GMC T Series 1994 Repair Manual page 864

4. M ainshaft Extension
7. Pump Retainer Housing
15. Drain and Fill Plugs
17. Rear Case Half
80. Identificatio n Tag
et to the mainshaft. As a result, torque is not transferred
to the driven sprocket.
In 4HI range, input torque from the input gear is
transmitted to the mainshaft in exactly the same fashion
as in 2HI range. However in the 4HI position, the mode
synchronizer sleeve is shifted into engagement with the
clutch teeth of the drive sprocket. This locks the drive
sprocket to the mainshaft through the synchronizer.
Torque is transmitted through the drive sprocket to the
driven sprocket by the connecting drive chain. Since the
front output shaft is splined to the driven sprocket,
I
15
Figure 1—231 Rear Case Half
torque flows through the front output shaft to the front
propeller shaft and axle resulting in high range
four-wheel drive.
In 4LO range, the path of torque through the transfer
case is exactly the same as in 4HI range but with one
major difference. In 4LO range, the range shift hub is
shifted into engagement with the planetary carrier. This
causes the input gear to rotate the planetary pinions
inside the annulus gear, causing the planetary carrier,
range shift hub and mainshaft to rotate at a gear reduc­
tion ratio of 2.72:1.
F5847