The ornamental design for a hammer drill, as shown and described.
FIG. 1 is a perspective view of a hammer drill showing our new design;
FIG. 2 is right side elevational view showing the design for the hammer drill of FIG. 1;
FIG. 3 is a left side elevational view showing the design for the hammer drill of FIG. 1;
FIG. 4 is a front elevational view showing the design for the hammer drill of FIG. 1;
FIG. 5 is a rear elevational view showing the design for the hammer drill of FIG. 1;
FIG. 6 is a top elevational view showing the design for the hammer drill of FIG. 1; and,
FIG. 7 is a bottom elevational view showing the design for the hammer drill of FIG. 1.
The broken line showing of portions of the hammer drill in the drawings is included for illustrative purposes only and forms no part of the claimed design.