Q2. What component(s) allow(s) the operator to operate the clutch?

Q3. What component(s) transfer(s) motion from the release mechanism to the release bearing and pressure plate?

Q4. What component(s) within the clutch disc absorb(s) vibration and shock produced by clutch engagement?

Q5. What component prevents the engine starting unless the clutch pedal is fully depressed?

Q6. If no service manual is available and an adjustment of the clutch is required, what amount of clutch pedal free travel will allow adequate clutch operation?

MANUAL TRANSMISSIONS

Learning Objective: State the operating principles, identify the components, and maintenance of a manual transmission.

A manual transmission is designed with two purposes in mind. One purpose of the transmission is providing the operator with the option of maneuvering the vehicle in either the forward or reverse direction. This is a basic requirement of all automotive vehicles. Almost all vehicles have multiple forward gear ratios, but, in most cases, only one ratio is provided for reverse.

Another purpose of the transmission is to provide the operator with a selection of gear ratios between engine and wheel so that the vehicle can operate at the best efficiency under a variety of operating conditions and loads. If in proper operating condition, a manual transmission should do the following:

Be able to increase torque going to the drive wheel for quick acceleration.

Supply different gear ratios to match different engine load conditions.

Have a reverse gear for moving the vehicle backwards.

Provide the operator with an easy means of shifting transmission gears.

Operate quietly with minimum power loss.

TRANSMISSION CONSTRUCTION

Before understanding the operation and power flow through a manual transmission, you first must understand the construction of the transmission. This is necessary for you to be able to diagnose and repair damaged transmissions properly.

Transmission Case

The transmission case provides support for the bearings and shafts, as well as an enclosure for lubricating oil. A manual transmission case is cast from either iron or aluminum. Because they are lighter in weight, aluminum cases are preferred.

A drain plug and fill plug are provided for servicing. The drain plug is located on the bottom of the case, whereas the fill plug is located on the side.

Extension Housing

Also known as the tail shaft, the extension housing bolts to the rear of the transmission case. It encloses and holds the transmission output shaft and rear oil seal. A gasket is used to seal the mating surfaces between the transmission case and the extension housing. On the bottom of the extension housing is a flange that provides a base for the transmission mount.

Front Bearing Hub

Sometimes called the front bearing cap, the bearing hub covers the front transmission bearing and acts as a sleeve for the clutch release bearing. It bolts to the transmission case and a gasket fits between the front hub and the case to prevent oil leakage.

Transmission Shafts

A manual transmission has four steel shafts mounted inside the transmission case. These shafts are the input shaft, the countershaft, the reverse idler shaft, and the main shaft.

INPUT SHAFT. - The input shaft, also known as the clutch shaft, transfers rotation from the clutch disc