| 摘要 |
PROBLEM TO BE SOLVED: To prevent a rope from being loosened automatically at the time of lowering a pile in piling work. SOLUTION: This consists of an induction motor 105 which winds and lowers a rope for hanging a pile, an operating lever 11a, a controller 11 which sets a rotational speed command NREF1 according to the operation of the operating lever 11a, a rotational speed command circuit 12 which determines the rotational speed command at the time of lowering the induction motor 105 as necessary, according to a load torque TFB in lifting the pile and outputs the rotational speed command NREF2 to restrict the rotational speed command NREF1 and an inverter 6 which controls the rotational speed of the induction motor 105 based on the rotational speed command NREF2 . |
