Abstract: A winch includes a coupling A, a coupling B, a rectangular spring, a gear wheel, a gear rack, a friction ring, and a transmission shaft, etc. By increasing the distance between the adjacent internal teeth of the two-stage planet carrier, it ensures that the three-stage sun gear can be smoothly inserted into the two-stage planet carrier even if the elasticity of spring A is reduced, such that the engagement width between the three-stage sun gear and the two-stage planet carrier can reach the normal requirements. With the design of sliding gear ring and spring C, it can greatly reduce the phenomenon of mis-engagement when the external teeth of the three-stage sun gear enter the internal teeth spacing of the two-stage planet carrier, protect the teeth integrity of the three-stage sun gear and the two-stage planet carrier.