[Laci1959]

Quote

Without the "Distributor" then I am unable to get graduated release.

Hello.

Not only with this. We have been using it for almost ten years for one and two pipe brakes in the following way. Although the two-tube is not really suitable for the push train operation we use, where the second tube passes through the cars without interruption.

TrainBrakesControllerMinPressureReduction ( 0.2 ) Comment (this setting is required for proper operation)
...
ORTSTrainBrakesControllerMaxOverchargePressure (6.2bar) Comment (Maximum value of overcharge)
ORTSTrainBrakesControllerOverchargeEliminationRate ( 0.025bar/s ) Comment ( The leakage rate at which it is reduced to 5 bar in RUN position. )
...
comment ( KNORR D 12 brake controller )
Brake_Train ( 0 1 0.02 1
NumNotches (13
  Notch (0 0 TrainBrakesControllerOverchargeStart) comment (overcharging possible up to 6.2 bar)
  Notch ( 0.01 0 TrainBrakesControllerReleaseStart ) Comment ( Run )
  Notch ( 0.1 0 TrainBrakesControllerHoldLappedStart ) Comment ( EQ RES tests for leakage )
  Notch ( 0.18 0 TrainBrakesControllerEPApplyStart )
  Notch ( 0.27 0 TrainBrakesControllerEPApplyStart )
  Notch ( 0.36 0 TrainBrakesControllerEPApplyStart )
  Notch ( 0.47 0 TrainBrakesControllerEPApplyStart )
  Notch ( 0.63 0 TrainBrakesControllerEPApplyStart )
  Notch ( 0.73 0 TrainBrakesControllerEPApplyStart )
  Notch ( 0.84 0 TrainBrakesControllerEPApplyStart )
  Notch ( 0.93 0 TrainBrakesControllerEPApplyStart )
  Notch ( 0.99 TrainBrakesControllerEmergencyStart )
  Notch ( 1 0 TrainBrakesControllerNeutralhandleOffStart ) comment ( key exception, leaving vehicle )
  )
)

Although the brake is not an EP brake at all. but this gave me the best solution. It's a bit like an MSTS solution, but if there's nothing better, this is it.

Sincerely, Laci1959

[darwins]

This was my suggestion for the Knorr type D, using Dummy rather than EP

Brake_Train ( 0 1.0 0.01 0.24

 NumNotches ( 13

 Notch ( 0.00 0 TrainBrakesControllerOverchargeStart ) Coment ( Sonderstellung )

 Notch ( 0.10 0 TrainBrakesControllerReleaseStart ) Comment ( Fahrtstellung )

 Notch ( 0.20 0 TrainBrakesControllerNeutralHandleOffStart ) Comment ( Mittelstellung )

 Notch ( 0.24 0 Dummy )  

 Notch ( 0.33 0 Dummy )  

 Notch ( 0.42 0 Dummy )   

 Notch ( 0.51 0 Dummy )  

 Notch ( 0.60 0 Dummy )  

 Notch ( 0.69 0 Dummy )  

 Notch ( 0.78 0 Dummy )  

 Notch ( 0.87 0 Dummy )  

 Notch ( 0.96 0 Dummy )  

 Notch ( 1.00 0 TrainBrakesControllerEmergencyStart ) Comment ( Schnellbremsstellung ) ) )

 
 

 Brake_Engine ( 0 1 0.5 0

 NumNotches ( 3

 Notch ( 0.0  0 EngineBrakesControllerReleaseStart ) Comment ( RELEASE )

  Notch ( 0.5  0 EngineBrakesControllerHoldLappedStart ) Comment ( LAP )

  Notch ( 1.0  0 EngineBrakesControllerFullServiceStart ) Comment ( APPLY ) ) )

The Handle Off is in a different position - combined with neutral for test for leakage (there were probably differences between type D versions) - but the general idea is the same.

[Laci1959]

Yes, I remember that. It didn't really work. I changed the Dummy to TrainBrakesControllerEPApplyStart just before writing this post.
D2 and D12 brakes are slightly different. HandleOff is after Emergency. Thus, the train driver is forced to brake the train if he wants to leave the train.

