Rack & Pinion Actuator

Rack and pinion actuators are mechanical devices used to automatically open and close valves or dampers, usually for industrial applications. “Rack and pinion” is a generic term for a pair of gears which convert linear motion into rotational motion.

A rack and pinion is a type of linear actuator that comprises a circular gear (the pinion) engaging a linear gear (the rack). Together, they convert rotational motion into linear motion. Rotating the pinion causes the rack to be driven in a line. With the rack & pinion construction the output torque of an actuator is obtained by multiplying the piston force (given by the air pressure) by the pitch shaft radius (lever arm) as shown in the below picture less the force lost by friction (efficiency).