Transfer Case 4
Some manufacturers of somewhat larger and stronger vehicles stay at the concept of the rear-wheel drive especially for a better driving dynamic. Manufacturers of heavy front wheel drive sedans don't want to follow
this argumentation. It is interesting that both groups hold to their concept developing a four-wheel drive. Also the here described, completely variable distribution of the driving powers to front/rear axle is build according
to this work philosophy. The four-wheel drive developed from a rear-wheel drive thus will have always more torque at the rear axle, except if it completely slips through.
How it works
Let us assume in the picture the engine would be inserted at the top on the right side. There are two more connection shafts possibeble, one at the top to the left side to the rear axle and one at the bottom to the right
side to the front axle. Right above beside the chain drive a planetary transmission leads 38% of the drive torque to the rear and 62% to the front axle, if all wheels have a good concact to the ground. This distribution is
fixed by relation of the diameters of sun and planet wheels inside the planetary gearbox.
Left of the chain drive a multiple disk clutch makes the distribution variable being in very short timeframes more or less
engaged by oil pressures or a strong electric motor. Eg. in curves it is possible to change the distribution in order to avoid a critical situation. The system places an addition of the
Electronic Stability Program. It works earlier and so gently that the average driver does not realize it.
For particularly torque-strong engines in the highest gear the clutch with revving up rear axle is also opened,
in order to hold the load of the front axle within limits.