Rule 4401. Motion for judgment during trial. Any party may move for judgment with respect to a cause of action or issue upon the ground that the moving party is entitled to judgment as a matter of law, after the close of the evidence presented by an opposing party with respect to such cause of action or issue, or at any time on the basis of admissions. Grounds for the motion shall be specified. The motion does not waive the right to trial by jury or to present further evidence even where it is made by all parties.