What is the function of a limit switch on an industrial brake?

Brake closed (braking state): The limit switch is not triggered or is pressed, signaling to the control system (PLC/relay) that "the brake is engaged."

Brake open (released state): When the brake opens, it triggers the limit switch, signaling that "the brake is disengaged."

This is used to confirm whether the brake operates correctly according to the command, preventing equipment damage or accidents due to "false opening" or "failure to release."

Lifting/motion mechanism interlock: For equipment like overhead cranes or winches, the motor is only allowed to start when the "brake is disengaged" signal is detected. If the disengagement signal is not received, the motor operation is prohibited.

Fault shutdown protection: If no change in the limit switch status is detected within a set time, the system determines a brake fault and triggers an alarm or emergency stop.

Some designs use two limit switches to detect:

Normal open position

Maximum open position / excessive retraction position

If the brake shoe retraction is excessive (indicating severe lining wear or improper adjustment), an alarm is triggered to prompt replacement or adjustment of the brake block.