Section 4
Manual Transaxles
Learning Objectives:
1. Identify the purpose and function of the transaxle
2. Describe transaxle construction
3. Identify and describe the operation of the following transaxle
components:
a. Input shaft
b. Output shaft
c. Differential
d. Shift mechanism
e. Bearings
f. Oil pump
g. Remote control mechanism
h. Reverse detent mechanism
i. Reverse one way mechanism
4. Describe transaxle powerflow
5. Describe transaxle lubrication
Manual Transmissions & Transaxles – Course 302
Section 1
Component Testing
Manual Transaxles
Introduction
Construction
A front wheel drive vehicle utilizes a transaxle to transfer power from the
engine to the drive wheels. The transmission portion of the transaxle shares
many common features with the transmission. Differences in design include:
number of shafts, powerflow, and the addition of final drive gears.
A complete description of components shared with transmissions is
found in Section 3: Manual Transmissions.
Understanding manual transaxle design features increases your
knowledge of transaxle operation, and provides for more accurate
problem diagnosis.
Toyota transaxles are constructed with two parallel shafts, a
differential, four to six forward gears and a reverse gear.
Transaxle
Construction
The transmission portion of
the transaxle shares many
common features with the
transmission. (This example
is the C50 series transaxle)
2 TOYOTA Technical Training
TRX – ESP Troubleshooting Guide
Input Shaft
Output Shaft
Differential
Open Differential
The input shaft connects to and is driven by the clutch disc. The drive
gears are located on the input shaft, one for each forward speed and
reverse. The input shaft is supported by bearings at the front and rear
of the transaxle case. No pilot bearing is needed.
The output shaft includes a driven gear for each forward speed. The
output shaft also includes the drive pinion, which drives the final
drive ring gear on the differential. The output shaft is supported by
bearings at the front and rear of the transaxle case.
The differential also also known as a final drive divides powerflow
between the half shafts connected to the front drive wheels.
Power exits the output shaft through the drive pinion gear driving the
final drive ring gear on the differential case.
The ring gear and drive pinion gear are helical gears, and have a gear
ratio similar to that in a rear axle. This gear set operates quietly and
doesn't require critical adjustments as in the rear axle hypoid gear set.
The simplest type of differential is called an open differential. It is
constructed of a final drive ring gear, side gears, pinion shaft and
pinion gears. The ring gear is attached to the differential case. The
pinion gears mount to the pinion shaft attached to the differential case.
The side gears mesh with the pinion gears and transfer the rotation of
the differential case to the side gears, which turn the drive axles.
When a vehicle is going straight, the pinion gears do not rotate, and
both wheels spin at the same speed. During a turn, the inside wheel
turns slower than the outside wheel and the pinion gears start to turn,
allowing the wheels to move at different speeds.
With an open differential, if one tire loses traction, the differential will
transfer power to the slipping wheel, leaving the wheel with traction
without torque. A viscous coupling Limited Slip Differential (LSD) uses
a viscous fluid coupling differential to increase torque to the drive
wheel with traction. If one wheel is slipping, some of the power is
transferred to the other wheel. This also allows the wheels to rotate at
different speeds when turning on dry pavement.
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