The distance a piston travels from its highest position to its lowest position is known as its ______.

The distance a piston travels from its highest position to its lowest position is known as its ______.

• A. Stroke
• B. Travel
• C. Throw
• D. Displacement

Answer: (A)

Piston motion in a reciprocating engine is described by the stroke, the distance from the piston’s topmost position (top dead center) to its bottommost position (bottom dead center). This distance is determined by the crank radius and is equal to twice that radius (stroke = 2 × crank radius). So if the crank radius is 2 inches, the piston travels 4 inches in one stroke. Travel is a general term for distance and isn’t specific to piston motion. Throw refers to the crank’s offset distance from the crankshaft center to the crankpin (the crank radius), which is half the stroke. Displacement refers to the volume moved by the piston (piston area times stroke) and, for an engine, the total swept volume across all cylinders. The term stroke specifically identifies the linear travel distance from TDC to BDC.

Piston motion in a reciprocating engine is described by the stroke, the distance from the piston’s topmost position (top dead center) to its bottommost position (bottom dead center). This distance is determined by the crank radius and is equal to twice that radius (stroke = 2 × crank radius). So if the crank radius is 2 inches, the piston travels 4 inches in one stroke.

Travel is a general term for distance and isn’t specific to piston motion. Throw refers to the crank’s offset distance from the crankshaft center to the crankpin (the crank radius), which is half the stroke. Displacement refers to the volume moved by the piston (piston area times stroke) and, for an engine, the total swept volume across all cylinders. The term stroke specifically identifies the linear travel distance from TDC to BDC.