Principles of Operation

Mechanical Operation
In the 2WD mode, torque from the transmission is transferred to the front input shaft, which in turn drives the output shaft that drives the rear axle.
The 2WD to 4x4 HIGH shift is accomplished when the 2WD to 4x4 HIGH shift fork moves the lockup collar to engage the drive sprocket to the rear output shaft. The drive sprocket turns the chain which turns the front output shaft driven sprocket on the front output shaft and the front driveshaft.
The 4x4 HIGH to 4x4 LOW shift is accomplished when the 4x4 HIGH to 4x4 LOW shift fork moves the shift collar to engage the planet carrier to the main shaft. Torque for the input shaft is then transmitted through the sun gear, which then turns the planets. The planets, which are now engaged to the output shaft, provide a gear reduction.

Neutral
With the shift selector in neutral, no power is transmitted to either the front or rear axles. All the planetary gears turn freely with the input shaft, and the chain sprocket floats freely on the output shaft.

2-Wheel Drive
When 2WD is selected, the shift collar hub at the center of the front planet slides forward, putting the transfer case into the high speed range (direct drive). The input shaft and the rear output shaft are locked together. This results in direct drive, straight through to the rear drive shall. In addition, the 4-wheel drive lockup collar is disengaged so none of the 4-wheel drive components turn.

4-Wheel Drive-4x4 HIGH
In 4x4 HIGH, the front planet remains in the same position as it was in 2WD. The action of the shift lever causes the 4-wheel drive lockup hub to move rearward, locking the chain sprocket to the rear output shaft. This causes both the front and rear wheels to be driven in the high range.

4-Wheel Drive-4x4 LOW
4x4 LOW allows for maximum pulling capacity. Shifting into 4x4 LOW causes the shift collar hub to move rearward and allows the front planet to lock to the output and fifth gear drive shaft. With the ring gear unable to turn, the planetary gears walk around the inside. The result is that the front planet now turns more slowly than the input shaft. Because the front planet is now locked to the output and fifth gear driveshaft, the output shaft now rotates at a slower speed than the input shaft. This action increases the pulling capacity available to the wheels.