The operation is quite simple. The movement of the flywheel moves the oscillating cylinder around an central axis and brings the steam inlet (1) then discharge opening (3) in line with the port in the cylinder. With this simple machine, the cylinder is single acting. Power is only provided on the downward stroke, the flywheel providing momentum for the rest of the cycle. The cylinder slides on a polished port face and is kept in contact by spring pressure. This spring has the additional function of a SAFETY VALVE. Excessive steam pressure lifts the cylinder from the port face releasing excess steam.

Click for increasing