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A question for the collective wisdom of the back room. I have heard it pop up here and there that drivers should avoid locking wheels by heavy breaking and instead try to mimic the behaviour of an ABS system. What is the ?proper? way of trying to re-create this effect and secondly is it ?more dangerous? to just break as hard as you can and lock up, or try to do a ?manual ABS? in the middle of the accident which will reduce your concentration on the road?
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Cadence braking to avoid wheel lockup was demonstated to me and practised off road as part of the training I was given to pass my first test. But I had a very thorough instructor.
Similar techniques are probably taught on more specialised training courses.
As to whether it is worth it...in a straight line skid to a stop it will reduce your braking distance, but it does require practise.
regards
Ian L.
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My "proper" training was of (and at) the Old School. (A long time ago!)
As part of that, we had to learn cadence braking.
To agree with Ian, it takes a lot of practice. And probably demo(s) to show you how.
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do you guys do it as second nature, or do you have to "think" to commence with the cedance braking?
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sorry one more thing, for one reason all my "brakes" have appeared as "breaks" !! either I am loosing it altogether, or its Bill Gates again....
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2 answers - "second nature" - no chance.
Took me HOURS to imprint on my little grey cells.
AND - have I done it on the road in the last 5-6 years? - Nope.
(With "real" ABS you just brake HARD. But how often do I do THAT? - Once a year?)
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Cadence braking is extremely effective on stopping a car without ABS. Braking hard to lock the wheels up means there is no longer any grip on the road and the car will take much longer to stop (or hit the object you are trying to avoid at higher speed). Once the wheels have locked there is also no steering available, so the need to keep the wheels rotating at maximum braking was the reason for the invention of ABS.
Aeroplanes have had the system since the early 60's (the HS748 had an ABS system called "Maxaret" which sounds like a good b******isation of French!)
I went on an Audi track driving day a couple of years ago. They had a stretch of wet tarpaulin laid on the track and we had to approach it at 50mph with two wheels on the dry, two on the wet and brake hard once on the tarpaulin. The ABS/ESP/ABD stuff had all been switched off.
The car spun about 3 360 degree turns and ended up goodness knows where with an emergency stop. We were then taught cadence braking and most people brought the car to a stop roughly in the right place. That proved to me that even a rough attempt at cadence braking works (my attempt was really rough!). The secret is to push the brake pedal as quickly and as hard as you can to lock the wheels then release it a tiny bit until the wheels unlock then push again. In reality I just pumped the pedal all or nothing and it seemed to work. Professional drivers can modulate the pedal right on the edge of the grip threshold and achieve a much better effect.
They then switched the electronic gizmo's on again and we tried one more time. The car stopped on a sixpence, exactly in line and in half the distance any of us did with the cadence method.
One of the problems apparently with ABS systems is that it's human nature to let go of everything and stop pushing the pedal just prior to impact. Exactly the time you still need to be decelerating and taking as much energy out of the car as you can. Hence manufacturers came up with "emergency brake assist" which holds the pedal down until you stop once it detects a rapid brake application.
Unless you have tried ABS and experienced the sensation, it can feel really unusual in some cars and lead a driver to believe there is a problem with the system and lead to them backing off on the pedal when they really need to keep that foot down.
I wish more "track days" concentrated on practical driving skills and experience like this rather than thrashing around a circuit trying to keep up with Lotus Elises etc.
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But 'track days' are meant for thrashing you car around a circuit/airfield.
What you are after is not a 'track day' by any means but rather a advanced/high performance driving course or skid pan training.
I have learnt both correct use of both ABS-equipped and ABS-free cars - switching between them regularly is a challenge as well!
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Had a good example of someone who needs to learn cadence braking at the weekend. I was in the process of overtaking a tractor when a car appeared around the next bend doing rather over the 60 limit. He slammed the anchors on in a cloud of smoke and started skidding towards the centre line. It was all rather amusing actually, as he was over 200 yards away at the time and I was starting to pull back in having passed the tractor. I was slightly worried that he was going to slide in to my lane more than anything else. I hope he didn't flat-spot the tyres on his boy-racer Corsa too much...
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Amin,
Type in 'threshold braking' in Google for yet more info.
Matt35
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guys thanks to all of you, very kind of you to reply. can I just add another side to the aspect of "safety" which was on my mind. Consider for example me trying to execute a cadence braking on my car which is a 10 year old AX. Can the braking system safely take the pressure which such an action will produce or will it fall apart? I mean can you "safely" execute cadence braking on older cars without fear of the braking system failing completely and leaving you with no braking what so ever, never mind locked wheels? I ask this because a friend of mine lost complete braking after the rear steel pipes ripped open and the system was depressurized within seconds. he said he only pressed it slightly harder than what would be considered a ?hard? braking, and I understand that it could have been something to do with his car, but per-say, in general, wouldn't you rather have a locked up wheel than no braking at all?
