Winch assembly

The utility model relates to a winch assembly which solves the technical problems that in an existing natural orifice surgical robot, a steel wire is wound around a winch of a wire driving structure, the winch is poor in movement stability, and the winch rotates in the transportation or carrying process so that the steel wire can loosen and retreat in the wire driving structure enabling the steel wire to be wound around the wire driving structure. The winch comprises a winch, a coupler, a driven rotating shaft, an input shaft and a spring, a screw groove is formed in the middle of the winch, the driven rotating shaft is provided with an inserting portion, a bearing mounting portion, a sleeving portion and a circular boss, the input shaft is provided with an inserting portion, a disc portion and a sleeving portion, the upper portion of the spring sleeves the sleeving portion of the driven rotating shaft, and the lower portion of the spring sleeves the inserting portion of the input shaft. The inserting part of