| 摘要 |
PURPOSE:To maintain a high engine speed and increase a braking effect by providing a speed change limit zone on the min. change gear ratio side of a speed change control pattern in continuous variation when a vehicle is traveling on the downward grade of a road surface. CONSTITUTION:A continuously variable transmission 10 the driving shaft 11 of which is connected to the crankshaft 2 of an engine 1 is formed by winding a V-belt 15 around the driving side pulley 12 of the driving shaft 11 and the driven side pulley 14 of a driven shaft 13. The continuously variable transmission 10 is controlled by an electronic control device 60 via each speed change control valve 43, load thrust control valve 45, and starting control valve 47. In such a structure, the electronic control device 60 detects the grade of a road surface from the inclination of a vehicle. When the detected grade of the road surface is a downward grade, a speed change limit zone is provided on the min. change gear ratio side of a speed change pattern in accordance with the degree of the downward grade.
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