96 Auto Suspension and Steering
Driving Solid Axle
The solid front axle used on four-wheel drive vehicles
is more complex than a non-driving solid axle. The solid
front axle used on four-wheel drive vehicles resembles the
rear axle of a rear-wheel drive vehicle. A final drive unit
consisting of a ring-and-pinion set and differential gears is
installed in the axle. Figure 5-27 shows a typical solid
driving front axle. Power from the final drive unit turns
internal axles that drive the front wheels. U-joints are used
at each steering knuckle to allow the wheels to turn. A stub
axle connects the U-joint to the driving hub and wheel.
Each end of the solid axle has a steering knuckle with ball
or roller bearings that allow the stub axle to rotate.
Locking hubs are used on some older four-wheel drive
vehicles, Figure 5-28. Locking hubs are used to engage and
disengage four-wheel drives when the transfer case is not
designed to do so.
On some larger four-wheel drive vehicles, a modified
kingpin assembly is used instead of ball joints. This system
consists of short kingpins in the upper and lower steering
knuckles. On some vehicles, the lower attaching point
also has a tapered wheel bearing to absorb loads. See
Figure 5-29.
Torsion
bars
Lower control
arm
Kingpin
Spindle
Kingpin bushing
(nylon)
Solid
axle
Locking pin
Shim
Thrust
bearing
Figure 5-24. A solid front axle incorporating a kingpin that
allows the spindle to be turned. (Moog)
Figure 5-23. A transverse torsion bar front suspension. The
torsion bar connects to the lower control arms. (Hunter)
Solid I-beam axle
Frame
Spring shackle
Leaf spring
Frame
Coil spring
Spring seat
Control
arm
Spindle
Axle
Rubber
bumper
Spring
clamp
Figure 5-25. A solid axle front suspension that uses leaf
springs. (Moog)
Figure 5-26. A solid axle front suspension that uses coil springs
for support. (Moog)