A Simple Guide To All-Wheel-Drive and 4x4 Systems

by Chandrutpal Kashyap | 25/12/2020
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An all-wheel-drive or 4x4 setup is of utmost importance if a vehicle wants to go off-roading effectively. But how does it actually work? We have this brief guide to help you understand.

If you have been around vehicles in any form, then you most probably have come across an all-wheel-drive or 4x4 vehicle. As its name suggests, in a 4x4 vehicle the engine’s power and torque are supplied to all four wheels. Today, we at IndianAuto have got this simple guide to help you how a 4x4  or all-wheel-drive system works and why it is needed. For that, we must understand how a differential works first. Let us begin. 


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Differential, what is it?

A differential is a fully mechanical component in a vehicle and is one of the most important parts. The differential is found at the centre of both the axles in a vehicle. In can also be found at the centre of the shaft that connects both differentials. In simple terms, a differential’s purpose is to distribute the engine’s power and torque to the wheels. This lets the wheels of a car rotate at different speeds, which is very necessary. For example, when a car goes around a corner, the distance covered by the outside wheels is higher than the inside wheels. To keep the car stable, the wheels need to move at different speeds. The differential allows this and ensures the vehicle is operating smoothly.

4x4 or All-Wheel-Drive System

In a normal car, the differential is usually kept in an open state so the torque is divided equally between both wheels. However, an off-road centric vehicle usually gets the feature of a rear-locking differential. When you use this feature, it connects the two wheels together and makes them rotate with each other. This comes in handy when one tyre isn’t getting enough traction and there is no point in supplying power to that wheel anymore. When you lock the differential, all of the power can be sent to the one wheel which still has traction, helping the vehicle move.

Similarly, when a vehicle comes with three differentials, one for each axle and one in the centre, it offers a very wide range of flexibility on how to put down maximum torque on the ground. But when all the differentials are locked, it becomes an extremely complex procedure. The system recognizes the amount of traction each wheel has and supplies the torque accordingly. But such a complex setup means it is very expensive as well, which is why three locking differentials are only found in premium and hardcore off-roaders.

To keep cost in check while providing capable off-roading abilities, one or two of the three differentials are kept open. The open differential will not provide variable torque to each wheel but just split the torque equally. This ensures that it serves the purpose of an all-wheel-drive system effectively without getting prohibitively expensive.

4x4 and all-wheel-drive systems may seem similar at first glance and they mostly are, but there is a subtle but important difference between the two. In all-wheel-drive systems, all the wheels receive torque as and when the situation demands because of a centre differential. The entire system is very flexible. However, in a 4x4 system, there is a transfer case at the centre which is connected to the engine/transmission. This can be shut down entirely and the vehicle can become completely rear-wheel or front-wheel drive. This video from Wonder World on YouTube will give you a visual representation. 


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Both all-wheel-drive and 4x4 systems are the most important parts of any off-road centric vehicle. Dirt roads give a vehicle a completely different and variable challenge compared to the tarmac. The probability of one of the wheels not being in contact with the ground is very high when off-roading. This is why the ability to send power or torque to an individual wheel which is still in contact with the ground and can pull you out is a very relevant one.

We hope this brief explanation about 4x4 and all-wheel-drive systems has made it a bit easier for you to understand how they work.

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