7.8. Matic (the all-wheel drive version) (only on certain models with the petrol engine)

The previous generation of the E-class had an all-wheel drive version also. For new model engineers of Mercedes could present modern development which was offered in combination with the V6 engines which appeared in March, 1997 and five-step AKP with electronic control. Simplification of a design was a main goal of development.

Fig. 6.24. Scheme of transmission of model 4Matic: 1 – the driveshaft (to differential of the back bridge); 2 – transfer case; 3 – a reducer with the cylindrical tooth gearing for the forward bridge; 4 – the driveshaft (to differential of the forward bridge); 5 – differential of the forward bridge; 6 – shaft of the drive of a forward wheel

The four-wheel drive in the new version 4Matic is carried out via constantly connected one-stage transfer case 2 (fig. 6.24) only mechanically with constant distribution of torque in the ratio: 65% – on the back bridge and 35% – on forward.
Function of alignment of torque between bridges is performed by the central differential with the double planetary mechanism. The drive on forward wheels is carried out by a reducer with the cylindrical tooth gearing and the improved antinoise characteristics which also works as the oil pump and provides the lubrication system of the transfer case.
Function of blocking of differential is performed by the electronic ETS traction control system which regulates torque size on separate wheels, reducing it braking and at the same time increasing traction effort on other wheels.
The electronic system of stabilization of stability of ESP which proved on other models of the Mercedes cars which on models 4Matic controls all four wheels when sensors fix a critical situation of coupling of a wheel with the road — for example, in turns or when overtakings on a slippery covering is added to it.
Besides, the so-called Brake-Assist (BAS) system which since 1997 serially is established on all model ranges of the Mercedes cars also is integrated into this complex control system. Here it is about management in situations of emergency brake application. Sharp braking in a critical case is estimated by the electronic device on the speed of pressing a pedal. From this point the management with ensuring the most effective braking of the electronic engineer undertakes until the driver does not begin to control effort to pedals (see also section "Brake system").
Diagnostics and elimination of malfunctions of the ETS, ESP and BAS systems anyway are destiny of experts. Even in usual replacement of oil in the transfer case and differential of the forward bridge there is no need now. In both units working liquid with a life sentence of service is used.