| 摘要 |
PROBLEM TO BE SOLVED: To securely prevent breakage of a driving force transmitting device and a drive system by preventing change into a four-wheel drive condition when front wheels are stuck to idle to a great extent. SOLUTION: A driving force transmitting device changeable from a two-wheel drive condition into a four-wheel drive condition is provided. A first change-over means 26 changeable between the two-wheel drive condition and the four-wheel drive condition, a second change-over means 28 changeable between an auto mode and a hard mode in the four-wheel drive condition, a front/rear wheel car speed detecting means 30, an accelerator opening detecting means 32, and an engine rotation speed detecting means 34 are provided. A comparing means to compare between input rotation speed to the driving force transmitting device determined based on output of the front/rear wheel car speed detecting means, the accelerator opening detecting means, and the engine rotation speed detecting means, and a control means to select the four-wheel drive condition by the first change-over means, and make changing control to the auto-mode when difference between the input rotation speed and the output rotation speed by the comparing means is smaller than a set value are provided.
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