Electromagnetic brake

1. An electromechanical brake comprising a stack of disks and at least one electromechanical actuator having a pusher for applying pressure to the stack of disks in controlled manner, the brake being equipped with a parking device for maintaining pressure on the disks at least while the brake is not fed with electrical current, wherein the parking device comprises a resilient member and a selector which is mounted to move between a first position in which the resilient member is mechanically decoupled from the pusher and is maintained in an elastically deformed state to form a potential energy reserve, and a second position in which the resilient member is mechanically coupled to the pusher so that the pusher exerts pressure on the stack of disks under drive from the resilient member.

2. An electromechanical brake according to claim 1 , wherein the resilient member is a spiral spring.

3. An electromechanical brake according to claim 1 , wherein the parking device is a single module housed in a housing mounted detachably on the actuator.

4. An electromechanical brake comprising a stack of disks and at least one electromechanical actuator having a pusher for applying pressure to the stack of disks in controlled manner, the brake being equipped with a parking device for maintaining pressure on the disks at least while the brake is not fed with electrical current, wherein the parking device comprises a resilient member and a selector which is mounted to move between a first position in which the resilient member is mechanically decoupled from the pusher and is maintained in an elastically deformed state to form a potential energy reserve, and a second position in which the resilient member is mechanically coupled to the pusher so that the pusher exerts pressure on the stack of disks under drive from the resilient member,

wherein the resilient member is a spiral spring, and

wherein the spiral spring has one end fixed, and its other end constrained to rotate with a hub that turns about an axis that coincides with the axis of the outlet shaft of the parking device.

5. An electromechanical brake according to claim 4 , wherein the selector comprises a plate that is mounted to rotate with the hub and to be movable axially between the first position in which coupling elements on the plate co-operate with corresponding fixed coupling elements, and the second position in which coupling elements on the plate co-operate with corresponding coupling elements carried by the outlet shaft.

6. An electromechanical brake according to claim 5 , wherein the plate is suitable for being placed in an intermediate axial position in which both of the coupling elements carried by the plate are in engagement with the respective corresponding coupling elements.

7. An electromechanical brake according to claim 5 , wherein at least one of the pairs of coupling elements is of the positive clutch type.

8. An electromechanical brake according to claim 5 , wherein at least one of the pairs of coupling elements is of the sliding type.

9. An electromechanical brake according to claim 4 , wherein the selector comprises a first plate which is movable axially between a coupling position in which coupling elements on the first plate co-operate with corresponding coupling elements carried by the hub, and a decoupling position in which said coupling elements are disengaged, said selector further comprising a second plate constrained to rotate with the hub and movable between a coupling position in which coupling elements on the second plate co-operate with coupling elements carried by the outlet shaft, and a decoupling position in which said coupling elements are disengaged.