| 摘要 |
PURPOSE:To make a center differential lock action into automation as well as to improve operatability in a differential lock with a simple control system, by operating a solenoid valve by means of an electrical signal for slip detection, while constituting it to feed or drain oil to or from a hydraulic clutch. CONSTITUTION:At the time of normal driving, with an off signal out of a control unit 50, a solenoid valve is made into nonconductivity, releasing a hydraulic clutch 31 by drain oil. So, an element of a center differential gear 20 is set free and power out of an automatic transmission 4 is transmitted to front wheels via a front differential gear 14 and also to rear wheels via a rear differential gear 30, respectively. And, if steering takes place in this driving state, both front and rear wheels are rotated while producting a rotational difference there due to differential action of the center differential gear 20. On the other hand, when either of these front and rear wheels gets slipped, the control unit 50 judges it and outputs an on-signal to each rotational difference signal of both sensors 46 and 47. Accordingly, the solenoid valve 40 operates, feeding the hydraulic clutch 31 with oil pressure, and engagement takes place. Therefore, a differential case 21 and a side gear 24 are coupled together so that differential locking is automatically carried out.
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