Talk:Anti-lock braking system/Archive 2

Archive 1

Archive 2

Reply to "The common average driver"

All good questions.

Friable surfaces - in Australia (where I live) only about 20% of the roads are paved. The vast majority of back country roads are colloquially known as gravel roads, consiticing of hard packed gravel. Conventional ABS does not like this stuff at all.

So far as hard packed snow goes, I don't know, we don't get much here, what I wrote is the conventional wisdom.

ABS faces the same problem on a flat sheet of ice as you, there is virtually no grip. That's just a fact of life. What it can do is to make sure that when you try and steer at least some grip is available for that, whereas if you lock the wheel then turning the steering wheel has no effect.

I'd say the main advantage with ABS is that in dry, damp, greasy, wet and some snow and ice conditions they offer increased controllability. On snow, and friable surfaces, they are probably less good than a reasonably skilled driver familiar with the conditions, who is not panicking. The last is a significant point.

I'd say for a normal driver in normal traffic conditions in non frozen conditions on sealed road ABS is an extremely positive safety system. I would specify it on my own car in preference to side air bags, which cost about the same.

Your friends don't understand about driving on loose snow. You don't tap, you brake hard, release, steer, straighten the wheel, brake hard, etc etc. It is a learned skill, I'd go on a driving course if I were you. I believe that a driver who has mastered this will probably be able to outbrake an ABS equipped car in some conditions, if he is wide awake.

Greglocock

The effect of ABS on loose ground has been tested with a Mitsubishi Pajero several years ago (in the sand dunes of some desert; the braking tests were done while driving down a sand dune). Without ABS, the car would dig into the sand and come to a rather abrupt stop. With ABS, the car would not lose any speed during the downhill section. This behavior is independent of the driver skill. Of course, both results (with and without ABS) are perfectly acceptable in such sparsely populated areas like the Sahara desert :-) --Klaws 10:02, 17 November 2005 (UTC)

Effect of vehicle weight

"It is worth noting that the heavier a vehicle is, the more it will benefit from ABS. This is particularly true of vehicles with less-sophisticated hydraulic braking systems where fine control is not as easy as with the more developed braking systems. Conversely, lighter vehicles, especially sports cars with highly-developed braking systems without ABS can outbrake comparable vehicles even with ABS."

In my opinion the overall meaning of this paragraph is bordering on hogwash. The last sentence is OK, but the first sentence is unmitigated tripe. Does anyone have any real evidence that heavy vehicles need ABS more than light ones? There may be some sort of valid idea in there, in which case it needs to be expanded. If there is any evidence for it, I guess the idea might be - "for a given set of tires a heavier vehicle is more likely to benfit than a light one.". But I still can't really justify that.

The middle sentence just seems to be flim-flam to me.

--Greglocock 22:44, 5 August 2005 (UTC)

Some types of "heavy vehicles" benefit from ABS in a somewhat different way. Yes, I'm talking about trucks and vans. When a truck is not loaded, the rear wheels will lock easier. So when a truck driver leavews a loading bay, the brakes will behave differently than maybe a few minutes ago. ABS relieves the driver from adjusting his braking power to the load. The same is, btw, true for Traction control systems. I checked it with different Merced-Benz Sprinters in both empty and fully loaded conditions (on wet tarmac). Yo, I guess any observers would have thought "Man, look at that idiot...where did he learn to drive...did he learn to drive?", but that didn't keep from conducting this important scientific experiment. ;-) --Klaws 10:02, 17 November 2005 (UTC)

That is what Electronic brakeforce distribution (EBD) is for - it appropriately apportions braking effort based on vehicle loading - efectively replacing the load sensing valves or pressure limiting valves for the rear brakes. -- Teutonic_Tamer (talk to Teutonic_Tamer) 10:07, 14 May 2008 (UTC)

Operation / effectiveness

I moved the para discussing the pulsing feel and driver responses from effectiveness to operation as it seemd to me more a development of the arguments in operation than the preceeding para in Effectiveness. I also referenced the (directly relevant) Munich & Copenhagen taxi driver experiments discussed in risk compensation.

