|
March 11, 2010
Electronic Stability Control
Tires and Electronics
Electronics have invaded the world of traction. Does this mean good tires are no longer important? Should tire vendors stand aside and let computers take over?
Three electronic tools have enhanced the ability of drivers to manage how their tires interact with the road:
• ABS: Anti-Lock Braking System (from the German antiblockiersystem)
• TC: Traction Control
• ESC: Electronic Stability Control
Most people do not understand how these systems work and how tires are a key component necessary to make these electronic tools function properly.
Antilock Braking Systems
ABS prevents wheels from locking up during braking. Locking individual wheels can cause vehicles to lose steering control and spin or slide aimlessly. Wheel speed sensors detect impending wheel lockup. ABS then pumps brakes rapidly to prevent individual wheels from locking. Advanced ABS technology varies hydraulic braking pressure to the wheels, balancing braking forces in response to available traction. Advanced technology may also sense panic stops and help the driver apply extra braking force.
Many people wrongly believe that ABS shortens braking distance. This depends on the road surface. On loose surfaces such as gravel or snow, ABS can significantly increase braking distance because locked wheels can build up a ridge of loose material in front of the tire that helps slow down the vehicle. The main benefit of ABS is to maintain steering control during hard braking.
Traction Control
Traction Control does for accelerating what ABS does for braking. Traction control detects when one wheel is spinning faster than the other. Most TC systems then use ABS to apply the brake to the faster wheel to balance traction between the drive wheels. This helps drivers get moving in low or uneven traction situations and accelerate under control.
Electronic Stability Control
Electronic Stability Control uses the ABS system to maintain steering control. It works whether braking, accelerating, or coasting. ESC detects understeer (when the front end slides out in a curve) or oversteer (when the back end slides out). Then ESC instantly and automatically brakes one wheel to help steer the vehicle where the driver intends to go. (Imagine dragging one foot to help steer a bicycle.)
ESC does what no driver can do, instantly detecting and correcting skids, typically applying individual brakes and reducing engine power before the driver realizes the vehicle has skidded. ESC works at high or low speeds, on bare pavement or slippery roads, in summer or winter, and for small passenger or large commercial vehicles.
ESC is so effective that it is called the greatest safety innovation since the seatbelt. The Insurance Institute for Highway Safety reports that ESC prevents:
-
40% of single-vehicle crashes
-
56% of fatal single-vehicle crashes
-
77-80% of fatal single-vehicle Rollovers
The role of tires
So, with all this fancy electronic wizardry, what is the modern role for tires? Well, traction still depends on the tiny contact patches where the rubber meets the road. These electronic systems work within the limits of available traction. ESC does not improve traction or enable vehicles to corner faster. Even though ESC offers a spectacular improvement in safety, proper tires are required for ESC to achieve its full potential.
Tire vendors know that, in winter, proper tires means winter tires. Typical “all season tires” are not really designed for all seasons because they harden in the cold. Hockey pucks stored in a freezer have reduced friction coefficients; that is, they slide. Frozen hockey pucks also lose elasticity so, when deformed, they do not return quickly to their original shape; that is, they don’t bounce back. All season tires generally suffer reduced performance when temperatures dip below +7ºC. However, winter tires are made of soft rubber compounds that maintain elasticity and grip in the cold.
How do ESC and winter tires work in real life? As a driving enthusiast, I realize that my grip on life becomes tenuous when snow, ice, slush, and water separate my tires from the asphalt. Blizzards, darkness, and dangerous drivers add to the challenges, making winter driving a death-defying experience.
The best investment I ever made was a new vehicle with ESC and top-quality winter tires. ESC, by itself, was very effective up to a point. However ESC alone only worked while I had traction. Winter tires, without ESC, worked as long as I had time to plan my manoeuvres. The combination of ESC and winter tires has transformed my winter driving, saving me from human errors and reducing the stress of winter driving.
The role of tire vendors
ESC is sweeping the market. Laws in Europe, Australia, and North America will soon mandate ESC (effectively including ABS and TC) for all new passenger vehicles. ESC is widely available from all auto makers, and some insurance companies are offering premium discounts for ESC.
For these systems to accurately monitor wheel speed, tires should be even. That is, unequal diameter or air pressure may fool the sensors, perhaps thwarting the driver’s intentions. While high technology improves safety, it also raises the responsibility of tire vendors to understand and inform motorists about the importance of proper tire maintenance. And electronics enhance the potential for appropriate (summer or winter) tires to perform like never before.
ESC is sold under many trade names such as Electronic Stability Program, Vehicle Stability Assist, Vehicle Dynamic Control, Stabilitrak, and Advance Trac. To see a list, Google “Names of ESC.” The following links take you to more information or videos on ESC:
The following link takes you to information and a video on winter tires:
www.tc.gc.ca/roadsafety/safevehicles/safetyfeatures/wintertires/
Glen Nicholson is a Prince George lawyer working to mandate and raise awareness of ESC in Canada. He is an independent safety advocate with no financial interest in ESC.
| |
Glen Nicholson
