Rod and piston-to-stroke ratio


In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts reciprocating motion into rotating motion.
Connecting rods may also convert rotating motion into reciprocating motion. As a connecting rod is rigid, it may transmit either a push or a pull and so the rod may rotate the crank through both halves of a revolution, i.e. piston pushing and piston pulling. The rod-to-stroke ratio is the ratio of the length of the connecting rod to the length of the piston stroke. A longer rod reduces sidewise pressure of the piston on the cylinder wall and the stress forces, increasing engine life. It also increases the cost and engine height and weight..

Related formulas


yRod and piston-to-stroke ratio (dimensionless)
rThe length of the connecting rod (m)
lThe length of the piston stroke (piston travelling the full length of its locomotive cylinder or engine cylinder in one direction) (m)