What are the power off brakes?
Power off brakes are devices designed to engage (stopping the drive) when the electrical power is off. There are 2 main types of power off brakes: spring applied brakes and permanent magnet brakes.
The main difference between Spring Applied Brakes and Permanent Magnet brakes are how do they operate internally to apply the torque. Spring Applied brakes use springs to keep the shaft blocked when there is not electricity and the Permanent Magnet brakes use rare earth magnets to do the same action. Engifield engineering provides mechanical power transmission consulting services to decide which of this two types of power off brakes are the best for your application.
Another difference is that permanent magnet brakes provide higher torque versus spring applied brakes for the same outside diameter. So, when there is small space applications, PMB works better. In addition, permanent magnet brakes construction may be considered as ‘torsionally rigid’ where linear movement is achieved via deformation of a diaphragm spring, not the clearance between rotating parts like in fail-safe brakes which often include splines.