Copyright by Goodheart-Willcox Co., Inc.
206 Manual Drive Trains and Axles
Transaxle case
Input shaft
assembly
Transaxle
cover
Output shaft Output shaft assembly Ring gear
Differential
assembly
Side gears
and spider
gears
Output to
CV axle
Input shaft
or mainshaft
Figure 10-1. This cutaway shows the major transaxle parts, including the case and covers, input and output shafts and gears, and
differential assembly. All transaxles, while varying in details, have these basic parts. Note that this particular transaxle is used with
a transverse engine. (Chrysler)
Introduction
Although rear-wheel drive vehicles are still used
today, front-wheel drive vehicles with transaxles are far
more common. The drive train of the front-wheel drive
vehicle is much lighter than that of the rear-wheel drive
vehicle, since it eliminates the drive shaft assembly and
rear axle housing. Placing all the drive train parts in the
front of the vehicle also allows the manufacturer to elimi-
nate the transmission hump found on the floor of rear-
wheel drive vehicles. This increases passenger room.
Manual transaxle operating principles are similar to
those of a manual transmission and differential assembly.
The major difference in a transaxle is that all parts are
usually together in one housing. The manual transaxle has
the same kinds of gears, synchronizers, and shift linkage as
a manual transmission. It contains the same type of differ-
ential case assembly, performing the same job as that
found on a rear axle assembly. The greatest differences
occur in the shape of the transaxle case and the placement
of the parts within the case. An obvious external difference
is the two CV axles connected to the transaxle, as opposed
to the drive shaft assembly that connects to the rear-wheel
drive manual transmission.
This chapter will familiarize you with the parts and
operating principles of manual transaxles. Many parts
resemble those used on a rear-wheel drive vehicle, although
they are arranged differently. This chapter indicates which
parts are different from those of a rear-wheel drive vehicle.
It explains how power flows through the two major types of
transaxles, as well as the differences in parts and layout
between the two types. Transaxles used on modern rear-
wheel drive vehicles are also briefly described.
Purpose of the Manual Transaxle
A manual transaxle (or automatic transaxle) is a drive
unit that combines a transmission and a differential assembly
in one case. See Figure 10-1 and Figure 10-2. Although
transaxles can be used on rear-engine, rear-wheel drive
vehicles, most transaxles are found on vehicles with front-
wheel drive. The transaxle is attached to the rear (output
end) of the engine. The transaxle and engine assembly is
attached to the vehicle’s frame and body through flexible
engine mounts. The flexible mounts reduce vibration transfer
from the engine and transaxle to the passenger compartment.
The basic job of the transaxle is to transfer power from
the engine to the drive axles. The transaxle must also be
able to provide the proper gear ratio for varying operating
conditions and allow the drive wheels to make turns.
Power is received from the engine through a clutch assembly.
The transmission portion of the transaxle is used to
select the proper gear ratio for any driving situation and to