Stroke, as used in piston movement, is defined as what?

• A. Distance piston travels from top to bottom
• B. Distance piston travels from bottom to top
• C. The crankshaft rotation angle
• D. The piston displacement per cycle

Answer: (A)

Stroke is the linear distance the piston travels between the two ends of its travel in the cylinder, typically from top dead center to bottom dead center. That makes the statement about the piston moving from top to bottom the best description, since it names the actual movement distance of one stroke. The crankshaft rotation angle is an angular measure, not the piston’s linear travel. Piston displacement per cycle would be zero after a full cycle because the piston returns to its starting position. Describing the reverse direction (bottom to top) is the same distance in magnitude, but the conventional definition uses top to bottom to denote one complete stroke.