| 摘要 |
A hydraulic confluence circuit for construction machinery is provided to secure workability by removing the cause of the incomplete operation of a confluence changeover valve which makes hydraulic oil of a hydraulic pump flow together to a working device when changing over with the supply of signal pressure. A hydraulic confluence circuit for construction machinery comprises first, second, third hydraulic pumps(P1,P2,P3), a first changeover valve(A) installed to a flow passage of the first hydraulic pump and composed of valves which control hydraulic oil supplied to working devices such as an arm, a boom and a bucket respectively when changing over, a second changeover valve(B) installed to a flow passage of the second hydraulic pump and composed of valves which control hydraulic oil supplied to working devices such as an arm, a boom and a bucket respectively when changing over, a third changeover valve(C) installed to a flow passage of the third hydraulic pump and composed of valves which control hydraulic oil supplied to working devices such as an arm, a boom and a bucket respectively when changing over, a fourth changeover valve(D) installed to the upper part of the flow passages of the first, second hydraulic pumps respectively and composed of valves which control hydraulic oil supplied to right and left working devices respectively when changing over, a confluence changeover valve(E) installed to the lower part of the flow passage of the third hydraulic pump and supplying hydraulic pressure of the third hydraulic pump to a working device of the first hydraulic pump side, or, a working device of the second hydraulic pump side selectively when changing over with the supply of pilot signal pressures(Pi1) through a confluence changeover signal passage(15), a signal line(13) for a traveling device connected to the confluence changeover valve signal passage and forming signal pressure when changing over the fourth changeover valve for a traveling device, and a signal line(14) for a working device connected to the confluence changeover valve signal passage and the signal line of a traveling device and forming signal pressure when changing over the first, second changeover valves for a working device connected to the first, second hydraulic pumps respectively. |
