Abstract: A casting mould consisting of closely collected uniform mould parts is advanced stepwise on a conveyor path by a main piston, exerting an endwise pressure on the endmost mould part, and by an auxiliary mould advancing device incorporating a hydraulic cylinder, the piston of which is greater than said main piston. Hydraulic fluid displaced by the main piston is supplied to the hydraulic cylinder together with additional hydraulic fluid admitted through a differential pressure valve responding on the pressure difference between the two sides of the main piston.

Abstract: A fluid flow control valve having a valve member which is urged away from a cooperating seat by the combined pressures at the valve inlet and outlet and urged towards the seat by fluid pressure prevailing in a chamber which is connected to the valve inlet or outlet, respectively, dependent upon whether an order signal requires the valve to close or to open. Connection between said chamber and the valve inlet and outlet is controlled by an auxiliary valve which in turn is actuated through pressure transmitting lines connected to the inlet and outlet via a switch valve actuated by the order signal.