vehicle with rear-wheel drive. A few of these advan-
tages are the following:
Improved efficiency and reduced drive train
Improved traction on slippery surfaces because
of increased weight on the drive wheels
Increased passenger compartment space (no
hump in floorboard for rear drive shaft)
Less unsprung weight (weight that must move
with suspension action), thereby providing a
Quieter operation since engine and drive train
noise is centrally located in the engine com-
Improved safety because of the increased mass
in front of the passengers
Most transaxles are designed so that the engine can
be transverse (sideways) mounted in the engine com-
partment. The transaxle bolts to the rear of the engine.
This produces a very compact unit. Engine torque
enters the transaxle transmission. The transmission
transfers power to the differential. Then the differ-
ential turns the drive axles that rotate the front wheels.
Both manual and automatic transaxles are
available. Manual transaxle uses a friction clutch and a
standard transmission-type gearbox. An automatic
transaxle uses a torque converter and a hydraulic
system to control gear engagement.
A manual transaxle uses a standard clutch and
transmission. A foot-operated clutch engages and
disengages the engine and transaxle. A hand-operated
shift lever allows the operator to charge gear ratios.
The basic parts relating to a manual transaxle are as
Transaxle Input Shaftmain shaft splined to the
clutch disc turns the gear in the transaxle.
Transaxle Input Gearseither freewheeling or
fixed gears on the input shaft and meshes with
the output gears.
Transaxle Output Gearseither fixed or free-
wheeling gears driven by the input gears.
Transaxle Output Shafttransfers torque to the
ring gear, pinion gears, and differential.
Transaxle Synchronizerssplined hub assem-
blies that can lock freewheeling gears to their
shafts for engagement.
Transaxle Differentialtransfers gearbox
torque to the driving axle and allows the axles to
turn at different speeds.
Transaxle Casealuminum housing that
encloses and supports parts of the transaxle.
The manual transaxle can be broken up into two
separate unitsa manual transaxle transmission and a
transaxle differential. A manual transaxle trans-
mission provides several (usually four or five) forward
gears and reverse. You will find that the names of
shafts, gears, and other parts in the transaxle vary,
depending on the location and function of the
components. For example, the input shaft may also be
called the main shaft, and the output shaft is called the
pinion shaft because it drives the ring and pinion gear
in the differential. The output, or pinion, shaft has a
gear or sprocket for driving the differential ring gear.
The clutch used on the manual transaxle trans-
mission is almost identical to the manual transmission
clutch for rear-wheel drive vehicles. It uses a friction
disc and spring-loaded pressure plate bolted to the
flywheel. Some transaxles used a conventional clutch
release mechanism (release bearing and fork); others
use a long pushrod passing through the input shaft.
The transaxle differential, like a rear axle differ-
ential, transfers power to the axles and wheels while
allowing one wheel to turn at a different speed than the
other. A small pinion gear on the gearbox output shaft
or countershaft turns the differential ring gear. The
ring gear is fastened to the differential case. The case
holds the spider gears (pinion gears and axle side
gears) and a pinion shaft. The axle shafts are splined to
the differ-ential side gears.
An automatic transaxle is a combination automatic
transmission and differential combined into a single
assembly. The basic parts of an automatic transaxle are
Transaxle Torque Converter(fluid-type clutch
that slips at low speed but locks up and transfers
engine power at a predetermined speed; couples
and uncouples engine crankshaft to transmission
input shaft and gear train).