Audi 100/A6

1990-1997 of release

Repair and car operation

14.16.2. ABS: a natural choice

THE GENERAL DATA

To formulate appointment ABS it is simple – it interferes with blocking of wheels at braking. The brake pedal is too strongly pressed? It doesn't matter – electronics, comparing signals of gauges of speed of rotation on each of wheels, defines the moment of a sudden stop of a wheel and, opening the electromagnetic valve, dumps surpluses of pressure from a brake highway in the special hydroaccumulator. Brake колодки are unclenched, wheel rotation is restored, the valve connects again a highway to pressure which by means of the vacuum amplifier of brakes is created by the right foot of the driver. And if this pressure is still too great, the cycle repeats again and again. In salon inclusion ABS is shown by a crash at work of the executive block and pushes on a brake pedal, more or less appreciable depending on a system design. Actually, ABS simulates actions of the skilled driver which on slippery road avoids blocking of wheels, using faltering braking. But ABS does it with frequency inaccessible to the person and accuracy – to 15 times a second.

As a result of ABS should not only provide to the car the minimum brake way, but also force it to answer the helm – after all wheels slide and perceive lateral force, coupling of tyres with a covering how much allows. Also it is the basic advantage ABS. After all in case of blocking of wheels the car it is uncontrollable slides directly, even when the steering-wheel is turned out against the stop.

FEARS

It would seem, all is already clear. Antiblocking systems are recognised by all civilised auto world and already became the standard equipment on cars, since middle class. But voices of the dissatisfied are often distributed also.

"No electronics will be compared to the skilled driver, – tell one. – give me the same car without ABS, and I will stop earlier!"

Another do not like that ABS, interfering with braking process, absolutely excludes participation of the person. As press on a pedal, it with not palatable vibration will be back pushed out. The car brakes itself, to affect a delay course it is impossible in any way, besides with ABS it is very difficult to calculate a brake way and to predict, where the car will stop. It is necessary to wait only... Intolerably for the driver, got used to own a situation!

And the third nod on раллистов. A pier, not without reason those are afraid ABS, as of a plague! And to them, sportsmen, more visibly...

The gauge of speed of rotation of a wheel settles down in a nave

TO DISCONNECT NOT DISCONNECTED

To place all in places, we have gone on a technological crime. Have found under a cowl the tip which approaches to executive block ABS, and have pulled out it from a nest, having forced to light up yellow контрольку ABS and is disturbing to start blinking a red bulb of brakes in a combination of devices. So we deactivated not disconnected antiblocking system. Tests passed under such scheme. We have chosen four basic exercises: braking on a straight line – on the homogeneous and mixed covering (миксте), in turn and during an obstacle detour (that is at performance of maneuver the rerate). Passat have equipped with a data-acquisition equipment precisely measuring speed and a brake way. And at the wheel there were our experts-verifiers. However, some of exercises were offered for making and to usual drivers of the most different qualification – from the beginning motorist to the skilled professional. All could be trained before control arrivals, get used to the car and "adjust fire" to the next maneuver.

Each exercise carried out in two series. At first did more than ten arrivals with working ABS, then disconnected system, and the car hastened again to the line of the next maneuver marked by bright landmarks.

HOW TO BRAKE?

With antiblocking system all is simple: you wish to receive the greatest possible delay – a bog, without thinking twice, a pedal in a floor. And how to brake without ABS?

At first we have tried to do all "under the theory" – to brake on the verge of blocking of wheels. Does not leave! Too sensitive фольксвагеновская the pedal does not allow to dose out precisely brake force – and we are mistaken, and both in that, and in other party. And it in quiet conditions. And try to make it in an extreme situation when failure threatens!

Then we have applied the tested way – faltering braking.

And for comparison tried, without philosophising crafty, to brake "in a floor", with blocking of wheels. In what a difference? On a straight line the main difference – in course stability. Especially brightly it was showed at braking on миксте. Under the left wheels there was a wet asphalt, and under right – a snow-covered roadside.

Braking with blocking of wheels

1. Faltering braking 2. Braking with ABS 3. The braking beginning, speed of 64 km/h

With included ABS the car at first starts to withdraw towards a covering with the best coupling, but electronics works regularly: Passat it is instantly levelled and further brakes on a straight line, practically without demanding подруливаний. During faltering braking without ABS to the driver it was necessary to taxi up a little, and the brake way has appeared more.

But with full blocking of wheels the car braked almost as effectively, as with ABS. But thus it sharply developed to the left on a dangerous corner – to 40 °! Prize ABS here is obvious.

COVERING SURPRISES

Ice happens smooth, as a mirror, and rough, as a sandpaper surface. Snow happens dense, unrolled, friable, bound together, frozen together...

To what it we? And to that each covering has the specificity, and after our tests to give an unambiguous answer on a question interesting all – in what conditions the brake way with ABS will be less, than without it – we cannot!

Variants weight. For example, when at numerous stops on the same straight line of a wheel of our car накатали a track of the rough ice crumbed by thorns the brake way with ABS and without it with the blocked wheels has appeared almost identical. Not without reason our sportsmen say that the most "tenacious" covering – not asphalt, and исполосованный "nails" an ice track. And on snow – here so a surprise! – the car with ABS stopped a bit later. All the matter is that on a snow covering the coupling factor has appeared more low, than on rough ice – thorns here work not so effectively. For ABS, probably, it has appeared unprofitable. But at "usual" faltering braking (has pressed – has released – has pressed) during blocking of wheels before them the snow platen which helps the car to be slowed down more intensively is formed. Work ABS interferes with wheel blocking – and the platen it is impossible.

BE NOT AFRAID TO TWIST THE WHEEL!

