In a single acting steam engine

• the steam is admitted on one side of the piston and one working stroke is produced during each revolution of the crankshaft
• the steam is admitted, in turn, on both sides of the piston and one working stroke is produced during each revolution of the crankshaft
• the steam is admitted on one side of the piston and two working strokes are produced during each revolution of the crankshaft
• the steam is admitted, in turn, on both sides of the piston and two working strokes are produced during each revolution of the crankshaft.