WORKING MACHINE

摘要

A working machine in which a boom (5) is fixed vertically pivotably to a vehicle body (4), to which boom an arm (7) is fixed vertically pivotably with a bucket (10) fixed vertically pivotably to the arm, the boom, arm and bucket being driven by a boom cylinder (6), an arm cylinder (8) and a bucket cylinder (11) repectively. A vibration generator (13) is fixed to the arm, and a rolling-compaction member (19), a chisel (58) or a pile driver to the vibration generator interchangeably. A float valve (84) is provided which allows an expansion chamber to communicate with a contraction chamber of at least one of the boom cylinder, arm cylinder and bucket cylinder, and establishes or cuts off communication between them and a tank. The float valve is opened when a rolling-compaction operation is carried out, and closed when a breaking operation and a pipe driving operation are carried out.