Imagine quite real situation: before you in slippery turn suddenly brings the truck, and it is developed across by roads. Or another: from lateral journey on rather narrow street directly before a nose the car jumps out and partitions off your strip, leaving free only counter.

On a wave of the adrenaline which has rushed in blood the driver in panic, reflex, with all the might will press a brake. Wheels will be blocked. And with the blocked wheels the car in the first situation will take off outside of turn, and for the second – врежется in an obstacle. For without ABS to avoid failure faltering braking will help only, and here from the driver it is required not only outstanding composure and endurance, but also uncommon skill.

And here our example. The most experienced expert needed to call to the aid all ability that, alternating strictly dosed out pushes on pedals of a brake and exact work as a wheel, to repeat and even hardly to surpass results of the same maneuvers with ABS.

But what from that? After all even the verifier needed to make for this purpose more than ten ranging arrivals, and in a real situation the chance will be only one! And electronics here will work reliably and in the blessing.

At braking in turn the problem of the driver in general was the elementary: has pressed a brake, has turned a wheel – and the car, accurately tracing the set trajectory, it is intensively slowed down. It is accessible to any. It is important to remember only that during braking with ABS by car it is possible and it is necessary to operate. Has not frozen to compress a wheel, and dared to operate with it!

At an obstacle detour (we braked at performance of maneuver of the rerate familiar to our readers) the situation was such. When speed of performance of maneuver has come nearer to limiting, after an obstacle detour drift of a back axis started to develop. It was both with ABS, and without it. But using ABS, it was possible to reduce speed so that drift was not so sharp both deep. And the brake way after a detour on 15 metres was shorter. Essentially!

However, to be kept on road, at drift correction it was necessary to release a brake pedal even at working antiblocking system. Why? We do not argue, ABS leaves possibility to change a trajectory at emergency braking, instead of to slide on a straight line with the blocked wheels. But at struggle against drift work ABS too reduces efficiency of correcting actions by a wheel. And even to those drivers, whose cars are equipped ABS, in similar situations it is necessary to be ready for an instant to release a brake pedal, meaningly having refused electronics services.

Car-revue

ABS it is worthy a hymn! Also the head from bewilderment is turned: how probably such? In cold winter evening, yes on slippery road, yes on decent speed it is possible to throw simply a wheel and stupidly to stamp a foot on brakes – and not крутанет the car, will not throw aside, a swallow... It only it is impossible to touch defect with impunity, and to a brake pedal by the car with ABS – it is possible! But it is cautious...

The delight and horror, horror and delight are tested by the "green" driver. Delight clearly from what – from sensation of permissiveness. And horror - from a deep-rooted presentiment "and suddenly?" Suddenly will not work ABS? The cord on a swing breaks! Wires of gauges of system ABS on wheels – by the way, a principal cause of its breakage break also.

Yes is not present, brakes continue to work, but unless as before? And here there is a question how this works ABS – antiblocking system of brakes?

In brief so: electronic block ABS by means of gauges watches speed of rotation of wheels in a braking mode. And operates effort of braking to each wheel so that the car kept straightforwardness of the movement to a full stop. That is you press to yourselves on a brake pedal, and the clever car to impropriety itself redistributes efforts of braking between wheels for their simultaneous stop. The brake pedal by the car with ABS unusually shakes, as though leads the life (not to confuse to curve brake disks, absolutely another подрагивание).

And if does not shake? Means, system ABS "has died", nobly having lighted before death on the instrument panel a display lamp "ABS" usually red, occasionally yellow colour.

In a normal mode at inclusion of ignition the inscription "ABS" should go out through нескольку seconds after regular self-diagnostics of block ABS (at some cars a display bulb "ABS" dies away if slightly to pass).

So: burns, does not die away "ABS"! That will show the specialised computer at connection of your concrete car, we do not know. Volumes of books about that are written, moreover and on years the different. Cases unusual enough are recollected, i.e. "Tasty".

Action 1. The inscription "ABS" that burns, does not burn. Variants of unpleasant behaviour of indicator "ABS" a little, and interesting – such. Полуось fastens in the bridge a cutting washer and more anything. Полуось has worn out, the washer "was ate" – both that, and another purely Russian illnesses – and now полуось is capable to leave from under the car together with a wheel. System ABS gauge strong costs on a bridge stocking, and faulty полуось goes by it there-here.

The owner of the car, clear business, feels nothing, but bulb blinking "ABS" disturbs him. Полуось rotates on a place, the gauge reads out from it a signal, ABS works. The car has turned, has jumped up and so forth – полуось leaves a bridge stocking, gauge ABS signal vanishes, system ABS finds out malfunction and lights an emergency lamp "ABS".

And all делов was to pull at a wheel.

Action 2. The complaint has arrived: the bulb "ABS" is lighted. Modestly we ask:

– And with car something did?

– Yes is not present, here headlights has put, and all.

It already "зацепочка". Not at once it is found out that capacity about Niagara Falls "expert" has connected headlights directly to block ABS. At their inclusion not only that planes go off-course, but also vanishes or pressure of a food on the electronic block of system ABS "sits down". Here he also does not wish to work, cannot. But it is a lot of light.

Action 3. Unusual, from a series "never trust the client". The circle "ABS" is lighted, then goes out – everything as it is necessary. But it is necessary to pass two-three metres – it is lighted. That is, system ABS informs that a pier – it is bad to it.

There is no urine, there are no forces to "fulfil" correctly ABS! Well all have checked up – there are no breakages. And suddenly, absolutely casually we look out for a gear on a semiaxis from which gauge ABS reads out speed of rotation of a wheel. On one semiaxis it differs from the others – because not that year release, and on it it is less than teeths. The system of tracking speed of rotation of wheels also "goes mad", as on its electronic concepts the wheel turns "incorrectly". And the client, as always, costs on the: assures that with its car anybody never did nothing!