Thanks for that. Interesting stuff

Greglocock 03:46, 11 November 2005 (UTC)

Instinctive Behavior of drivers in cars with ABS/ABS can kill

I figured I would add this under operation/effectiveness subheading.

Unlocking the Mystery of Anti lock Brakes https://www.youtube.com/watch?v=fEudqGL5n2Y

This is a great driver training video discussing the proper use of ABS brakes.

It is rarely known with all of the propaganda out there promoting the benefits of ABS but this video describes a situation where under application of brakes in a typical emergency situation involving a stopped car in front. the driver in the car with ABS will instinctively turn the steering wheel to avoid crashing into the car in front but will as a result of doing this end up being hit side on by an oncoming car or truck. The proper method of stopping a car as described in the video is to find a direction to go which wont put your car into oncoming traffic. Unfortunately this could also result in your car going up on the side of the road and killing a pedestrian or going off the side of a mountain.

The video also describes the act of instinctively lifting your foot off the brake pedal of a car with ABS in the very situation that you shouldn't be doing so. The proper method of stopping a car with ABS in this situation is to keep your foot on the pedal until you come to a stop and don't ever lift it.

I know this from an event which occured to me in an australian Ford Fairmont Ghia EF Series 2 with ABS. I hit a patch of black ice on the road and ABS didn't do anything except make the car fishtail after I instinctivley let go of pressure on the brake (I thought something was wrong with the car, the brake pedal was puslating and I've never experienced that before), I then instinctivley turned the wheel to try and correct the fishtail which resulted in the car doing a full 360 at least once and I was along for the ride without any control over the car at all. all I could do was put the transmission into neutral which managed to slow it down a little bit. I ended up in a ditch on the other side of the road almost hitting a telegraph pole (I missed it by 1 foot).

Needless to say I'll be driving cars with ABS like the pulsating effect of the pedal isn't there and as according to the video I'll be driving cars without ABS by letting up a little bit to unlock the wheels so I regain traction (if needed).

Car has ABS = Don't let up on the brake. Don't jerk the wheel.

Car doesn't have ABS = Let up a little bit to keep the wheels spinning and maintaining control of the car.

Here are a few other articles associated with the deadliness of ABS:

http://www.thetruthaboutcars.com/2006/08/killer-abs-abs-braking-increases-rollover-risk-by-51/

http://www.4x4abc.com/4WD101/ABS_offroad.html

https://www.aaafoundation.org/sites/default/files/absprobe.pdf

https://one.nhtsa.gov/cars/rules/regrev/evaluate/808206.html

--RushHour (talk) 13:07, 7 July 2017 (UTC)

Yawn. Actually most drivers just go straight on in real crashes. Hot news for you, youtube videos are not reliable sources. Incidentally in my driving courses I was taught to steer under emergency braking without ABS, which would have just the same potential for disaster, except that even fewer people will do it in a real emergency. I have been in a car when the driver realised the truck behind couldn't stop and steered around the braking car in front to prevent getting sandwiched (a) no ABS and (b) no problem with traffic in the adjacent lane. We still got a tap up the arse, but no whiplash or squishy noises.Greglocock (talk) 06:21, 8 July 2017 (UTC)

Operation - Detection needs more info?

In the article, it states:

The electronic unit constantly monitors the rotation speed of each wheel. When it senses that any number of wheels are rotating considerably slower than the others (a condition that will bring it to lock1) it moves the valves to decrease the pressure on the braking circuit, effectively reducing the braking force on that wheel and causing a characteristic pulsing feel through the brake pedal.

and I'm sure that's how some ABSs work.

However the How Stuff Works article mentions a system that senses a rapid deceleration in the wheel to activate. (btw: this system seems to me to make a lot more sense - it wouldn't be fooled by multiple wheels locking up)

Can anyone verify this?

Budbrake

unless anyone can find proof of the opposite I suggest that the Budbrake is not an ABS device. It is a brake proportioning system. ref http://www.bikeforums.net/archive/index.php/t-83704.html . I'll give it a week and then rv the advert for Budbrake.

Greglocock 03:24, 16 January 2006 (UTC)

Safety during ABS failure

This is probably something that should be mentioned. Back when ABS was first introduced, cars still had a manual proportioning valve for braking. While this was not as important when a car was equipped with disc brakes on the front, and drum brakes on the rear.. it was absolutely ESSENTIAL when a car was equipped all around with disc brakes.

