Elvas Tower: BrakePipe charging and discharging. 395-style - Elvas Tower

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BrakePipe charging and discharging. 395-style Rate Topic: -----

#1 User is offline   Weter 

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Posted 08 June 2020 - 08:06 PM

Another question: is it possible to model in ORTS, using features, that we already have, the 394&395Э trainbrake controller's behavior?
https://техучеба.рф/wp-content/uploads/2017/10/Кран-машиниста-395.jpg
Note the sector in the next picture to see, wich position is notched, wich-no.
http://rcit.su/gif/tiM0-10.gif
First, at I handle position, the BP is connected to the MR directly, so its recharging goes rather fast and BP gains high pressure.
As a result-fast recharging of long freight trains and guaranteed release of triple valves in each wagon (as some of them may be hardly released)

Second, at II handle position, feeding of the BP is made through the reductor, which releases excessive air till the pre-setted by the engineer pressure is achived, then, as leakage from BP continues, the reductor compensates that losses (is it equal to "Running" state?)
It's possible to perform "normal" brake release by II position, BUT MSTS (ORTS?) can't release brakes such way (or I don't know, how?)

The dream is to have special control, simulating reductor adjusting (say, +- 0,8 bar around 6), but it's not so principial, at last.

Third:
III,IV,V and VI positions can be modelled rather good (they looking much like Lap, Hold, Service and Emergency, resp.)

But there's V-A and it can mean either:
-very slow discharging of BP, for prevent stressing of couplers in case of very long freight trains (the "Soft tempo")
and I don't see, if the "MinimalReductionStart" is adequate substitute for this (again, maybe I'm not clever enough);
-or, in case of passenger modification, the V-Э is the NOTCH, where Hold status remaining, but EP signal is issued to train, so wagons apply their brakes without BP discharge.
I see, it's not possible to combine EP and Auto brakes in one consist yet (am I right?), furthermore, when I use "EP Apply", I observe a pressure drop in BP, so it's not good.

So, What and how EP(ECP) brake controller model in ORTS can do at this time?

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Posted 25 October 2020 - 01:37 PM

There are cool illustrations of 394 and 254 valves, explaining their work.
As well, the illustration of the 483 triple valve, working with them.

Translations:
Valve 394
Spoiler

Air distributor 483
Spoiler


#3 User is offline   darwins 

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Posted 26 October 2020 - 04:26 AM

Hello
The answer is no it can not be done in OR at the moment.
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 reservoir pipe 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
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.

In general I have used TrainBrakesControllerFullQuickReleaseStart for the RELEASE position on brake controllers (although it does not do overcharge) and TrainBrakesControllerReleaseStart for the RUNNING position as it will maintain train pipe against leakage and slowly return TP to normal pressure after a reduction.

Three main types of controllers used for air brakes in UK were as follows.
1. For older electric trains and steam trains using Westinghouse brakes - air single pipe system
  	Brake_Train ( 0 1 0.01 0.50
      	NumNotches ( 5
         	Notch( 0.0 0 TrainBrakesControllerFullQuickReleaseStart ) Comment ( RELEASE - connects brake pipe to main reservoir )
         	Notch( 0.25 0 TrainBrakesControllerReleaseStart ) Comment ( RUNNING )
         	Notch( 0.50 0 TrainBrakesControllerHoldStart ) Comment ( LAP )
         	Notch( 0.75 0 TrainBrakesControllerFullServiceStart ) Comment ( APPLY )
         	Notch( 1.0 0 TrainBrakesControllerEmergencyStart ) ) )

These did not have graduated release - so it would be good if this could be put in the eng file rather than on the options tab.
2. As used here on diesel and electric locos in 1960s and 1970s with twin pipe system (with graduated release!)
Brake_Train ( 0 1 0.1 0.2
 NumNotches ( 4
  Notch ( 0.0  0 TrainBrakesControllerFullQuickReleaseStart ) Comment ( RELEASE - sprung position - overcharges train pipe )
  Notch ( 0.1  0 TrainBrakesControllerReleaseStart ) Comment ( RUNNING )
  Notch ( 0.2  1 TrainBrakesControllerContinuousServiceStart )
  Notch ( 1.0  0 TrainBrakesControllerEmergencyStart )))

Comment ( add ANTI SLIP brake )

Brake_Engine ( 0 1 0.1 0.0
 NumNotches( 1
  Notch( 0 1 EngineBrakesControllerContinuousServiceStart ) ) )


