Automatic Connecting Rear-Wheel Drive

The above figure shows the gearbox (on the right) and the final drive for the four-wheel drive (on the left), this originates from a front-wheel drive with a transverse mounted engine. The flange on the left, to the right axle drive shaft, can be clearly recognised. At the rear, and at a right angle, the cardan shaft is flanged on. On the opposite side (hidden), it leads - seen in the direction of travel - to the left axle drive shaft.
Apart from the differential unit with the two flanges for the drive shafts, the final drive also contains a crown and pinion drive with the flange to the cardan drive at the rear. The gear ratio of 20 to 21 teeth in the front is compensated in the final drive at the rear, by a ratio of 21 to 20. A ratio of 1:1 is avoided, so that the teeth of the cog do not always mesh at the same place. Before the rear final drive, there is also a viscous clutch or a hydraulically operated multi-disc clutch mounted. 05/10