Caterpillar Inc.

Caterpillar Tractor Co.

Howard A Marsden

Willard J Haak

John James Krone

Lonnie J Devier

Stephen V Lunzman

Noel J Rytter

Dwight S Holloway

Michael S Lukich

James R Sturges

Jerry D Marr

Orrin A Stemler

James P Mueller

Rollin P Van Zandt

Paul C Moots

An apparatus is provided for use in a vehicle having a source of pressurized fluid and a pair of hydraulic drive motors connected to the pressurized fluid source and powered thereby. First and second ground engaging devices are connected to and driven by the first and second motors, respectively. The apparatus includes first and second control members, each being positionable at a plurality of locations for indicating a desired speed and direction for a respective drive motor. First and second actuators are adapted to sense the position of the first and second control members, respectively, and responsively control the direction and rate of fluid flow to the first and second drive motors. A set switch is movable between first and second positions and is adapted to produce a set speed signal in the second position. A set speed device is provided for receiving the set speed signal and operating the drive motors at a constant speed in response to the set speed signal, wherein the speed of the motors is responsive to the position of the control members upon reception of the set speed signal.

Cruise control for hydraulically driven vehicle

An apparatus for controllably actuating a hydraulic actuator is provided. The apparatus is connected between a source of pressurized hydraulic fluid and the hydraulic actuator. The apparatus controllably provides pressurized hydraulic fluid to the hydraulic actuator. The apparatus includes a controller for receiving an operating signal and a load pressure signal and responsively actuating the hydraulic actuator.

Hydraulic control apparatus

A control system is provided for use with a hydraulic system which includes a source of pressurized fluid, a plurality of flow regulator means, and a plurality of fluidly powered components. Each flow regulator means is adapted to receive the pressurized fluid and is responsive to a respective control signal for regulating the flow of pressurized fluid to respective fluidly powered components. The control system includes a plurality of control members, each being movable to a plurality of locations for indicating a desired fluid output for a respective flow regulator means. A plurality of sensors are provided for sensing the position of respective control members and responsively producing respective position signals. A primary controller is adapted to receive the position signals, process the received signals to responsively produce the control signals, and deliver the control signals to the flow regulator means. A secondary controller is normally disabled and is adapted to receive the position signals, process the position signals to responsively produce the control signals, and deliver the control signals to the flow regulator means. A first device is provided for controllably disabling the primary controller and enabling the secondary controller.

Redundant control system for a work vehicle

An apparatus for limiting the power output of a hydraulic system is disclosed. The hydraulic system has a variable displacement pump. The variable displacement pump has a movable swashplate and is driven by a source of motive power. The apparatus includes a memory device for storing a set of power modes. Each power mode has a predetermined power level associated with the hydraulic system and is defined by a plurality of set points. Each set point corresponds to a predetermined flow rate and discharge pressure of the pump. A device senses the speed of the source of motive power and producing a signal representative of the actual speed in response to the sensed speed. A device senses the pressure of the variable displacement pump and produces a signal representative of the actual pressure in response to the sensed pressure. A device senses the swashplate angle of the variable displacement pump and delivers a signal representative of the actual swashplate angle in response to the sensed swashplate angle. A device receives a desired power mode signal having a desired power level. The desired power level is different from the predetermined power levels associated with the set of power modes. A control device receives the actual speed, pressure and swashplate angle signals, and responsively determines a desired flow limit of the pump. The desired flow limit corresponds to the desired power level.

Method and apparatus for limiting the power output of a hydraulic system

Vehicles having front and rear pairs of steerable wheels are sometimes provided with large springs for moving one pair of the wheels to a straight-ahead position during emergency steering. Large amounts of hydraulic energy are expended solely for the compression of such springs every time the pair of wheels are steered. A back-up steering control system (19) of the present steering control arrangement (10) has a servo valve (76) operative to control the flow of pressurized fluid from a back-up pump (60) to a steering control valve (21) which in turn controls the flow of pressurized fluid from the back-up pump to a hydraulic actuator (13) to hydraulically move a first pair of steerable wheels (11) to a straight-ahead position during emergency steering conditions. A manual control valve (68) is operative to control the flow of pressurized fluid from the back-up pump (60) to another steering control valve (22) which in turn controls the flow of pressurized fluid to a hydraulic actuator (16) for effecting steering of a second pair of steerable wheels (12) during the emergency steering condition.

Steering control arrangement

An apparatus controls a fluid system of a work vehicle. The work vehicle has an engine and at least one fluid circuit which has a pump driven by the engine. A plurality of control valves controllably pass fluid from the pump to a plurality of respective work elements. The control valves have movable valve stems. A work attachment which has a respective control valve is added to the fluid system. A plurality of operator control elements provide demand signals in response to selected settings. Each demand signal is indicative of a requested fluid flow to a respective work element or work attachment. A memory device stores select parameters of the fluid system. One of the select parameters is a predetermined priority value representing the precedence in which fluid is delivered from the pump to the control valve of the work attachment. A controller receives the predetermined priority value of the work attachment and the demand signals. The controller responsively determines the sequence in which fluid is distributed from the pump to the respective control valves. Then the controller delivers control signals to the rerspective control valves in response to the determination, selectively positioning the stem of the respective control valves.

Control system for integrating a work attachment to a work vehicle

The steering system of some lightweight vehicles are electronically controlled and have a manually operated mechanical control as a backup. Such manual backup control would not be adequate for large earthmoving, construction and industrial type vehicles. The subject steering system includes an electrically controlled circuit actuated by rotation of a steering wheel for controlling a main pilot operated steering valve as the primary steering control. A hydraulic control circuit is also actuated by rotation of the steering wheel for controlling the same steering valve as a backup control when the electrically controlled circuit is not active. The hydraulic steering circuit is disabled when the electrically controlled circuit is activated. By using the same steering valve as an integral part of both circuits, the complexity and cost of the overall steering control system is reduced.

Steering control system

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

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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Pekin, IL, United States of America

Howard A Marsden