The ornamental design for a winch crank, as shown and described.
FIG. 1 is a front perspective view of the winch crank design;
FIG. 2 is a front elevation view of the winch crank design, with the rear side being symmetrical thereto;
FIG. 3 is a left side elevation view of the winch crank design;
FIG. 4 is a right side elevation view of the winch crank design;
FIG. 5 is a top plan view of the winch crank design; and,
FIG. 6 is a bottom plan view of the winch crank design.
The broken line disclosures of the bolt shown in FIGS. 1, 3,and 4 of the winch crank design are for illustrative purposes only and form no part of the claimed design.