Limit Switch

Limit Switch Terminology
Pretravel — the distance or angle that the actuator must go through to trip the contacts
Operating Point — position of the actuator at which the contacts snap to the operated position
Release Point — the position of the actuator at which the contacts return to their original state
Differential — distance (degrees) between contacts trip and contacts reset
Overtravel — movement of the actuator beyond the contacts trip point
Initial Position — position of actuator when no external force is applied to the actuator

Some other important terms associated with limit switches:
Operating force (torque) — force required to move the actuating element
Minimum return force (torque) — minimum force required to return actuator to its initial position
Total Travel — the maximum allowable distance the actuating element can travel
Repeat Accuracy — ability of a switch to repeat its characteristics precisely from one operation to the next operation