Without a proportioning valve (anywhere from 65%-75% for the front disc brakes, and the rest to the rear), such a car will receive a 50/50 split in braking power, front and back. This is _very_ bad, as you will soon find the rear of your car attempting to slide in front of you, as it is much lighter than the front. This is especially evident when trying to brake whenever the road is slippery, be it rain, snow or ice.

This is why such a proportioning value exists, and all pre-ABS (and most 80s and 90s ABS systems) still had a value in place. These days, however, ABS is more advanced. ABS can actually detect individual wheel skid, and apply pressure independantly on each wheel, something early ABS could not to. This has lead to the removal of manual proportioning, which means that each wheel in a modern ABS system recieves equal braking pressure, if ABS is offline.

This is bad, very very bad. If ABS malfunctions, not only is the driver (and likely a driver that has never learned to brake without the ABS crutch) without ABS, they now have a car that can not effectively brake in poor braking conditions. While a skilled driver can easily compensate for the rear sliding out of control, it does make the situation more difficult. Even a skilled driver would have to reduce braking power significantly, with 50% braking power at the rear. An unskilled driver, especially one braking without ABS for the first time, would find themselves in serious trouble.

This removal of the proportioning value is a relatively new thing for standard consumer automobiles. Subaru, for example, just started doing it in 2004, I believe. VW and others have been doing it for quite some time, but I believe well under a decade. While on the surface it may appear to make sense (hey, this means we can fully use the rear brakes), this is seldom the case. Front and rear brakes are tuned, matched to the car, the proportioning value meant to prevent skidding of the rear brakes before the front. Many cars had a value that would even auto-adjust dependant upon the weight over the rear axle.

This is all gone now, in an attempt to simplify construction and save costs. I deem it a serious and potentially fatal mistake. Effectively, the "backup system" that ABS had (reversion to manual proporitioning) is now gone. ABS fails, and braking turns into a very dangerous matter.

I think there should be some mention of this, in this article ....

Comments?

Nicely written. You'd have to do a comparison between the safety advantages of a full authority ABS, versus the safety advantages of an ABS that had stopped working but which operates better in that mode. Actually, I sort of agree with you anyway. My specific concern is that if we are cornering at say 0.4 g and apply 0.4 g of braking, without a proportioning valve we have not changed the balanace of the car, that is, it will tend to drift outwards (ie braking is neutral steer). With a proportioning valve we tend to overload the front tire more, so giving more understeer. In an emergency it is probably better to give more understeer to the average driver.

Greglocock 10:51, 22 June 2006 (UTC)

More thoughts on brake proportioning valve. Even if the vehicle does not have a BPV it does still have a natural brake balance, governed by the relative sizes of the pistons. Typically I see 40mm rear pistons, and 60 mm front pistons, ie almost exactly the traditional 70:30 split in braking force, as it is a square law. Alternatively they vary the number of pistons per calliper. I can see no advantage in commonising on the larger size, and obviously the front piston diameter is set by required performance and system pressures, so at a guess production cars with ABS, without BPVs, will still brake in a reasonably balanced fashion if the ABS fails. Greglocock 23:51, 16 September 2006 (UTC)

History of ABSs

I just wanted to point out that soem Ford vehicles starting in the early 1970's had a "SurTrak" braking system, and in fact the Lincoln Mk IV article directs to this one. There is no mention of this system at all in the article, which is curious since this would predate the Mercedes introduction by several years. Any thoughts? --Mfree 16:16, 12 July 2006 (UTC)

Awfully bosch-centric

Lots of other brake skid control systems have been used, including analog systems. A poster already mentioned the Ford/Lincoln system of the early 70s. Another was the Chrysler system used initially on the '71 Imperial. Brake pressure modulation was achieved through remote mounted vacuum servos (like power brake boosters) and cylinders under control of an electronic module. Very clever, moderately complicated, and quite effective from everything I've read. —Preceding unsigned comment added by 146.6.202.126 (talk • contribs) 21:04, 24 July 2006

Fair enough, so why not add your information to the article? The reason the article is Bosch-centric is that Bosch publish the most information on ABS, and (at a guess) supply most systems that are used. Greglocock 02:39, 25 July 2006 (UTC)

The 0-100-0 Test

This test is a very poor indicator of braking performance. For most cars the 0-100-0 test result is mostly a test of power to weight ratio, not primarily braking performance. The only cars for which it is truly a test of braking performance are those which are traction limited for the entire run, which discounts any production car. Also, what on earth is a comparable car? Same tires, same engine, same gearing, same suspension, similar weight?

