| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To save the execution of works. <P>SOLUTION: When the first tread supporting member 25 and the second tread supporting member 29 are combined by oppositely facing a fitting groove 27 and the fitting groove 31, fitting the second tread supporting member 29 into the fitting groove 27 and fitting the first tread supporting member 25 into the fitting groove 31, the tread placing surface 25b of the first tread supporting member 25 and the tread placing surface 29a of the second tread supporting member 29 are made flush with each other. <P>COPYRIGHT: (C)2003,JPO</p> |
