Oil Supply For 4Matic Transfer Case Function - GF28.55-P-3010AVK
Transmission 725 (except 725.096) in model 213 up to model year 2021 with code M005 (Vehicles with 4MATIC/all-wheel drive)
Transfer case with engine 256
Function requirements, general
- Vehicle is moving or rolling
Oil supply in general
The oil supply system ensures that the components of the transfer case are sufficiently greased and cooled.
The transfer case and the automatic transmission have separate oil systems.
The oil supply on vehicles without engine 256 is designed as a pure splash lubrication.
On vehicles with engine 256 an oil pump (25) is bolted on to the outside of the transfer case housing. The oil pump (25) delivers the oil from the lower area in the rear section of the housing upwards through an oil duct. The oil flows from above into the transfer case, lubricates and cools all moving parts and gathers at the bottom again.
View of fluid reservoirs; shown on double planetary gear set
View of oil hole at vehicle standstill; shown on double planetary gear set
The tank compartment (1) and the front axle transmission output compartment (3) are connected via oil holes (4). When the vehicle is stationary, the oil level is identical in both of these compartments.
View of oil supply in differential gear system compartment (2), shown on double planetary gear set
View of oil supply in differential gear system compartment (2)
In drive mode the oil is pumped out of the differential gear system compartment (2) through the rotation of the planetary gear differential (5). The oil is hurled into the collecting groove (6) and routed through the front axle transmission output compartment oil duct (7) up to the transverse passage (8). The accumulated, excess oil runs directly into the tank compartment (1) again.
View of oil supply for front axle transmission output thrust bearing (9) and front axle transmission output radial bearing (12)
View of oil supply for radial bearing for front axle transmission output (12)
View of oil supply for planetary gear differential (5), shown on double planetary gear set
The volumetric flow rate is distributed from the transverse passage (8) to the thrust bearing for front axle transmission output (9) and to the planetary gear differential (5) thereby lubricating these components.
The oil is forwarded through the tank compartment oil hole (10) and the tank compartment oil duct to the front axle transmission output (11), axial bearing to front axle transmission output (9) and to the front axle transmission output radial bearing (12). This then assures that both bearings are lubricated. The oil is forwarded by the pump action from the thrust bearing on the front axle transmission output (9) into the front axle transmission output compartment (3).
View of load change damper oil supply and planetary gear differential, output gear of front axle transmission output (14) and output gear of front axle transmission output (15)
View of load change damper oil supply (17) and planetary gear differential (5), shown on dual planetary gear set
View of plastic nozzle (16), shown on double planetary gear set
The oil is supplied by the front axle transmission output compartment collecting groove (13) over the plastic nozzle (16) straight to the load change damper (17) and the planetary gear differential (5). This takes place through tooth engagement of the front axle transmission output drive gear (14) and from output gear of the front axle transmission output (15). Once there it is routed by the centrifugal force to the outer wall of the differential gear system (2). The oil then gathers in the drip trough (6).
View of ventilation system; shown on dual planetary gear set
Ventilation is through the ventilation system inlet, inlet bore hole (20), vent pipe (21) and the ventilation system outlet (22). The oil runs through the drain slot (19) into the front axle transmission output compartment (3). The pressed-in vent pipe (21) prevents any oil from escaping at the ventilation system outlet (22).
Oil change and oil level check, connecting screw (23) screwed in (shown on double planetary gear set)
Oil change and oil level check, connecting screw (23) unscrewed (shown on double planetary gear set)
For an oil change or an oil level check, the tank compartment (1) must be connected to the differential gear system compartment (2). This is achieved by unscrewing the connecting screw (23) up to the end stop on the drain screw (24). The connecting screw (23) must not be fully unscrewed. This would lead to a loss of oil. After the oil change or the oil level check, the connecting screw (23) must always be screwed completely back in again.
| Overview of system components, automatically controlled all-wheel drive (4MATIC) | GF28.00-P-9998AVK |