[darwins]

So far so good.
It seems most air brake and EP brake possibilities that have been used in UK can now be modelled.
Two exceptions are:

1. The modern EP brakes without a brake pipe.

2. Goods wagons with only two discrete values of brake force. (Rather than brake force proportional to load.)

Would it be possible the ORTSBrakeRelayValveRatio ( ) which represents an Air : Air proportional valve extended to include an Air : Vacuum or Vacuum : Air relay valve?


In the meantime I need to get some prototype information.

TripleValveRatio ( 2.5 ) is presumably the North American standard.

TripleValveRatio ( 1.9 ) seems to give the correct performance for older Westinghouse brakes in UK.

TripleValveRatio ( 2.34 ) seems appropriate for UIC standard systems.


Also now that we have ORTSBrakeCylinderVolume ( ) it would be good if anyone could tell me the size of brake cylinders fitted to modern diesel and electric locomotives in Europe.
(Also for carriages and wagons currently in use!)
It seems very difficult to get any data.
So far I have been relying on the charts on the Coals to Newcastle website to make guesses, but I am not sure how accurate these are in most cases.


@ Laci

My original version of the D2 used TrainBrakesControllerEPApplyStart, but as this is not an EP brake system then the brake code was changed to allow Dummy to be used for a notched train brake instead. I have not tried it again recently so I don't understand why it has stopped working. It makes more sense to have a not EP token for a not EP notched brake!

Difference of D2 and D12 duly noted. Thanks.

[pschlik]

cesarbl, on 15 May 2023 - 11:10 PM, said:

Looks like a sensible thing to do. I'll add the ORTSEngineBrakeRelayRatio() parameter.

Tried this out with a more practical example than F7 + GEVO (DDA40X + SD40-2) and it worked like a charm. Got 45 psi on the centennial and 72 psi on the SD40-2 with a full loco brake application, and 26 psi on the centennial and 64 psi on the SD40-2 with full-service automatic braking, just as it would be in real life. I've been wanting this sort of thing for a long time, thanks for acting on the suggestion so quickly.

[cesarbl]

Quote

TripleValveRatio ( 2.34 ) seems appropriate for UIC standard systems.

I'd say 2.5. Release is at 5bar, full serv at 3.5bar. Max cyl pressure is 3.8bar => Ratio = 3.8/1.5=2.53

Quote

The modern EP brakes without a brake pipe.

You could "fake" it by specifying neither "triple valve" nor "distributor" in BrakeEquipmentType(). You'd still have indications related to BP, which you have to ignore. Also the continuity wire is missing.

Quote

Would it be possible the ORTSBrakeRelayValveRatio ( ) which represents an Air : Air proportional valve extended to include an Air : Vacuum or Vacuum : Air relay valve?

Unfortunately the vacuum braking code is completely split from the air brakes. A major refactoring is needed, which I have started multiple times but never finished. The idea is to define which pipes does the car have: main res, air brake, vacuum brake, ep...

[Traindude]

I'm confused about the whole discussion on factoring the CoF into the max brake force calculations. What's the takeaway? The way I'm understanding the discussion is that the MaxBrakeForce parameter should reflect the full (100%) braking force, and ORTS will automatically multiply that by the friction curve value during operation. So in terms of the CTN calculator, the CoF field should be left at "1.0".

Is that right or am I missing something?

[pschlik]

Traindude, on 17 May 2023 - 03:24 PM, said:

I'm confused about the whole discussion on factoring the CoF into the max brake force calculations. What's the takeaway? The way I'm understanding the discussion is that the MaxBrakeForce parameter should reflect the full (100%) braking force, and ORTS will automatically multiply that by the friction curve value during operation. So in terms of the CTN calculator, the CoF field should be left at "1.0".

Is that right or am I missing something?

