Caterpillar Inc.

Shin Caterpillar Mitsubishi Ltd.

Daniel T Mather

David P Smith

Carl McIlheran

Thomas J Hajek

Srikrishnan T Tolappa

Michael D Hudson

Jonathan L Buelow

John Cody Vacca

Eric R Lauterbach

Igor Strashny

Dayao Chen

Larry W Lorimor

Michael Anthony A'Hearn

Daniel Harry Killion

David Mork

Andrew Kleitsch

Wayne W Lark

Steven R Wells

Robin S Arndt

Troy A Shawgo

Kenneth Alan Dust

Christopher W Johnson

Vishnu Irigireddy

Deepak Amaravadi

Matthew Hempel

Ryan M Ludwig

Derek W Holmes

Alfred J Abraham

Bala Natarajan Balashanmugam

Michael E Nesbitt

Partiban Chengalvarayan

Thomas Dale Morris

Charles E Rector

A hydraulic fluid supply portion of a hydraulic steering control system may include an accumulator holding a quantity of pressurized steering fluid, and a priority valve. The priority valve may have a priority supply inlet port fluidly connected to the accumulator for receiving pressurized steering fluid from the accumulator, and a priority supply outlet port fluidly connected to a steering flow amplifier circuit. The priority valve may have a normally open position with a minimal pressure drop between the priority supply inlet port and the priority supply outlet port, and a flow restriction position where fluid flow between the ports is restricted. A load signal line from a steering control circuit to the priority valve may bias the priority valve toward the normally open position in response to an operator steering command to provide pressurized steering fluid to the steering flow amplifier circuit.

Hydraulic steering control system

A relief valve in a hydraulic system in a machine selectively sends pressurized oil to both a brake cooling apparatus and a cylinder used to hoist a load. A relief valve lowers pressure spikes in a brake cooling line by dumping fluid in a brake cooling line to tank responsive to a pressure spikes at the head end of the cylinder during hoisting or other transitions in the hydraulic system. Reducing the pressure spikes in the brake cooling line improves reliability of the brake cooling apparatus by protecting seals from undue stresses.

Hydraulic system with an unloading valve

A valve for a brake cooling system may include a body including a first and a second end, a first at least one radial passage, and a second at least one radial passage fluidly communicable with the first end. A first seat may be disposed within the body proximate the first end, while a plug may include a stop, a collar, and a first trunk disposed between the stop and the collar. The collar and the first trunk may be disposed in the body while an adapter may include a second seat, a head, and a second trunk disposed between the second seat and the head. The second seat and the second trunk may be disposed in the plug with a chamber, fluidly communicable with the adapter and the first at least one radial passage, being defined in the first trunk of the plug. An actuator may be slidably disposed in the chamber, and be in operative association with a biasing member. A poppet may be in operative association with the biasing member and the first seat.

Unloading relief valve

A hydraulic system having an actuator having a piston and associated rod forming head and rod chambers and being adapted to move between retracted and extended positions within a cylinder, and first and second sources of fluid. A first pump provides fluid from the first source to the head chamber at a first pressure. At least one valve provides fluid from the second source at a second pressure to supplement fluid provided to the head chamber from the first pump when the second pressure is greater than the first pressure.

Method and arrangement for active make-up in an overrunning actuator

A hydraulic energy recovery device for a hydraulic system is disclosed. The hydraulic energy recovery device has a first impeller configured to receive a flow of pressurized liquid, and a second impeller configured to pressurize a flow of liquid. The hydraulic energy recovery device also has a common shaft connecting the first and second impellers.

Hydraulic system having in-sump energy recovery device

A sprag is disclosed. The sprag is configured to operate in a first mode allowing substantially mutual rotation of inner and outer races about an axis and a second mode allowing relative rotation between the inner and outer races. The sprag includes at least one actuator configured to selectively extend and retract and an outer surface configured to selectively lock the inner and outer races together as a function of the at least one actuator selectively extending.

Fluidly actuated sprag

A fluid motor including an inner race and an outer race is disclosed. The inner and outer races are configured to rotate about a substantially common axis. The motor also includes at least one fluid actuator configured to produce substantially linear motion as a function of selectively receiving pressurized fluid. The fluid motor also includes at least one sprag configured to rotate the inner and outer races about the axis as a function of the substantially linear motion.

Fluid motor

A hydraulic system for a work machine is provided. The hydraulic regeneration system has a tank, a primary source, a first actuator, an accumulator, and a first valve mechanism. The tank is configured to hold a supply of fluid. The primary source is configured to pressurize the fluid and has a suction inlet and a discharge outlet. The first actuator is configured to receive pressurized fluid from the discharge outlet of the primary source. The accumulator is in fluid communication with the tank, the suction inlet of the primary source, and the first actuator. The first valve mechanism is disposed between the suction inlet of the primary source and the accumulator, and is movable between a first position at which fluid returning from the first actuator is directed to the suction inlet of the primary source, and a second position at which fluid returning from the first actuator is directed to only the accumulator.

