| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a telescope part/jib having optimized weight and strength. SOLUTION: At least one part of a jib of a crane, for example, of movable type, has a composite cross-section including a steel layer 11 covered with one or more fiber composite layers 12. One favorable embodiment includes a plurality of fiber composite layers 12 and 13, which are arranged so that they intersect one another so as to heighten the overall strength of a telescope part. According to one favorable embodiment, the steel layer 11 of composite material is provided on the inner surface of the telescope part in order to minimize the thermal stress due to a temp. change generated by solar beams. In another embodiment, the composite fiber layer is arranged only on the cross-section range of the telescope part and subjected to a tensile force during service.</p> |