Note that I agree, a good skilled driver, in a straight line, on dry roads should be able to beat ABS. Demonstrably in the wet in turns even very skilled drivers have problems where ABS would help. That's one of the reasons they 'banned' it in F1

Greglocock 02:15, 12 September 2006 (UTC)

If you consider the braking segment of the test, certainly that would be a good indication of braking performance. That's one of the reasons the test is set up as a "0-100-0" test - as opposed to quarter-mile sprints and other such things in which folks from North American like to indulge. Wouldn't you agree? --SpinyNorman 04:08, 12 September 2006 (UTC)

OK, so do you have access to these split times? If so can you put together a comparison? The only information I have seen that looks like a halfway reasonable comparison is the motorbike one, where, braking from high speed, the BMW rider could beat the BMW ABS, but the Yamaha guy could not beat the Yamaha ABS.

To be honest this article needs a rewrite, as there is too much scrappy information in there (the locked brake comparison is silly for example), I'd suggest : quick desrciption, history, longer technical description of typical current system, advantages, disadvantages, studies of impact on accident rates, would be a better format. For the latter section I have seen (but need to find again) a pdf with a breakdown of accidents across 5 states Greglocock 05:19, 12 September 2006 (UTC)

No, even the number of the breaking segment doesnt's indicate "anything": Aerodynamics start playing a role in how much force the tyre can transfer to the road above 30mph and those forces increase with square of the speed - other Factors are the Tires (wider and softer is better), the Suspension (how "constant" is the contact between Tyre and road) ..

Unless you test _exactly_ the same car once with ABS and once without, those numbers don't tell anything about the general capabilities of ABS.

And considerd that a good driver may be able to hold one Tyre at the optimal point (10-20% friction), since he just has one Pedal the 3 other Tyres most likely are not exactly at the optimal Point - ABS however can break every Tyre individually... (on a motorbike the Situation might be a little different, since the rider actually can controll every single Tyre - at least on most of the bikes) —Preceding unsigned comment added by 14:18, 16 September 2006 (talk • contribs) 80.128.179.237

I don't think you are right, threshold braking is possible, is regularly practiced, and is demonstrably better than ABS at stopping in a straight line in the dry. If you were to take a production car and switch the ABS off then these days you would probably find the rear locking up too early, since we no longer bother with a brake proportioning valve. So, you'd actually need to set the non ABS car up properly first. Incidentally the brake proportioning setting is surface dependent, so fine tuning the brake proportioning is in itself a driver aid. If I get time (unlikely) I'm going to investigate whether I can beat the ABS in an ABS car by using threshold braking, as opposed to mashing the pedal, which is the recommended technique. Incidentally can you sign your posts in future? Greglocock 22:36, 16 September 2006 (UTC)

Too automotive-centered - more about aircraft

I couldnt find a similar article for aircraft anti-skid systems - i guess this could be something somebody could add - their is hardly anything on this topic in this article 81.221.177.166 07:56, 27 September 2006 (UTC)

There's a 1954 Flight advertisement for the original Dunlop Maxaret system here: [1] —Preceding unsigned comment added by 86.112.203.140 (talk) 13:04, 14 April 2009 (UTC)

If I get a chance, I'll paraphrase some of the basic information in my repair manuals at work. Most of the anti-skid devices in aircraft are painfully manufacturer specific. 184.153.196.39 (talk) 00:22, 3 November 2010 (UTC)

I believe that the Lear Jet, first marketed in 1963 was equipped with antilock brakes. This may have been the first vehicle to universally use an ABS system, and I'll keep looking for verification...to be added later Homebuilding (talk) 13:23, 27 March 2012 (UTC)

Maxaret was a standard fitting on numerous aircraft (below) in the 1950s so pre-dating Lear's use by at least ten years.