MaxBrakeForce does NOT get multiplied by the brake friction curve. MaxBrakeForce gets multiplied by the ratio between the current brake friction value and the friction value at zero speed (then gets multiplied by the adhesion correction factor...for some reason. Setting the adhesion correction higher gives you stronger brakes.)

                if (UserFriction != 0)  // User defined friction has been applied in WAG file - Assume MaxBrakeForce is correctly set in the WAG, so no adjustment required 
                {
                    BrakeShoeCoefficientFrictionAdjFactor = UserFriction / ZeroUserFriction * AdhesionMultiplier; // Factor calculated by normalising zero speed value on friction curve applied in WAG file
                    BrakeShoeRetardCoefficientFrictionAdjFactor = UserFriction / ZeroUserFriction * AdhesionMultiplier;
                    BrakeShoeCoefficientFriction = UserFriction * AdhesionMultiplier; // For display purposes on HUD
                }

That means if you have a friction curve where the friction at the current speed is 50% and at zero is 100%, or if the current speed is 2.5% and zero speed is 5%, in both cases the adjustment factor will be 0.5 (assuming 100% adhesion multiplier). A MaxBrakeForce of 10,000 pounds on both of these hypothetical wagons would lead to a maximum brake force of 5,000 pounds at the current speed, even though one of the wagons claims to have 20 times the brake shoe friction.


https://i.imgur.com/mEFnlcS.png

In short: set MaxBrakeForce to the maximum brake force at the rail you want. Don't worry about the exact % brake shoe friction, all that matters is the ratio between brake shoe friction values.

[Traindude]

pschlik, on 17 May 2023 - 05:53 PM, said:

MaxBrakeForce does NOT get multiplied by the brake friction curve. MaxBrakeForce gets multiplied by the ratio between the current brake friction value and the friction value at zero speed (then gets multiplied by the adhesion correction factor...for some reason. Setting the adhesion correction higher gives you stronger brakes.)

                if (UserFriction != 0)  // User defined friction has been applied in WAG file - Assume MaxBrakeForce is correctly set in the WAG, so no adjustment required 
                {
                    BrakeShoeCoefficientFrictionAdjFactor = UserFriction / ZeroUserFriction * AdhesionMultiplier; // Factor calculated by normalising zero speed value on friction curve applied in WAG file
                    BrakeShoeRetardCoefficientFrictionAdjFactor = UserFriction / ZeroUserFriction * AdhesionMultiplier;
                    BrakeShoeCoefficientFriction = UserFriction * AdhesionMultiplier; // For display purposes on HUD
                }

That means if you have a friction curve where the friction at the current speed is 50% and at zero is 100%, or if the current speed is 2.5% and zero speed is 5%, in both cases the adjustment factor will be 0.5 (assuming 100% adhesion multiplier). A MaxBrakeForce of 10,000 pounds on both of these hypothetical wagons would lead to a maximum brake force of 5,000 pounds at the current speed, even though one of the wagons claims to have 20 times the brake shoe friction.


https://i.imgur.com/mEFnlcS.png


In short: set MaxBrakeForce to the maximum brake force at the rail you want. Don't worry about the exact % brake shoe friction, all that matters is the ratio between brake shoe friction values.

Oh. I see-the "Zero Speed" value should be used when specifying MaxBrakeForce. I gotcha! So if my current speed is 0 mph (stopped) and the "Zero Speed" CoF is 50%, then 50/50 = 1 adjustment factor.

[steamer_ctn]

pschlik, on 17 May 2023 - 05:53 PM, said:

MaxBrakeForce does NOT get multiplied by the brake friction curve. MaxBrakeForce gets multiplied by the ratio between the current brake friction value and the friction value at zero speed (then gets multiplied by the adhesion correction factor...for some reason. Setting the adhesion correction higher gives you stronger brakes.)

After reflecting upon this arrangement, I agree it is confusing, and I would like to modify it back to what it probably should have been originally, ie MaxBrakeForce is the Brake shoe Force, and this is then multiplied by the CoF to get the actual force applied to the wheel. This will then be the "retardation force" used by OR to slow the train down.

I will make the relevant changes in the next day or so.