HYDRAULIC CONTROL SYSTEM IN WORKING MACHINE

摘要

A hydraulic control system in a working machine, configured such that the potential energy of a vertically moving working section is recovered and stored as pressure into an accumulator, wherein the accumulator is adapted to be able to store pressurized oil having a high pressure capable of coping with work under a high load and wherein the pressurized oil in the accumulator can be used for various hydraulic actuators. A hydraulic control system in a working machine comprises: an openable and closable unload valve (41) for causing pressurized oil in a head-side oil chamber (8a) of a first boom cylinder (8), among a pair of first and second boom cylinders (8, 9) for lifting and lowering a working section (4), to flow to an oil tank (12), the unload valve (41) being adapted such that, when the working section (4) is lowered, the unload valve (41) is opened to cause the pressure in a head-side oil chamber (9a) of the second boom cylinder (9) to hold the weight of the working section (4); an accumulator (59) for storing the pressure of oil discharged from the head-side oil chamber (9a) of the second boom cylinder (9) when the working section (4) is lowered; and a converging oil path (16) for converging the pressurized oil in the accumulator (59) into a discharge line (15) of a main pump (10).