Transfer case (VG), function - GF28.10-P-0002G
MODEL 463.306/336/346 with TRANSFER CASE 750.654 as of Model Year 2011/YoM 10
MODEL 463.202/222/236/237/270/271/303/340/341 with TRANSFER CASE 750.654 as of Model Year 2009/YoM 08
Power flow characteristic curve
Power flow characteristic curve
The input torque on the transfer case is transferred through the drive shaft over the intermediate shaft to the two output shafts. The two gears "LOW" and "HIGH" can be engaged here. Shifting control for the two gears is fully electronic and the electric shift signals are realized by means of an electromotive shift mechanism.
A gear shifting in the transfer case starts with a straight-line movement of the shift fork, which is directly-coupled to the shifting mechanism of the electromotive shift mechanism.
Function of the synchronization when shifting from "LOW" to "HIGH"
The gearshift sleeve is in the "LOW" shift position. An internal toothing means that the gearshift sleeve is positively connected to the external toothing of the transfer case's drive shaft and the shift teeth (roof-type gearing) of the off-road gearwheel.
The off-road gearwheel transfers the input torque through an intermediate shaft gear to a gear, which is directly connected with the center differential.
From the center differential the output torque is forwarded over the two output shafts to the front axle and rear axle.
If a shift from "LOW" to "HIGH" is initiated, the gearshift sleeve is moved by the shift fork towards the "HIGH" shift position.
While the gearshift sleeve is disengaged from the shift teeth on the off-road gearwheel the holding ability, as generated by the undercut has to be overcome.
The synchronization is vented here and the gearshift sleeve moves through the "NEUTRAL" shift position.
Once the friction surfaces of the gearshift sleeve and the synchronizer cone of the on-road gearwheel abut (start of synchronization) the gearshift sleeve movement briefly comes to a standstill.
The end of the synchronization is reached when the drive shaft and on-road gearwheel run at the same speed. The gearshift sleeve can now be moved further towards the on-road gearwheel.
When the gearshift sleeve makes contact with the on-road gearwheel's shift teeth an increase in force is required at the start.
After overcoming the shift teeth the gearshift sleeve keeps moving until it meets the on-road gearwheel's shaft shoulder. After reaching the end position the actuator motor reverses it rotation thereby ensuring freedom of movement of the shift fork to the gearshift sleeve.
The shift from "HIGH" to "LOW" takes place in the opposite direction.
Operating instructions:
Shift into neutral from the on-road or off-road gear (towing)
- Terminal 15 ON
- Operation of transfer case (S97/5) for ≥5s
- Vehicle speed v = 0 km/h
- Operating voltage U ≥ 11 V
- Automatic transmission in neutral
- Service brakes operated
- Parking brake operated
Shift into on-road or off-road gear from neutral
- Terminal 15 ON
- The transfer case must
- be operated at terminal 61 OFF for ≥ 5 s,
- only be operated briefly at terminal 61 ON.
- Vehicle speed v = 0 km/h
- Operating voltage U 11 V
- Automatic transmission in neutral
A shift to HIGH can only be made when a differential lock was not preselected or is not active.
Preconditions for "LOW/HIGH" shift
- Operating voltage U > 11 V
- Engine speed n > 400 RPM
- Reverse travel: Vehicle speed < 3 km/h
- Forward travel: Vehicle speed < 40 km/h (for shift command from "HIGH" to "LOW") or vehicle speed v < 70 km/h (for shift command from "LOW" to "HIGH")
- Automatic transmission when the transfer case switch is shifted to neutral
- No differential lock preselected or active (when shifting to HIGH)
Advantages of electromotive shift mechanism
- Improvement in shift comfort and shift quality
- Easier and quicker gearshift operation
- No effort required when shifting
- Reduction of noise level inside the vehicle
- Direct transmission of transfer case vibrations to the body not possible
- Prevention of shifting errors and incorrect operation
- Improved safety when driving through recognition of shifting problems and their rectification without distracting the driver's attention from the traffic.
If a gear is not engaged in the transfer case, an acoustic chime sounds along with an optical signal.
| Transfer case (VG), location of components | GF28.10-P-0002-06G | ||
| Transfer case (VG), block diagram | GF28.10-P-0002-08G | ||
| Transfer case control, function | GF28.19-P-3000G | ||
| Electromotive circuit, function | GF28.60-P-3000G |