The ornamental design for a strap winding apparatus, as shown and described.
FIG. 1 is a perspective view of a strap winding apparatus showing my new design; with the handle in an open position;
FIG. 2 is a perspective view of the strap winding apparatus, with the handle in an open position, the broken line showing of the attached strap winding assembly being provided for purpose of environment and forming no part of the claimed design;
FIG. 3 is a perspective view of the opposite side of the strap winding apparatus, with the handle in a neutral position;
FIG. 4 is a side elevation view thereof, with the handle in a closed position;
FIG. 5 is a perspective view thereof, with the handle in a closed position;
FIG. 6 is a front view thereof, with the handle in an open position; and,
FIG. 7 is a rear view thereof, with the handle in an open position.