Abstract: The invention relates to a hydraulic pump or motor having expansible chamber section at one end thereof, which may be a gerator gear set, and a drive shaft at the other end thereof. A distributor valve having a central bore directs fluid between inlet and outlet ports in the housing and the expansible chamber section. The leakage of pressurized fluid into the central bore of the valve causes certain problems including the problem of directly or indirectly causing destructive forces to be applied to the seal provided between the drive shaft and the housing. This problem is addressed by providing check valve arrangements in the housing between the central bore of the valve and the inlet and outlet ports. The check valves open in the direction of the inlet and outlet ports so that when fluid pressure in the valve bore exceeds the fluid pressure in either of the ports, the pressure in the bore is lowered by fluid being forced outwardly through the port having the lower pressure.

Abstract: The invention relates to a hydrostatic steering device comprising a servo-motor operable in dependence on direction and a control device having connections for a pump, a tank and the servo-motor as well as a valve arrangement which influences the flow of pressure medium from the pump to the servo-motor and from the latter to the tank and having two valve members which are relatively movable against the force of a neutral position spring depending on the comparison of the adjustment of a steering element and the follow-up motion of a metering motor.