| 摘要 |
PURPOSE:To improve the durability of an endless chain decreased in its curvature change by interposing the first and second intermediate pulleys between input and output shafts and performing a two-shift speed change by the first and second endless chains. CONSTITUTION:Integrally forming the first and second intermediate pulleys 20, 21 to be interposed between an input side pulley 12 and an output side pulley 13 and mounting the first endless chain 22 to be wound between the input side pulley 12 and the first intermediate pulley 20 while the second endless chain 23 to be wound between the output side pulley 13 and the second intermediate pulley 21, a speed change ratio changing share is decreased respectively as the two-shift speed change, that is, a curvature change of each endless chain 22, 23 for each pulley 12, 13, 20, 21 is decreased. Accordingly, the endless chains 22, 23 increase their curve larger, enabling the thickness to be increased. While in the time of high speed, directly connecting an input shaft 2 to an output shaft 38 by a top gear 48 and decreasing a pressure of oil in a pulley type cylinder 27 by an automatic control part 29, both the endless chains 22, 23 are placed in a racing condition. In this way, durability of the endless chain can be improved.
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