Mannesmann Rexroth Corporation

Brueninghaus Hydromatik Gmbh

Mannesmann Rexroth Ag

Bernd Obertrifter

Armin Stellwagen

Karl-Heinz Vogl

Dieter Roth

Mikko Erkkilae

Felix Zu Hohenlohe

A hydraulic steering system, which is used, in particular, for a mobile working machine, and has a steering unit that can be actuated by a first steering member, which is constructed as a steering wheel, that has a first fluid connection, which is connected to a pressure chamber of a steering motor, the pressure chamber being subjected to pressure for a steering movement to the left, and that has a second fluid connection, which is connected to a pressure chamber of the steering motor, the pressure chamber being subjected to pressure for a steering movement to the right, and which has a control valve that can be actuated by a second steering member, which is constructed in the manner of a joystick, and likewise has fluid connections that are connected to the pressure chambers of the steering motor. There is provided priority for steering with the first steering member over steering with the second steering member, wherein the control valve can be activated only when the steering unit is in the neutral position.

Hydraulic steering system for a vehicle, especially for a mobile working machine

Output regulation with load sensing

For a load independent control of a plurality of simultaneously actuable hydraulic users, a throttle valve (pressure compensator) is assigned to the control valve of each user at a location downstream with respect to the metering orifice formed by said control valves; said throttle valve is subjected in opening direction to the pump pressure and in closing direction, via a shuttle valve, either to a load pressure of the respective user or to a pressure which is determined by the highest load pressure occurring for one of said users. Said highest load pressure which is reported by a shuttle valve chain is supplied as control pressure to a pressure reducing valve, the input side thereof being connected with the pressure line of the pump and the output side thereof being connected to control lines leading to the throttle valves assigned to the individual control valves and to the control line for the pump control. The control of the pump control as well as of the pressure compensators by means of the highest indirect load pressure LS to the pressure reducing valve has the advantage that for starting and changing of direction, respectively, the danger of a sinking of the user is avoided.

Load independent valve control for a plurality of hydraulic users

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Steinfeld, Germany

Bernd Obertrifter