Automatically Controlled All-Wheel Drive (4MATIC), Function - GF28.00-P-0001AVM

Model 217, 222 with transmission 725.096 

Courtesy of MERCEDES-BENZ USA

Block diagram 

Automatically-controlled All-wheel drive (4MATIC) in general 

The automatically-controlled all-wheel drive (4MATIC) is a permanent all-wheel drive with variable drive torque distribution and an interaxle differential.

The separate transfer case is fitted to the transmission housing. Due to the design, there is the advantage that there is no reciprocal damage due to contamination (e.g. due to metal abrasion) through the separate oil circuits (of the automatic transmission and of the transfer case).

The lubrication is designed as splash lubrication. A transmission oil heat exchanger is fitted on the transfer case to cool the transmission oil. The pre-lock torque of 40 to 50 Nm serves to improve traction at low engine torque while also helping to avoid any vibrations in the drivetrain. The drive torque distribution is adapted variably to the ground and driving situation. The electric power steering control unit transmits the steering wheel angle to the all-wheel drive control unit via the suspension FlexRay. If, during comparison with the signals of the Electronic Stability Program control unit, understeer or oversteer is detected, the all-wheel drive control unit regulates the drive torque distribution via the integrated all-wheel drive actuator and the multidisk clutch. The drive torque is distributed via a single-speed transfer case without off-road ratio to the drive axles (drive train).

View of multidisk clutch actuation 

Courtesy of MERCEDES-BENZ USA

Further subfunctions are described in separate documents: 

• 4MATIC transfer case, function 
• Front axle transmission output 4MATIC function 
• 4MATIC front axle transmission, function 
• Oil supply for 4MATIC transfer case function 
• Transfer case oil cooling system, function 
• 4MATIC electronic traction system, function