Patent attributes
A parking brake has the function of monitoring a malfunction of the parking brake, thereby preventing accidents. The parking brake includes an electric motor and a linear motion mechanism which are connected together through a speed reduction mechanism. The parking brake further includes a locking pin which can be brought into engagement with the speed reduction mechanism by a solenoid. The parking brake further includes a monitor for detecting a change in reactance of the solenoid. Since the change in reactance as detected corresponds to a displacement of a plunger, it is possible to prevent accidents by monitoring deteriorated sliding properties of the locking pin based on the displacement detected.