Abstract: A hydraulic lock valve assembly (10) includes a valve body (16) having an axially extending main bore (18) and first and second axially spaced pump ports (20, 22). A tank passage (23) is in communication with said main bore (18) and first and second valve chambers (24, 26). The assembly (10) includes a spool valve (74) for opening either of the first and second check valve (36, 38) to allow fluid flow from the cylinder ports (28, 30) through the check valve (36, 38) and the inner passage (32, 34) to the pump ports (20, 22) to define a first return flow passage and for opening either of the first and second return ports (84, 86) to allow fluid flow to and from the tank passage (23) to and from the pump port (20, 22) through the return port (84, 86) to define a second return flow passage, whereby the spool valve (74) opens either of the first and second check valves (36, 38) in response to a predetermined delivery pressure in the delivery flow passage in opposite check valve chamber.

Abstract: An axial piston pump assembly includes a housing having first and second interconnected housing portions (12,14). A cylinder barrel (18) has an axis of rotation and is rotatably supported in the housing about the axis of rotation. The cylinder barrel (18) includes a plurality of pistons (22). The pistons (22) are reciprocally supported in the each of the piston cavities (20) for reciprocating movement parallel to the axis of rotation reacting with a cam surface (30) and causing the reciprocating movement of the pistons (22). The pistons (22) include a body portion (44) having a longitudinally extending central bore (46). One end of the bore (46) defines a fluid inlet (48) into the bore (46) and the other end defines a fluid outlet (51). The fluid inlet (48) includes a ball seat (50) and a ball member (52) seated therein and substantially over the fluid inlet (48), the ball member (52) engaging the cam surface (30).