DESCRIPTION
The BW 44-46 is an electronically controlled active part-time transfer case.
The low range provides a 2.64:1 reduction ratio.
OPERATION
The input gear is splined to the transmission output shaft. The input gear drives the mainshaft through the planetary assembly and range sleeve. The front output shaft is operated by a drive chain that connects the shaft to a drive sprocket on the mainshaft. Torque is transmitted through the input shaft to the drive sprocket assembly. The torque is also transferred directly to the rear propeller shaft, to the front output shaft by the drive chain when 4WD is selected. The oil pump circulates gear lube throughout the case to provide internal lubrication and cooling.
The shift motor consists of a permanent magnet D.C. motor with gear reduction to convert a high speed-low torque device into a low speed-high torque device. The output of the device is coupled to a shaft which internally moves the range fork that change the transfer case operating ranges. The shift motor uses a digital encoder to monitor the shift motor position. The motor is rated at 20 amps maximum at 25° C (77° F) with 14 volts at the motor leads.
The transfer case shift motor responds to the Drive Train Control Module (DTCM) commands to move the transfer case shift range fork, as required, to obtain the correct transfer case operating range indicated by the instrument panel mounted selector switch. The motor only shifts between 1:1 ranges, 2.64:1 range, and neutral. Switch changes between 2WD, 4WD LO and 4WD HI are assisted by the transfer case coil.