Avro Vulcan, Vickers Viscount, Vickers Valiant, de Havilland Comet 2c, Handley Page Victor, BAC TSR.2, English Electric Lightning, de Havilland Sea Vixen, and later aircraft, such as the Vickers VC10, Hawker Siddeley 125, Hawker Siddeley HS 748 and derived British Aerospace ATP, and BAC One-Eleven. — Preceding unsigned comment added by 95.149.173.43 (talk) 10:31, 9 August 2016 (UTC)

When did anti-lock brakes become more widespread?

We need something on when anti-lock brakes became more widespread.

Also, do all vehicles nowadays come equipped with anti-lock brakes? We should include something along those lines as well. —Preceding unsigned comment added by SkinnyZan (talk • contribs) 05:08, 29 October 2006

this article needs to be looked at. it's full of confusing mistakes!69.122.62.231 02:28, 2 February 2007 (UTC)

Anti Lock Brakes do come standard on a lot of vehicles, but they are still an option on a decent number of of other vehicles as well. —Preceding unsigned comment added by 72.236.173.22 (talk) 18:26, 19 September 2007 (UTC)

This article is poorly organized and unclear

As an individual who is not car savvy and reading this article for the first time, I'd like to voice my concern that it is a bit disorganized and unclear. It starts out OK, but seems to degenerate into a jumble of conflicting information about whether or not ABS is good or bad. Could someone please reorganize it and make it more concise? Maybe a "pro" and "con" section? Right now it is very difficult to come away from the article with any clear sense of the subject matter. 68.61.241.9 01:40, 3 February 2007 (UTC)DB

Observation

Thought this ancectodal evidence, I must drive, on a daily basis, a vehicle equiped with hydraulically-actuated, four-wheel drum brakes, of the dual-servo, self-adjusting type. Since re-shoeing all four wheels several thousands of miles ago, I have, in a wide variety of braking conditions, experienced no brake fade. Could it be the modern linings? My car is a piece of crap, you dont even know.

I also wish to point out that the brakes lack power assist, which the servo action seem to make up for, and, that braking control driving on ice and snow was much better than what I have experienced on ABS and non-ABS power-assist front disc/rear drum equiped vehicles.-WK-139.78.96.115 01:27, 8 March 2007 (UTC)

ABS and braking distances.

Sigh. After skim reading through some of the comments above, I was compelled to reply myself. There is a massive debate about whether or not ABS reduces stopping distance (or more specifically, braking distance). Well I'm not a mechanic or a scientist so I'm not going to be the one to say whether or not it does, but what I CAN say, is that you are all missing the point. The anti-lock braking system was designed for one purpose: to allow the driver to steer the vehicle whilst applying maximum braking pressure. It was NOT designed to reduce braking distance, although this is possibly a side-effect of ABS.

If a child runs out in the road in front of you, your first instinct is to brake as hard as you can and steer to avoid them. Without ABS, there is a high chance your wheels will lock, thus causing the steering to have zero effect, and therefore you hit the child. With ABS, you brake as hard as you can and steer, since the anti-lock brake assist computer is ensuring the wheels do not lock at the same time as keeping a high amount of braking force on them, you are able to steer away from hitting the child.

OK: so you argue that locked wheels will stop a vehicle faster than ABS can. But who cares? I'd happily sacrifice a metre or two if it meant I was able to steer around the obstacle I was aiming to avoid, because why does it matter if it takes you longer to stop, since you've already swerved around it anyway?

For the less enlightened of you, I suggest you take a look at this video. --Janipewter 12:24, 8 August 2007 (UTC)

Yes I agree that if what you are trying to avoid is a randomly moving object, ABS is clearly the better choice. HOWEVER, if you are just trying to stop (ie you are coming up on a busy intersection and you have a red light), you don't need to steer around anything... You just need to stop! There have been plently of times that I have come up on intersections on a snow packed road, and the ABS has completely over reacted because the tires naturally don't grab as well on flat snow. As a result I've sliped into the intersection because the car thought I was doing an emergency stop and had to avoid something, when really, I just wanted to stop in time for the red light...

