| 摘要 |
PROBLEM TO BE SOLVED: To provide a swing cylinder control device and a control method capable of reducing rigidity required for a working device and alleviating a load, in a turning working machine in which the working device is made to be swingable by the swing cylinder. SOLUTION: The swing cylinder control device of the turning working machine is mounted to a relief valve (100) for setting the relief pressure (Ps) of a rod-side pressure chamber (34a) and a bottom-side pressure chamber (34b) of the swing cylinder (34), respectively. The swing cylinder control device comprises a control pressure chamber (104) capable of receiving the control pressure in a direction against an urging force of a relief spring (102), and solenoid proportional pressure-reducing valves (114a, 114b) generating the control pressure based on an operation signal of a turning operation lever (46m) using a supply pilot pressure from a pilot pressure pump (58) as initial pressure, and supplying the control pressure to the control pressure chamber (104) of the targeted relief valve (100). COPYRIGHT: (C)2008,JPO&INPIT
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