The valve piston (2) guided within the valve body (1) is pressed into the valve seat (3) by the hydraulic power and the spring force (6) generated by the control pressure (X) on the control surface (5). Thus, the lines (A, B) are separated. By switching the pilot valve (4), the control surface (5) is depressurised and the hydraulic power along the lines (A, B) can be used to lift the valve piston (2) off the valve seat (3), i.e. as soon as the hydraulic pressure is applied to the lines (A, B), the valve piston (2) moves into the opened position up to the mechanical end position. Thus, the lines (A, B) are connected. Depending on the design of the pilot valve (4), the basic valve position normally closed (NC) or normally open (NO) is provided. The valve functions depend on the interconnection of the X- and Y-lines, e.g. the closing of the valve depends on the load pressure, i.e. a weight load can be maintained by the load pressure applied.