Abstract: A hydraulic system for mobile industrial equipment wherein the wheels or tracks of the mobile equipment are driven by a hydraulic transmission system having an engine-driven pump assembly, and wherein the hydraulic accessories mounted on the equipment are powered by a separate engine-driven hydraulic pump which draws its fluid from the hydraulic transmission pump assembly, and particularly the charge pump component thereof.

Abstract: A hydropneumatic pumping arrangement comprising at least two double-acting hydropneumatic force multipliers, pneumatic chambers of pneumatic cylinders of the multipliers communicating, through two two-position directional valves with an air source, and the chambers communicating through hydraulic non-return valves, with hydraulic pressure and return lines connected to actuating hydraulic cylinders of the associated processing equipment. The valves are cylindrical slide valves, an inlet passage of one slide valve is in communication with an air source and outlet passages are in parallel communication with the pneumatic chambers and with control chambers of another slide valve, outlet passages thereof being in communication with the control chambers of the one slide valve of the other force multiplier for alternate communication of the pneumatic chambers of both multipliers with the air source in the course of travel of the pistons of the pneumatic cylinders thereof.

Abstract: A mixed loop hydrostatic transmission circuit for use principally with orbit, gear, vane and other non-piston type motors, which generate contaminants making them less suitable for applications using conventional closed loop hydrostatic transmission circuits. The mixed loop hydrostatic transmission drive retains the precise load control and high efficiency of a closed loop system, while introducing the benefits of contamination control of open loop hydrostatic transmission circuits. While maintaining the speed of the motor proportional to the output flow of the pump, both in positive and regenerative modes of operation, the flow of fluid is diverted from the motor to an injector type inlet booster connected to the reservoir, which supplies the full flow of fluid, required by the pump.

Abstract: A charge pump augmenting device includes a jet pump, powered by fluid flow from a main pump, to draw fluid through a check valve from a reservoir to supply additional fluid to the main pump when the charge pump supplying the main pump is inadequate to meet the demands of the main pump.

Abstract: An oil hydraulic motor is provided with a casing in which a rotor is disposed in an eccentric position. An oil having a preselected pressure is sealed in the chambers defined between the rotor and the inner wall surfaces of the chambers and a high pressure is intermittently propagated into said chambers from a high pressure generating device with which it is in communication thereby rotating said rotor to develop an output.

Abstract: A control valve for a variable displacement pump or motor. The valve includes a pair of solenoids which are independently actuatable to port relatively high pressure fluid to their respective servo motor. A shuttle valve actuated by the high pressure fluid is used to simultaneously port the fluid from the other servo motor to a low pressure fluid source. A manual valving system is also provided having a pair of balls each biased into engagement with a seat to seal a passage to one of the servo motors. Movement of either ball off of its seat allows high pressure to flow to the respective servo motor. The high pressure fluid actuates the shuttle valve to port fluid from the other servo motor to the low pressure fluid source.

Abstract: A power shovel comprising a body; a front end assembly mounted on the body including a dipper; means for crowding the dipper; means for hoisting the dipper; and an energy regeneration system including an energy storing means and means actuated by a predetermined movement of at least one component of the front end assembly for charging the energy storing means, the energy storing means providing in the loaded condition a force applicable to a component of the front end assembly for at least biasing such component toward a predetermined movement.

Abstract: A mixed loop hydrostatic transmission circuit for use principally with orbit, gear, vane and other non-piston type motors, which generate contaminants making them less suitable for applications using conventional closed loop hydrostatic transmission circuits. The mixed loop hydrostatic transmission drive retains the precise load control and high efficiency of a closed loop system, while introducing the benefits of contamination control of open loop hydrostatic transmission circuits. While maintaining the speed of the motor proportional to the output flow of the pump, both in positive and regenerative modes of operation, the full flow of fluid is diverted from the motor to the reservoir, while the full flow of fluid, required by the pump, is supplied directly from the system reservoir.

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 closed loop hydraulic control system for a piston type fluid actuator maintains an average pressure on the piston during all operating conditions of the actuator. The system includes a first pump which controls the actuator and a makeup pump which supplies additional fluid to compensate for fluid losses in the system. An average pressure maintaining valve sums the fluid pressure on each side of the actuator and supplies additional fluid from the makeup pump to maintain a predetermined average pressure on the actuator piston.

Abstract: A hydrostatic vehicle drive system having a closed loop front wheel drive circuit and a closed loop rear wheel drive circuit with bi-directional pressure compensating crossover flow between the two closed loop circuits. Another hydrostatic circuit for driving auxiliary equipment also operates as a source of pressurized fluid for charging the wheel drive circuits. The auxiliary hydrostatic circuit includes priority flow to the auxiliary equipment and a flow control with pressure relief means to maintain a constant charging pressure and a predetermined fluid flow for operating the braking circuit as well as charging the wheel drive circuits.

Abstract: A cavitation suppressor for use in a hydraulic system, the cavitation suppressor serving to prevent excessive pressure in the system by bypassing hydraulic fluid around a mixing section to reduce the need for aspiration of additional fluid from a reservoir. The cavitation suppressor also prevents dissolved air in the system from coming out of solution. It includes inlet, mixing and outlet sections, and fluid bypass means communicating the inlet section with the outlet section.

Abstract: An improved hydraulic drive system for a doubleacting hydraulic cylinder which drives or rocks the walking beam of an oil well pump. A closed circuit hydrostatic drive system is used to operate the double-acting hydraulic power cylinder unit and includes a variable displacement reversing swashplate pump driven at a predetermined constant speed by a prime mover such as an electric motor. Suitable automatic control means are provided for synchronizing the reversing movement of the swashplate with the rocking movement of the walking beam.

Abstract: Hydrostatic transmission having a crossover which is provided with check valves. The check valves are automatically controlled by a series of power chambers that respond to different hydrostatic pressures.