The ornamental design for a mainnut for hydraulicjacks, as shown and described.
FIG. 1 is a front elevational view of a main nut for hydraulic jack showing
my new design, the rear view being a mirror image of that shown. The
broken lines are for illustrative purposes only and form no part of the
claimed design;
FIG. 2 is a top perspective view thereof;
FIG. 3 is a right side elevational view thereof, the left side being a
mirror image of that shown.