Emergency braking system for big arm during power failure of tower crane

The utility model relates to a tower crane power failure big arm emergency braking system which comprises a base, a tower crane body is arranged at the upper end of the base, a charger is fixedly installed at the upper end of the base, a battery pack is fixedly installed at the upper end of the base, and the output end of the battery pack is electrically connected with a bridge rectifier circuit. The bridge type rectification circuit is electrically connected with a rotation braking control switch, a direct current V alternating current contactor, a rotation braking electromagnet coil and a V alternating current contactor, and the rotation braking control switch, the direct current V alternating current contactor, the rotation braking electromagnet coil and the V alternating current contactor are electrically connected to the bridge type rectification circuit. According to the emergency braking system for the power-off big arm of the tower crane, the big arm of the tower crane can be effectively controlled to