The disclosure provides a brake including a magnetic yoke iron core, a movable plate, a friction disk, a coil, an armature and an elastic part; a first mounting space penetrates through a center position of the magnetic yoke iron core in the axial direction; an opening of a second mounting space faces a second shaft end; the movable plate is located in the first mounting space and close to a first shaft end; the friction disk is arranged in the first mounting space and located at a side of the movable plate close to the second shaft end; the coil is arranged in the second mounting groove; the armature is located at the second shaft end, and the armature is connected with the movable plate through a connector; and the elastic part has pre-tightening force that enables the armature to be far away from the magnetic yoke iron core.