Abstract: A valve for cooling a reversible hydraulic machine includes a valve piston in a connecting channel extending between supply and discharge passages. Pressure in these passages displaces the spring-centered piston from neutral position to an end position. A central reduced-diameter portion of the piston carries a spring-centered closing member which closes a discharge conduit leading to a leakage space when the piston is in its central position. When the piston is displaced out of the neutral position toward one of the end positions, pressure from one of the connecting passages which has the lower pressure prevailing therein is permitted to propagate through one of the spring-receiving spaces delimited by the closing member and through an annular throttling gap present between the closing member and the central portion of the piston into the other spring receiving space and from there into the discharge conduit and into the leakage space.

Abstract: A radial or axial piston type hydraulic motor has a plurality of cylinders connected by pressure conduits to a pressure fluid distributor. A check valve spring-biased in closing direction is built in at least one pressure conduit and has a first surface portion acted upon by pressure from the cylinder, a second surface portion which is exposable to pressure fluid from the distributor to act on the check valve either in opening direction or in closing direction and a third surface portion exposed to a control pressure in opening direction. The second surface portion being at least as large as the first surface portion and larger than the third surface portion, and the combined area of the first and second surface portions exceeding the surface area of the second surface portion.