a circuit - like system which includes a lower conveyor line , an upper conveyor line and a pair of lift or transfer mechanisms at the end of each line constructed for moving a work piece . a travel and hoist mechanism and a beam assembly are provided for discontinuously moving work pieces along the lower line and raising and lowering them for treatment . a hook assembly is provided for restraining the downward movement of a work piece at a selected location when the hook assembly is in an operative position . the lift or transfer mechanism is provided which includes telescoping arms for grasping a work piece , which arms are carried by a vertically moveable carrier that is mounted in a stationary frame .