AA Car Care: How do ABS and ESC protect us?
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Ever since electronics have been added to motor vehicles to improve safety, one of the first systems to receive the benefits (starting in the late 1960s) was vehicle braking.
With the application of valves, solenoids, and speed sensors to a hydraulic braking system, it was given a “brain” that could control the amount of force applied and which brakes are activated. This function created what is now known as Anti-lock Braking System (ABS), and the more recent evolution, Electronic Stability Control (ESC).
ABS prevents the wheels from locking up during hard braking, maintaining tractive contact with the road surface and allowing the driver to maintain more control over the vehicle; it can also reduce the stopping distance.
ABS is an automated system that uses the principles of threshold braking (the optimal amount of braking force is developed at the point when the wheel just begins to slip) and cadence braking (pumping the brake pedal), techniques which were once practiced by racing/skilful drivers before ABS was widespread.
ABS operates at a much faster rate and more effectively than most drivers could manage. Early systems could pulse the brakes (up to 15 times a second) in order to prevent wheel lock-up and uncontrolled skidding of the tyres.
Since ABS was introduced in production vehicles, it has become increasingly sophisticated and effective. Modern versions may not only prevent wheel lock under braking, but may also alter the front-to-rear brake bias. This latter function, depending on its specific capabilities and implementation, is known variously as EBD (Electronic Brakeforce Distribution), TCS (Traction Control System), EBA (Emergency Brake Assist), or ESC (Electronic Stability Control).
ESC is a crash prevention system that assists the driver in reducing the risk of skidding or loss of directional control due to lack of traction. It’s also commonly known as ESP (Electronic Stability Program), VDC (Vehicle Dynamic Control) or DSC (Dynamic Stability Control).
This is similar to and often confused with traction control, but operates in a different way. ESC helps keep the car in control when the vehicle is in danger of going into a skid or slide. It does this by applying the brakes (ABS) to one or all of the wheels to keep the car pointed in the right direction. It may also cut engine power if the computer determines it will help maintain vehicle in control.
TC (Traction Control) limits wheelspin during acceleration. It does this by applying the brakes (ABS) to the drive wheels only when slip is detected. Just like stability control, it can also cut engine power if you get overzealous with the throttle.
The tech stuff
ESC uses data from sensors around the vehicle, including wheel speed sensors and the steering wheel sensor, to determine if the vehicle is starting to veer off the driver’s chosen path. The computer can then apply the anti-lock brakes to one or all of the wheels independently. It may also cut engine power if the computer determines it will keep the vehicle in control.
While there are limits to what it can achieve, ESC is very effective in assisting the driver to regain control of a vehicle in an emergency.
Upping minimum safety requirements for NZ
On July 10 2014 the Land Transport Rule: Light vehicle brakes 2002 was amended, mandating ESC for light vehicles entering our fleet. This was gradually implemented into various classes of imported vehicles. As of 1 March 2020, Waka Kotahi NZ Transport Agency has mandated that all imported vehicles new and used must be equipped with ESC.
So chances are that if you don’t have it currently, your next vehicle will have this important safety feature.
The requirement to have ESC will not apply to some specialist vehicles, such as vintage, motorsport and scratch-built vehicles. This is consistent with other Land Transport Rules.
How do I know if my vehicle is ESC equipped?
Vehicles fitted with ESC have an indicator light on the dashboard which extinguishes once the self-check process has completed. This feature activates when the ignition is switched on.
If the lamp remains illuminated, it may be an indication a fault is present and the system may not operate correctly. There may also be a separate button in order to turn the traction control off if needed (not recommended unless stuck in heavy mud or snow). The most common icon displayed to identify ESC is a silhouette of a vehicle with squiggly skid marks depicted under the wheels.
If in doubt about the system that may be fitted to your vehicle, consult the manufacturer’s handbook, or visit your local vehicle manufacturer’s representative for more information.