| 摘要 |
PURPOSE:To perform a continuously variable speed change automatically, by making a weight separate from the turning shaft center along a cam surface by dint of the centrifugal force according to the speed-up of a driving pulley and so as to pull a movable pulley nearer to the fixed pulley side. CONSTITUTION:When the revolving speed of a crankshaft 3 comes higher, centrifugal force working on a weight roller 32 grows large, whereby this weight roller 32 is moved in direction of separating from a turning shaft 5 along a cam surface 16 of a cam body 15, and a movable pulley 11 and a pulley cover 20 are approached to the side of a fixed pulley 6 against a compression coil spring 25, narrowing its interval with this fixed pulley 6, and the winding radius of a V belt 2 to a driving pulley 1 is increased to some extent, a transmission gear ratio is reduced in stepless, thus automatic gear shifting takes place. In this structure, mounting/demounting of a holding piece 34 for pressing a base of a weight arm 30 will not be hindered by a cylindrical edge of the movable pulley 11, so that assembling and disassembling operations are easily performed. In this connection, the cam body 15 is formed separately from the movable pulley 11 so that it is interrupted from heating even if the weight roller 32 is made of resin.
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