Apparatus for feeding material to a metalworking machine

A feed apparatus for feeding material to a metalworking machine comprising first and second alternately operating gripping means, the first gripping means comprising a reciprocating transport gripper element which moves the material forward by steps and the second gripping means comprising a stationary non-return gripper element which retains the material during the return stroke of the reciprocating transport gripper element, a closed container means for a non-circulating pressure medium, spring means responsive to the non-circulating pressure medium for applying a spring force to at least one of the gripper elements, means for displacing the pressure medium, the closed container means connected between the displacing means and the at least one gripper element, the closed container means having extensible wall sections, the wall sections being connected to the at least one gripper element and the displacing means.