GF28.10-P-0002VG Transfer Case (VG), Function
GF28.10-P-0002VG Transfer case (VG), function
- with engine 156, 272, 273, 642 with Transmission 722.9 [model 164.1]
- with engine 273, 642 with Transmission 722.9 [model 164.8]
Component Identification:
Sectional view of transfer case
Component Identification:
Sectional view of transfer case (AMG version)
Transfer case (VG), general
Permanent all-wheel drive has advantages not only off road but also on roads which provide good grip. The permanent all-wheel drive increases the number of driven wheels, thus improving tire-to-road adhesion. As a result, slip is reduced and the driving power is distributed to all of the wheels. The distributed driving power results in higher traction and higher lateral stability at the driven wheels.
The standard version (model 164.1, 164.8) of permanent all-wheel drive is equipped with three open differentials (transfer case, rear and front axle). The torque split of 50:50 % between the front axle and rear axle is specified as a fixed value in the transfer case. The transfer case gear ratio is 1:1.
Using the off road program switch (N72/1s25) (except code (430) Off road package, AMG version) which is located in the upper control panel control unit (N72/1) the driver can activate the off road function (modified shift characteristic) in the automatic transmission (NAG2). In addition a changed accelerator pedal curve is activated in the CDI control unit (N3/9) or ME-SFI [ME] control unit (N3/10) and the off road ABS function in the ESP control unit (N47-5).
The driver can switch the Downhill Speed Regulation function on or off via the Downhill Speed Regulation switch (N72/1s24) (except code (430) Off road package, AMG version) or (N72s30) (with code (430) Off road package).
Sectional view of transfer case with code (430) Off road package
With code (430) Off road package
A permanent all-wheel drive with two lockable differentials (transfer case and rear axle) and an open differential (front axle) is used in the Off road package equipment. The torque split of 50:50 % between the front axle and rear axle is specified as a fixed value in the transfer case.
The "Low/High" function in the transfer case can be used to select two gear ratios. The on-road ratio "High" is 1:1, the off road gear ratio "Low" is 2.93:1.
The transfer case control unit (N15/7) and the rear axle differential lock control unit (N15/9) control the two ratios. Via the Low Range switch (N72s31) which is located in the lower control panel control unit (N72), the driver can switch over between the "High" on-road ratio and the "Low" off road ratio.
The differential locks in the transfer case and in the rear axle can be operated or adjusted by the driver via the differential lock selector wheel (N72s34).
The differential lock selector wheel is located in the lower control panel control unit.
The following control units are involved in controlling the transfer case and the rear axle:
^ Transfer case control unit
^ Rear axle differential lock control unit
^ Lower control panel control unit
^ ME-SFI [ME] control unit (with gasoline engine)
^ CDI control unit (with diesel engine)
^ ESP control unit
^ Fully integrated transmission control (VGS) control unit (Y3/8n4)
Further partial functions are described in separate documents:
^ Transfer case/rear axle differential lock control, function (with code (430) off road package)
^ Downhill Speed Regulation, function
^ off road transmission mode, function (except code (430) Off road package)
^ Transfer case oil supply, function
^ "Low/High" shift, function (with code (430) Off road package)
^ Interaxle differential lock, function (with code (430) Off road package)
^ Interwheel differential lock, function (with code (430) Off road package)
