Caterpillar Inc.

Glenn G Smith

Edward L Stapleton

Load sensing hydraulic systems conserve energy by generating only the fluid flow demanded by the system and at a pressure only slightly greater than the highest load pressure of the system. Optimizing the operating characteristics of the system for certain applications also caused the variable displacement pump to go to its maximum displacement setting with the excess fluid generated thereby not doing any useful work. The load sensing hydraulic system includes a flow control valve connected to a directional control valve and has an operating position in which fluid exhausted from a hydraulic jack is transmitted therethrough to a tank. A signal valve is disposed in a control pressure signal line for controlling fluid flow therethrough from a supply conduit to one end of the flow control valve. When the signal valve is blocking fluid flow through the signal line, the flow control valve is in the above-noted operating position. When the signal valve permits fluid flow through the signal line, the flow control valve is moved to a position to block fluid flow therethrough to the tank. The signal valve is connected to the directional control valve for movement therewith to establish the blocking or fluid transmitting positions.

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Lockport, IL, United States of America

Glenn G Smith