Auxiliary device for bridge crane installation and bridge crane installation method

The invention relates to an auxiliary device for mounting a bridge crane, which is applied to a transmission shaft of a driving motor and comprises a cylindrical pin shaft hoop, a regular polygonal outer ring operation hand ring and a connecting rod, and the outer ring operation hand ring is arranged outside the pin shaft hoop; the pin shaft clamp comprises two symmetrical half clamps, the outer ring operation hand ring comprises two half operation rings, each half operation ring is fixedly arranged on the side face of one half clamp through a plurality of connecting rods, the two ends of each half clamp are outwards provided with fixing parts with threaded holes, and the fixing parts at the two ends of the two half clamps are correspondingly aligned. The fixing bolt penetrates through the fixing parts of the two half hoops and is in threaded connection with the fixing nut, the two half hoops are fixed outside the transmission shaft of the driving motor, and the two half operating rings form an outer ring ope