Hydraulic regeneration system

A metering valve for a work machine hydraulic system is disclosed. The metering valve has an inlet and an outlet, a main poppet, and a solenoid-operated pilot element. The main poppet is movable to pass fluid from the inlet to the outlet, and to block fluid from the inlet to the outlet. The solenoid-operated pilot element is movable between a first position at which pressurized fluid from the inlet pressurizes a control chamber in communication with a control end of the main poppet to urge the main poppet toward the flow-blocking position, and a second position at which the control chamber is communicated with a drain to move the main poppet toward the flow-passing position. The metering valve also has a relief valve element configured to drain pressurized fluid from the control chamber to move the main poppet toward the flow-passing position in response to a pressure at the inlet exceeding a predetermined pressure.

Metering valve with integral relief and makeup function

A metering valve for a work machine hydraulic system is disclosed. The metering valve has a valve body with an inlet and an outlet. The metering valve also has a main poppet disposed within the valve body between the inlet and the outlet. The main poppet has a nose end and a chamber end, and is movable between a flow-passing position at which fluid flows from the inlet to the outlet, and a flow-blocking position at which fluid flow between the inlet and outlet is blocked. The metering valve also has a pilot element movable to selectively communicate the chamber end of the main poppet with a drain, thereby affecting movement of the main poppet between the flow-passing and flow-blocking positions. The metering valve further has a solenoid mechanism operable to move the pilot element. The position of the pilot element is affected by a fluid pressure at the inlet.

Electro-hydraulic metering valve with integral flow control

A fluid system is provided wherein two different fluid circuits are connected in parallel with a single source of pressurized fluid and the two fluid circuits can function together even when one of the loads is lighter than the other. This is accomplished by having the lightly loaded circuit having a directional control that when operated in one of its operative positions the flow from the rod end of the cylinder is directed through the directional control valve and combined with the supply flow being directed to the head end of the cylinder. With the other heavier loaded circuit also being actuated, the pressure of the fluid from the rod end of the fluid cylinder is equalized with the pressure of the heavier loaded circuit. Consequently, the speed of the heavier loaded circuit does not stall or slow down relative to the lightly loaded circuit. In the case of a machine having a bucket used for backdragging, the circuit needs a diverter system that provides protection from the cylinder rod of the fluid cylinderfrom buckling during backdragging while maintaining the ability for pressure equalization when not performing a backdragging operation.

Hydraulic circuit having pressure equalization during regeneration

In a fluid system, a source of pressurized fluid operably communicates with first and second actuators. First and second control valves control fluidly communicates with the first and second actuators. A first pressure compensating valve fluidly communicates with the first control valve and first actuator. A first signal conduit fluidly communicates with fluid flow being directed by the first control valve to the first pressure compensating valve and first actuator. A second pressure compensating valve fluidly communicates with the second control valve and second actuator. A second signal conduit fluid communicates with fluid flow being directed by the second control valve to the second pressure compensating valve and second actuator. A control signal pressure generated from a greater of a first signal pressure carried by the first signal conduit and a second signal pressure carried by the second signal conduit fluidly communicates with the first and second pressure compensating valves.

Pressure-compensating valve with load check

A control system is provided with a float condition to permit a double acting hydraulic cylinder to freely extend or retract in response to external forces acting on the hydraulic cylinder. The system includes a pair of pilot operated poppet valves disposed between the opposite sides of the hydraulic cylinder and a directional control valve. The pilot condition is obtained by opening a pair of pilot operated control valves to vent the control chambers of the poppet valves to a tank through a pair of float check valves. The float check valves are operative to prevent higher pressure fluid from being transmitted from the tank to the control chambers of the poppet valves when a negative pressure occurs in the side of the hydraulic cylinder that is connected to the control chamber.

Control system providing a float condition for a hydraulic cylinder

A hydraulic cylinder snubbing arrangement includes a pilot operated control valve having a predetermined snubbing position at which flow exhausted from a hydraulic cylinder actuating chamber must pass through a plurality of flow restricting orifices in a valve spool when the hydraulic cylinder is retracted to a predetermined position. The valve spool is shifted to the snubbing position automatically by reducing the fluid pressure in a pilot chamber at the end of the valve spool to a predetermined level so that a snubber spring device resiliently moves the spool from a lower or float position. By forcing the fluid to pass through the restricted flow path created by the orifices, the gravity induced velocity of the hydraulic cylinder is greatly reduced as the hydraulic cylinder approaches its end of stroke position.

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Lockport, IL, United States of America

Daniel T Mather