20 Section 1 Introduction to Automotive Technology
Drive Shaft
The drive shaft, or propeller shaft, transfers power
from the transmission to the rear axle assembly. It
is a hollow metal tube with two or more universal
(swivel) joints. The universal joints allow the rear
suspension to move up and down without damag-
ing the drive shaft.
Rear Axle Assembly
The rear axle assembly contains a differential
and two axles. The differential is a set of gears and
shafts that transmits power from the drive shaft to
the axles. The axles are steel shafts that connect the
differential and drive wheels, Figure 1-20.
Transaxle
The transaxle consists of a transmission and a dif-
ferential in a single housing. Although a few rear-
wheel drive vehicles are equipped with transaxles,
they are most commonly used with front-wheel
drive vehicles. Both manual and automatic trans-
axles are available. The internal parts of a modern
transaxle assembly are illustrated in Figure 1-21.
Front Drive Axles
The front drive axles connect the transaxle differ-
ential to the hubs and wheels of the vehicle. These
axles are equipped with constant-velocity joints,
which allow the front wheels to be turned to the left
or right and to move up and down.
Suspension, Steering, and Brake Systems
The suspension, steering, and brake systems are
the movable parts of the chassis. They bolt or anchor
to the frame and provide directional stability when
maneuvering. Directional stability is the ability of a
vehicle to corner, brake, and accelerate with body
roll and body dive. Poor directional stability will
Clutch
housing
Manual
shifter
Helical
gear
Output
to drive
shaft
A—Manual Transmission
Transmission housing
Output
shaft
Torque
converter
Valve
body
Clutches
Planetary
gearset
B—Automatic Transmission
Figure 1-19. Study the three major types of automobile transmissions. (Chrysler, Ford)
Drive shaft
from transmission
Differential
housing
Drive axle
Drive
axle
Ring gear
Figure 1-20. The rear axle assembly contains the differential
and two axles that turn the rear drive wheels. The drive shaft
sends power to the rear axle assembly. (Mazda)