| 摘要 |
PURPOSE:To prevent belt skipping from occurring by always keeping distance between a pulley on a driving side i.e., motor side and the one on a driven side i.e., rotary brush side constant. CONSTITUTION:The rotary brush 3 is driven by a motor 2 via a timing belt 9, and the pulley 7 around which the timing belt 9 is stretched in the rotary brush 3 is provided at a part other than both-end parts where the rotary brush 3 is pivotally supported. Ball bearings 13, 12 are provided near by the driving shaft and the pulleys 7, 8 around which the belt 9 of the brush is stretched, respectively, and a rigid member 14 coming into contact with the outer wheel of each bearing is provided on the lower case 1 of this suction port body along a straight line connecting those bearings.
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