Shay and smoke unit with one heating elememrnt vs two hearing elements

I can answer the first part.  The chuff rate for all Shays varied in real life because they had different gear ratios depending on how they were ordered.  There are about 6 chuffs per drive shaft revolution, but the gear ratio from the drive shaft to the wheels would affect the number of chuffs per wheel revolution.  For example, if we take Cass Scenic Railroad #5 that has a gear ratio of 2.065/1 we would have a chuff rate of about 12.39 which is approximately 12 when rounded since we can't pick a fraction in DCS.  For Western Maryland #6 (also at Cass) that has a gear ratio of 2.45/1 we would have a chuff rate of about 14.7 which is approximately 15 when rounded up since we cannot have a fraction.

If you have a specific model in mind that has an actual prototype, the gear ratio could be looked up and we could calculate the answer.  If you just want a generic figure, based on the gear ratios I have seen for 3-Truck Shay prototypes, I would say anywhere from 11 to 15 chuffs per revolution.

Short answer - 12.

Long answer - it depends on the prototype engine.  The MTH model has three cylinders (double acting) on a three throw crank shaft.  Each throw is evenly spaced by 120 degrees.  So, each revolution of the drive shaft running along the side of the engine results in 6 chuffs.  However, the bevel gears between the drive shaft and each axle add gear reduction.  If the gear ratio is 2:1 (like the MTH model), you get 12 cuffs per revolution of the wheels.  If the gear ratio is 3:1 you should hear 18 chuffs per revolution.  Different engines used different ratios which were spec'ed according to customer's needs. In reality, most of these gears were actually off by a tooth just like the differential in a car.  The odd number of teeth ensures even wear.

 Not a problem.  The engine with the smaller smoke unit has a different version of the PS2 board (known as a flash board) which has different software stored on a separate part of memory from the sound.  Changing the sound file will not change the software that drives the smoke unit.

My recollection when I rode the Cass many years ago is that you normally couldn't detect chuffing except occasionally for a second or so.  IKt was not at all like the Shay MTH had running at York.

I wonder at what rate the ear no longer detects puffs and the noise becomes a hum (like a gasoline engine, which also is puffs)????

Sorry, I failed to note that the subject sound board and sound file are PS 3.

Still not a problem.  The PS3 boards use the sound file only for sound.  You can use any PS3 or PS2 O/G sound file on a PS 3 O/G board.

Dave,

You can use any PS3 or PS2 O/G sound file on a PS 3 O/G board.

You can use only 3 volt PS2 sound files in a PS3 engine. Even if the Loader Program allows you to load a 5 volt file, and it might, a 5 volt file can cause problems in a PS3 engine.