3. A modern stepped brake

Brake_Train ( 0 1.0 0.01 0.2
NumNotches ( 9
Notch ( 0	0 TrainBrakesControllerFullQuickReleaseStart ) Comment ( RELEASE )
Notch ( 0.01 0 TrainBrakesControllerReleaseStart ) Comment ( RUNNING )
Notch ( 0.02 0 TrainBrakesControllerEPApplyStart )
Notch ( 0.16 0 TrainBrakesControllerEPApplyStart )
Notch ( 0.40 0 TrainBrakesControllerEPApplyStart )
Notch ( 0.65 0 TrainBrakesControllerEPApplyStart )
Notch ( 0.80 0 TrainBrakesControllerEPApplyStart )
Notch ( 0.99 0 TrainBrakesControllerEPApplyStart )
Notch ( 1.00 0 TrainBrakesControllerEmergencyStart )))

Comment ( RELEASE has separate overcharge button )
 
Brake_Engine ( 0 1 0.3 0
NumNotches ( 3
Notch ( 0	0 EngineBrakesControllerReleaseStart )
Notch ( 0.3  0 EngineBrakesControllerHoldStart )
Notch ( 0.6  0 EngineBrakesControllerFullServiceStart )))

Although the brake token says 'EP' this will also give you a regular air brake with steps.





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Posted 26 October 2020 - 08:27 AM

Thanks for joining the discussion: it seemed to me, that I'm alone here, who is interested in making air brakes more prototypic.
The first question, wich I want to ask you is why do you calling the brake pipe as

Quote

the reservoir pipe
?
I was confused a little and at first time, I thought, you was mistaken, but it was repeated further.
I suppose, there are 3 pipes:
- the brake pipe(wich causes automatic brake application in case of pressure drop in it) marked RED;
- the feeding, or the MAIN RESERVOIRE ( as it called at *.eng-file's statements) pipe, marked BLUE;
- and sometimes, the independent brakes pipe, wich connects MUed locos to synchronize their loco brake applications marked YELLOW

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Posted 26 October 2020 - 09:10 AM

A single pipe air brake system usually has only the train pipe running the length of the trainhttp://www.railway-technical.com/_Media/whse-brake-block-v1_med_hr_med.png
Older electric multiple units with Westinghouse also had a second pipe running the length of the train. The second pipe connected together the reservoirs on all of the motor coaches. This was not a "reservoir" pipe in the sense of the two pipe system, I was really just a way to make a larger air reservoir by joining together all the main reservoirs to create one large reservoir. The brake system on these electric multiple units was still a single pipe system like the one in the diagram as the auxiliary reservoirs are charged from the train pipe.
A twin pipe air brake system has both a main pipe and a reservoir pipe running the length of the train:http://www.railway-technical.com/_Media/two-pipe-air-brake-pic_med.png
This provides for a faster release of the brakes by charging the auxiliary reservoirs from the "reservoir pipe" rather than from the train pipe. (Twin pipe vacuum brakes work in a similar way.)


Until recently EP brakes worked in a similar way to twin pipe air brakes as they had both a reservoir pipe and a train pipe running the length of the train. In addition they had electric cables that could then provide for both fast release and fast application.http://www.railway-technical.com/_Media/whse-ep-brake-elec-pic_med.png

More modern EP brakes have replaced the train pipe with an electric cable so that now the reservoir pipe provides for all the air requirements.
http://www.railway-technical.com/_Media/brake-system-architecture_m_med.png
The diagrams are from the Railway Technical website which has more detail on different types of train brakes.

In UK at present locomotive hauled passenger trains, "freightliner" trains and most "high speed trains" use a twin pipe air brake system; freight trains use a single pipe air brake system and most multiple unit trains have EP brakes.
As a bit of history the USSR at one time developed a twin pipe system for freight trains.


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Posted 26 October 2020 - 09:13 AM

Colour coding can be a bit confusing.
In the above diagrams - train pipe is red and reservoir pipe is blue - but on real trains the angle cocks and hose connections are red for train pipe and yellow for reservoir pipe.
The MU air connections between locomotives generally seem to have white connectors and angle cocks.


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Posted 26 October 2020 - 11:16 AM

Oh, i see now, that you mean exactly the RESERVOIRE PIPE, as long as you mentioned a twin-pipe system (I thought, single-pipe)
Lets see the shunter's pneumatic brake diagram:
https://myswitcher.ru/tomt/tomt_1.html
And a freight car's system-single piped:
https://myswitcher.ru/tomt/tomt_6.html

Quote

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 reservoir pipe was gradually returned to normal working pressure when the brake handle is returned to the "RUNNING" position.

