| 摘要 |
PROBLEM TO BE SOLVED: To provide a device to automatically position a sheave in a central position. SOLUTION: This device is formed such that when a sheave 19 is fed between a pair of frame bars 31 and 32, shafts 40 and 41 are rotated by a motor 51, a pair of center blocks 53 and 54 are caused to approach each other together with a pair of frame bars 31 and 32 through ball right-handed screws 42 and 43 and ball left-handed screws 44 and 45, and a shieve 19 is moved to a central position by one set of rollers 59 and 60 and 65 and 66 of a pair of the center blocks 53 and 54, respectively.
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