What Is a Differential?


Every part on a car serves a purpose to keep it moving while on the road. The differential is a key player that works to apply torque (a rotational force) to the drive wheels. Whether the car is front-wheel drive, rear-wheel drive or all-wheel drive, the differential is needed.

How did the differential get its name? The root word of differential is different. The differential is a system that allows the drive wheels to turn at different speeds, which is required when the car is negotiating a turn. In a turn, the outside wheel must travel farther, which means it must travel faster than the inside wheels.

Maybe you’ve heard the term before but are unsure about what this part does and how it works. Keep reading to learn more about the different kinds of differential systems and why they’re important.

How Does a Differential Work?

The differential is made up of many parts. The main components are the ring and pinion gears. The ring gear is attached to the carrier assembly, and inside the carrier is a set of smaller gears.

These smaller gears are often referred to as spider gears, which are made up of another set of pinion gears and the side gears. It is this set of gears that supplies the differential action. Following the power flow inside the differential, the pinion gear drives the ring gear, which rotates the carrier.

The carrier then drives the smaller pinon gears, which in turn drive the side gears. The drive axles are splined into the side gears, which then drive the wheels.

The differential is found in the front- or rear-axle assembly on all late-model cars and trucks. In all-wheel drive (AWD) applications, there will also be a center differential driving both front- and rear-axle assemblies.

What Is a Transaxle? Is It the Same Thing?

The differential can be located in various areas, depending on what drive system the vehicle operates with.

When the differential is located inside the transmission housing, it’s called a transaxle. The drive axles then plug directly into the transmission/transaxle. The difference between a differential and transaxle is that the differential is a part on its own, whereas the transaxle combines the differential and transmission into a single unit.

This type of housing is often found in front-wheel drive vehicles, although some sports cars will have a rear transaxle. What is a rear differential? In this case, the differential is separated from the transmission and connected by a drive shaft in rear-wheel-drive applications.

AWD and four-wheel-drive vehicles often have a center differential. In an AWD vehicle, both the front and rear axles turn at different speeds during a turn. Some electric or hybrid vehicles often feature electronic all-wheel drive that eliminates the need for a differential, as power can be delivered directly to the wheels via the electric motors.

Types of Differentials

There are a few different kinds of differential systems that are used in vehicles today. These include:

Open Differential

Most differential systems have open designs, which are considered to be the most reliable and simple. They feature a powered pinion gear that engages with a ring gear to send power to both axles.

The only major issue with an open differential is the possibility of tires slipping in less-than-ideal conditions. Engine torque will transfer regardless of whether a wheel has traction, causing that tire to spin while the other tire does nothing.

Limited-Slip Differential

A limited-slip differential is similar to an open one, except it can transfer power to both wheels if one wheel loses traction. A limited-slip differential contains a few extra parts to allow this to occur. These parts (clutch packs) work to lock the left and right sides of the axle together when traction is lost to one of the wheels.

Locking Differential

A locking differential system is most likely going to be found on off-road vehicles and sometimes on performance models. It utilizes springs and clutches that activate locks, ensuring the same amount of power is sent to each wheel regardless of traction.

Torque-Vectoring Differential

A torque-vectoring differential is the most advanced when it comes to differential technology. It operates using a complex range of sensors and different electronics that pull data from the steering system and more.

This allows the differential system to distribute power to each wheel as needed and helps provide maximum traction, making this system great at increasing performance.

Signs a Differential Is Wearing Down

Over time, a differential can start to wear down. It’s good to know some of the signs that could indicate yours is starting to go bad so you can have it checked sooner rather than later.

Some things to watch out for include:

  • Driveline noise and vibrations
  • Grinding or clunking sounds
  • Strange sounds when handling around corners
  • Whining or whirring sounds
  • Oil leaking from the differential area

Your differential plays a key role in helping steer your vehicle and keeps the power balanced between your tires. Be sure to keep it in good condition so you can remain safe while driving.

Work on Differentials as an Automotive Technician

If you’re interested in learning more about how differential systems work, training for a career as an automotive technician could help you. Not only could you gain knowledge for working on your own vehicle, you could also apply your education toward working in an in-demand industry.1

The Automotive Technology program offered at Universal Technical Institute (UTI) can help teach you the skills that employers are looking for when hiring. Courses cover several topics, including the Powertrains & Transmissions course, which teaches students how to assemble and disassemble differentials.

Find out more about the program and how you can graduate in less than a year7 by requesting information or by calling 1-800-834-7308.

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1 ) UTI is an educational institution and cannot guarantee employment or salary.
2 ) For program outcome information and other disclosures, visit www.uti.edu/disclosures.
7 ) Some programs may require longer than one year to complete.

Universal Technical Institute of Illinois, Inc. is approved by the Division of Private Business and Vocational Schools of the Illinois Board of Higher Education.


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