Spring-applied brakes are single-disc brakes with two friction surfaces. In the de-energised state, the braking torque is generated by one or more compression springs through frictional engagement. The brake is released electromagnetically. To release the brake, the coil of the magnetic part is energised with DC voltage. The resulting magnetic force pulls the armature disc against the spring force on the magnetic part. The rotor is thus relieved of the spring force and can rotate freely.