The biggest single advance in automotive engineering over the last couple of decades has been in the role that electronic technology plays in managing various functions. It started when electronic ignition systems replaced points and condensers, and from there simple engine management systems evolved into complex computers that now do everything from fine-tuning fuel-injection systems to altering the length of inlet tracts and adjusting camshaft timing and valve lift to suit changing conditions.
Automatic transmissions today monitor individual users’ driving styles, and reprogram gearshift points to suit different people, and traction control systems constantly override driver input when wheel sensors detect a skid or spin coming on. The car may apply the brakes to one or more wheels, back off the throttle, and delay an automatic transmission’s gear change until it feels the danger is past. Fortunately most of these duties are carried out so unobtrusively that the average driver doesn’t even know they exist.
One feature that is fast becoming de rigueur in even entry-level cars is anti-lock brakes, or ABS. Most motorists don’t realise that the biggest benefit of ABS braking systems is that they allow you to steer around a problem even with the brakes fully applied. In a typical rear-end accident scenario, the driver sees a problem looming and stands on the brake pedal as hard as he can. The car’s wheel’s lock up – especially in the rain – and the vehicle carries on at speed until it hits whatever’s in front. Any attempts to turn the car are futile – the wheels turn to the side, but the car carries on sliding in a straight line.
Experienced drivers use a technique well known to racing drivers to overcome this problem. Pumping the brakes as fast as possible when the wheels begin to lock up allows the front wheels to start turning again during the short periods that the brakes are off. Traction is regained, the car’s direction of travel is corrected, and when the brakes are reapplied speed is scrubbed off again until the next cycle begins. The problem with this is that most drivers find it very difficult to deliberately release the clamps even for a half second while they’re skidding towards the car that’s fast looming in their windscreen.
ABS brakes carry out cadence braking at a much faster and more effective rate than any human can – dozens of times per second. They also enjoy the benefit of working only on the wheel that is losing traction, while driver-induced cadence braking affects even the wheels that are still turning.
How does the system work? Wheel sensors monitor how fast each wheel is spinning, and the moment they detect that a wheel is locked they notify head office, a CPU that releases the braking on that wheel until it starts to turn again. The process is repeated until no more slippage is detected, whereupon the system backs off and allows the driver to resume full control. ABS systems intervene only when the sensors detect that a skid is starting, so a car with good tyres on a good road in dry weather will not stop any faster than a car without ABS. In bad conditions, though, ABS can reduce stopping distances by around 25%, and the driver will also be able to retain control of the direction the car is travelling.
As they say about guns, it’s better to have them and not need them than need them and not have them. You won’t be aware that your car has ABS brakes until they start working, and then you’ll be extremely grateful. When the system starts its high-speed cadence routine you’ll probably feel a rapid pulsing through the brake pedal, often accompanied by a devilish din – a grinding sound that makes you feel that something has gone horribly wrong mechanically. Whatever you do, don’t release the brakes when that happens, as some drivers do. You just make it harder for the system to catch up with rapidly changing events when you stand on the pedal again. Keep the brakes hard on, and don’t forget to steer away from the object you look like colliding with.
It’s also important to remember that in most situations ABS brakes won’t allow your car to stop any faster than it would with non-ABS brakes. In bad conditions they’ll be far less than a match for non-ABS brakes in the dry. They just make the situation a lot easier to handle when things go wrong. For that reason it’s important to always maintain a safe following distance. ABS brakes may be skid-proof, but they’re not idiot-proof.