More Canadian shoppers than ever are seeking out vehicles with all-wheel drive (AWD), and automakers are working to appeal to these shoppers in many new and clever ways. In recent years, the technology and engineering available to automakers has expanded greatly – and AWD systems have advanced as a result. Today, modern AWD systems are faster, smarter, more efficient, and more effective than ever.
Below, we’ll look at some high-tech tricks and treats and enhanced functionalities that are becoming increasingly popular in the AWD scene – as well as a primitive bit of AWD tech that’s still working well for at least one major AWD automaker.
Mazda’s i-ACTIV AWD
Mazda might not be the first brand that comes to mind when shoppers think of AWD, though they do offer some of the most advanced AWD technology on the road today. Mazda’s i-ACTIV AWD system is computer-controlled, and constantly monitors numerous inputs – including outside temperature, speed, steering angle, and even the currently selected wiper setting – to help the system make better choices about enhancing traction and control.
The heart of the i-ACTIV AWD system is a part called the centre coupler, which uses electromagnets and clutches to meticulously alter the amount of power delivered to each axle. As quickly as you can alter the voltage flowing through a circuit (instantly), the centre coupler can clamp up or release its internal clutches, seamlessly tailoring traction to the conditions in real time.
And how’s this for slick: each power coupler unit is bench-tested and analyzed before being installed to a vehicle. The tests detect minor performance variations caused by slight manufacturing differences, and test results are pre-loaded into the vehicle’s computer system, which fine-tunes the responsiveness of the system for the specific characteristics of the specific power coupler in use. This is key in i-ACTIV AWD’s ability to work with incredible precision.
Using AWD can reduce fuel economy, partly because various parts and components related to the system are still engaged and spinning away, even when the system isn’t powering all four wheels.
Chrysler (FCA) was one of the first automakers to quell this problem, with a feature called Front Axle Disconnect. In simple terms, when all-wheel traction isn’t required, this system physically disconnects the front axles from the AWD system, eliminating fuel-sucking drag. This translates into fuel savings, and the system can re-engage the axles in milliseconds when needed for maximum traction. Numerous other AWD systems give drivers added control over their currently desired blend of traction and fuel economy via selectable AWD system drive modes, and the ability to switch the AWD system off with a button-press when it’s not needed.
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Automakers like Ford, Hyundai, and many others use a clever bit of programming to enhance AWD traction when it’s needed most: from a dead stop. In older AWD vehicles, and even some new ones, some amount of wheelspin is required at one axle before the other is engaged. This means that you’re stuck, for just a moment, before full traction comes online.
With modern AWD system hardware and computer programming, AWD systems are getting smarter – combating this problem with a simple bit of computer code. When the vehicle detects a speed of 0 km/h, the AWD system is pre-engaged, generating four-wheel traction from the first inch of movement. If traction is plentiful, the system quickly reverts to two-wheel drive to save fuel. If things are slippery, the AWD system remains engaged for maximum grip. From the driver’s seat, you get grip galore, each and every time you set off.
The Viscous Coupling (AKA, the Caveman Coupling)
The viscous coupling AWD system is a primitive and low-tech approach to powering all four wheels – and it works so well, without any computer input, that some automakers still use it today. In the past, this setup was even used by Lamborghini to power all four wheels in some models, and today, one version of Subaru’s Symmetrical AWD system uses a viscous coupler at the centre of the action.
The viscous coupler is a small cylinder that contains a series of plates. Some of the plates are attached to the front axle, and others are attached to the rear axle. The plates within the coupler are submerged in a special silicone-based liquid with a secret ability: when one set of plates starts to spin faster than the other, the silicone liquid thickens up.
Here’s how it works: When the axles (and therefore, the plates attached to them inside of the coupler) spin at different speeds, a shear effect thickens the silicone liquid, which sort of glues the two sets of plates (and therefore, the axles) together, for added traction. As traction is regained, the axles spin at the same speed, and the silicone fluid “releases” the plates from one another, until additional traction is needed again.
AWD Handling Heroes
Though AWD is commonly viewed as a wintertime feature, many automakers use it to help improve vehicle handling and responsiveness in all conditions. Many AWD systems employ a strategy called torque vectoring, in which the distribution of power across the front and rear axle is manipulated.
For instance, by sending more power to one rear wheel than the other, the torque-vectoring AWD system can help turn and steer the car. Special sensor networks monitor numerous variables, and fine-tune the power delivery to each wheel to enhance handling and control. Many modern AWD sports cars rely heavily on torque vectoring AWD to generate a signature handling feel, even on dry pavement.
Acura has a system that goes a step further. Their patented Super Handling AWD system, dubbed SH-AWD, can even spin one rear wheel faster than the other to help “push” the vehicle around corners in spirited driving, and even enhance steering feel.
Some automakers use torque-vectoring AWD in sync with the latest in hybrid technology, which may see the front wheels driven by the gas engine, and the rear wheels driven by an electric motor.
Audi Quattro Ultra
Audi is one of the world’s foremost AWD manufacturers, and their well-known AWD system is known around the globe as Quattro. The latest in AWD technology and innovation have allowed the Quattro system to evolve, and today, Audi is equipping various models with the next-generation Quattro Ultra system.
Quattro Ultra is defined by several advancements. Key among them? Special clutches allow for total disconnection of the rear portion of the drivetrain and axles to save fuel when required, and an intelligent control strategy allows full traction to be re-enabled in the blink of an eye. Often times, even in the snow, AWD traction isn’t needed – for instance, while cruising at a steady speed. In situations like this, Quattro Ultra can disable and disconnect the system, saving fuel.
But here’s the interesting part: where many advanced AWD systems stay off until the vehicle finds some reason to turn it on, Quattro Ultra works the opposite way. Effectively, the system leaves AWD traction engaged, until there’s enough data to validate switching it off. The result from the driver’s seat? Seamless traction, fuel savings, and no compromise.