| 摘要 |
PURPOSE:To enable a lost-motion to be functioned by a method wherein a pressure sensitive change-over valve for performing a change-over of passage by sensing hydraulic oil supplied from the pump unit is arranged at the supplying passage of the hydraulic cylinder. CONSTITUTION:The feeding passages 20 and 21 for supplying fluid pressure to both chambers 18 and 19 of the hydraulic cylinder 17 are provided with a change-over valve 30 which is changed over by a pilot pressure from the pilot valve 35. Both chambers 18 and 19 of the hydraulic cylinder 17 are normally connected and the piston 15a is held in such a way as it may be floated and then the hydraulic pressure can selectively be supplied to both chambers 18 and 19 of the hydraulic cylinder 17 when the change-over valve 30 is to be changed over. Therefore, irrespective of a simple and inexpensive structure, it is possible to provide a lost-motion function of which operation is simple and highly reliable.
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