Hydraulic driving system of construction machinery

摘要

The invention relates to a construction machine comprising a travel body (79), a swing body (13) swingably mounted onto said travel body (79), a boom (75), an arm (76), and a bucket (77) and a hydraulic drive system. The hydraulic drive system comprises a plurality of directional flow control valves (10a-f; 10a-h) including a boom, arm and bucket directional flow control valves, a boom inflow control valve (201), an arm inflow control valve (202), and a bucket inflow control valve (203). It is proposed that said boom inflow control valve (201), said arm inflow control valve (202) and said bucket inflow control valve (203) are provided only for the rod pushing-side chamber (5aA, 5bA) of a boom hydraulic cylinder (5a, 5b), the rod pushing-side chamber (6A) of an arm hydraulic cylinder (6) and the rod pushing-side chamber (7A) of a bucket hydraulic cylinder (7). Furhter, said plurality of directional flow control valves (10a-f; 10a-h) including the boom, arm and bucket directional flow control valves are disposed in said swing body,said boom inflow control valves (201), said arm inflow control valves (20) and said bucket inflow control valve (203) are all disposed together in one control valve unit (190), and said one control valve unit (190) is disposed on the upper surface of said boom (75).