Abstract: The invention includes a passive shaft, having a first gear and an outer thread; a fixed disc, being axially passed through by the passive shaft, having a sleeve located at a center thereof; a ratchet, being a hollow body around the sleeve, and having two friction discs separately on two opposite sides thereof, wherein a first bearing is put around the sleeve and sandwiched between the fixed disc and the ratchet; a second gear, having an inner thread screwed onto the outer thread and an annular wall at a center thereof, wherein a second bearing is received in the annular wall and sandwiched between the second gear and the ratchet; and a pushing disc, movably put around the annular wall, and sandwiched between the ratchet and the second gear.

Abstract: An electromagnetic brake contains a coil seat including plural receiving holes disposed on a front end thereof to receive plural compression springs respectively and an electromagnetic coil mounted on the front end thereof; a movable friction piece fitted on the front end thereof; a brake member fixed in a front end of the friction piece and including a transmitting shaft fitted thereon; a fixed member secured on a front end of the brake member, wherein the electromagnetic coil includes a first silicon steel ring, a plurality of slots and a number of elongate grooves, and each slot includes an isolation holder fitted therein, and the isolation holder includes a recess formed on one side thereof to correspond to the groove of the first silicon steel ring, and between two abutting isolation holders is provided with a coil set formed by an enameled copper wire.

Abstract: An electromagnetic brake contains a coil seat including plural receiving holes disposed on a front end thereof to receive plural compression springs respectively and an electromagnetic coil mounted on the front end thereof; a movable friction piece fitted on the front end thereof; a brake member fixed in a front end of the friction piece and including a transmitting shaft fitted thereon; a fixed member secured on a front end of the brake member, wherein the electromagnetic coil includes a first silicon steel ring, a plurality of slots and a number of elongate grooves, and each slot includes an isolation holder fitted therein, and the isolation holder includes a recess formed on one side thereof to correspond to the groove of the first silicon steel ring, and between two abutting isolation holders is provided with a coil set formed by an enameled copper wire.