HYDRAULIC CIRCUIT FOR AUGER LIFTING APPARATUS OF PILE DRIVER

摘要

PROBLEM TO BE SOLVED: To allow descending speed of an auger rotation driving apparatus to follow the excavating speed of an auger screw through a simple operation, when the excavating speed of the auger screw is increased. SOLUTION: A hydraulic motor 9 for lifting and lowering an auger rotation driving apparatus 6 has a lift-up-side circuit 9a, which is connected to a bypass circuit 21 which in turn is connected to a tank 11. The bypass circuit 21 has a switch valve 22 and a variable flow rate control valve 23 arranged thereacross.