All Important Question: 2WD vs AWD vs 4WD

We have come across all sorts of SUV’s claiming to be either two wheel drives, all wheel drives or four wheel drives. It is crucial to understand these differences before spending your hard earned money. Your reasons to purchase any one of these drivetrains would lie in the usage of your vehicle.

Two Wheel Drive
If you use your vehicle for daily commutes in the city or longer drives on paved roads, ideally this is the best kind of vehicle to purchase. These are vehicles where the engine only powers the front or the rear wheels through an open front or open rear differential respectively. This open differential allows the tyres to move at different speeds to compensate for a turning vehicle as the outer tyres will travel a longer distance as compared to the inner tyres while turning.

All Wheel Drive
These SUV’s would be best suited for the weekend camper who likes to drive on unsealed roads to get there. The power from the engines in this case, is sent from the engine to all four wheels through an open central differential. Again, the open differential helps in being able to turn the vehicle without snapping a CV shaft!

The benefits of these vehicles are endless. From them, safety is something that always springs to mind! During difficult driving conditions, having power in all four wheels will ensure greater traction as compared to a two wheel drive, hence making it safer behind the wheel for you and your family.

Keeping these benefits in mind, it is also important to understand that these vehicles are not the best choice for real bush work. The drawback of this system comes in when one tyre is lifted off the ground, which is very much a possibility when on off-road tracks. As soon as this happens, all the power from the engine is sent to the tyre with the least amount of traction. This results in you coming to a complete halt with one freely spinning tyre. Modern SUV’s today are fitted with a lot of driver aids to try and overcome this issue.

Four Wheel Drive
This is where things get interesting. In order to overcome the drawbacks of all wheel and two wheel drive systems, four wheel drives were invented! These vehicles are best suited for some real off road driving. While on road, these vehicles are configured to act like either two wheel drive or all-wheel drive systems.

What sets these apart from the rest is the presence of a lockable central differential. In a lot of older vehicles, the driver could lock the central differential using a mechanical gear lever, today most vehicles are equipped with a button or a knob to do the same.

Locking the central differential ensures a 50:50 ratio powersplit between the front and rear axles. This means that once locked, the power is equally divided between the two axles, ensuring higher levels of traction on demand!

Given the benefits of such vehicles, one must also understand the drawbacks. These vehicles usually are costlier on the back pocket due to higher fuel consumption and higher maintenance costs! Do note that locking the central differential does not mean 100% traction, the vehicle still has an open front differential and an open rear differential which would send all the power available to them, to the tyre with the least traction on the given axle. The best way to overcome this, is by installing front or rear differential locks. Some car manufacturers are even selling these as factory equipment on their vehicles.

Stay tuned for more information on front & rear differential locks, dual range transfer cases and other ways to best equip your SUV for the great outdoors!

 

Article by Sujay Vasist

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