What is a Car Powertrain?

by Cayden Conor

The powertrain of a car consists of many components, including the engine, transmission, driveshaft and any of the internal workings of the engine. Powertrain management is a function of the electronic control module (ECM). Depending on the car, the ECM may also be called the powertrain control module (PCM). The ECM or PCM gets inputs from sensors and sends outputs via other sensors.

Function

The powertrain provides power to the car. Power is made by the engine, then transferred to the driveshaft through the transmission. The driveshaft, in a rear wheel drive car, turns the gears in the rear, which in turn turns the axles and finally, the wheels. The rear and the axles are also part of the drivetrain.

Types

There are two types of powertrain setups---the front wheel drive and the rear wheel drive. The front wheel drive powertrain employs a horizontally opposed engine. The transmission also sits sideways. The driveshafts (there are two of them) go to the front wheels via a hub bearing. In a rear wheel drive powertrain setup, the engine faces the front of the car, and the transmission is behind the engine. There is one driveshaft (it may be in more than one piece, as in some trucks), which leads to the rear end. The axles protrude from either side of the rear to the wheels.

Features

The sensors that are included in a powertrain warranty do not provide direct power to the vehicle, but for warranty purposes are considered part of the powertrain. They provide input and output to and from the powertrain control module (PCM). Some sensors send the computer information, which transcribes the information and sends it to output sensors. They all work together to make the car run cleanly, smoothly and efficiently.

Identification

The engine is located in the engine compartment. Each sensor is located in its proper location on the engine. The transmission, in both front and rear wheel drive vehicles, is attached to the rear of the engine. In front wheel drive vehicles, the transmission can also be accessed via the engine compartment. In rear wheel drive vehicles, the transmission must be accessed from below the vehicle. Transmissions can be automatic or manual.

Size

The engine, which is the main part of the powertrain, comes in various sizes, from a 3-cylinder in a Geo Metro to big V-10 in some trucks. The most common engine sizes are the 4-cylinder, 6-cylinder and 8-cylinder engines. Depending on the year, make and model, each type of engine has different sizes (i.e. the 4-cylinder has 1.8, 2.2 and 2.4 liter engines, 6-cylinders have 2.8 and 3.0 liter engines and the common sizes in an 8-cylinder engine are 5.0 and 5.7 liter engines).

About the Author

Cayden Conor has been writing since 1996. She has been published on several websites and in the winter 1996 issue of "QECE." Conor specializes in home and garden, dogs, legal, automotive and business subjects, with years of hands-on experience in these areas. She has an Associate of Science (paralegal) from Manchester Community College and studied computer science, criminology and education at University of Tampa.