Patent ID: 6877594

Claim:
A disc brake to be opened by torque arranged between a drive shaft and a driven shaft and comprising a brake wheel arrangement arranged between the drive shaft and the driven shaft, a friction surface arrangement arranged to co-operate with the brake wheel arrangement, at least one spring device arranged to press the brake wheel arrangement and the friction surface arrangement axially against each other, and cam means arranged between the drive shaft and the brake wheel arrangement, and the torque resulted by the rotation of the drive shaft causes the displacement between the brake wheel arrangement and the friction surface arrangement to change in order to detach at least partly the braking engagement against the spring force caused by the spring device, wherein, the brake wheel arrangement includes a first brake wheel non-rotatably but axially movingly arranged to the driven shaft, and a second brake wheel axially movingly arranged between the first brake wheel and the drive shaft and co-axially with the first brake wheel, while the spring device affects the first brake wheel, the friction surface arrangement includes a first set of friction surface means arranged between the first and second brake wheel, and a second set of friction surface means arranged between the second brake wheel and a fixed body, whereby the frictional coupling between the first and second brake wheel is smaller than the frictional coupling between the second brake wheel and the fixed body, and the cam means include a first cam part, which is mechanically controlled by the drive shaft, and a second cam part, which is non-rotatably arranged to the second brake wheel, wherein the brake is mounted in connection with an electric motor, whereby a rotor of the electric motor, the first cam part, the second cam part and the second brake wheel are arranged sequentially to the drive shaft and in such a manner that the rotor and the first cam part are non-rotatable and axially immovable, whereas the second cam part and the second brake wheel are axially moving, and wherein a thrust ring is arranged to the drive shaft adjacent to the second brake wheel at a determined distance therefrom in order to restrict the axial motion of the second brake wheel.