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

Model 253 with transmission 725.096 

Sectional view of transfer case 

Courtesy of MERCEDES-BENZ USA

4MATIC transfer case, general 

The separate transfer case is bolted onto the housing of the automatic transmission. It has a separate oil circuit (transfer case disconnected from automatic transmission). The lubrication is designed as splash lubrication. To cool the transmission oil and for faster heating of the warm-up phase, a transmission oil heat exchanger (plate heat exchanger) is mounted on the transfer case. What makes the transfer case so special is its single-speed front axle transmission output with integrated universal joint (3). Thanks to the single-speed design, a spur gear set with bearing mount is not required. This acts positively on efficiency, weight and the noise characteristics of the drive train. A multiplate clutch (5) is also integrated into the transfer case that is controlled through the all-wheel drive control unit (N45) and operated through the integrated all-wheel drive actuator (N45/1). Depending on requirements, the multiplate clutch (5) distributes the drive torque from 0 up to 50 % to the front axle transmission output.

In the event of any defects, certain components such as, for example the rear axle output flange, radial shaft sealing rings, plate heat exchanger, all-wheel drive control unit (N45) with all-wheel drive actuator (N45/1) and transmission oil temperature sensor (B91) are available as replacement parts. In the event of other defects, the entire transfer case must be replaced.