles have not changed much, in view of the need to ensure compatibility of different types of rolling stock (today, old type cars, passenger and freight cars must be provided with properly working brakes even if being put into single train, that can be lead by locomotives of different systems) after all, this is important transportation-security condition. It is necessary to mention international rail traffic too.
This way, there is common or similar terminology in brake system hardware and its operations naming worldwide.
Furthermore, the Electropneumatic equipment (wich are quite similar too) that were developed later, became only an addition to above-mentioned systems.
As for MSTS and its legacy, which we have using ORTS now, I came to the conclusion that there are many factual errors, not only flaws, in the way brake systems were implemented.
Many model developers had to find some "tricks" to make real-like content, but having ORTS now, I suppose it's unproductive to follow this way further.
The offer The subject.
Let' s focus on historic rolling stock, built at 20-th century, because
-there is the topic already started here to discuss the modern braking systems ;
-we need to keep some "sharpness" in our discussion, not to "spread";
-there are enough of persons, I believe, who is interested in that rolling-stock type. The questions.
At this moment, I see three kinds of "problems":
-Absence of important brake features;
-Incorrect naming or working of features, that exist;
-Lack of precise or verbose documentation. The procedure.
As for the third "problem" we have already the topic for accumulating notes about such issues.
And about first two ones, let me invite you to say some words from your point of view and your own experience. The goal
I hope that, the result of this discussion and the synthesis of our opinions will be formulation and bringing the objective wishes about the brake systems improvement up to the ORTS development team.
The topic is huge and I am wondering if it needs perhaps to be broken down further into sections - according to brake types.
Having worked on research and testing with one of the developers for two years or so now, I have some feeling for the size of the topic and can understand why some things may get greater priority than others. Below is a list of braking systems with my own thoughts on progress on Open Rails so far. No brakes at all - very early trains - train stopped by putting steam loco into reverse gear (or telling horse to stop!) - now possible in OR using manual braking options Manual braking - early trains, trams, goods trains until mid or late 20th century - handbrake or brakesman on each car or wagon or in brake van - now possible in OR using manual braking options. Steam brake, automatic air brake or vacuum brake can now be combined with manual braking.
Straight air brake used with manual braking should be possible but still seems to have some bugs to iron out.
Non automatic train braking systems - late 19th century - including Eames Vacuum Brake and straight air brake - not possible in OR and unlikely to be a priority as very few models if any would use these.
Mechanical train braking systems - late 19th century - Webb Chain Brake - not possible in OR and unlikely to be a priority as very few models if any would use this.
Automatic air brake - both single and twin pipe systems currently function well in OR - these could be enhanced by a number of improvements including
Make graduated release an option in the eng file / brake system definition rather than on the options tab
Allow Overcharging - including "sprung" release or overcharge position
Allow reservoir pipe pressure to be less than main reservoir pressure
Additional application rate - that could be used for TCS braking or soft braking
Add anti-slip brake
Add anti-slide to prevent brakes locking in modern systems
Additional brake token(s) or possibility to allow user defined or scripted brake token
Not having to describe an emergency reservoir for systems that do not have an emergency reservoir
Automatic vacuum brake - single pipe system currently functions well in OR - this could be enhanced by a number of improvements including
Solving problems with TCS brake application with some brake tokens
Additional application rate - that could be used for TCS braking
Model correct auxiliary reservoir and transfer valve behaviour for systems with vacuum pump
Add visual effects for ejectors
Model twin pipe vacuum brake system (requires mechanical exhauster and high vacuum reservoir)
Add alternative types of vacuum exhauster
***allow blending of dynamic brake with vacuum train brake - although in reality locos concerned use air brakes for loco and vacuum brakes for train - mixed braking problem***
***add anti-slip brake - although in reality locos concerned use air brakes for loco and vacuum brakes for train - mixed braking problem***
EP brakes - these currently function in OR - they could be enhanced by
Add option to allow train pipe pressure not to be reduced during EP brake operation
Make graduated release an option in the eng file / brake system definition rather than on the options tab - separate options may be needed for EP and air operation
Variations on EP braking such as SMEE - using air to apply service brake rather than to release it - not currently possible in OR there may be some demand to develop such models for US or Japanese trains
EV brakes - the vacuum brake version of EP braking - not currently possible in OR - unlikely to be a priority as limited to mostly South African EMUs and possibly one historic British design ECP braking - is available as an option in OR.
Dynamic brakes - currently possible in OR - no distinction between mechanical, hydraulic, rheostatic or regenerative types - such distinction may not be needed but capacity for all except regenerative brakes could be limited - we may wish to consider things such as possible overheating of resistor banks in rheostatic systems.
Magnetic track brakes - not currently modelled in OR - historically used for trams / streetcars / mountain railways now used for high speed trains - we may wish to add this into OR.
Mixed braking systems - some options for OR have been developed as part of the work on Manual Braking - these include
Steam brake on locomotive and vacuum brake on train
Steam brake on locomotive and manual brakes on train
Vacuum brake on locomotive and manual brakes on train
Air brake on locomotive and manual brakes on train Blended dynamic braking is currently possible in OR. There is some work going on to improve this - discussion in a separate thread.
