| 摘要 |
PROBLEM TO BE SOLVED: To smoothly slide a sliding shaft or the like while sealing stably with simple constitution and to optionally set sealing pressure to obtain optimum sliding resistance without causing torsion and wear. SOLUTION: In this seal structure, a shaft 15 is loosely fitted in a hole 13 of a casing 1 of a rotary joint or the like, and an O-ring is mounted into a groove 5 circumferentially provided at either one of the hole 13 and shaft 15, to seal a shaft support part slidably. The groove 5 is formed of side walls 5b coming in slidable contact with both side faces of the O-ring 6 to hold the O-ring 6 so as to be diametrically enlargeable and contractible. A fluid pressure supply path 7 is opened to a groove bottom 5a, and a clearance 8 dimensioned to allow the O-ring 6 to be enlarged or contracted in diameter to seal in contact with a sliding face opposed to the groove 5 is provided between the sliding face and the inner diameter face or outer diameter face of the O-ring 6.
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