HYDRAULIC CONTROLLER FOR HYDRAULIC WORKING MACHINE

摘要

PROBLEM TO BE SOLVED: To provide a hydraulic controller for a hydraulic working machine capable of bringing engine output torque close to pump input torque required substantially for holding pump discharge pressure at cut-off set pressure while suppressing excessive rotation of an engine when performing cut-off control of a variable displacement hydraulic pump driven by the engine.

SOLUTION: When deviation of pump discharge pressure and cut-off set pressure becomes a value showing that pump discharge pressure has a tendency to exceed cut-off set pressure, small number of revolutions set in advance by a small number of revolutions computing part 21a is calculated. When start of cut-off control and reduction of pump discharge flow rate to the minimum discharge flow rate are detected by a limit switch 21c, a switch part 21d operates, and either of smaller number of revolutions of target number of revolutions inputted manually by an accelerator dial 3 and small number of revolutions is selected by a selection part 21b. A target number of revolutions command signal corresponding to the selected number of revolutions is given to an electronic controller 2a controlling an electronic governor 2.

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