I'm a pretty "clear headed" driver, and I would NEVER be going fast enough on a residential road (where a child might run out) that being able to steer would be an asset. To me, if you are going 60mph on a highway and you see an accident happen right infront of you, yes, ABS is good because you obviously don't have enough time to completely stop since you are travelling at such a high rate, so being able to steer is still good! On a 20mph city street, the kid has to run out at the VERY last second for you to not be able to brake the car normally anyways (because it's a low rate of speed)... Therefore, if the kid runs out right at the last second, I doubt there is enough time for your brain to say to your head "turn the steering wheel!" much less "hit the brake!". Last summer I was involved in a crash, where a person made a left turn from the opposing direction, right in front of me at the last second... It was so sudden, that I didn't even have time to get my foot to the brake before I hit the side of their car... I was only travelling at probably 20mph, and there just wasn't enough time to react because she pulled out maybe 10 feet infront of me...

All those videos of ABS working on a snow covered track somewhere are misleading too... Only an idiot would jam on a non ABS brake, thus causing the typical skid/fishtail. The ABS cars always stop right infront of the pylons! The only problem is that they are probably going at about 40mph and then jam on the brake... I'd like to see a slow speed ABS stop on snow... It would "shudder" right over the pylons! --mmmfloorpie 14:14, 31 January 2009 (UTC)

In my book someone who repeatedly ends up sliding through an intersection for the same reason is rather a long way from being a clear headed driver. YMMV. Greglocock (talk) 22:18, 31 January 2009 (UTC)

This winter when it snows I will make a video comparing stopping distances on loose surface with, without, and while interrupting ABS function. I have a switch which can disable ABS on the fly in my vehicle (which I use while racing, mostly), and I've tested this before. I assure you that ABS causes a HUGE increase in stopping distances on loose surfaces. On tarmac the difference is negligible, and the benefits certainly outweigh the drawbacks for an average driver.

History Section Nearly Plagiarized...

http://www.absbrakes.co.uk/

The only difference is the 3rd paragraph was switched up a little...this was only the 2nd result when ABS was searched on google. It should probably be rewritten/cited, but i don't have the time to do Either, unfortunately, at this moment. —Preceding unsigned comment added by 72.236.173.22 (talk • contribs) 18:24, September 19, 2007

• Well spotted, it looks like the majority of the article is copied from that site. 62.31.71.203 00:49, 28 September 2007 (UTC)

The (BMW) standard fitment section/line circa 1986

The article states that BMW were the 1st to fit ABS as standard. IIRC it was Ford who in 1985, a full year ealier fitted ABS as standard across the range to its Granada & Scorpio cars. —Preceding unsigned comment added by 86.128.81.243 (talk • contribs) 22:39, 18 November 2007

Yes, for the Granada and Scorpio ONLY, not over the entire vehicle line. M-B and BMW introduced ABS (as standard) on the 7-Series and S-Class (W126) sometime in the early 1980s. OSX (talk • contributions) 04:56, 9 February 2009 (UTC)

I was really surprised to see that there is no connection to Mercedes-Benz in this article since the company has been a pioneer in many areas of automobile safety. Daimler-Benz became the world's first motor manufacturer in August 1978 to officially launch the second-generation anti-lock braking system and to offer it as an option from December 1978 – initially in the S-Class. Since 1984, ABS has been standard equipment on Mercedes-Benz passenger cars. Mercedes-Benz also adopted a pioneering role where ABS for commercial vehicles was concerned. As early as 1981 ABS was offered for compressed-air brakes, a joint development with Wabco. ABS has been standard equipment on all touring coaches of the brand since 1987 and on all trucks of the brand since 1991.

I am not German but would like to have the facts right. If one reads the German version of Wikipedia then one notices that the articles are not the same though they do share some information (facts). — Preceding unsigned comment added by Runarsson (talk • contribs) 14:38, 2 December 2012 (UTC)

What do you mean by second generation? Are you sure that isn't just a marketing term? Germans are pretty gullible by and large when it comes to asserting engineering prowess by a German company. Greglocock (talk) 20:28, 2 December 2012 (UTC)