| 摘要 |
<p>PURPOSE:To prolong the life of a packing by sending cleaning water forcedly into a water-reservoir part on the outer periphery of a piston. CONSTITUTION:When a piston 11 is retreated in a B-direction, the cleaning water in a backside chamber 15 of a piston 11 is pressurized, and consequently, the cleaning water 14 is forcedly sent into a water-reservoir part 22 via connecting holes 24a and b. On the contrary, when the piston 11 advances in a C-direction, a negative pressure is generated in the backside chamber 15 of the piston 11, and the cleaning water 14 in the water-reservoir part 22 is sent to the backside chamber 15. Therefore, the cleaning water 14 is circulated to the backside chamber 15 and the water-reservoir part 22 via connecting holes 24a and b, and by this circulating work, the peripheral face 16 of a piston main body 18 is cleaned.</p> |
