Emergency braking device acting on traction sheave of traction machine

An emergency braking device acting on a traction sheave of a traction machine belongs to an uplink overspeed protective device for an elevator cabin. The traction comprises a stand, a motor, a brake, a reduction box, a traction sheave and a supporting seat. The emergency braking device is characterized by comprising a first braking arm component, a second braking arm component, an electromagnet, a connecting seat and a compressed spring assembly, wherein the first braking arm component and the second braking arm component comprise a first braking arm, a second braking arm, a first brake shoe component and a second brake shoe component; the electromagnet is fixed with the first braking arm and the second braking arm through a first pull rod and a second pull rod; the compressed spring assembly comprises a compressed spring, a compressed spring seat and a long screw; and the emergency braking device is arranged on one of the supporting seat or the gear box of the traction machine. The emergency braking device has the advantages of no damage to the surfaces of an inner circle and an outer circle of a steel wire rope or the traction sheave, no requirement for the traction sheave on enough width, large effective brake area, favorable brake effect, guarantee for safe running, simple structure, small size, low manufacturing cost and no need for special mounting space.