Tuesday, December 9, 2014

How do a 4WD and an AWD Differ?

In automobile circles, the terms AWD (all-wheel drive) and 4WD (4-wheel drive) are always mentioned, often interchangeably. The problem is, while the two terms may seem similar (they still both technically drive on all four wheels), they’re really not. Here are a few ways they differ.

4WD, otherwise known as Four by Four or 4x4, is often used on off-road vehicles. It was first developed as part of the WWII effort of the Allies against the Nazis, and is characterized by a component known as the transfer case. This gear-filled component is responsible for splitting power from the transmission between the front and rear axles, which ensures that each of all four wheels turn at the same speed.


The 4WD configuration is extremely ideal for maximum power straight forward; however, it makes turning problematic. For one, the inside wheel must rotate more slowly than the outside wheel when a car makes turns. Making a turn with a 4WD car requires great skill, as 4WD cars often tilt to their sides whenever they make a turn—the inside wheel lifts off the ground and spins freely.


On the other hand, AWD is the direct opposite; specifically designed to contradict the problems brought about by the 4WD system. AWD systems include a mechanism that allows rotational difference between the front and rear axles. Crossover SUVs typically sport AWD systems.

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