The Compact quarter-turn pneumatic actuator has been developed to be a simple, reliable, and efficient valve operator by utilizing a patented rack and pinion design. Four separate racks, each driven by its own piston, develop torque around the centrally located pinion. The four rack concept permits operating air pressure to be applied to four pistons simultaneously, increasing torque output and reducing piston diameter and overall actuator size, compared to single and double rack designs. Symmetrically spaced at 90 degree angles around the central pinion, the Compact’s four racks also achieve a more uniform load distribution between the rack and pinion, greatly reducing gear wear at these contact points and curbing stress on the pinion and piston seals. The result is a high cycle actuator design.