Patent ID: 6560962
Filing Date: 2003-05-13
Classification: F15B,F16D

Abstract:
A control system of a hydraulic construction machine having a variable displacement type hydraulic pump, a hydraulic actuator driven by hydraulic fluid delivered from the pump, a flow control valve for controlling the flow rate of the hydraulic fluid in response to a travel amount of a manually operable lever to the hydraulic actuator, a variable bleed-off valve disposed in a bleed-off hydraulic circuit which exhausts the hydraulic fluid supplied to the hydraulic actuator, and a controller of the variable bleed-off valve for controlling the flow rate of the exhausted fluid through the variable bleed-off valve,wherein said controller contains a storage unit for storing a plurality of functions as a function of opening area function which determine the desired flow rate of the exhausted fluid through said variable bleed-off valve to a reservoir by the actuation of said manually operable lever which is connected to the said controller.