| 摘要 |
PURPOSE:To permit the certain advance and retreat of a car by setting the low-speed retreat stage when the road slope or the car load weight is over a prescribed value or by setting the high-speed retreat stage in other cases, in an automatic transmission having the high/low speed retreat stages. CONSTITUTION:An automatic transmission selectively obtains the low-speed retreat stage and the high-speed retreat stage by switching a sub-gear transmission between the direct connection stage and the speed increasing stage under the retreat stage state of a main gear transmission. When a shift position sensor 8 detects the selection to the R range in shift range, an electronic controller 80 judges if the road slope alpha detected by a slope sensor 84 is larger than a prescribed shift-down value or not, and a load weight sensor 85 judges if a car load weight W is larger than the prescribed shift-down value or not. A frictional engagement means for speed change is controlled so as to set the low-speed retreat stage when the road slope or the load weight is over a prescribed value, or further to set the high-speed retreat stage in other cases.
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