Because cars have evolved to become very complicated beings, there are many different ways cars now work. You have cars ranging from 8 seats to 1, being powered by petrol, diesel, LPG, electric and so on. But one of the questions we hear the most is, how does 4×4 work? There are a whole range of different four-wheel-drive systems out there, and this is because every manufacturer wants to be unique and come up with the very best 4wd system.
Firstly, What Does 4×4 Mean?
4×4 is a term used when a manufacturer labels their car as 4 wheel drive. 4×4 – not to be confused with AWD (which we will come to later) – is a part-time system that is designed to be used in low traction conditions, such as off-road, snow and ice. But, how does 4×4 work? We refer to this system as 4×4 because it simply means all four wheels have power sent to them. For example, many not so powerful hatchbacks with around 100bhp will be given a 2wd system (front 2 wheels get all the power) meaning each wheel has 50bhp to deal with – where as if the same car had the same power but had 4 wheel drive, the wheels would only have to deal with 25bhp each, meaning less chance of wheel spin, and more chance of better grip.
The common layout for most road cars include an engine that is mounted in the front of the car, designed to power just the front wheels. The engine’s power will then be sent through the gearbox and onto the differential. Torque is applied to the differential and is sent along two drive shafts, which are joined to each wheel, causing them to rate in the direction you’re travelling.
All wheel drive systems are a little different, in AWD vehicles the power is sent through the gearbox to a centre differential. This then splits the power to the front and back axles where it meets differentials at the front and rear. These differentials distribute power between the rear wheels as well as the front wheels, equalling all wheel drive.
Difference Between 4 Wheel Drive and All Wheel Drive
4 wheel drive and all wheel drive might sound the same, but there are slight differences for example;
AWD cars – All wheel drive cars have constant power going to all wheels at all times.
4WD cars – 4 wheel drive systems have a temporary system that operates as two-wheel drive until a loss of traction is detected. The computers on board will detect the loss of traction and send power to all wheels to regain the loss of traction.
Different types of all-wheel drive
All wheel drive cars permanently send power to all four wheels, while four wheel drive vehicles only power all four wheels on occasion. An example of a 4WD car is the Skoda Yeti, while the Land Rover Defender is a typical all-wheel-drive car.
AWD cars tend to be for more specialised uses – for example – having all four wheels being powered at the same time is perfect for the avid off roader, this is because when you’re off roading you can’t be sure which wheels are going to be able to get any grip, meaning an AWD system will force all four wheels to spin, so you’re more than likely to get yourself out of an inevitable rut.
It is worth mentioning that many AWD cars this day in age, allow the drive to switch between two- and all-wheel drive – typically using another controller next to the gear stick.
Why Isn’t Every Car Four-Wheel Drive?
2 reasons: cost and efficiency. When a car is 4WD it will have extra drive shafts, differentials and electrical systems to keep everything under control – which adds more weight, while the losses through rotating these extra masses makes the vehicle less efficient, burning more fuel.