The ornamental design for a liftarm for a motor grader, as shown and described.
FIG. 1 is a left side view of a lift arm for a motor grader showing our new design in use condition;
FIG. 2 is a left front perspective view thereof, shown in use condition;
FIG. 3 is a rear view thereof, shown in use condition, in cross-section along line 3—3 of FIG. 1;
FIG. 4 is an enlarged front perspective view thereof;
FIG. 5 is an enlarged rear perspective view thereof;
FIG. 6 is an enlarged top view thereof;
FIG. 7 is an enlarged right side view thereof;
FIG. 8 is an enlarged front view thereof; and,
FIG. 9 is an enlarged left side view thereof.
The broken lines showing portions of a motor grader are included for the purpose of illustrating environmental structure and form no part of the claimed design.