How 4-wheel Drive Works

A 4WD (four-wheel drive) vehicle assembly is a system in a vehicle which powers and controls all the four wheels at all times. In short, it is a drive-train that permits all the four wheels to incur torque from the vehicle's engine.

The best part about 4WD is that the system avails an option to switch over to the engine's all wheel drive anytime while driving. It's called an interchangeable system and majority of the vehicles manufactured today do not offer this feature at all.

All the other vehicles either offer a sole front wheel drive or rear wheel drive system. This is why we need to learn all the major components and working of a 4WD.

Speaking of the main components of 4-wheel drive vehicles, there are two differentials; the rear and the front and there is the transfer case. What is more to components is the part-time system which consists of locking hubs too. The above mentioned systems have high-end electronics which avail the traction to the utmost.

In the debate of AWD vs 4WD, an AWD (all wheel drive) system is one of the types of four-wheel drive systems which is usually driven full-time on a dry sidewalk as well as on ordinary road without scathing the drive-train.

Many people are confused about the concept of these two systems. However, they are similar to each other but not identical. So to briefly state the differences between the two, here is some information on an all wheel drive system and a four wheel drive system.

In an all wheel drive system, the center differential cannot get locked nor can the system get disengaged. And because of the center differential a car is able to receive the power from the engine and accelerate ahead. Hence vehicles having an all wheel drive system is mainly used on a dry sidewalk.

This system is mostly seen in vehicles which have wheels more than four, like trucks and SUVs. In such vehicles, all the wheels are powered at all times. As mentioned earlier, this system has a center differential that evenly splits power to both the axles, i.e. front and rear axle.

However, when the vehicle suspects an irregular condition, perhaps a slippery road or whatsoever, all the power is instantly transferred to the other axle in a matter of few seconds.

Nevertheless when it comes to a 4WD system, the concept is usually referred to as a part-time system. These systems are generally meant for ideal and extreme (low-traction) conditions like ice, snow, mud and rain as well.

As aforementioned, the 4WD is a part-time drive system, which powers all the four wheels just when the 4WD mechanism is engaged. It is generally seen that, in horrible weather conditions or even ideal conditions, just to lessen the wear and tear of the drive-train, the system powers the rear wheels at this time.

This in turn increases the fuel economy of the vehicle. In 4WD vehicles, all the power from the engine is transferred to the transfer case which is assembled on the rear of the transmission. In this assembly there is something called drive shafts that are linked to both the rear and front differentials of the vehicle.

Hence in the system it is the transfer case that evenly separates the torque in the vehicle, i.e., 50% to the rear and 50% to the front drive shaft.

On the contrary, when the four wheel drive is operated, all the power is engaged straight to the front and the rear wheels of a car. So the next time if you have any confusion regarding the working of a 4WD or an AWD, you can always refer to this content here!