Basic Function Of Automatically Controlled All-Wheel Drive - GF28.00-P-9900A

Model All (4xWD) 

Model All (CAR) 

Overview 

This document contains information on:

• General
• Function
  • Vehicles with transversely mounted engine and dual-clutch transmission 
  • Vehicles with longitudinally mounted engine and automatic transmission 

General 

Contrary to front wheel drive or rear wheel drive, the drive force is forwarded to all wheels in all-wheel drive. Traction increases and improved off-road capability is achieved.

For automatic controlled all-wheel drive, there is a distinction between the following equipment variants:

• Vehicles with transversely mounted engine and dual-clutch transmission
• Vehicles with longitudinally mounted engine and automatic transmission

Function 

Vehicles with transversely mounted engine and dual-clutch transmission 

The power take-off distributes the torque to the rear axle and is integrated into the dual-clutch transmission. The torque is output to the rear axle variably depending on the driving situation and the wheel slip of the front wheels. The power take-off compensates differences in rpm between the front and rear wheels which occur in all-wheel mode while cornering.

Depending on the following situations, torque is distributed to the rear axle:

• Dynamic cornering
• Wide open throttle acceleration
• Extremely varying road surfaces

Vehicles with longitudinally mounted engine and automatic transmission 

In the case of vehicles with longitudinally mounted engine and transmission, the torque distribution is predefined by the transfer case. Active-selective brake application takes over the function of the differential lock and vehicle dynamics control. The automatically regulated all-wheel drive is usually a permanent all-wheel drive with fixed force distribution.

	Additional basic functions
	Basic function of all-wheel drive with dual-clutch transmission	Model all with transmission 700.4, 724.0/1 with code M005 (Vehicles with 4MATIC/all-wheel drive)	GF28.00-P-1000A
	Basic function of all-wheel drive with automatic transmission	Model all with transmission 725.0/1 with code M005 (Vehicles with 4MATIC/all-wheel drive) Model all with transmission 725	GF28.00-P-1001A