***Straight air brake on locomotive - vacuum brake on train - would be a valuable addition as this was the situation with almost all vacuum braked diesel and electric locomotives used around the world. Development of this in OR may solve some of the problems listed with vacuum brakes above such as blending with dynamic brakes and addition of an anti slip brake.***
Have I misunderstood? Or would you like to narrow it some more perhaps? Possibly just to automatic air brake systems? All of the following were used in the 20th century:
Manual Braking
Automatic Air Brake
Automatic Vacuum Brake
Steam Brake
EP Brake
SMEE Brake
EV Brake
I had two reasons:
Not to conflict with Blended brakes topic started earlier;
Not to spread an attention for having more effective output;
and, being agree with You, that the theme is wide enough and had to be splitted.
Anyway, your review of existing brake systems implementation statuses and problems is magnificent!
It gives us a clear picture as things are done for now.
In another thread you posted a question about "bail-off" on a brake valve. This interested me to find out what "bail-off" means as it is not a term used in UK. Bail-off it seems means releasing the locomotive brake whilst the train brake is still applied. As far as I can tell this was never a common practice in UK and was not possible on many British locomotives. So a quick look at this brings up some related points to add to the list.
Vacuum Braked (Steam) Locomotives hauling Vacuum Braked Trains
All vacuum braked vehicles locomotives, carriages and wagons have a Vacuum Release Valve - this is the equivalent of the bleed off valve in the OR air brake model. It allows air to enter the auxiliary reservoir and destroy the vacuum. Since the brake is applied by the difference in pressure between the auxiliary reservoir and the brake cylinder this causes the partial or total release of the vacuum brake (depending on how much air was let in). On GWR locos the engine and tender shared a single vacuum reservoir and by using the vacuum release valve to admit air to this reservoir the locomotive and tender brakes were released without releasing the train brakes.
BR Standard Steam Braked Locomotives hauling Vacuum Braked Trains
On the BR standard locos (and some LNER SR and GWR locos) the steam brake was controlled by a vacuum reservoir. As with the vacuum braked locos, operating the Vacuum Release Valve to admit air to this "auxiliary reservoir" allows the locomotive and tender brakes to be released without releasing the train brakes.
Air Braked (Diesel and Electric) Locomotives hauling Vacuum Braked Trains
Most diesel and electric locomotives both vacuum braked and air braked use a straight air brake as the independent brake. In the case of vacuum braked locomotives the straight air brake was controlled by a "vacuum control reservoir" in the same way as for steam brakes described above. Some locomotives had a loco brake release button that allowed the loco brake to be released by admitting air to this "auxiliary reservoir".
The present case for vacuum braked trains in OR is that neither the bleed off valve on the F9 menu nor the bail off key on the keyboard release the locomotive brakes. A functioning Vacuum Release Valve - (bleed off valve) is needed for all vacuum braked vehicles to allow for shunting and for the use of different vacuums by different locomotives. Air Braked (Diesel and Electric) Locomotives hauling Air Braked Trains
In this case I am finding the reverse problem. I need to do more research but as far as I can tell from driving manuals and other documents very few modern British locos (if any at all) permit the release of the locomotive brake independently from the train brake. However in this case the bail off key works in OR even though it should not. Possibly we need ORTSLocomotiveHasBailOff ( ) so that we can disable this function when it should not be present. Air Braked and EP Braked Multiple Unit Trains
I am quite sure that there was no means to release motor car brakes and not trailer car brakes on any multiple unit train in this country. I very much doubt this is either possible or desirable on EMU, DMU or subway trains anywhere in the world. Yet using an EP braked EMU I find that when I press the bail off key in OR all the brakes on all the motor cars in the set are released. So once again please can we have the option to use ORTSLocomotiveHasBailOff ( 0 ) so that we can disable this function when it should not be present. Perhaps this should be the default setting - I have a feeling there were probably more trains without this than with it. The need for it seems to be only for operating very long freight trains.
...
The answer applies not just to those specific controllers, but to very many air brake controllers old and new.
Two things that will need to change in the model to allow this:
1. Overcharging needs to be allowed. At present the system can never exceed the value of TrainBrakesControllerMaxSystemPressure - so an overcharge value would need to be added. Then, as you say, we would need to ensure that the brake pipe<'s pressure> was gradually returned to normal working pressure when the brake handle is returned to the "RUNNING" position.
2. For twin pipe systems different values need to be allowed for the main reservoir pressure and the reservoir pipe pressure - at present both are determined by AirBrakesMainMaxAirPressure
So what if we let the Brake Pipe's pressure to approach the Main Reservoir's pressure - in other words - to raise the SYSTEM MAXIMAL PRESSURE's value to, say 7 or 8 kgf/cm2. Or retire from use this MSTS statement completely, as it is inadequate/simplified.
But then we will see the missing of the ORTS NOMINAL (RELEASE) BRAKE SYSTEM PRESSURE statement, wich is 5,1-6,8kgf/cm2 usually.
And, I repeat, this last value is adjustable IRL by locomotive's driver for tuning-up the brake system capabilities according to the particular operation mode (freight, passenger, flat terrain or hilly)
So, another idea is in introducing the new cab control for Brake Pipe's normal pressure adjustment.
Another note is that OR brake token names do not correspond to the common positions on many brake handles.
In OR TrainBrakesControllerRunningStart has only the effect of a HOLD or LAP position - it does not restore the brake pipe to normal pressure after a reduction.
darwins, on 29 October 2020 - 03:20 AM, said:
Interesting that at least 4 out of 6 OR brake token names are different to those that might appear on the controller.
Whilst I understand that token names used in the eng file must be the same for everyone (and they are more or less in English), I think it would be good if we could have different names appearing on screen - which could be in different languages as well.
This can be deal partially by translation of ORTS strings, but the different position's names for different countrie's locomotives (brake controller's positions display names, coded in *eng-files) would be pleasant.
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