| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to retain freely and securely the opening of an extending blade by using a hydraulic cylinder without springs as a widening/contraction means of the extending blade, driving the cylinder by a liquid passage of one unit longitudinally passing the cylinder in the working rod, thereby simplifying the additional joint of working rod, miniaturizing it. SOLUTION: A sensor detecting the pressure of a fluid fed to a hydraulic cylinder and the detecting variation pressure are used as signals in the head rod, and the head is provided with an electromagnetic valve changing over a fluid passage to the hydraulic cylinder and a discharge passage and a battery for driving these as a feature. The head is connected to a hydraulic pump arranged in the outside and a fluid circuit including at least a change over valve opening/closing the fluid passage. A flow meter measuring a flow volume into the hydraulic cylinder is provided in the fluid passage and by the flow volume, the opening of the extending blade can be freely and securely retained. COPYRIGHT: (C)2006,JPO&NCIPI
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