What is the function of an Rack & Pinion pneumatic actuator?

Generally speaking,  pneumatic actuators  are divided into two types of working modes: double-acting and single-acting (spring return). Their selection principles are as follows: Selection of double-acting actuator The selection of double-acting actuator takes Rack & Pinion series Pneumatic Actuator as an example. The output torque of the rack and pinion actuator is obtained by multiplying the piston pressure (supplied by the air source) by the radius of the pitch circle (the arm of the force). And the friction resistance is small and the efficiency is high. Both clockwise and counterclockwise rotation of the output torque are linear. Under normal operating conditions, it is recommended that the safety factor of the double-acting actuator is 25-50%.

Selection of single-acting actuators. The selection of single-acting actuator takes ATS series pneumatic actuator as an example, in the application of spring return, the output torque is obtained in two different operation processes, and each operation produces two different torque values according to the stroke position. The output torque of the Spring Return Actuator is obtained by multiplying the force (air pressure or spring force) by the force arm: the output torque is obtained by the air pressure after entering the compression spring in the middle cavity, which is called "air stroke output torque" In this case, the air source pressure forces the piston to turn from 0 degrees to the 90 degree position, and due to the reaction force generated by spring compression, the torque gradually decreases from the maximum value at the starting point until the second condition: the output torque is obtained by the spring recovery force acting on the piston when the middle cavity loses air, which is called " Spring stroke output torque"In this case, due to the elongation of the spring, the output torque gradually decreases from 90 degrees to 0 degreesAs mentioned above, the single-acting actuator is designed on the basis of generating a balanced moment in both cases. In each case, it is possible to obtain an unbalanced moment by varying the number of springs on each side and the pressure of the air supply (e.g. 2 springs per side and a 5.5 bar air supply or vice versa), and in the case of spring return applications, two conditions can be obtained: the loss of air on or the loss of air off. Under normal operating conditions, it is recommended that the optional safety factor of the single-acting (spring return) pneumatic actuator  is 25-50%.