Overview

There is no component more complex and essential than a car’s transmission. Automatic transmissions are responsible for shifting gears without driver input to change gear ratios in an efficient manner as the vehicle moves forward, freeing the driver from having to shift gears manually.

Transmissions are needed because internal combustion engines always output the greatest amount of power at a high rotational speed. At this high rotational speed, it is impossible for this high power to be driven to the wheels to be used for acceleration, low speeds or starting.

Using gear ratios, an automatic transmission reduces the engine’s rotational speed and increases the torque (or “power” to the wheels) in the process, using a torque converter as a fluid coupler.

Vehicles are usually described as 5 or 6 “speed” meaning then have that many gear ratios to allow the vehicle to travel at the full range of speeds required and to make use of the engine’s output power as efficiently as possible.

Due to their complexity, constant use and function within a vehicle’s operation, transmissions experience a lot of wear and tear. Add to this the fact that many owner’s forget to check and change the fluid on a regular basis and it’s easy to understand why so many people have transmission problems.