Abstract: A closed-loop hydrostatic drive unit having a variable displacement fluid pump driven by an electric motor for generating high-pressure fluid adapted to be communicated to a fluid motor and returned to the fluid pump via a high-pressure filter. The closed-loop hydrostatic drive unit is mounted to a rectangularly-shaped reservoir housing having upper and bottom surfaces connected by side walls and end walls to define therein a chamber for the storage of fluid at a low pressure which is communicated to the fluid pump via a charge pump and suitable conduits and check valves. In a first embodiment of the invention the interior of the reservoir housing is divided by means of a partition to define the fluid-holding chamber, while the remaining portion of the reservoir housing defines a separate chamber for the mounting and storage of the high-pressure filter and/or other selected fluid power components.

Abstract: The present invention relates to a hydraulic jack with a base plate on which are attached a pump cylinder, a jack cylinder, and a reservoir concentrically surrounding the jack cylinder, the reservoir being connected to the pump cylinder by means of a first passage, passing through the base plate, and a first nonreturn valve which enables hydraulic medium to flow from the reservoir on pumping, the pump cylinder being connected to the jack cylinder by means of a second passage, passing through the base plate, and a second nonreturn valve which enables hydraulic medium to flow from the pump cylinder on pumping, and the jack cylinder being connected to the reservoir by means of a relief passage and a blocking member including an adjustable bolt.

Abstract: A hydraulic circuit comprises a first tank elevated above a second tank and openly communicating therewith by a conduit adapted to continuously maintain the second tank at full capacity with a hydraulic fluid. The hydraulic fluid is pumped out of the second tank and to a work system wherefrom it is recircuited back through a filtering system, retained in the first tank. Upon malfunctioning of the filtering system to prevent the egress of hydraulic fluid therethrough, the increased pressure level of the recircuited hydraulic fluid will function to open a directional control check valve in the second tank to by-pass the conduit normally communicating hydraulic fluid from the first tank to the second tank.

Abstract: An air extracting system for a hydraulic steering apparatus which has a pump, a reservoir and a piston-cylinder mechanism which is geared to the steering gear. A two-position changeover valve is positioned in the hydraulic circuit between the pump and the piston cylinder mechanism, which in one position connects them in a closed circuit and in the other position connects the return portion of the hydraulic circuit to the reservoir. The piston has a bore therethrough with a two way check valve therein with a check valve opening element which opens the check valve at the end of the stroke of the piston. When the changeover valve is positioned to connect the return of the hydraulic circuit to the reservoir, when the piston reaches the end of its stroke, the check valve is opened to cause air in the system to pass through the check valve and through the changeover valve to the reservoir.

Abstract: Power is transmitted between reciprocating crank drives by piston, pump and motor assemblies of the single-acting type interconnected in an open fluid circuit. A valve arrangement in the fluid circuit maintains the pump assembly and the pressure conduits interconnecting the assemblies completely filled with fluid during the return strokes of the pump and motor assemblies.

Abstract: A hydraulic pressure amplifier with a scavenging pump operable to establish a negative return line pressure to effect a positive and rapid return of the rod of a one-way hydraulic actuator and thereby eliminate the necessity of third line-type systems that depend on gravity and/or spring-loaded actuators to return the hydraulic fluid to the tank.

Abstract: A hydraulic door opener comprising a closed hydraulic circuit including a motor for actuating a door operating spring surrounded by a housing which forms a component part of the hydraulic circuit and serves as a reservoir for the hydraulic liquid.

Abstract: The invention discloses a power-steering mechanism for an automotive vehicle, having a double acting actuator with two pressure chambers separated by an actuator piston. The actuator is connected both to the chassis of the vehicle and to a linkage associated with the direction controlling wheels of the vehicle. The pressure in the actuator chambers are controlled by a distributing valve operated by the steering wheel moved in either direction from a central, idle position. A reaction device adapted to create a return force biasing the steering wheel into its central position includes a circular cam eccentrically mounted on the rotating shaft of steering wheel and subjected to a thrust transmitted by a tappet. The tappet is projecting into a closed compartment to engage a reaction piston submitted to the pressure prevailing in a fluid accumulator. Two plungers are slidably mounted in the compartment and are submitted to the pressure prevailing in the actuator chambers.