So what if we raise the SYSTEM MAXIMAL PRESSURE's value to, say 7 or 8 kgf/cm2 and let it never be exceeded as is, but then we will see the missing of the NOMINAL BRAKE SYSTEM PRESSURE statement, wich is 5,1-6,8kgf/cm2 usually.
And, I repeat, this last value is adjustable IRL for tune-up the brake system capabilities according to the particular operation mode(freight, passenger, flat terrain or hilly)

Also, the RESERVOIR PIPE pressure is equalized with main reservoirs and never be lower-that is its NORMAL working pressure.
This way, the given thesis is true in case of single-piped system:

Quote

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

Quote

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.

I agree, but I think, that was from MSTS...
So why do ORTS maintain this incorrect behavior at RUNNING position?

Quote

In general I have used TrainBrakesControllerFullQuickReleaseStart for the RELEASE position on brake controllers (although it does not do overcharge) and TrainBrakesControllerReleaseStart for the RUNNING position as it will maintain train pipe against leakage and slowly return TP to normal pressure after a reduction.

So do I. But can you say, are there adjustable values for quick and normal release rates?

Please, clear for me:
1.What distinction is between "Full Service" and "Continious Service" in ORTS?
2. Is it right , that "EP Apply" notes the handle's position value (digits) similar as "dummy" does?
I had assigned "EP Apply" at 0,4 of the handle's way and it applies about half of max pressure to BC
I tried to model VA position (see 1st post) and pasted EPApplyStart at 0,4 of handle's full span, so...

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Posted 26 October 2020 - 11:51 AM

The typical EMU's pneumatic system diagram:
Single pipe brake system with a main reservoir pipe. It connects all Main reservoirs and supplies OTHER pneumatic equipment (doors, sanders etc.) with air.
EP mode is default, but the Brake Cylinders is filled by the BrakePipe directly, wich is feed as at Hold position.
http://scbist.com/scb/uploaded/1_1386393089.jpg

#9 User is offline   darwins 

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Posted 26 October 2020 - 01:18 PM

Quote

So do I. But can you say, are there adjustable values for quick and normal release rates?


TrainBrakesControllerMaxQuickReleaseRate
and
TrainBrakesControllerMaxReleaseRate
should allow for different values.

Quote

What distinction is between "Full Service" and "Continious Service" in ORTS?

Full Service - is for older non-self lapping brakes - the brake pipe pressure will continue to drop if the handle is left in this position - to hold an application you must move back to the hold or lap position.
This type of controller needs to have both TrainBrakesControllerHoldStart and TrainBrakesControllerFullServiceStart
Continuous Service is for more modern self lapping brakes - move the handle to any position between 'Running' and 'Full Service' and the brakes will gave a proportionate application - no lap or hold position needed.


Quote

2. Is it right , that "EP Apply" notes the handle's position value (digits) similar as "dummy" does?
I had assigned "EP Apply" at 0,4 of the handle's way and it applies about half of max pressure to BC.

It is not exactly the same as dummy. The EP brake handle positions depend on the values used for TrainBrakesControllerFullServicePressureDrop and TrainBrakesControllerMinPressureReduction. You may need to adjust those to get the steps you need.
So in my example if I use
	TrainBrakesControllerFullServicePressureDrop( 24 )
	TrainBrakesControllerMinPressureReduction( 6 )

Then I should get the following brake pipe pressures -
Brake_Train ( 0 1.0 0.01 0.2
NumNotches ( 9
Notch ( 0	0 TrainBrakesControllerFullQuickReleaseStart ) Comment ( RELS = Overcharges ATP to 5.40 bar )
Notch ( 0.01 0 TrainBrakesControllerReleaseStart ) Comment ( RUN = 5.00 bar )
Notch ( 0.02 0 TrainBrakesControllerEPApplyStart ) Comment ( INIL 1 = 4.60 bar )
Notch ( 0.16 0 TrainBrakesControllerEPApplyStart ) Comment ( 2 = 4.35 bar )
Notch ( 0.40 0 TrainBrakesControllerEPApplyStart ) Comment ( 3 = 4.10 bar )
Notch ( 0.65 0 TrainBrakesControllerEPApplyStart ) Comment ( 4 = 3.85 bar )
Notch ( 0.80 0 TrainBrakesControllerEPApplyStart ) Comment ( 5 = 3.60 bar )
Notch ( 0.99 0 TrainBrakesControllerEPApplyStart ) Comment ( FULL SERV 6 = 3.35 bar )
Notch ( 1.00 0 TrainBrakesControllerEmergencyStart ) Comment ( EMGCY )))

It works near enough for everything except the 5.40 bar!







