4Matic

4Matic is the name of a four-wheel drive system developed and used by Mercedes-Benz. It is good for driving through slippery terrain.

Almost all their vehicles featuring this system also have an automatic transmission in standard equipment (except naturally aspirated 300 D was also with manual transmission) and that's where its name is derived from (4-wheel drive and automatic). The first design of 4Matic (or 4MATIC) system was introduced in 1986 on the W124 series (E Class) saloons (four door) and estate (station wagon) cars. It was available with the 2.6 L and 3.0 L 6 cylinder petrol (gasoline) and diesel engines.

A complex electronically controlled system with automatically engaging four-wheel drive (4WD), the system employs locking central and rear differentials to provide additional traction in slippery conditions. The centre differential, also known as the transfer case, contains two clutches. Each hydraulically enabled clutch is controlled separately to allow for three modes of operation; 2WD (100% of available torque is available to the rear axle, while the front axle is disconnected) and two 4WD modes which allowed for 35% front / 65% rear axle torque split or 50% front axle / 50% rear axle torque split. The rear differential, previously known as ASD on Mercedes-Benz models, can also be locked if rear wheel slip is still present while in the 50%/50% 4WD mode. The 4MATIC system uses inputs from the three channel ABS system and a steering wheel angle sensor to decide when to intervene. 4WD is disengaged automatically if the ABS brakes were applied. Two W124 variants of the 4MATIC system were produced, the first system (1986-1991) used a mechanical pressure lever to disable the system hydraulically while the second system variant (1992/1993) used an electrical switch to break power to the system. Plagued with reliability problems at first, the multiplate clutch central differential were prone to failure -- Ritter, S: Mercedes-Benz E class Owners Bible Problems Section page 314 Bentley Publishers 2007 ; it was withdrawn in 1993.

The four wheel drive system was developed in conjunction with Steyr-Daimler-Puch, who manufactured the Mercedes-Benz G-Class in Austria. The second generation of 4Matic was re-introduced on the W210 series in 1998/1999. Available only in left hand drive the cars were again manufactured at the Magna-Steyr plant in Austria. The second generation of 4MATIC used a full time 4 wheel drive system with three open differentials front, centre and rear. Traction control is achieved using ETS (Electronic Traction System). This employs the ABS system with additional valves to monitor and then partially brake any wheel which loses traction. This much simpler system is also used in the Mercedes-Benz M-Class SUV.

The 4MATIC system is currently available on the E-Class, C-Class, R-Class, S-Class, Viano and the entire Mercedes-Benz SUV range.

References

• Comprehensive history of Mercedes traction control and four wheel drive systems

• The MERCEDES-BENZ E CLASS OWNERS BIBLE 1986-1995 Bentley Publishers 2007 ISBN 0-8376-0230-0

See also

• W124 Mercedes-Benz E Class (1985-1995)
• Quattro is a similar system from Audi.
• Locking differential provides additional information on differentials.