| 摘要 |
PROBLEM TO BE SOLVED: To protect a pin seal to seal sliding end surfaces facing against each other between two members connected to each other by a pin from being abraded and broken by storing the pin seal in a ring groove of a cross-section roughly V shape formed on the inner side than an outside diameter of a bearing part at a position on the inner side than the bearing part. SOLUTION: An O ring type pin seal 5 is provided to seal between sliding end surface 14 and 13 of a boss 14 of a bracket 10 and a boss 3 of an arm head end from outside. An outside diameter of the boss 3 is set larger than a outside diameter of the boss 4, and a cross-section roughly V shaped circular groove 17 is formed on the siding end surface 13 of the boss 3. A circle drawn by a groove bottom part of the circular groove 17 is made to roughly coincide with the outside diameter of the boss 4. A tapered surface 18 is formed on a shoulder part of the sliding end surface 14 of the boss 4, and a cross-section roughly V shaped ring groove 19 is formed of a tapered surface 18 and an inside tapered surface 17a of the circular groove 17. As an outside tapered surface 17b of the circular groove 17 is shaped to cover this ring groove 19 over, the pin seal 5 is never pressed on sediment, and it is possible to avoid abrasion and breakage of the pin seal 5 due to sediment. |
