Patent ID: 6167702
Filing Date: 2001-01-02
Classification: E02F,F04B

Abstract:
Hydraulic controller for the control of a rotating mechanism of an excavator comprising: a hydraulic drive circuit (2, 3, 4) with a drive hydraulic pump (2) and a drive hydraulic motor, and two working lines (3, 4) connecting the drive hydraulic pump (2) and the drive hydraulic motor, a feed arrangement (19) for feeding pressure fluid into the drive circuit (2, 3, 4), an adjustment arrangement (9) for adjusting a setting piston (12) arranged between two setting pressure chambers (10, 11) and acting upon the displacement volume of the drive hydraulic pump (2), a pre-control arrangement (8) which acts upon the setting pressure chambers (10, 11) with a setting pressure in dependence upon the pressure difference between two control lines (6, 7), and said pre-control arrangement (8) including a pressure regulation valve (56) which is connected with the feed arrangement (129), the pre-control arrangement (8) when in a control position (542, 43), connecting one of the two setting pressure chambers (10; 11) with the feed arrangement (19) via the pressure regulation valve (56) and connecting the respective other setting pressure chamber (11; 10) with a pressure fluid tank (17) and, when in a neutral position (41), connecting both setting pressure chambers (10, 11) with the feed arrangement (19) via the pressure regulation valve (560, and wherein the pressure regulation valve (56) sets the setting pressure to a pressure which is at least slightly higher than the control pressure prevailing in the control line (6, 7) having a higher pressure.