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Tuesday / 27 July 2021
HomeFeaturesThe difference between four-wheel-drive and all-wheel-drive

The difference between four-wheel-drive and all-wheel-drive

There is a good chance that you have heard the terms four-wheel-drive and all-wheel-drive before, and thought they were the same thing.

While both drivetrains do turn all four wheels of a vehicle, there are key distinctions that set them apart.

We explain these below.

All-wheel-drive

All-wheel-drive (AWD) configurations drive all four wheels of a car, but oftentimes there are two variations of this drivetrain.

The first is referred to as permanent, or full-time, all-wheel-drive.

In this configuration, drive is normally sent to the wheels that need it most, rather than every corner receiving an equal ratio.

This allows the vehicle to adjust power delivery to best suit the surface conditions at that moment, thus maximizing grip in every situation.

Another interpretation of the AWD drivetrain is the part-time, or automatic, AWD system. These vehicles are able to power all four wheels, but function in two-wheel-drive the majority of the time.

Depending on the vehicle, the driver will be able to adjust torque delivery manually, or the car will sense that it needs additional traction and then activate the second pair of wheels.

Cars in South Africa with all-wheel-drive systems include:

Four-wheel-drive

While the four-wheel-drive (4WD) drivetrain also sends power to all four wheels, it generally sends an equal amount of power – more or less 25% – to every wheel at all times.

This variation is often used in more robust vehicles like bakkies and ladder-chassis SUVs – and comes in various shapes and sizes, too.

As with the AWD system, permanent and part-time modes are on offer – but the ability to install 4×4 low range gears are also available.

A vehicle with this feature comes equipped with a transfer case that houses a set of low ratio gears where the gear that is attached to the transmission, also known as the pinion gear, has fewer teeth than the one it is turning.

This causes the pinion gear to spin at higher revolutions than the rest of the cogs, which significantly increases torque at the wheels.

The low range mode of operation is ideal for towing heavy loads, slowly navigating harsh terrains, and conquering steep inclines.

High-ratio gears are then better suited for tricky situations where more traction is needed than what two-wheel-drive provides, such as on muddy or icy roads.

Cars in South Africa with four-wheel-drive configurations include:

Pros and cons

Both these drivetrains offer noteworthy advantages over the two-wheel-drive layouts used in most cars.

They are better equipped at handling adverse conditions both on-road and off-road, and will often increase the car’s utilitarian abilities such as maximum load and towing capacity.

However, they do come with a set of drawbacks – which mostly impact price.

Vehicles with these drivetrains are generally more expensive than two-wheel-drive models, and out-of-warranty service and maintenance costs are usually higher, too.

Additionally, depending on the make and model, the robust drivetrains may have a negative effect on ride comfort and fuel economy.

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