| 摘要 |
A safety control mechanism for a load line forming part of an extensible boom crane which has a plurality of sections moved relative to each other by power means. The cable supports a load supporting member on one of the crane sections and is reeled or unreeled from a driven drum supported adjacent another of the sections. The safety control means incorporates mechanism which will render the power means inoperative when the tension on the cable reaches a certain level. The safety control means consists of a bracket pivotally supporting the drum and pivoted about an axis. The bracket is normally biased to a first position, with the biasing means accommodating movement from the first position after the tensile load exceeds a lower level to actuate control means, forming part of the power means, to render the power means inoperative when the tensile load on the cable exceeds a desired maximum level.
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