Abstract: A hydraulic control valve with a main stage, having spool valves movable in a valve housing having at least four ports and provided with control edges formed on piston collars. A hydraulic pilot stage is provided to control the spool valve of the main stage, and is characterized by the fact that the spool valve of the main stage is designed hollow to form the hydraulic pilot stage. The wall of the hollow spool valve has at least one opening, to which a piston collar formed on the pilot valve is assigned with two control edges arranged on the outside, and in which the pilot valve penetrates a thrust plate inserted into the valve housing, enclosing the spool valve and creating a front pressure chamber for the spool valve to form a defined constant outflow path for the hydraulic fluid introduced into the annular space between spool and pilot valves.

Abstract: Provided is a hydraulic control valve with a main stage, having a movable spool valve in a valve housing with at least four ports P, A, B, T to block or release the ports, and provided with control edges formed on piston collars, and with a hydraulic pilot stage provided to control the spool valve of the main stage. If the spool valve of a hydraulic control valve requires a control to release or block the valve housing ports, in addition to electromechanical pilot valves, hydraulically operating pilot stages are also known, in which a pilot valve, controlled by means of a connected drive, regulates a stream of hydraulic fluid acting upon the spool valve of the hydraulic main stage and therefore moving the spool valve between its control positions.