PMB Operation:
With current off to the electric coil, the permanent magnet provides ongoing magnetic flux to engage the armature plate with the brake’s inner and outer friction faces. The load attached to the hub/diaphragm spring/armature plate assembly is held continuously without power consumption.
When current is applied to the coil, the permanent magnet flux path is counteracted, thereby reducing the magnetic force at the friction face contact points to zero. This allows the diaphragm spring to pull the armature plate away from the magnet case, allowing the load to rotate freely — only while power is applied to the coil.
