| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent the runoff of grease from a pivot bearing portion. <P>SOLUTION: A vent hole 18 is provided at the pivot bearing portion 11a of a boom attachment, and the vent hole 18 functions to provide communication between a grease sealing chamber 14 and outside. When the inner pressure inside the grease sealing chamber 14 increases, pressured air escapes from the vent hole 18 to the outside, so that the inner pressure of the grease sealing chamber 14 does not increase abnormally high, and thus the runoff of grease 19 in the grease sealing chamber 14 from the seal portion 16 to the outside can be prevented. <P>COPYRIGHT: (C)2003,JPO</p> |
