| 摘要 |
PROBLEM TO BE SOLVED: To provide a chain block installing an overload preventive mechanism which can use parts of a chain block installing no overload preventive mechanism commonly and more often, and can realize the simplification of the manufacturing process, and can reduce the cost. SOLUTION: To an overload preventive mechanism 8, a first hub 13 screwed to a driving shaft 6, and to support a hand wheel rotatable is provided, and a first recess part 32 is formed to the small diameter tube part 31 of the first hub 13. In the recess part 32, a lock nut 34 is fixed immovable in the axial direction to the driving shaft 6. Consequently, the driving shaft 6 practically same as a driving shaft 6 used to a chain block with the same specification installing no overload preventive mechanism 8 can be used.
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