Abstract: A mold assembly is described for molding smooth-bottomed battery cases in which the necessary compression locking of the free ends of the elongated cantilever mounted cores is achieved by providing transverse locking pins which are carried within, and actuated to extend from, the interior of the cores themselves. Since no locking pins extend from the cavity, the interior surface of the base wall of the battery case is formed relatively smooth and flat.

Abstract: (1) A wall cleaning unit including a housing with an open side for placement in contiguous relationship to a wall, upper and lower spray bars in the housing for directing high pressure water against the wall, sealing members on the housing around the opening for effecting sealing relationship with the wall, an outlet on the housing for conducting liquid away from the housing, and a high pressure liquid jet arrangement for creating a venturi effect to produce a suction for pressing sealing members against the wall. (2) A system for washing vertical walls including a vehicle mounted for movement along the top of the wall, a boom on the vehicle, a reel on the boom for moving a spray housing vertically on the wall, a source of high pressure water, a second reel on the boom for mounting a hose conducting high pressure water to the spray housing, and a motor on the vehicle for selectively moving the boom to cause the spray housing to move toward and away from the wall.