Gantry crane girder load shedding support

The invention provides a load shedding support for a main beam of a portal crane, and relates to the technical field of portal cranes. The portal crane main beam load shedding support comprises a main beam, a cavity is formed in the middle of the main beam, two motors are fixedly connected to the right side of the interior of the cavity, the output ends of the motors are fixedly connected with rotating rods, and the left ends of the rotating rods penetrate through the main beam and are fixedly connected with a first winding wheel; a first bevel gear is fixedly connected to the middle of the rotating rod on the front side. A first winding wheel rotates to wind a second connecting rope, the second connecting rope fixes the two ends of the light anti-drag material, meanwhile, a second winding wheel is matched to wind the corresponding first connecting rope, the first connecting rope fixes the middle of the light anti-drag material, and therefore the light anti-drag material is not prone to falling off, and the s