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# Position of the piston of an engine with respect to crank angle

## Description

A piston is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. The motion of a non-offset piston connected to a crank through a connecting rod (as would be found in internal combustion engines), can be expressed through several mathematical equations.echnically, the reciprocating motion of the connecting rod departs from sinusoidal motion due to the changing angle of the connecting rod during the cycle. The position of piston pin from crank center with respect to crank angle can be calculated by the rod length, the crank radius and the crank angle.

Related formulas

## Variables

 x The position of piston pin from crank center (in) r The crank radius (distance between crank pin and crank center) (in) A The crank angle (from cylinder bore centerline at top dead centre) (degree) l The rod length (distance between piston pin and crank pin) (in)