What do the predicted, passed and total strokes mean in automatic control?

In the information of stroke and micro switch or the maintenance report of production line, you will often see the expressions of: pre-stroke/over-stroke/total stroke; this issue will help you to clarify the meaning of these three and the relationship between them.

Pre-travel (PT): This refers to the distance or angle that the actuator rod moves from the free position (FP) to the actuated position (OP). In other words, it is the distance or angle that the actuator rod moves from the moment force is applied until the moment the internal contacts of the micro switch switch switch.

Overtravel (OT) is the distance or angle the actuator travels from the operating position (OP) to the travel limit position (TTP). This refers to the distance or angle the actuator can continue to move after the internal contacts of the micro switch have completed their state transition. Overtravel ensures that the contacts are reliably closed or opened.

Total travel (TT): is the distance or angle that the actuator rod moves from the free position (FP) to the limit position (TTP). It covers the entire distance or angle that the actuator rod travels, including pre-travel and over-travel.