Rack and pinion

In pipelines and other industrial piping systems, a rack displaced by a linar actuator turns a pinion to open or close a valve.

[5][6] The use of a variable rack (still using a normal pinion) was invented by Arthur Ernest Bishop[7] in the 1970s, so as to improve vehicle response and steering "feel", especially at high speeds.

He also created a low cost press forging process to manufacture the racks, eliminating the need to machine the gear teeth.

By the same token, a rack and pinion mechanism yields a smaller linear force than a worm gear, for the same input torque.

[8] The teeth of a rack and pinion pair may be either straight (parallel to the rotation axis, as in a spur gear) or helical.