Crane with lifting trolley, suspending trolley and telescopic cantilever beam

The invention discloses a crane with a lifting trolley, a suspending trolley and a telescopic cantilever beam. The crane comprises a double-beam bridge frame formed by main beams and end beams. I-typesteel rails are arranged below the main beams. The lifting trolley is connected between the two rails. Large vehicle driving devices and safety hooks are arranged at the two ends of the end beams. The suspending trolley is further connected to the rails. A rotating mechanism is arranged on the suspending trolley. The lower end of a suspender shaft in the rotating mechanism is connected with a cantilever component, and the upper end of the suspender shaft is connected with a safety ruler. A touch head of the safety ruler is in touch connection with travel switches, and the two travel switchesare connected to the upper face of a trolley frame. The cantilever beam in the cantilever component is a telescopic beam. Telescopic activities of the cantilever beam are controlled by a hydraulic cylinder. One end of the cant