Figure 29-18. Hellical Gear Drive for Steerable Wheels.
axle passes directly beneath the rear cross-member of
(4) Another arrangement is the tandem drive
(fig. 29-20), employing double-reduction axles. A single
propeller shaft from the transmission transfer assembly
(3) Vehicles having this equipment may be
is connected to the forward rear-axle drive pinion through
either four- or six-wheel drive. Sometimes the dual rear
a shaft, and another short interaxle propeller shaft
axles are driven by Independent propeller shafts (fig. 29-
connects the drive pinion shaft of the forward rear axle
19) from a transfer assembly. In this case, the propeller
with the drive pinion shaft of the rearward rear axle.
shaft to the rearmost rear axle is divided into three parts,
Ordinarily, no Interaxle differential is used, but one that is
the short middle part passing through bearings mounted
built Into the forward rear axle is used sometimes. With
on the forward rear axle. The transfer assembly may
the tandem drive, no transfer assembly is required If the
contain an interaxle differential, but usually does not.
vehicle drives on the four rear wheels only. If the front
wheels also are driven, a transfer assembly is required.