Caterpillar Inc.

Bryan G Poorman

Geoffrey D Ginzel

Mark B Rinkel

An operator control assembly for a work machine has an armrest, an operator interface, and a base common to the armrest and operator interface. The operator interface has at least one control device. An electronic control module is in communication with the operator interface and at least one component of the work machine, and is mechanically coupled to at least one of the armrest, the operator interface, and the base.

Operator control assembly

A closed loop hydraulic system having a variable charge pressure capability without parasitic power losses is disclosed. The present system includes a variable displacement hydraulic pump driven by a power source, a tilt control means for controlling a tilt angle of the variable displacement hydraulic pump, and a hydraulic motor having a pair of inlet/outlet ports connected in a closed circuit to a pair of inlet/outlet ports of the variable displacement hydraulic pump by way of a pair of main conduits. The system has a charging system including a charge pump driven by a power source, the charge pump including an inlet connected to a supply of oil, and an outlet port connected to the closed circuit for supplying pressurized oil to the variable displacement hydraulic pump. The charge system further includes an electrohydraulic proportional relief valve including means for varying an operating pressure setting thereof, which electrohydraulic proportional relief valve is connected to the charging system for controlling the pressure level of the pressurized oil supplied to the variable displacement hydraulic pump. The means for varying the operating pressure setting of the proportional relief valve are controlled by control means responsive to at least a pressure condition in the closed circuit. According to another aspect of the invention, the charging system is also connected to a hydraulic circuit of the tilt control means for supplying pressurized oil thereto.

Closed loop hydraulic system with variable charge pressure

A control system for a hydraulic circuit having a tank, a pump, a supply conduit connected to the pump, a reversible hydraulic motor, an input conduit connected to the motor and an output conduit connected to the motor is disclosed which comprises a first, second, third, and fourth independently operable electrohydraulic metering valve, the second and third valves being disposed between the supply conduit, the first and second valves being disposed between the input conduit, and the third and fourth valves being disposed between the output conduit, a first pressure sensor connected to the supply conduit for sensing a pressure within the supply conduit, a second pressure sensor connected to the input conduit for sensing a pressure within the input conduit, a third pressure sensor connected to the output conduit for sensing a pressure within the output conduit, a speed and directional sensor connected to the motor for sensing the speed and direction of the motor, and a controller connected to the pump, the valves, and the sensors for controlling operation of the pump and the valves and for receiving signals from the sensors indicative of the pressure within the supply and motor conduits and the speed and direction of the motor, the controller for determining whether an overspeed condition is present and for actuating one of the valves when an overspeed condition is present.

Control system for controlling the speed of a hydraulic motor

The present invention provides an electro-hydraulic steering system for an articulated vehicle having a front frame and a rear frame. The system includes a controller and a hydraulic steering system having a pump for providing hydraulic pressure. A steering input control, typically a steering wheel, transmits mechanical steering inputs to the hydraulic steering system. A pair of articulation cylinders rotate the front frame with respect to the rear frame in response to hydraulic pressure to steer the vehicle. Position sensors transmit input signals to the controller indicating the position of the steering input control and each of the articulation cylinders. An electro-hydraulic valve receives electrical control signals from the controller to control the hydraulic pressure to each articulation cylinder. In this manner, the present invention can perform steering performance enhancements, such as snubbing, steering jerk limit control, and electronic steering adjustment.

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Tiskilwa, IL, United States of America

Bryan G Poorman