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Posted 26 October 2020 - 10:47 PM

At the start you asked about

Quote

The dream is to have special control, simulating reductor adjusting (say, +- 0,8 bar around 6)

This should be possible depending on the values you choose for TrainBrakesControllerMinPressureReduction and Notch ( x 0 TrainBrakesControllerEPApplyStart )

Quote

when I use "EP Apply", I observe a pressure drop in BP, so it's not good.


Good point. For a train that has an EP system the train pipe pressure should not drop in normal operation.


This should not depend on the EPApply token though. That brake token can be used for single pipe and twin pipe air brakes to give a notched brake.

What we should have is something like this -
For BrakesTrainBrakeType( "Air_twin_pipe" ) or BrakesTrainBrakeType( "Air_single_pipe" ) the train pipe pressure should drop.
For BrakesTrainBrakeType( "EP" ) there should be no drop in train pipe pressure when the brake is applied. (This applies to both old type with a real train pipe and the modern version with a virtual train pipe.)

(I do not know how ECP brakes work either in real life or in OR - as far as I know they, like emergency reservoirs, are something found on North American freight trains.)

I have made three types of EP brake controller. This is a very early EP controller from the 1920s:
Brake_Train ( 0 1 0.05 0.1
NumNotches ( 6
Notch ( 0	0 TrainBrakesControllerReleaseStart )
Notch ( 0.1  0 TrainBrakesControllerEPHoldStart )
Notch ( 0.2  0 TrainBrakesControllerEPFullServiceStart )
Notch ( 0.7  0 TrainBrakesControllerHoldStart )
Notch ( 0.8  0 TrainBrakesControllerFullServiceStart )
Notch ( 0.9  0 TrainBrakesControllerEmergencyStart )))


The first notches are EP braking only and should not reduce the train pipe pressure - the later notches are ordinary Westinghouse air brake and should work like the older non - self lapping brakes without graduated release.

From the 1930s to the 1980s EP controllers in UK were self lapping like this
Brake_Train ( 0 1 0.05 0.15
NumNotches ( 5
Notch ( 0.0  0 TrainBrakesControllerReleaseStart )
Notch ( 0.1  1 TrainBrakesControllerEPApplyStart )
Notch ( 0.7  0 TrainBrakesControllerHoldStart )
Notch ( 0.8  0 TrainBrakesControllerFullServiceStart )
Notch ( 0.9  0 TrainBrakesControllerEmergencyStart )))

Again the first part of the controller operates the EP brake and the second part the conventional air brake. In this version the EP brake is self-lapping. As explained in this video the EP brake has graduated release but the conventional air brake does not.As before the pressure in the train pipe should not drop when the EP brake is used, but only drops when the air brake is used.

The more modern EP brakes replace the train pipe with a virtual train pipe - an electric cable - which is either ON - for all normal operation or OFF for emergency such as train divided. These are often combined with throttle and dynamic brake. They may be continuous like this one
        	Brake_Train ( 0 1 0.1 0.2
            	NumNotches ( 3
                	Notch( 0	0 TrainBrakesControllerReleaseStart )
                	Notch( 0.1  1 TrainBrakesControllerEPApplyStart )
                	Notch( 1.0  0 TrainBrakesControllerEmergencyStart ) ) )

or notched like this one
        	Brake_Train ( 0 1 0.01 0.26
            	NumNotches ( 5
                	Notch( 0	0 TrainBrakesControllerReleaseStart )
                	Notch( 0.26 0 TrainBrakesControllerEPApplyStart )
                	Notch( 0.55 0 TrainBrakesControllerEPApplyStart )
                	Notch( 0.90 0 TrainBrakesControllerEPApplyStart )
                	Notch( 1.0  0 TrainBrakesControllerEmergencyStart ) ) )

...this last one being used with TrainBrakesControllerMinPressureReduction( 1 ) in order to get the desired positions.


But yes... point well made - IRL the train pipe pressure does not fall when the EP brake is used.







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