Drivetrain Parts

Automobiles are complex machines, and you may have found yourself wondering at one point or another what exactly a drivetrain is and what the drivetrain parts are. This article will help give you a basic understanding of what the parts of the drivetrain are and how they work.

Engine

The engine is what provides the power to move your vehicle.

Transmission

The transmission allows your engine to operate within a relatively small range of speeds whether the car is stopped, accelerating or cruising. This is accomplished through a set of gear ratios within the transmission.

The three types of transmissions commonly used today are manual transmissions, automatic transmissions, and continuously variable transmissions (CVTs). In manual and automatic transmissions, gear ratios are pre-determined and selected by either the driver or automatically by the transmission. In a CVT, the gear ratios continuously change based on the speed of the car.

Clutch and Torque Converter

Between the engine and the transmission is the component that allows the engine to be de-coupled from the transmission, allowing your engine to run while the vehicle is not moving.

In a manual transmission, this is accomplished by the clutch. When you press the clutch pedal inside the car, the parts inside the clutch completely separate the engine from the transmission, and when you release it, the parts come into contact again.

In an automatic transmission or CVT, this is done by the torque converter. Its inner workings can be illustrated by two fans set facing each other. When one is turned on, the air it blows hits the other fan's blades, causing them to turn. A torque converter works in much the same way, only it is self-contained and uses transmission fluid instead of air. At low engine speeds, there is not enough force to turn the blades on the transmission side, allowing the engine to run while your vehicle sits still.

Front Wheel Drive

In a front wheel drive vehicle, the transmission sits next with the engine in the engine bay. Power flows from the engine to the transmission and then to the differential, which is integral to the transmission in a front wheel drive vehicle.

Rear Wheel Drive

In a rear wheel drive vehicle, the transmission sits rearward of the engine bay behind the engine, and the differential is a separate unit located between the rear wheels. Power is sent from the transmission to the differential through the driveshaft.

All Wheel and Four Wheel Drive

In an all wheel or four wheel drive vehicle, power is sent to all four wheels. The transfer case distributes power to the front and rear differentials, and is either integral to the transmission or a separate unit. All wheel drive systems allow the front and rear wheels to rotate at different speeds while four wheel drive systems don't.

Differential

The differential allows the driven wheels to spin at different speeds. This allows the vehicle to take turns smoothly. Two differentials are necessary when all four wheels are powered.

Constant Velocity and Universal Joints

Constant velocity (CV) and Universal joints (U-joints) allow power to be transmitted to components that move with the suspension, such as the wheels. CV joints are often used for the axle shafts that transmit power from the differential to the wheels while U-Joints are generally used for driveshafts.

As you can see, automobiles are complex and so are the systems within them. However, with the help of the information provided in this article, understanding what they are and what they do is relatively easy.