This type of mechanism produces a swinging or rocking motion of a link.   The motion is generally less than 360^o and is an oscillatory motion.

This is simply a rotating arm (b) with a link fitted with a toothed rack (c) which meshes with a gear (d) to produce a rocking motion of the gear.

Toothed Rack System

This is simply a four bar linkage (the frame provides the first link).   The operating characteristics are dependent on the length of the links and the design of the frame setting the pivot points..Rotation of the arm (b) produces a rocking motion of arm (d).

Crank and Rocker Mechanism

The arm (b) rotates and results in a rocking motion of arm (d)via the slider (c).    The action is a quick return action because the angle (b) rotates through in one direction ,assumed to be the forward direction, is greater than the angle which result in the return motion.

Quick Return Linkage

A very simplified version on this system is shown below.  Rotation of the cam (c) produces a rocking motion of the lever (d) via the sliding interface (b).    The arrangement below only identifies the principle involved.  In practice some means would have to be provided to ensure the lever is maintained in contact with the lever.

Cam and Follower Mechanism