| 摘要 |
PURPOSE:To reduce wear of a speed change gear at the region of its transmission ratio, by employing such as an arrangement that power is not transmitted by a stepless transmission during the while when power is being transmitted by a step transmission and the step transmission is operated at a transmission ratio near or outside of the end of the stepless speed changing range. CONSTITUTION:A speed change mechanism of this invention consists of a stepless transmission 12, a step transmission the transmission ratio of which is fixed at a value near and/or outside of the end of the change-speed range of the stepless transmission 12, and a selector mechanism for operating either of the avove two transmissions selectively. During the while when power is being transmitted at stages 14, 16 of the step transmission, the stepless transmission 12 is made not to transmit power. Therefore, the transmission ratio at the time is near or outside of the end of the stepless speed changing range. By employing such an arrangement, durability at the region of the transmission ratio where wear is caused most can be increased as compared with the case in which speed is changed only by use of the stepless transmission 12. Further, the range of transmission ratio is also increased since the fixed-step change- speed range is added to the stepless change-speed range. |
