manual update

Author: peternewell

Source/Documentation/Manual/physics.rst

@@ -4395,6 +4395,60 @@ drag constants are used in calculating the still air resistance, then it might b
 inputting these values.
 
 
+.. _physics-track-sanding:
+
+Track Sanding
+=============
+
+Sanding of the track is required at times to increase the wheel adhesion.
+
+Open Rails supports air and steam operated track sanders which consume air or steam and sand. Typically 
+OR has standard defaults which it uses to allow track sanding to operate, however if the user knows the 
+actual values for the locomotive that they are modelling then they can override these values by entering 
+the following parameters in the engine section of the ENG file. Note - if values are not known then it is 
+highly recommended that the default values be used.
+
+When using any of the following parameters, the sanding system type needs to be set by allocating either "Steam" or 
+"Air" to the ``SandingSystemType`` ( x ) parameter in engine section of file.
+
+**Steam Consumption**
+
+``ORTSMaxTrackSanderSteamConsumptionForward`` - total steam consumption for all sanders when traveling in 
+forward direction, ie in front of wheel.
+
+``ORTSMaxTrackSanderSteamConsumptionForward`` - total steam consumption for all sanders when traveling in 
+reverse direction, ie behind wheel. Note, = 0 when not used.
+
+All steam consumption parameters are in lbs/sec.
+
+For steam sanding there will be a visible presence of steam when the sander is operated, this steam effect 
+can be added by using one or both of the following aparmeters.
+
+``SanderSteamExhaustForwardFX`` - steam effect when travelling forward, ie in front of wheel.
+
+``SanderSteamExhaustReverseFX`` - steam effect when travelling in reverse, ie in behind the wheel.
+
+**Air Consumption**
+
+``ORTSMaxTrackSanderAirConsumptionForward`` - total air consumption for all sanders when traveling in reverse 
+direction, ie behind wheel. Note, = 0 when not used.
+
+``ORTSMaxTrackSanderAirConsumptionForward`` - total air consumption for all sanders when traveling in forward 
+direction, ie in front of wheel.
+
+All air consumption parameters are in cuft/sec.
+
+**Sand Consumption**
+
+``ORTSMaxTrackSanderSandConsumptionForward`` - total sand consumption for all sanders when traveling in forward 
+direction, ie in front of wheel.
+
+``ORTSMaxTrackSanderSandConsumptionReverse`` - total sand consumption for all sanders when traveling in reverse 
+direction, ie behind wheel. Note, = 0 when not used.
+
+All sand consumption parameters are in cuft/sec.
+
+
 .. _physics-trailing-locomotive-resistance:
 
 Trailing Locomotive Resistance