A manual transmission (Figure 10-11) 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.
