Technical terms and explanations
A microswitch is a mechanically actuated electrical switch. DIN 41635 and DIN 41636 refer to snap-action switches and differentiate between types A to E (installation dimensions, connection types, switching principle).
Here is an overview / technical explanation of the terms used in the DIN 41636 standard.
Forces
Initial force
The force required to move the actuator from the rest position
Actuating force
The force required on the actuator to move it from free position to operating position.
Final actuating force
The force required to hold the actuator in the end position.
Release force
The force to which the actuating force must be reduced so that the snap-action mechanism returns to its initial position.
Differential force
The difference between actuating force and release force.
Position of actuator
The dimensions for the actuator positions are always related to a specific reference line.
Free position
The free position is the position of the actuator in which no external force is applied on it.
Operating position (switching point) (mech.)
Position of the actuator when contact changeover takes place.
End position / total travel position
Position of the actuator at the end of the permissible travel.
Release position (mech.)
The point on the actuator’s path back to the free position at which the snap-action mechanism snaps back into its initial position.
Movement of the actuator
Pre-travel
The distance between free position and operating point.
Over-travel
The distance between operating point and end position. To ensure safe switching, at least 50 % of the overtravel must be utilised
Return travel
The distance between the end position and release point.
Idle travel
The distance between release point and free position.
Total travel
The total travel is the sum of pre-travel and over-travel or return travel and idle travel (post release).
Movement differential
The distance between operating point and release point.
