| 摘要 |
PURPOSE:To increase an elevating amount of a running device, by a method wherein a carrier roller, supporting in contact with the return route side of a crawler belt is mounted in an intermediate position between two coupling points of a slewing arm with a stationary and a moving frame. CONSTITUTION:A carrier roller 1, supporting the return route side of a crawler belt 13, is set in an intermediate position between two coupling points 15a and 15b of a slewing arm 17B with a stationary frame 6 and a moving frame 8. A slewing radius l1 of the carrier roller can be decreased over a slewing radius l of the slewing arm 17B, and an elevating amount of the carrier roller 1 can be decreased over that of the moving frame 8. Thus, where an elevating amount of the carrier roller 1 is set to L0 in a range where a change in the extension length of the crawler belt 13 is suppressed and contact with the stationary frame 6 can be prevented from occurring, an elevating amount L of a running device 4 can be set to a value higher than the elevating amount L0.
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