ONE of the most dreaded feelings for a driver is loss of traction. Whether it be under braking or under acceleration, the feeling is like driving on ice.
The main causes are slippery roads due to rain or other fluids on the surface or, more likely, worn out tyres. It used to be that a driver had to resort to feathering the accelerator or brake pedal to overcome the situation (if there is time, of course) but nowadays a lot of cars (and bikes) feature anti-lock braking and also traction control.
We covered anti-lock braking systems (ABS) in the previous article and traction control systems (TCS) are very closely related to ABS. In fact, it is fairly simple for a manufacturer to add a traction control system if the vehicle already has ABS.
Both systems work on similar principles and use the same sensors but override different systems to achieve the desired result.
In a nutshell, TCS limits tyre slip on slippery surfaces during acceleration. The four wheels of a car may move at different speeds at any different moment so TCS acts on each individual wheel as needed.
The TCS processor (most of the time it is integral with the ABS unit) brakes the wheel individually to maximise traction and keep the car moving in a straight line (just like ABS but in reverse).
Just like ABS, the TCS processes signals coming from the individual wheel speed sensors and cross references the data against the accelerator pedal position and actual vehicle speed. This is one method that TCS employs.
A more sophisticated TCS system will also be able to control the amount of power actually transmitted to the wheels. Usually, these systems are fitted to extremely powerful cars that are able to spin their tyres at will.
A prerequisite to having such systems is a fly-by-wire throttle. What fly-by-wire means is that you are not the one pressing the accelerator pedal but the car’s Electronic Control Unit (ECU) is the one doing it for you!
The first few attempts at fly-by-wire by manufacturers were sometimes confusing as the ECU, too, was as confused as you were. Pressing the pedal would result in poor response or worse, no response.
But nowadays, it is as good or better than a cable connected to a carburetor (or throttle body).
The ECU now decides, based on your accelerator pedal movement and information from the wheel speed sensors, how much power would be transmitted to the wheels.
In effect, it tells the engine to accelerate as hard as conditions allow. It does this by processing the wheel speed sensor information and cross-references it against your needs, many times a second. It may even cut fuel flow or sparks to achieve this, in addition to actually controlling the throttle movement.
However, all you feel is the car responding to your needs in a smooth and straight line (or curved line, if you are in a turn). Amazingly powerful processors allow this magic trick without you ever knowing you were on the brink of disaster in that turn.
The question is whether these driver aids are actually helping or actually just a band-aid for unskilled drivers? If you were to introduce a driver used to these aids to a “normal” car, would he be climbing the nearest guardrail in the next corner? There is no definite answer to this question.
The next query would be on the reliability of these drivers aids. It used to be that some components did not last as long as those on your dad’s Corolla KE30, but then again, what does?
Many other “advancements” have come along since drivers aids and some have been better than others, witness the CVT transmission and electric/hybrid cars. It always takes time to iron out the best and most reliable components and with regard to drivers aids, most, if not all bugs have been ironed out.
There are many other drivers aids out there, from yaw control to electronic limited slip differentials and more are coming your way. All we can do at the shop is try to keep up with all the latest developments.
Excuse me, I have to attend to this dual-clutch thingy now.
See you soon!