Caterpillar Global Mining Europe Gmbh

Michael N Wheeler

Robert M Weber

Karl-Heinz Post

Richard G Wheeler, Sr

A hydraulic switching mechanism for the mobile hydraulics of, for example, hydraulic excavators, with a valve block, with electrohydraulically activatable valve units for controlling the movement of a working cylinder whose cylinder chambers can be selectively connected to a pump connection for hydraulic fluid, to a tank connection or to one another, and with pre-control valves for activating the valve units, wherein the hydraulic switching mechanism, by means of separate tank valve units and pump valve units, and also a suitable pre-control system, makes it possible to achieve a directional control valve function and a directly controlled and superimposed pre-controlled lowering braking function, a maximum pressure safeguarding of the cylinders and a proportional throttle valve function for the controlled displacement under negative load forces in the direction of movement and braking in an emergency; and mobile hydraulic machines having such a hydraulic switching mechanism and also to valve units therefor.

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South Point, OH, United States of America

Michael N Wheeler