Abstract: Apparatus for modifying a drive system for a lehr loader in which a rotating cam functions to raise and lower a pusher bar for moving ware from a cross-conveyor onto a lehr belt, with a crank arm being connected to the rotating cam and the pusher bar to effect forward and reverse movement of the loader bar. In this arrangement, the effective length of the crank arm which is moving the loader bar forward and backward in response to rotation of the rotating cam, is changed by having its connection to the rotating cam shiftable in response to the rotational position of the rotating cam. This changing position is accomplished by having the crank connected to the rotating cam through a radially extending slot, with the position of the crank connection in the slot being regulated by a stationary box cam that circumscribes the path of rotation of the rotating cam.