Front Differential

Front Differential Construction
The differential assembly using a hypoid bevel pinion and gear is installed to the front axle. 4WD control system controls drive force to be transmitted to front axles or not. The reduction ratio is different respectively among several kinds of engineers or transmissions.
The differential assembly is decisive in that the drive power is concentrated there. Therefore, use of genuine parts and specified torque is compulsory. Further, because of sliding tooth meshing with high pressure between bevel pinion and gear, it is mandatory to lubricate them by hypoid gear oil.

4WD Control System Description
When the 4WD switch is turned ON by shifting the transfer shift lever, ECM (PCM) actuates (energizes) the air pump assembly. Then positive pressure is sent from the air pump assembly to the actuator installed to the differential case and causes the axle lock clutch and the free axle hub in the differential case to be engaged, resulting in the 4WD mode.
Only when running in the 4WD mode, front axles are joined to differential case, and they become free when 2WD mode is used (or when transfer shift lever is shifted to N position) thereby reducing the power loss.





4WD Control System Locator





4WD Control System Circuit and Operation





4WD Control System Components and Functions