| 摘要 |
PURPOSE:To carry out speed change to a high speed side and avoid a speed change shock at the time of failure while traveling at a high speed by making a first control valve for controlling a driving side pulley generate the maximum oil pressure while a second control valve of controlling a driven side pulley generate the minimum oil pressure at the time of the OFF of an input signal. CONSTITUTION:When an engine speed Nin is less than a cranking rotating speed, an electronic control device 60 sends a signal of zero duty ratio to a speed change control valve 43 and a load thrust control valve 45, and feeds the maximum oil pressure to the speed change ratio controlling oil chamber 16 of a driving side pulley 12 while feeding the minimum oil pressure to the load thrust controlling oil chamber 17 of a driven side pulley 14, to improve a starting property as the maximum speed change ratio. Then, as traveling is started by turning on a starting control valve 47, both control valves 43, 45 are controlled at a defined duty ratio in accordance with the traveling condition to obtain a desired speed change ratio. In this case, if the solenoids 44, 46 of the control valves 43, 45 or the signal system thereof fail and are turned off while traveling at a high speed, speed change is always carried out to a high speed ratio side. Thereby, a speed change shock can be avoided.
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