Section 3
Manual Transmissions
Learning Objectives:
1. Identify and describe manual transmission design features and operation.
2. Describe transmission powerflow.
3. Describe manual transmission construction.
4. Identify and describe the operation of the following transmission
components:
a. Synchronizers
b. Shift mechanisms
c. Key inertia lock mechanism
5. Identify and describe gear shift control.
6. Describe transmission lubrication.
Manual Transmissions & Transaxles – Course 302
Section 3
Manual Transmissions
The manual transmission transfers power from the engine to the propeller
shaft. It converts and multiplies rotational speed, allowing engine RPM to
remain in it's limited optimal power range while providing a wide range of
RPM to the propeller shaft; which, in turn, controls vehicle speed.
Multiple gear sets within the transmission provide gear ratios to best
utilize the engine's torque. A gear ratio of about 4:1 in first gear
provides high torque to begin moving the vehicle. In contrast, a higher
gear ratio of about 1:1 reduces engine speed at higher vehicle speeds
when less torque is required to maintain momentum.
Understanding manual transmission design features increases your
knowledge of transmission operation, and provides for easier and more
accurate problem diagnosis.
The rear wheel drive transmission is constructed with three shafts, five
forward gears, and a reverse gear.
The input shaft also known as a main drive gear or clutch shaft is
driven by the clutch disc and drives the counter gear shaft. The input
shaft is supported by the pilot bearing at the end of the crankshaft and
a bearing at the front of the transmission case.
The output shaft also known as the mainshaft drives the propeller
shaft. It is splined at the rear to allow a sliding connection to the
propeller shaft. The output shaft gears rotate on the shaft and are
locked to the shaft by synchronizers. The synchronizers are splined to
the output shaft. The output shaft is supported by a pocket bearing at
the rear of the input shaft, a bearing at the intermediate plate and a
bearing at the extension housing of the transmission.
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