4Matic Transfer Case, Function - GF28.10-P-1000AVK

Transmission 725 (except 725.096) in model 213 up to model year 2021 with code M005 (Vehicles with 4MATIC/all-wheel drive) 

Transfer case, general 

The transfer case is mounted onto the housing of the automatic transmission. The lubrication system for the transfer case is designed as a splash lubrication system without any external cooling. The design of the transfer case has the following advantages:

• Automatic transmission and transfer case can be replaced or repaired separately.
• In case of repair, certain components of the transfer case can be replaced.
• The separate oil circuit means that there is no reciprocal impairment (automatic transmission and transfer case) due to fouling (e.g. by metal abrasion).

Sectional view of transfer case 

Courtesy of MERCEDES-BENZ USA

The planetary gear set acts as a planetary gear differential (3) between the front and rear axle. This then distributes the engine torque. The pre-lock torque of 40 to 50 Nm improves traction at low engine torque and minimizes vibrations in the drivetrain. The drive torque distribution is 45 % at the front axle and 55 % at the rear axle on all vehicles and is implemented via a double planetary gear set.

The transfer case is a single-speed design without off-road ratio. A universal joint is integrated into the front axle transmission output. The single-speed version means that a spur gear set including mounting is no longer required. This acts positively on the efficiency, weight and noise characteristics for the drive train.