Patent ID: 7810321
Filing Date: 2010-10-12
Classification: E02F,F15B

Abstract:
1. A relief pressure switching apparatus for hydraulic working machine, comprising: a hydraulic actuator circuit, a relief pressure of the hydraulic actuator circuit being switched in accordance with the type of a working apparatus to be installed; electromagnetically variable relief valves for determining the relief pressure; and a controller for storing a plurality of relief pressures preliminarily set in combination with a flow rate of oil, and commanding a relief pressure selected from the stored relief pressures as matching the working apparatus to said relief valves, wherein said controller is adapted to be switched between a setting mode for setting a plurality of relief pressures and a selection mode for selecting a relief pressure from the plurality of relief pressures set in the setting mode, and in the setting mode, by the controller, the relief pressure is set on the basis of a sensed pressure generated when a hydraulic actuator is brought into action at a predetermined flow rate of the working apparatus to be installed.