| 摘要 |
PROBLEM TO BE SOLVED: To provide an over-hoisting preventive device free of generation of failure using a simple facility as improvement of a conventional over-hoisting preventing means involving such problems as easily broken, requiring a mounting space, and complicated in the mechanism. SOLUTION: The over-hoisting preventive device applies to a hoist traction machine equipped with a load sheave 2, a chain 3 wound round the sheave 2 and having a hook 7a at the end, and an over-hoisting prevention sensor 6 for the chain, wherein the arrangement consists of a magnetic sensor 6 installed on the body of the hoist traction machine and magnetizing means 4a and 4b which are installed on the hook side and no-load side of the chain 3 and whose lines of magnetic force are directed vertically. COPYRIGHT: (C)2004,JPO
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