All Wheel Drive (AWD) is an old but recently rejuvenated technology present in the automobile world. It effectively functions with other technologies in a car to make the vehicle secure and stable on road. This article will help you understand how AWD actually works.
Since the invention of the first automobiles to those manufactured today, there have been several different technologies incorporated in cars. Some have failed to make their place in cars produced today, whereas there are few which have become a standard. One of such prominent technologies is the all wheel drive, which in simple words, runs all the axles of the automobile. Before getting to know how AWD works, let us understand in general about AWD.
All Wheel Drive (AWD)
There are many types of drive setups in cars and SUVs; namely front wheel drive, rear wheel drive, and all wheel drive. Front wheel drive relates to only the front axle being powered by the engine; whereas in rear wheel drive, the axle at the behind is provided with engine power. On the other hand, all wheel drive deals in the engine power being distributed to all available axles of a vehicle, and allowing the driver to have control over all wheels simultaneously. This contributes to additional power and traction while the car is driving on surfaces covered by snow, gravel, and different terrains.
Many auto enthusiasts think that AWD and Four Wheel Drive (4WD) are one and the same concept. However, for marketing purposes, car brands may use both these terms interchangeably. But when it comes to the technical working, they vary a lot. A common aspect in both these advanced drive technologies is that the axles are driven all at the same time, unlike in just FWD or RWD vehicles.
The Difference Between AWD and 4WD
AWD generically refers to the drive system wherein all axles of the vehicle are active, regardless of the number of axles and wheels. This is usually found in multi-axle automobiles like cargo trucks and military vehicles. On the other hand, in 4WD cars; just four wheels or two axles of the vehicle are powered, which is normally found in cars and SUVs.
Another difference to note between the two technologies is that AWD is associated with a permanent all-axle control, whereas 4WD is concerned with permanent two-axle control for a specific period of time as required. So technically, an AWD car cannot be driven in the 2WD mode, since power to all wheels is provided continuously. However, a 4WD car can first start as a 2WD, and then when needed its drive can be transformed into a 4WD. The transformation from 2WD to 4WD can be either manual (driver-controlled) or completely automatic as per road conditions.
Another difference also lies in the amount of power provided to all wheels or axles. In AWD, all wheels may individually receive different amounts of power, whereas in 4WD, all wheels receive constantly get equal power. So when taking a sudden turn on snow, an AWD will allow the outer wheels to get more power as compared to inner wheels which have to cover a less surface. This contributes to proper control, when the power distribution operates with the Electronic Stability Control (ESC) system.
How AWD Works
There are two main components installed in a typical AWD system, viz. the differentials and the transfer case. The system has two differentials, one located in the middle of the front wheels and the other at the center of the rear wheels. These differentials do the job of directing torque from the drive shaft to the wheels. The front differential allows both wheels of the front axle to spin at different speeds, which is the key in proper traction during a turn. The same work pattern is applicable for the rear differential as well. So both wheels of one axle rotate at different speeds individually.
The functioning of the transfer case is also very important. The transfer case comprises a setup that controls the speed of the front and the rear axles separately. The setup mostly is a viscous coupling or a center differential. The viscous coupling is a mechanical component made up of two plates filled with thick fluid. This is what causes all wheels to rotate while being in proper traction. The transfer case and differentials are what makes the AWD system work.
All Wheel Drive Cars
All wheel drive cars are manufactured and offered by almost all car brands. However, this technology has been ever evolving, which is why there are many unique technical functionalities developed within the standard working of the AWD system. As a result, companies have come up with their own trademarks for AWD setups installed in their vehicles. A few of the AWD trademarks are mentioned below.
- Audi: quattro
- Saab: Cross-Wheel Drive (XWD)
- Mitsubishi: All Wheel Control (AWC)/ Super All-Wheel Control (S-AWC)
- BMW: xDrive
- Mercedes-Benz: 4Matic
- Subaru: Symmetrical All-Wheel Drive
- Volkswagen: 4MOTION
- Suzuki: intelligent All-Wheel-Drive (i-AWD)
- Nissan: Advanced Total Traction Engineering System for All-Terrain (ATTESA)
- Honda: Variable Torque Management
- Lincoln: Intelligent All-Wheel Drive
- Toyota: All-Trac
- Jeep: Command-Trac/ Selec-Trac/ Quadra-Trac/ Freedom Drive
- Ford: ControlTrac
- Acura: Super Handling All-Wheel Drive (SH-AWD)
This is a simple explanation of how AWD works. Remember that these advanced systems are most effective when their working is supported by ESC systems. If you want to be stable on the road with snow, terrain, gravel, or mud, an AWD car is the best bet.