Different relay valve ratio for engine brakes

Author: cesarBLG

Source/Documentation/Manual/physics.rst

@@ -2947,6 +2947,7 @@ MaxAuxilaryChargingRate and EmergencyResChargingRate.
    single: ORTSEmergencyValveActuationRate
    single: ORTSMainResPipeAuxResCharging
    single: ORTSBrakeRelayValveRatio
+   single: ORTSEngineBrakeRelayValveRatio
    single: ORTSBrakeRelayValveApplicationRate
    single: ORTSBrakeRelayValveReleaseRate
    single: ORTSMainResChargingRate
@@ -2991,6 +2992,7 @@ MaxAuxilaryChargingRate and EmergencyResChargingRate.
   This is achieved via a relay valve which sets BC pressure proportionally.
   Relay valves may be installed to achieve higher brake cylinder pressures,
   dynamic brake blending or variable load compensation.
+- ``Wagon(ORTSBrakeRelayValveRatio`` -- Same as above, but for the engine brake
 - ``Wagon(ORTSBrakeRelayValveApplicationRate`` -- Brake cylinder pressure application
   rate achieved by the relay valve, if fitted.
 - ``Wagon(ORTSBrakeRelayValveReleaseRate`` -- Brake cylinder pressure release

Source/Orts.Simulation/Simulation/RollingStocks/SubSystems/Brakes/MSTS/AirSinglePipe.cs

@@ -56,6 +56,7 @@ public class AirSinglePipe : MSTSBrakeSystem
         protected float EmergAuxVolumeRatio = 1.4f;
         protected bool RelayValveFitted = false;
         public float RelayValveRatio { get; protected set; } = 1;
+        protected float EngineRelayValveRatio = 0;
         protected float RelayValveApplicationRatePSIpS = 50;
         protected float RelayValveReleaseRatePSIpS = 50;
         protected string DebugType = string.Empty;
@@ -129,6 +130,7 @@ public override void InitializeFromCopy(BrakeSystem copy)
             HoldingValve = thiscopy.HoldingValve;
             RelayValveFitted = thiscopy.RelayValveFitted;
             RelayValveRatio = thiscopy.RelayValveRatio;
+            EngineRelayValveRatio = thiscopy.EngineRelayValveRatio;
             RelayValveApplicationRatePSIpS = thiscopy.RelayValveApplicationRatePSIpS;
             RelayValveReleaseRatePSIpS = thiscopy.RelayValveReleaseRatePSIpS;
             MaxTripleValveCylPressurePSI = thiscopy.MaxTripleValveCylPressurePSI;
@@ -256,6 +258,7 @@ public override void Parse(string lowercasetoken, STFReader stf)
                         RelayValveFitted = false;
                     }
                     break;
+                case "wagon(ortsenginebrakerelayvalveratio": EngineRelayValveRatio = stf.ReadFloatBlock(STFReader.UNITS.None, null); break;
                 case "wagon(ortsbrakerelayvalveapplicationrate": RelayValveApplicationRatePSIpS = stf.ReadFloatBlock(STFReader.UNITS.PressureRateDefaultPSIpS, null); break;
                 case "wagon(ortsbrakerelayvalvereleaserate": RelayValveReleaseRatePSIpS = stf.ReadFloatBlock(STFReader.UNITS.PressureRateDefaultPSIpS, null); break;
                 case "wagon(ortsmaxtriplevalvecylinderpressure": MaxTripleValveCylPressurePSI = stf.ReadFloatBlock(STFReader.UNITS.PressureDefaultPSI, null); break;
@@ -324,6 +327,7 @@ public override void Initialize(bool handbrakeOn, float maxPressurePSI, float fu
                 EmergResVolumeM3 = 0.7f;
 
             if (MaxTripleValveCylPressurePSI == 0) MaxTripleValveCylPressurePSI = MaxCylPressurePSI / RelayValveRatio;
+            if (EngineRelayValveRatio == 0) EngineRelayValveRatio = RelayValveRatio;
 
             BrakeLine1PressurePSI = Car.Train.EqualReservoirPressurePSIorInHg;
             BrakeLine2PressurePSI = Car.Train.BrakeLine2PressurePSI;
@@ -593,7 +597,7 @@ public override void Update(float elapsedClockSeconds)
             }
             else
             {
-                demandedPressurePSI = Math.Max(AutoCylPressurePSI, BrakeLine3PressurePSI);
+                demandedPressurePSI = AutoCylPressurePSI;
                 if (loco != null && loco.EngineType != TrainCar.EngineTypes.Control)  // TODO - Control cars ned to be linked to power suppy requirements.
                 {
                     if (loco.LocomotivePowerSupply.MainPowerSupplyOn)
@@ -630,22 +634,20 @@ public override void Update(float elapsedClockSeconds)
                                         demandedPressurePSI = CylPressurePSI;
                                     }
                                     demandedPressurePSI /= RelayValveRatio;
-                                    if (demandedPressurePSI < BrakeLine3PressurePSI)
-                                        demandedPressurePSI = BrakeLine3PressurePSI;
                                 }
                             }
                             else if (loco.DynamicBrakeAutoBailOff)
                             {
                                 if (loco.DynamicBrakeForceCurves == null)
                                 {
-                                    demandedPressurePSI = BrakeLine3PressurePSI;
+                                    demandedPressurePSI = 0;
                                 }
                                 else
                                 {
                                     var dynforce = loco.DynamicBrakeForceCurves.Get(1.0f, loco.AbsSpeedMpS);
                                     if ((loco.MaxDynamicBrakeForceN == 0 && dynforce > 0) || dynforce > loco.MaxDynamicBrakeForceN * 0.6)
                                     {
-                                        demandedPressurePSI = BrakeLine3PressurePSI;
+                                        demandedPressurePSI = 0;
                                     }
                                 }
                             }
@@ -655,7 +657,7 @@ public override void Update(float elapsedClockSeconds)
             }
             if (RelayValveFitted)
             {
-                demandedPressurePSI *= RelayValveRatio;
+                demandedPressurePSI = Math.Max(RelayValveRatio * demandedPressurePSI, EngineRelayValveRatio * BrakeLine3PressurePSI);
                 if (demandedPressurePSI > CylPressurePSI)
                 {
                     float dp = elapsedClockSeconds * RelayValveApplicationRatePSIpS;
@@ -688,7 +690,7 @@ public override void Update(float elapsedClockSeconds)
             }
             else
             {
-                CylPressurePSI = demandedPressurePSI;
+                CylPressurePSI = Math.Max(demandedPressurePSI, BrakeLine3PressurePSI);
             }
 
             // During braking wheelslide control is effected throughout the train by additional equipment on each vehicle. In the piping to each pair of brake cylinders are fitted electrically operated