| 摘要 |
A tilt cylinder device has an exterior oil passage 61 outside a cylinder 51 for bringing oil chambers S6 and S7 into communication with each other, the exterior passage 61 is provided with a pump 72 and a control valve 73. A piston 13 is formed with a communication passage 34 for bringing oil chambers S6 and S7 into communication with each other. The communication passage 34 is provided with a first relief valve 15 which opens when a pressure in the rod side oil chamber S6 exceeds a set pressure. A hollow piston rod 14 is provided therein with a delay mechanism 16 for delaying the closing operation of the first relief valve 15 by pushing a valve body 15b of the first relief valve 15 in its valve opening direction for a predetermined time period after the relief valve 15 is opened.
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