HYDRAULIC CIRCUIT HAVING SUBSTITUTE SUPPLY FOR HYDRAULIC OIL IN WHEEL LOADER

摘要

A hydraulic circuit having a substitute supply for working fluid in a wheel loader is provided to improve a fuel consumption of the wheel loader by constructing a capacity of a hydraulic pump as minimum as requiring to operate each system. A hydraulic circuit having a substitute supply for working fluid in a wheel loader includes a loader pump(30), a steering pump(20), a brake, a cooling fan, and an auxiliary pump supplying the working fluid to a pilot system. The auxiliary pump has a first auxiliary pump(110) and a second auxiliary pump(120). A first hydraulic line(210) supplies the working fluid from the first auxiliary pump to the selected system. A second hydraulic line(220) supplies the working fluid from the second auxiliary pump to the remaining systems. An auxiliary hydraulic line(230) is branched from the first hydraulic line and combined to the second hydraulic line. A pressure switch(400) is installed to be operated according to the pressure of the second hydraulic line. An alternative channel switching valve(300) is installed at a blanch point of the auxiliary hydraulic line to selectively supply the working fluid to the second hydraulic line or the auxiliary hydraulic line according to an electric signal from the pressure switch.