generate questions: In most reciprocating piston engines, the steam reverses its direction of flow at each stroke (counterflow), entering and exhausting from the cylinder by the same port. The complete engine cycle occupies one rotation of the crank and two piston strokes; the cycle also comprises four events – admission, expansion, exhaust, compression. These events are controlled by valves often working inside a steam chest adjacent to the cylinder; the valves distribute the steam by opening and closing steam ports communicating with the cylinder end(s) and are driven by valve gear, of which there are many types.[citation needed]
What is a term for the reversing of steam flow in a piston engine after each stroke? {sep_token} How many piston strokes occur in an engine cycle? {sep_token} How many crank rotations are there in an engine cycle? {sep_token} How many events occur in an engine cycle? {sep_token} Along with admission, exhaust and compression, what is an event in the engine cycle?