What is the difference between a single acting and a double acting cylinder?
In a single acting cylinder the piston is pushed from top dead center by steam pressure and returns back from bottom dead center by the inertia of the balance wheel. In a double acting cylinder the piston is pushed by steam in both directions which naturally increases the power of the engine. Steam is leaking out of safety valve. Small leaks out of the safety valve may be caused by a faulty gasket, but are usually a case of the valve not being seated properly. Tap the top of the valve with your finger a couple times, this usually seats it properly.
