Transmissions 101

Feb 1, 2016 by Cedric (Driver Weekly)

Just because you own a car or have been driving for decades doesn’t mean you necessarily understand what the transmission does. You know that this is a crucial part of your vehicle and you need to maintain it. You also probably know that transmissions have multiple gears and can be automatic or manual. Whether that is all you know, or you simply want to learn more about the transmission in your vehicle, keep reading.

What It Does


Transmission Cutaway

The transmission in your vehicle is responsible for ensuring that your wheels receive the appropriate amount of power to function correctly at each speed. The general idea is similar to how a bicycle with multiple speeds works. Picture how the bike won’t move without the chain and if you have it in a higher gear, it takes more effort to start the bicycle. The same thing is true of the transmission. Even worse, not maintaining it can reduce your fuel economy and sometimes even stop you from driving entirely.

Key Components

To better understand your vehicle’s transmission, you need to know a few important terms. The gear is a group of toothed wheels that all work together. These toothed wheels adjust the balance between the speed of the wheels and the speed of the car’s engine. The word ‘gear’ is also used to describe the various options you can select. Gear in this sense is the ratio of gears you select on the output and input shafts.

The clutch is the mechanism that connects and disconnects the engine of your car from its transmission. A shift lever is a lever the driver uses to control or manage the gear range or current gear of the transmission. Finally, the H pattern is a specific arrangement of gears. It is usually indicated on your shift lever knob, where your gears appear in parallel rows.

Manual vs. Automatic

Today, automatic transmissions are much more popular than manuals, especially in the United States. Manual transmissions, however, are simpler to describe. These have gears on a set of shafts, which are the input and output shafts. You choose the gears with a manual transmission by adjusting the shift lever. This then starts the linkage that controls gears on the input shaft; you change the linkages when you move the shift lever right or left. To engage the gear, you push on the clutch pedal to disconnect the engine and the transmission’s input shaft. You can then pick the gear and release the clutch to re-engage engine power, and get your vehicle moving on your selected gear ratio. Automatic transmissions use the same general process, but most of the actions take place behind the scenes so you don’t have to worry about them. An automatic won’t use a clutch since the transmission will instead have a torque converter that de-couples your gear and engine for you. Automatic transmissions are easier, particularly in traffic or hilly areas. Manuals, on the other hand, are more affordable, give you better control, and tend to get better fuel economy. 

Tell us what you think