A mechanical linkage is an system of connected bodies. The connections are called joints, that come in many flavors. Linkages allow you to design various path movements, speed profiles and force changes. The simplest possible linkage is a four bar mechanism and its special case the crank mechanism.

A mechanical linkage is a system of connected bodies. The connections are called joints, that come in many flavors. Linkages allow you to design various path movements, speed profiles and force changes.

This tag could be used for questions asking about the design or use of various mechanisms as described.

The simplest possible linkage is a four bar mechanism, because a triangle is fully defined. Another simple mechanism is the crank mechanism that can be thought of as a special case of the four bar.

A four bar mechanism

Image 1: A simplified schematic of a four bar mechanism. Links A-B, B-C, C-D and the ground connection form four bars. The circles represent rotational joints.