Abstract: A valve piston (1) is axially movably arranged in a valve housing (8) having a cylindrical flow passage. A circumferential groove (2) of the piston (1) carries a sealing ring (3) for separating a high pressure side (H) from a low pressure side (L) of the valve. The sealing ring (3) has a cross-sectionally trapezoid shaped portion (4) of which the narrow side (3a) may be pressed tightly to seal against the inner valve seat surface (8') of the housing (8). At least one spring ring (7) is arranged to radially outwardly bias the sealing ring (3) for sealing against the valve seat surface (8').

Abstract: A check valve or non-return valve has a valve body (9) which is connected with a piston (15) by a rod (14). The piston is guided by a sleeve (17) mounted inside an inner housing of the valve. The sleeve is provided with two radially extending openings (21, 22) which are axially spaced from each other. These openings provide communication between the inner space in the sleeve and the inner space in the inner housing (1) depending on the position of the piston (15). This structure permits a rapid closing of the valve, whereby nevertheless, the pressure shock caused by the rapid movement of the valve body is substantially reduced by these openings causing a pressure build-up inside the sleeve with a respective damping action on the valve body.

Abstract: A fluid control valve is equipped with a plurality of sleeves nested one within the other to form a cage for pressure reduction between the inlet and outlet ports of the valve housing. Each sleeve is provided with blind bores, through-bores and interconnecting grooves which cooperate to repeatedly divide the flow into more and more partial flows which keep colliding with one another. Volume control is achieved by a slidable piston cooperating with the cage.