What Does the Transmission Do?

Sun Auto Service Expert, published on 07/08/2015

Not all car owners understand what it is that their vehicle’s transmission does – likely because it’s a complex part of your vehicle that can be difficult to decipher unless you’re trained to do so. The transmission works to take power from the engine or motor and delivers it to the wheels. This means that the transmission plays a key role in controlling your vehicle, as it is responsible for ensuring the power generated gets to where it needs to be.

Converting Speed

The transmission works to maximize the efficiency of your car’s engine so it can reduce the fuel consumption without negative effects on the driving dynamics.

When taking off from a stoplight, your vehicle’s transmission uses a lower gear ratio which provides more torque at lower RPMs which provides enough power that the wheels to get the car moving. During highway driving, the transmission uses a gear with a much higher ratio to move the vehicle at much higher speeds while keeping engine RPMs relatively low.

Manual Transmission

Although automatic transmissions are now more popular, manual transmissions can be easier to understand. The transmission is made up of gears, output shafts and input shafts. Gears of one shaft engage the gears from the other shafts. When using a manual transmission, a gear is selected by moving the shift lever. This links with an element that controls the gears’ movement in the input shaft, with each linkage working with two gears. Links are changed by shifting the shift lever either right or left. Then the gear is engaged by pushing the clutch pedal, which disconnects the engine and the input shaft. The gears on the shaft can then move and disconnect power between the transmission and engine. Next, the gear is selected and the clutch is released to re-engage engine power toward the input shaft.

Automatic Transmission

Automatic transmissions work in a similar manner, but you don’t have to trigger them yourself. Automatics typically don’t have clutches; instead they have a torque converter that de-couples the gear set and engine. Even though you may not physically need to shift with an automatic transmission, it does all the work of a manual transmission for you.