Caterpillar Inc.

Catepillar Inc.

John D Duffy

William E Allen

Douglas W Koehler

Michael Angel Cobo

Mark R Hawkins

James E Schimpf

Robert E Stone

Lee R DenBraber

Cynthia M Gardner

Steven J Zmuda

R Carl Wilbur

An apparatus controllably moves a moveable element within a hydraulic motor. A lever device establishes an operator command signal indicative of a desired velocity and direction of movement of the moveable element. A position sensor senses the position of the moveable element and produce a position signal. An electronic controller receives the operator command signal and position signal, determines the actual velocity of the moveable element, and determines a limit value in response to the actual velocity of the moveable element. Additionally, the controller compares the operator signal magnitude to the limit value and produces a flow control signal in response to the comparison. An electrohydraulic controller receives the flow control signal and responsively controls the movement of the moveable element.

Method and apparatus for controlling the actuation of a hydraulic cylinder

A method and apparatus for preventing underdigging of a work machine, which may occur if the implement digs under or too close to the work machine, is disclosed. An underdigging boundary or a space of allowable implement movement is established relative to the work machine. The position of the implement is sensed, and the movement of the implement is controllably prevented from underdigging the work machine.

Apparatus and method for preventing underdigging of a work machine

An apparatus for controllably moving a work implement is disclosed. The implement is connected to a work machine and is moveable in response to operation of a hydraulic cylinder. The apparatus includes an operator controlled joystick. A joystick position sensor senses the position of the joystick and responsively generates an operator command signal, which is indicative of a desired velocity. A velocity sensor senses the velocity of the lift cylinder and tilt cylinders and responsively producing respective cylinder velocity signals. A microprocessor receives the cylinder velocity and operator command signals, determines the difference between the actual and desired cylinder velocity, and responsively produces an electrical valve signal in response to the velocity difference. An electrohydraulic valve receives the electrical valve signal, and controllably provides hydraulic fluid flow to the hydraulic cylinder in response to a magnitude of the electrical value signal.

Method and apparatus for controlling an implement of a work machine

An apparatus for controllably moving a work implement is disclosed. The implement is connected to a work machine and is moveable in response to operation of a hydraulic cylinder. The apparatus includes an operator controlled joystick. A joystick position sensor senses the position of the joystick and responsively generates an operator command signal. An implement position sensor senses the position of the work implement and responsively produces an implement position signal. A microprocessor based controller receives the implement position and operator command signals, modifies the operator command signal, and produces an electrical valve signal in response to the modified operator command signal. An electrohydraulic valve receives the electrical valve signal, and controllably provides hydraulic fluid flow to the hydraulic cylinder in response to a magnitude of the electrical valve signal.

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Peoria, IL, United States of America

John D Duffy