Image Gallery: Car Safety
Image Gallery: Car Safety

Image Gallery: Car Safety Cars spray water in downtown Auckland, New Zealand, as they drive through deep puddles during heavy rain.

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Introduction to How Traction Control Works

When it comes to driving safety, we all know the basics. Start with an alert driver -- one who hasn't been drinking or who isn't tired -- then add in some safety and regulatory devices. Safety devices are things like seatbelts, air bags and crumple zones that keep drivers and passengers safe in an accident. Regulatory devices are safety features that help regulate a car, truck or SUV's travel, keeping it under control, even in extreme or adverse driving conditions.

When it comes to driving safety, one of the most misunderstood features available today is traction control. It sounds simple enough. From its name, you can guess that traction control has something to do with traction and controlling it. But in actuality, traction control is a sophisticated system that manages one type of traction (yes, there is more than one kind) in specific situations. If you're stuck in deep snow and ice, traction control won't help you, but in other situations, it definitely will.

Keep reading to learn how and when traction control works to keep you safe.

The Toyota Mark X is driven to demonstrate its VGRS safety system. VGRS, which stands for variable gear ratio steering, controls steering, braking and turning of the tires to reduce spinning and skidding when braking and turning on slippery surfaces.

AP Photo/Koji Sasahara

Traction Control Explained

At their best, regulatory devices work seamlessly, without any input from the driver, to enhance driving safety. Safety and regulatory devices work in concert to help the driver avoid accidents and protect occupants if an accident does occur. However, traction control and other devices are no substitute for driving safely. Rather, they work best when a safe driver encounters an extreme situation.

Traction control is a system that's becoming more common on modern cars. As its name implies, traction control manages the car's traction. Traction, as you probably know, is the friction the car uses to get going, stop and stay on the road. Think about traction like this: We've all worn sneakers with rubber soles, right? It's pretty hard to slip in sneakers, because the rubber soles give good traction. However, just because slipping in sneakers is rare, that doesn't mean it doesn't happen. If you wear sneakers on ice, wet leaves or if you're running fast while making a turn, you can still slip. Your car's tires are like its sneakers. Most of the time, the tires provide plenty of traction. But in certain situations, they can lose traction -- and that's where traction control steps in.

This might surprise you, but the system in your car that traction control has the most in common with is the anti-lock braking system (ABS). When you brake hard in a car, there's a risk that the tires will lock up; that is, instead of rolling to a stop, the tires will freeze, and start skidding. When a tire skids instead of rolls, the odds of the driver losing control are pretty high. ABS lowers the risk of a wheel freezing up by monitoring the speed at which all the wheels are rolling. If one stops rolling, or rolls at a different speed than the others (a recipe for a skid), ABS steps in, corrects the braking pressure and gets everything moving at the same speed.

Traction control is basically an anti-lock braking system in reverse. Anti-lock brakes prevent the wheels from locking up when the car is decelerating. Traction control keeps the wheels from locking up or skidding when the car is accelerating. When you step on the gas, a lot of power gets routed to the car's wheels, and that can sometimes cause a skid. Think about trying to go from a standstill to an all-out sprint while wearing sneakers -- it's easy to slip, especially if you're accelerating on a slick road.

Click over to the next page to see how all the parts of traction control work together to keep you in control when your car is accelerating.

This Lexus GS makes good use of complex engineering to keep the car straight and deliver a safe ride.

AP Photo/Koji Sasahara

Traction Control Components

Like all safety and regulatory devices in your car, traction control has a number of parts that work together to make sure you're driving safely. As mentioned on the previous page, traction control is basically ABS in reverse; it enhances driving safety by keeping your wheels from slipping when you're accelerating. Even older model cars had a rudimentary traction control system. Ever see an old, rear-wheel-drive muscle car peel out of a parking lot? If the rear end swayed and fishtailed all over the place, that car probably didn't have a limited-slip rear differential. A limited-slip rear differential keeps the car's two rear wheels (where the engine's power is going) turning at the same speed. Limited slip rear differentials are still used in powerful rear-wheel-drive sports cars, but traction control is a much more sophisticated system that's used in all types of cars.

In a basic car setup, there's a mechanical linkage between the throttle and the accelerator pedal. Sometimes, that mechanical link is replaced with an electronic drive-by-wire system. That means that, instead of a direct link from the pedal, to the throttle (which increases the engine power, and thus the force applied to the wheels), you have an electronic connection that sends signals to a sensor. The sensor translates the pressure you put on the accelerator into an electric signal that gets sent to a control unit. The control unit reads the input as well as the feedback from the wheels and routes power to the wheels according to the driver's input and whether or not the wheels are slipping. In cars with traction control, the hydraulic unit that controls the ABS system also gets a traction control component. If the sensor detects too much wheel slippage, it can use the hydraulic ABS unit to apply braking pressure to some (or all) of the wheels.

All of these components work together, constantly monitoring driver inputs and wheel slippage and reacting in a split second if a slippery situation is detected. As a driver, you may notice a traction control light on your dashboard when the system activates, but for the most part, if it weren't for that light, you might not even know that the system was there.

Up next, learn about the benefits of traction control.

A Chevrolet Camaro burns its tires alongside a Navy fighter jet during a demonstration on the flight deck of the USS Midway in San Diego, Calif.

AP Photo/Lenny Ignelzi

Benefits of Traction Control

When it comes to driving safety, safety and regulatory devices like traction control are easy to take for granted. After all, if they work well, they typically operate so seamlessly that you may never even know that they're active. Plus, since traction control works when your car is accelerating, it's easy to see it as a less than useful system. Because really, if you're just accelerating and aren't already going fast, how much damage can you do? The answer is plenty.

Traction control is most evident when you're accelerating from a stop. And while you're likely to not be going very fast in those situations, having your wheels spin can still cause you to lose control of the car and potentially cause significant damage to those around you, too. Traction control is particularly beneficial when roads are wet, slick or icy. Rather than the driver having to feather the gas pedal and guess the correct amount of power to send to the wheels, traction control can step in. It seems like whenever there's a snow storm, there's plenty of local news footage of cars spinning their wheels as they leave stoplights. Traction control can help keep that from happening.

Traction control is also particularly helpful when you're driving a powerful car. Tromp on the gas of a powerful car, and you're likely to set the tires spinning and the car into a skid in a direction you didn't intend on. Traction control regulates the power to the tires, keeping the car on the path you set. While a truly bad (or reckless) driver can overcome traction control, for most drivers, it's a system that helps keep them on track and in control.

For more information about traction control as well as other safety and regulatory devices, follow the links on the next page.

Lots More Information

Sources

  • J.D. Power and Associates. "Traction Control." (Nov. 19, 2009)http://www.jdpower.com/autos/articles/Traction-Control
  • Memmer, Scott. "Safety Tips: Traction Control." Edmunds.com. (Nov.19, 2009) http://www.edmunds.com/ownership/safety/articles/46352/article.html