Caterpillar Tractor Co.

Willard J Haak

Howard A Marsden

James R Sturges

Orrin A Stemler

James P Mueller

Rollin P Van Zandt

Paul C Moots

Rollin P Vanzandt

A high pressure hydraulic system, including a bidirectional fluid motor having two ports, a pair of normally closed, pilot operated poppet valves, each connected to an associated port, a fluid reservoir, a flow sensor having a flow path interconnecting each of the poppet valves and the reservoir and having an output for providing a signal representing the flow rate, along the flow path, a pair of metering valves each connected to the pilot of an associated poppet valve for controlling the flow of fluid through the associated poppet valve, control signal inputs for each of the metering valves, and flow rate signal inputs connected to the output of the flow sensor for each of the metering valves so that each poppet valve is ultimately controlled by both control signals and the flow rate through the flow sensor.

High pressure hydraulic system

A hydraulic system including a hydraulic motor having a port adapted to be connected to a reservoir and a hydraulic fluid pump. A normally closed check valve connects the port to the reservoir and includes two, hydraulically opposed, differential surfaces, one being smaller than the other and being disposed to be responsive to pressure at the port. Included is a normally closed, pilot-operated, first metering valve having an inlet and an outlet and a second metering valve also having an inlet and an outlet along with a shiftable metering element interposed therebetween. A spring biases the element towards a position minimizing flow between the inlet and the outlet and a pressure responsive surface is disposed on the element in bucking relation to the spring. The first valve inlet is connected to the second valve outlet and to a larger surface of the check valve and the port is connected to the second valve inlet as well as connected to direct pressure to the second valve pressure responsive surface. The first valve outlet is connected to the reservoir. The first valve controls the degree to which the check valve may open while the second valve provides load compensation in the circuit.

Overrunning load control for hydraulic motors

In a vehicle including a stick cylinder movable to change the attitude of a stick relative to a boom, and an implement cylinder movable to change the inclination of an implement relative to the stick, hydraulic circuit means are provided for serially connecting the cylinders so that as the stick cylinder moves the stick in one direction, discharge of fluid from the stick cylinder is used to actuate the implement cylinder to maintain substantially the same attitude of the implement relative to the ground. A flow divider is interposed between the cylinders to provide the desired degree of actuation of the implement cylinder in response to actuation of the stick cylinder. A dual pressure-responsive bypass valve provides a relatively high pressure relief to the implement cylinder when the implement cylinder is operated independently of the stick cylinder and provides a relatively low discharge path for the implement cylinder when operated in series with the stick cylinder.

Attitude control for implement

A vehicle includes an auxiliary front wheel drive system including fluid motors, and a valve movable to supply fluid pressure thereto for driving thereof. A second valve is included in communication with the exhaust conduits of the motors, blocking flow therethrough when the first-mentioned valve is not supplying fluid to the motors. Further a transmission is included for regulating the fluid pressure provided to the fluid motors. Another aspect includes a pressure relief valve and means for selectively varying the relief pressure of the pressure relief valve to provide proper torque characteristics to the front wheel drive system.

Front wheel drive system for a vehicle

A track-type vehicle comprises a track roller frame mounted on either side thereof and an endless track assembly mounted on each of the frames. Each frame further carries a final drive thereon, including at least one planetary gear set and a sprocket drivingly engaged with a respective track assembly. The power input to the final drive preferably comprises a hydrostatic motor for selectively driving a carrier of the planetary gear set which is attached to the sprocket for simultaneous rotation therewith.

Final sprocket drive for track-type vehicles

A track-type vehicle comprises a track roller frame mounted on either side thereof and an endless track assembly mounted on each of the frames. An endless track assembly is entrained on the track roller frame and adapted to be driven by a sprocket operatively engaged therewith. The final drive for the sprocket comprises a rotatable input shaft having a sun gear secured thereon and meshing with a first set of planetary gears which react against a stationary first ring gear. Each gear of a second set of planetary gears is rotatably mounted on a rotatable carrier by a common shaft also having a respective gear of the first planetary gear set mounted thereon. The gears of the second planetary gear set mesh with a second ring gear rotatably mounted in the final drive and secured to the sprocket for simultaneous rotation therewith.

Epicyclic final drive for track-type vehicles

An overrunning load control for a hydraulic jack includes a pair of variable orifice means in series, with the degree of metering of one of such orifices being determined by fluid pressure in the end of the hydraulic jack resisting the load. The degree of metering of the other variable orifice may be selectively chosen, through actuation of a relatively low pressure hydraulic pilot system.

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Peoria, IL, United States of America

Willard J Haak