| 摘要 |
<p>PURPOSE:To shift an engine to a four-wheel-drive state with high response, by a method wherein, if, when a steering angle is high and an engine is brought into a two-wheel-drive state, a difference in a rotation speed is produced between front and rear wheel stems, the delivery pressure of a main pump is increased by means of oil delivered from a differential pump. CONSTITUTION:When a steering angle is low, the throttle area of an electromagnetic throttle valve 21 is decreased. Thus, since an oil pressure fed to an oil chamber 15 of a hydraulic clutch 12 is increased and a clutch plate 13 is pressed by a piston 14, drive axles 10 and 11 of front and rear wheels, respectively, are intercoupled to bring an engine into a two-wheel-drive state. Under a two- wheel drive state that a steering angle is high, the drive axles 10 and 11 of the front and rear wheels, respectively, are separated from each other by the reverse action to the above, and the engine is brought into a two-wheel drive state. Under a two-wheel drive state that a steering angle is high, since, when the number of differential revolutions exceeds a given value, a throttle part 26 of a control valve 25 is reduced with the aid of a differential pump 17, the oil pressure of a hydraulic clutch 12 is increased with the aid of a main pump 16, and the engine is set to a 4-wheel drive state.</p> |
