Actuating Terminology

Limit-switch actuating terminology describes how the actuator moves and when the internal contacts change state. The free position (FP) is the resting state, and pre-travel (PT) is the movement needed to reach the operating point (OP) where switching occurs. Pushing beyond OP enters over-travel (OT)—extra safe movement before damage. When the actuator returns, contacts reset at the release point (RP) after moving through differential travel (DT). Terms like operating force (OF) define how much force is needed to actuate the switch. Together, these terms define sensitivity, precision, and mechanical limits—critical for correctly selecting or comparing limit switches.