| 摘要 |
PROBLEM TO BE SOLVED: To enable a crawler to be rotated desirably by preventing a truck link of the crawler from being fitted with an entire circumferential groove part formed on a rolling element of an upper roller. SOLUTION: The rolling element 28 of the upper roller 26 is provided with left and right expansion diameter collars 28B dividing between left and right rolling face parts 28A, and between the left and right expansion diameter collars 28B, the entire circumferential groove part 28C is provided by reducing its diameter. Here, the entire circumferential groove part 28C sets a width W3 of an outer diameter side at or below a width W1 of an inner circumferential side of each truck link. Accordingly, even when the crawler 18 catches a foreign substance and is displaced to the left or right and the truck link 20 is fitted in the entire circumferential groove part 28C, the narrow entire circumferential groove part 28C receives the truck link 20, whereby the truck link 20 can be prevented from being fitting deeply. COPYRIGHT: (C)2010,JPO&INPIT
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