(PS. before you say, I am obsessed with these things and check my car all over every fortnight, so I am sure there are no rusts or anything like that and things are they should be, the question is, is that good enough?)
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With locked up wheels you might as well have no braking at all, especially in the wet. You'll get to the accident in either case pretty smartly.
Talking of "Maxaret" which someone was earlier, it was pretty lethal on the Trident, but kept Dunlop in the black for 20 years. Short runway + rain + maxaret = "bang bang" or if you were unlucky "bang bang" "bang bang"......... + tow truck.Oops!
Anti skid now nearly foolproof for yous of a nervous disposition.
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Well, could you believe it?
I've just had to do this today.
It was raining heavily today, after a long, hot dry spell.
I should have expected a layer of rubber on the roads, with rainwater on top, would give slipperiness.
Someone decided to pull out right in front of the car ahead of me. We were both travelling at 30mph. I was closer than normal, at about 30 feet behind this car. He jammed his brakes on. So did I, then started to skid. I released, reapplied etc for a second or two and stopped OK.
If I'd just kept the anchors on I would have rammed the car ahead. Absolutely my fault.
The hardest thing with caedence braking is to not freeze and just keep pressing, especially when you see the rear of the car ahead looming.
Deo gratsias alleluia. ( I got away with it! )
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I have successfully used cadence braking in the past to avoid hitting someone. I find it comes as second nature to me, especially when I start seeing my no claims bonus flash before my eyes....
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I was actually taught to do this, albeit in an amateurish fashion, by my instructor, before I passed my driving test at 17. It\'s not second nature by any means but when braking hard in the wet, I can release the pedal and find the end fairly well.
Of course, it is much better not to use this capability at all - the main use for me is when I am at the cusp of going through on amber or red and hard braking gets me to the right side of the line, rather than sailing across it.
I would stress that no one should feel that cadence braking should be part of their arsenal of every day driving techniques, nor a substitute in an emergency for ABS braking unless your surname is Schumacher.
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is candence realy any better ?
i would have thought the best non ABD technique is holding the pedal down just short of locking the wheels, and if you are used to the car you can do this, and if they do lock release and immediately re-apply
candence requires less skill than the above technique but is probably better with harsh brakes/car you are not used to/extreme slippy road
of course im spoilt with ABS these days, never give it a second thought just slam the anchors on
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and if they do lock release and immediately re-apply
But that is cadence braking I thought.
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Genereally I have found that for straight line stopping in a non-ABS car the cadance braking makes little difference to stopping distances.
Now try going around a tightish corner just as an artic dumper truck appears straddling the centre line. I cadence braked there without realising it. I needed to as the road surface was wet and had some loose gravel. As I was going around the corner when I needed to lose speed quickly locking the wheels wasn't an option!
Blue
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no candence is intentional pumping rapidly up and down the brake pedal
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mait, the things get messy when you consider how the ABS is *supposed* to work. technically the system is supposed to pulsate only if a skid is detected, as in, if there is no skid, no ABS should kick in because any depressing of the pedal (if the wheel are not locked) will only reduce braking and not increase. Hence there is no such thing as a cadence braking in a proper working ABS system. the system should do as you said, which is to ease, only a touch to release the wheel then clamp back in. So unless it?s a cheap Chinese version the ABS system should not just pulsate madly. Of course what you mention is *correct* about a human trying to do ABS, which is why I asked what is the proper way. I think most of us, well me included at least, either jam the pedal or pump it like a bat out of hell, because as one post just said, once you see that car in front getting close to you and your NCD flashing past you, you will go in panic mode. I have in the past *successfully* done this so called threshold braking, however that situation was not a make or break one and the only reason I managed to pull it off was because I knew if it went wrong I had enough destine and this allowed me to think and not panic ( I mean I had a lot of margins in case things went wrong) however couple of weeks ago doing 40 in Princess road in Manchester, the guy in front slammed his brakes, and then it was REAL (I mean stuffing your bonnet under his boot) and I just panicked and pressed the damn pedal as hard as I could, luckily avoided the guy but I had NO steering and because my tyres where not matched on the rear, the back of the car had started to skid side ways.
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no candence is intentional pumping rapidly up and down the >> brake pedal
Well clearly that's what I did, I just didn't realise until the point I started skidding towards the chevron corner road sign thingy that I was actually capable of cadance braking.
Not blowing my own trumpet here, but I was well taught (for someone of my age) and on that occasion it showed, unlike some of the other examples of my driving that I could mention! :-)
Blue
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