| 摘要 |
PROBLEM TO BE SOLVED: To store a hook block at a position closer to a lower face of an expansion boom by forming a recessed part corresponding to the shape of a lower projection of the lower face of the expansion boom or the space where a wire rope for loading is stretched along the expansion boom, on a face opposite to the lower face of the expansion boom, of the hook block. SOLUTION: A face opposite to a lower face of an expansion boom 2, that is, an upper side plate 15a to be kept into contact with the lower face of the expansion boom 2 in a storage state, comprises a recessed part 19b corresponding to the shape of a downward projecting part (b) of the lower face of the expansion boom 2. Further a recessed part 19c corresponding to the shape of the stretching space (c) of a wire rope 3 for loading, is formed. Whereby the interference of the hook block 1 with the lower projecting part (b) of the lower face of the expansion boom 2 and the wire rope 3 for loading can be prevented when the hook block 1 is stored along the lower face of the expansion boom 2. As a result, the hook block 1 can be stored at a position closer (δs) to the lower face of the expansion boom 2.
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