Aristo Mallet Sound, When to Chuff

[jasher817]

OK I know I mite Get some flak for this but here it goes. When should the chuff sound be made, when the piston is fully extended or fully retracted. I want to put sound in my Mallet and don't like the auto chuff. I want to get the sound synced, and is there 4 chuff's or 2 and witch drivers get the chuff if there is only 2?

[RhB_HJ]

Jasher,

I'd say four chuffs synched to the front drivers - now there are those who find the four chuffs too busy when running at speed.

BTW four chuffs because there is a 90º offset between the left and right cylinder which means one chuff at each end for each cylinder or one chuff for each 90º rotation of the wheels.
At least that's how it works on two cylinder engines or four cylinder compounds like the Aristo Mallett.

[devils]

What sound unit were you going to use and are you intending synching with a sensor or electronically? 4 even chuffs is the realistic number per revolution as a cylinder exhausts each time the each piston changes direction. As steam is applied to drive the piston forward, away from the cylinder end, the steam from the last power stroke is exhausted from the opposite side of the piston head causing the chuff up the blastpipe.
The chuffs are even because the cranks on the driving wheels are set at 90 degrees to each other so for each 1/4 turn of the driver alternate cylinders exhaust. In one rev each cylinder exhausts twice, once from each side of the piston head.
This is the very basic reason for a 2 cylinder loco, 3 cylinder will give 6 chuffs!

[jasher817]

The plan is to use a Sierra sound but if I could afford a Phoenix I would like to use it.

[cacole]

I haven't seen the Aristo Mallet to know what type it represents, but a Mallet locomotive sounds different according to whether it is a simple or compound design.

A simple Mallet sends high-pressure steam to both sets of cylinders, so you have 4 cylinders exhausting through the stack. The sound will appear to be 8 chuffs per wheel revolution unless they are exactly in sync.

A compound Mallet sent high-pressure steam only to the rear cylinders, and the exhaust steam from them was then sent to the front cylinders to be used again before being exhausted through the stack; so a compound Mallet would have 4 chuffs per wheel revolution.

The compound Mallets had larger cylinders in the front because they were operating from used steam that was under less pressure, whereas a simple Mallet had cylinders of equal size.