| 摘要 |
PURPOSE:To achieve stable high speed running without causing braking phenomena when turning by finding the point where the loci of the front and rear wheels will match under turning when running with higher speed than predetermined level and by automatically making changeover to 4 wheel drive in this condition. CONSTITUTION:An oil pump 26 is communicated through an oil path 28 having a changeover valve 27 to the clutch 22. The valve 27 is constructed to move a spool 34 through power supply to a solenoid 32 and the function of a return spring 33. The solenoid 32 is connected through a manual changeover switch 40, a 4 wheel drive pilot lamp 41 and an injection switch 42 to a battery 43 while a switching circuit 45 to be switched on/off through a signal from a car speed sensor 44 is connected in parallel with the switch 40. Changeover speed 0.5-0.8 times of the critical speed Vc at which the loci of the front and rear wheels will match is set for the switching circuit which is turned on upon reaching to said car speed.
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