BW4470 Transfer Case
The Borg Warner 4470 transfer case is a chain-driven, four-position unit providing the following features:
| • | A four-wheel drive high range (4HI) |
| • | A four-wheel drive low range (4LO) |
| • | A two-wheel high range (2HI) |
| • | A neutral position |
The BW4470 is a part-time four-wheel drive unit.
Torque input in four-wheel drive is undifferentiated.
The range positions are selected by a floor-mounted gear shift lever.
The unit has a gear reduction ratio of 2.69:1.
The BW4470 has a three-piece aluminum case with provisions for a power take off (PTO) and uses an electric synchronizer when shifting into four-wheel drive.
Identification
The identification tag is an aluminum tag.
It is attached under the self-tapping extension housing bolts.
This tag provides the following information:
| • | The transfer case model number |
| • | The serial number |
| • | The build date |
This information on this tag is necessary for servicing the transfer case.
If the tag is removed or becomes dislodged during service operations, keep the identification tag with the unit.
Power Flow
The input torque is transmitted to the transfer case gear train through the transfer case input gear. (This occurs in all drive range positions.)
Torque flows along the following path in the 2HI range:
- Torque flows from the input gear to the range shift hub and the mainshaft.
- Torque flow continues through the slip/fixed yoke that is splined to the mainshaft.
- Torque flow continues to the rear propeller shaft and the axle.
In the 2HI range, the mode synchronizer remains in the neutral position. As a result, torque is not transferred to the driven sprocket.
In the 4HI range, input torque from the input gear is transmitted to the mainshaft in the same manner as in the 2HI range.
However, in the 4HI position, the mode synchronizer sleeve is shifted into engagement with the clutch hub teeth on the mainshaft. This locks the drive sprocket to the main shaft through the synchronizer assembly.
The connecting drive chain transmits torque through the drive sprocket. Torque then flows along the following path:
- Through the front output shaft/driven sprocket.
- To the front propeller shaft and axle.
Torque flow along this path results in the high range four-wheel drive.
The path of torque in the 4LO range is similar to the path of torque in the 4HI range. However, in the 4LO range, the range hub is shifted into engagement with the planetary carrier. This engagement causes the following events:
- The input gear rotates the planetary pinions inside the annulus gear.
- The planetary carrier, the range shift hub, and the mainshaft rotate at a gear reduction of 2.69:1.
