Borg-Warner 44-05 Transfer Case

DESCRIPTION
The Borg-Warner 44-05 transfer case is used in the Explorer (4WD) vehicle. The transfer case transfers power from the transmission to the rear axle, and also to the front axle when electronically activated.

MECHANICAL OPERATION
In the 4X2 mode, torque from the transmission is transferred to the input shaft which, in turn, drives the rear output shaft that drives the rear axle assembly. The 2WD through 4WD auto shift is accomplished through an electromechanical ball ramp clutch assembly.

The electromechanical ball ramp clutch assembly drives the drive sprocket after the GEM activates the clutch coil. The drive sprocket turns the chain which rotates the front output shaft and front driveshaft.

The high-low shift is accomplished when the reduction shift fork moves the reduction collar to lock the planetary gear set to the output shaft. Torque from the input shaft is then transmitted through the sun gear, which then turns the front planetary gear set front planet. The front planetary gear set front planet which is now engaged provides transfer case speed reduction.

TRANSFER CASE FUNCTIONS
There are three modes on the transfer case, Auto, 4WD Low, and 4WD High. Neutral is only available as a dealer installed option.

C-TRAC FUNCTION
The C-Trac transfer case transmits torque to the front wheels through an electromechanical shift assembly after a predetermined change in speed between the front and rear driveshafts is detected. These driveshaft speeds are determined by two Hall effect sensors which send a signal to the generic electronic module (GEM). If the GEM detects a change in speed between the front and rear driveshafts, it activates the transfer case clutch coil with a varying current to minimize the change in driveshaft speeds.

LOW RANGE FUNCTION
In 4WD Low Range, the transfer case electromechanical clutch locks the front and rear driveshafts for maximum 4WD traction. The transfer case motor also rotates the shift cam to move the reduction fork to the 4WD low range position. This low range shift is accomplished through a planetary gear set which changes torque to the driveshaft from 1:1 to 2.48:1 ratio.