| 摘要 |
PURPOSE:To enable belt tension to be adjusted, by rotatably supporting a pulley shaft, which has an intermediate gear in one end and a driving pulley in the other end, in parallel with a main spindle and providing a transmission belt between a driven pulley and the driving pulley. CONSTITUTION:A main spindle 20 is driven rotating in low and intermediate speeds by a rotary driving device 15 through a driving gear 31, slide gears 32, 33 and driven gears 34, 35 by moving the slide gears 32, 33 to be meshed with any one of the driven gears 34, 35 provided in the main spindle 20. If the slide gear 33 is moved and meshed with an intermediate gear 36 of a pulley shaft 41, the main spindle 20 is driven rotating in a high speed by the rotary driving device 15 through the driving gear 31, slide gear 33, pulley shaft 41, driving pulley 43, transmission belt 44 and a driven pulley 42. Accordingly, gear transmission is switched to belt transmission only by a shift control of the slide gear 33.
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