[Weter]

https://electri4ka.com/er2r/images/er2r_198.png
Head motorless car with cab and compressor (brake system is shown only)
https://konspekta.net/lektsiiimg/baza1/1034515943662.files/image018.jpg
Motorized car without both: a cab and compressor (brake system is shown only)
https://konspekta.net/lektsiiimg/baza1/1034515943662.files/image020.jpg
Trailing middle car with no motors and cab, but does have compressor and main reservoirs:
https://konspekta.net/lektsiiimg/baza1/1034515943662.files/image021.jpg
Section of EMU: head, motorized and trailer(facultative) cars. Complete pneumatic scheme:
https://konspekta.net/lektsiiimg/baza1/1034515943662.files/image023.jpg
You can see wipers, sanders, doors, pantographs with auxiliary compressors, MRCs there.
https://konspekta.net/lektsiiimg/baza1/1034515943662.files/image016.jpg

[darwins]

There were many variations, particularly in electric multiple units. Often the compressor and main reservoir were on a trailer car but not on a motor car in order to share out the weight more evenly.

[Weter]

ЭР 22 is different: head cars with cab were motorized and had compressors.

[Laci1959]

Is it so hard to solve for the rear air compressor to work?
I'm giving up, I'm not trying to convince you anymore.
Okay, so let’s have a fictitious infinitely powerful air compressor and add a fictitious engine of similar power.
Real train drivers already laugh because the real air compressor doesn’t work on the rear locomotive.

[Coolhand101]

darwins, on 13 September 2021 - 10:33 PM, said:

There were many variations, particularly in electric multiple units. Often the compressor and main reservoir were on a trailer car but not on a motor car in order to share out the weight more evenly.

This mostly applied to the old A.C units that had the motor coach always in the middle of the formation ( MBS etc ). The trailer cars had the batterys/compressor.

On the old southern D.C units, the 51 stock had two compressors - one on each motor coach, 57 stock had one compressor but two motor cars, and 63 stock had the motor car in the middle of the formation where the compressor was.

As I cannot update OR to the latest version, 75% of my multiple units have cab cars. The cab cars are ENG files having zero power and force, and the minus restart for the compressor( if the cab car had no compressor ). This all works 100% except when wind resistance is turn on, the cab cars( engines ) produce too much drag, compared to a WAG car with the same dimensions and weight. Has this been adjusted on controlled trailer cars?

Thanks

[Weter]

Quote

produce too much drag, compared to a WAG car with the same dimensions and weight

Very interesting phenomenon: now I suspect, thAt was a reason of some of issues with my stock...

[darwins]

Zero power and zero force was working quite well for electric trains and steam trains. In older versions it worked also for first generation dmu with manual gears, but not in recent versions. With regard to resistance, the wind resistance of the front vehicle in the train is greater than that of the intermediate vehicles. In the case of a fixed formation train (having the same shape at either end) then the total resistance of the train should be the same in either direction. This is possible either with or without the control car definition. In the eng file for driving motor cars and in the eng file for driving trailer cars you can use both ORTSDavis_C ( ) and ORTSTrailLocomotiveResistanceFactor ( ). If you do that then the extra wind resistance of the leading vehicle is only applied to the leading vehicle, it will not be applied to other eng vehicles elsewhere in the train. [For non-driving motor cars, the ORTSDavis_C value would be the same as for unpowered cars of the same size.
Many things to do with braking at the moment are restricted by the OR model that has all braking controlled by the leading vehicle. This means that there are a lot of limitations. TrainPipeLeakRate is one of these - all leakage happens from the leading vehicle. Ideally we could have different leak rates for each individual vehicle in set greater leakage for an old battered goods wagon than for a fresh out of the works passenger car. Similarly inside the code I am told the front vehicle always has the compressor and reservoir, though by a bit of magic it can be made to appear on another vehicle. Similarly the internal model is one where the leading vehicle has an equalising reservoir. Most vacuum brake systems and some air brake systems did not have equalising reservoirs, so magic illusions can be used to hide some of the equalising reservoir effects. Realistically we will have to live with these situations until some code writer with a lot of spare time and patience is willing to do a total rewrite of the braking code. In the meantime we should be thankful for the effort that the developers do put in. We may not have every feature we want available in Open Rails, but as time goes by, more and more things become possible. (That never happened with MSTS and I doubt that it happens in response to user requests for most payware simulations.)

[Coolhand101]

darwins, on 14 September 2021 - 07:38 AM, said:

With regard to resistance, the wind resistance of the front vehicle in the train is greater than that of the intermediate vehicles. In the case of a fixed formation train (having the same shape at either end) then the total resistance of the train should be the same in either direction. This is possible either with or without the control car definition. In the eng file for driving motor cars and in the eng file for driving trailer cars you can use both ORTSDavis_C ( ) and ORTSTrailLocomotiveResistanceFactor ( ). If you do that then the extra wind resistance of the leading vehicle is only applied to the leading vehicle, it will not be applied to other eng vehicles elsewhere in the train. [For non-driving motor cars, the ORTSDavis_C value would be the same as for unpowered cars of the same size.

All true, but I was referring to cab cars(ENG) in the middle of the formation, ie a 12-car EMU. The remaining cab cars produce too much drag as they are ENG files compare to a WAG file of the same coach dimensions. I believe it's the way ENG files are coded differently to WAG cars for wind resistance. I spent a great deal of time finding workarounds and solutions to this, but nothing prototypical.

And example below of an 8-car EMU ( 2 x 4-car )

ENG+WAG+WAG+WAG+WAG+WAG+WAG+WAG = Wind resistance is correct.

The same EMU above but with cab cars(ENG) :-

ENG+WAG+ENG+ENG+ENG+WAG+ENG+ENG = Wind resistance is twice as high for the intermediate and the last cab cars( ENG ).

The same EMU above but with cab cars(TRAILER) :-

CAB+WAG+ENG+CAB+CAB+WAG+ENG+CAB = Wind resistance of the intermediate and last cab cars should be lower as they are not ENG file .

Thanks

[Coolhand101]

darwins, on 14 September 2021 - 07:38 AM, said:

Similarly inside the code I am told the front vehicle always has the compressor and reservoir, though by a bit of magic it can be made to appear on another vehicle.

This is where the minus compressor charge figure comes in handle. It can also cause a loss of Main Reservoir air if the sander button is pressed when the Max Main Reservoir pressure is lower somewhere else in the train formation.

Not wishing to go off topic, but with some digging, I have found in the real world that cast-iron blocks at high speed will not produce any more brake effect beyond 35PSI up to the maximum of 50PSI ( the max for my UK EMUs ). This explains why mainline drivers always used between 15 and 20 PSI because the brake gave a better retardation rate.

My working around for this, is to lower the 'BrakeCylinderPressureForMaxBrakeBrakeForce' pressure from 50 to 35PSI for the two intermediate WAG coaches. The good news is the stopping distance is the same as before when full brake pressure is used. But it does cause unwanted very high Aux Reservoir pressure in the braking HUD.

Another thing is that a longer EMU train had better braking performance than a shorter EMU train. I cannot seem to duplicate this in OR unless additional WAG/ENG are used in the formation with a higher brake force or of lowering the MaxBrakeCylinder pressure as described above.

Thanks

[Weter]

I have read nice words here about "unreal" parameters. They are looking right.
But "complete measure" seem to me in introducing new configuration file-types for tenders and cabbed cars. They ARE neither engines/carriages, nor regular cars, after all. Please excuse me, if it could sound rough for you.
So, we will free from spoiling eng-files and suffering due to functionality lack of wag-files.