Caterpillar Tractor Co.

Wayne A Peterson

Lawrence F Schexnayder

Leon E Hicks

Edward J Ohms

Kenneth W Kelly

John W Grant

Loyal O Watts

A loader vehicle includes a loading implement movable to a dump and a rack-back position by means of actuation of cylinders. The movement of the cylinders is provided by fluid control valves in turn operated by actuator means which provide for both a slow dump and a fast dump movement of the implement.

High pressure implement circuit for loader with slow and fast dump

A priority system has a valve assembly which has an inlet, first and second outlets, and apparatus for controllably limiting fluid pressure at the first outlet to a preselected maximum value by controllably communicating the second outlet with the inlet. The priority system has a fluid reservoir, a work element and control apparatus connected to the work element, second outlet and reservoir which receives fluid from the second outlet and passes the fluid to the fluid reservoir or work element.

Priority system

A loader vehicle includes a loading implement movable to a dump and a rack-back position by means of actuation of cylinders. The movement of the cylinders is provided by fluid control valves in turn operated by actuator means which provide for both a slow dump and a fast movement of the implement.

A hydraulic brake system with pilot actuation for the braking of a vehicle is disclosed. The brake system includes a service brake valve, a park brake valve and a retard brake valve. The hydraulic brake system further includes an additional brake valve including two separate spools slidably disposed within a valve body, each being responsive to pilot pressure from the above-disclosed valves. The first of the spools in the additional brake valve communicates pilot pressure from a fluid pressure source to the rear brakes of the vehicle and from the rear brakes to a fluid pressure reservoir or sump. The second spool communicates fluid from the fluid pressure source to the front brakes and from the front brakes to the fluid pressure reservoir. The first spool of the additional brake valve is also independently responsive to pilot pressure from at least one of the above disclosed valves which responsiveness allows for a variance in braking force between the front and rear brakes.

Brake system with pilot actuation

A method and plural embodiments of apparatus for delivering a pressure-compensated supply of fluid to a hydraulic steering circuit, wherein first and second pumps are respectively operated by a vehicle engine and by a ground wheel when the vehicle is in motion, output fluid from the two pumps being simultaneously directed to the steering circuit by a control valve with inlet relief valve means modulating output pressure of the sources in response to operation of the control valve. One embodiment contemplates dual inlet relief valves for separately modulating output from the two pumps while another embodiment contemplates one of the pumps having a variable output.

Dual source hydraulic steering system

A pressure responsive check valve permits fluid flow therethrough in a first direction and blocks fluid flow therethrough in the reverse direction until the fluid pressure at the blocked side exceeds a preselected pressure level at which time the check valve is controllably opened for reverse flow therethrough.

Pressure responsive check valve

A pilot operated, control valve providing for two speed operation of a hydraulic jack in a first direction, the control valve including centering spring means for resisting movement of its spool in either direction and additional spring means for resisting movement of the spool in the first direction in order to establish two operating positions of the spool corresponding to the two speeds of operation for the jack, the first operating speed being accomplished by communicating the rod end of the jack with a drain and simultaneously communicating a source of fluid under the pressure with a head end of the jack, the second operating speed being accomplished by communicating both ends of the jack with the pump, a pilot valve being manually operable to regulate the control valve and having first and second springs to indicate the operating position of the control valve spool and the corresponding speed of operation for the jack in the first direction.

Control valve providing two speed operation for a motor

Apparatus and method for controlling the velocity of an engine driven vehicle having a hydraulic system pump driven by the engine. Means are provided for controllably restricting the passage of fluid from the pump of the hydraulic system for controllably loading the engine and thereby controlling the velocity of the vehicle.

Vehicle speed control apparatus and method

Flow sensing and control apparatus is provided to selectively combine the fluid output of an auxiliary pump with a hydraulic system. The apparatus includes a valve body having a primary pump passage therein through which fluid from one of a pair of primary pumps is conducted to its respective inlet of a control valve, an auxiliary pump passage interconnected between the auxiliary pump and the primary pump passage and a fluid receiving passage which is connected to the auxiliary pump passage. A pilot operated valve is disposed within the fluid receiving passage and operative in response to fluid flow through the primary pump passage for selectively controlling fluid to the fluid receiving passage so as to permit the combining of any available fluid from the auxiliary pump with that of the primary pump up to a predetermined minimum flow rate through the primary pump passage and for diverting any excess fluid from the auxiliary pump to the receiving passage above that necessary to maintain the minimum flow rate.

Flow sensing and control apparatus

A pair of hydraulic motors are operatively drivingly connected to a common rotatable member and are employed for transmitting power thereto from a pair of prime movers. A first hydraulic circuit communicates with one of the hydraulic motors and includes a pump driven by one of the prime movers while a second hydraulic circuit communicates with the other of the hydraulic motors and includes a fixed displacement pump and a variable displacement pump driven by the other prime mover. A device associated with the variable displacement pump is responsive to fluid pressures in the first and second hydraulic circuits for automatically varying the output displacement of the variable displacement pump so that a predetermined relationship is maintained between the fluid pressures in the first and second hydraulic circuit.

Dual motor hydrostatic drive system

Multiple embodiments of a hydraulic control circuit for a double-acting hydraulic motor to provide fluid at a relatively high pressure for operating the motor in a selected direction and otherwise providing operating fluid to the motor at a relatively low pressure, the control circuit including a dual pressure relief valve which is operatively responsive to the motor or an implement positioned by the motor to provide the two operating pressures. An additional dual pressure relief valve regulates the flow of exhaust fluid from one side of the motor to allow controlled response of the motor to external forces. The hydraulic control circuit of the present invention is preferably contemplated for operating a push-pull coupling to permit selective tandem operation of two vehicles.

Growing community of inventors

Washington, IL, United States of America

Wayne A Peterson