Patent ID: 6915600
Filing Date: 2005-07-12
Classification: E02F,F15B,Y10S

Abstract:
1. A hydraulic circuit of an excavating-and-slewing working vehicle, comprising: actuators for a boom, a bucket, a blade, slewing, an arm and right and left traveling; directional control valves for the respective actuators; two hydraulic pumps delivering pressure oil to the actuators through the respective directional control valves, wherein one of the hydraulic pumps delivers hydraulic oil to the right traveling directional control valve for the right traveling actuator, and the other hydraulic pump to the left directional control valve for the left traveling actuator; a pair of check valves for preventing pressure oil from flowing backward to the respective hydraulic pumps; a confluent passage formed by mutually connecting delivery oil passages of the hydraulic pumps on the downstream of respective branch points of hydraulic oil supply passages to the right and left traveling directional control valves through the respective check valves; and parallel hydraulic oil supply passages branching from the confluent oil passage through respective orifices to inhalation ports of the respective directional control valves for the hydraulic actuators for boom, bucket, blade, slewing and arm. wherein the branch point of the hydraulic oil supply passage to the blade directional control valve on the confluent oil passage is located on the substantially middle point between the branch points of the hydraulic oil supply passages to the right and left traveling directional control valves on the delivery oil passages of the hydraulic pumps.