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Old 25th October 2008, 16:46   #16
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Pumping of brakes = ABS??? No, exactly the opposite! ABS, when the electronics senses a wheel-lock conditions, momentarily releases the pressure at the actuator so that the wheel can continue rotating. Yes, it acts independently on each wheel, and takes action only on those wheels that have lock condition.

Rapid pumping, on the other hand, increases the fluid pressure at the actuator, which actually tends to lock the wheel. This is akin to the Brake Force Multiplication function in EBD systems. In this, the system senses the rate at which the brake is being depressed and, after the trigger point, increases the fluid pressure at the actuator. This function makes it easier for ladies and elderly persons to brake harder than normal in emergency conditions.

Pumping helps in vehicles where sometimes the brakes don't inspire confidence by feeling mushy. Driving ones own vehicle, one sort of memorizes the trend of pedal travel v/s stopping distance or stopping rate. In 'emergency' conditions, the mushy feeling leads to anxiety - and pumping results from reflex action.

One can try pumping the brake in an ABS-equipped vehicle - it will result in ABS cutting in early.

Last edited by DerAlte : 25th October 2008 at 16:49.
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Old 25th October 2008, 17:05   #17
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I think people are getting consfused with the word "funtionality".

Yes, i agreee that a driver can do everything an ABS system can do, which is to brake hard, come off the brakes when the wheels lock and brake hard again.

But this is like saying that my Honda city can do what ever an F1 car is capable of, which is to accelerate, brake and go around corners. Not quite the same isn't it.

Being able to replicate the functioning of ABS is easy, but whats important to note is how efficiently can a driver do this when compared to these electronic gizmos.

In the time it takes the driver to realise the wheels have locked up and pump the brakes once, the system would have already done it 50 or more times.

I too am not a big fan of ABS, TCS, ESP and the lot since they take away the pleasure out of your driving experience........which is fine to think when you're gunning your car around a track but on normal roads, they do make a lot of sense.

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Old 25th October 2008, 17:56   #18
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Quote:
Originally Posted by Shan2nu View Post
I think people are getting consfused with the word "funtionality".
you mean functionality!

Quote:
Originally Posted by Shan2nu View Post
Yes, i agreee that a driver can do everything an ABS system can do, which is to brake hard, come off the brakes when the wheels lock and brake hard again.

But this is like saying that my Honda city can do what ever an F1 car is capable of, which is to accelerate, brake and go around corners. Not quite the same isn't it.
Yes it is not at the same rate, but in slow motion!

Quote:
Originally Posted by Shan2nu View Post
Being able to replicate the functioning of ABS is easy, but whats important to note is how efficiently can a driver do this when compared to these electronic gizmos.

In the time it takes the driver to realise the wheels have locked up and pump the brakes once, the system would have already done it 50 or more times.
Agreed again, also much of this braking hard stuff is intuitive driving! One should intutively brake hard, come off the brake and brake again, and 8 out of 10 times, we do NOT get it right!

Thats why ABS is popular and consistant.


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I too am not a big fan of ABS, TCS, ESP and the lot since they take away the pleasure out of your driving experience........

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Old 25th October 2008, 18:51   #19
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Rapid pumping, on the other hand, increases the fluid pressure at the actuator, which actually tends to lock the wheel.
True, you are not supposed to pump the break with ABS. I was using the term 'pumping' to the way ABS break engages and disengages rapidly.
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Old 25th October 2008, 19:09   #20
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.... I do not want to quote those with supreme abilities - agree that skill, ability and experience does help a long way non-ABS vehicles, but that is not an arguement for not using ABS.
In some ways, why use fliud breaks at all, go and use wire and rim brakes which is lesser technology and no chance of fluid leakig out. What I mean is the arguments can go on, but for heavens sake in the larger interest please do not say ABS is not required.
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Old 25th October 2008, 22:04   #21
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Sorry about not replying to individuals, but many thanks to all for your replies and i have learned a few things that I was not aware of. After going through the replies, what i have now come to know is that you can come out of a sticky situation unscathed if you have the required skill/experience even on a non-ABS car, but its not a substitute for ABS!
I have never driven a ABS/ EBD/ TCS car for the last 10 years that i have been driving. But i definitely dont say ABS is not required because safety comes first when driving/riding, everything else next.
I was only wondering if not the exact simulation, atleast a slow motion simulation of the ABS functionality be tried on a non-ABS car!!
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Old 26th October 2008, 09:27   #22
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I dont think even a slow motion simulation of an ABS is possible in a non ABs vehicle. Or else the vehicle should have four separate brake pedals and the driver, two pairs of legs (plus one more for the accelerator of course!), further assuming that he can - even in slow motion - judge which of the four wheels is about to enter into a lock at any given moment!
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Old 26th October 2008, 13:21   #23
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... I was only wondering if not the exact simulation, atleast a slow motion simulation of the ABS functionality be tried on a non-ABS car!!
There cannot be a "slow motion simulation". If you go into the physics and maths of ABS, you will find the reason why that is not possible.

The objective is to prevent wheel slip w.r.t. road surface. On a wheel-lock, the friction break-down renders braking useless. Momentary release allows a ffresh section of the wheel to make contact, and increasing the possibiliy of better grip to make braking effective again.

Now imagine: the slower you do the above, the longer is the wheel slipping on the road, reducing the effectiveness. Also, the braking pressure is off the brake longer. Ergo, manual simulation will defeat the principle of ABS, and make the braking distance longer.
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Old 26th October 2008, 14:02   #24
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Agree with Shan2nu:
A computer can calculate and react much faster than you. So either you have an ABS vehicle, or you go slower.

Any amount of verbal diarrhoea or random anecdotes cannot change facts.
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Old 26th October 2008, 14:51   #25
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Practice 'Cadence breaking'. It is not exactly pumping of breaks. Google for more details.
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Old 26th October 2008, 22:27   #26
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Practice 'Cadence breaking'. It is not exactly pumping of breaks. Google for more details.

Thanks for the term clevermax. Googling for Cadence Braking actually gave me a lot of info required and in fact i also landed upon a site Welcome to Safe Speed where they have a whole list of braking techniques! Kudos to you mate!
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Old 27th October 2008, 21:51   #27
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Ofcourse you can! Crazy Taxi Jeep drivers here in Rajasthan do it all the time. They apply brake and release and again brake within seconds.
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Old 27th October 2008, 23:49   #28
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"Within seconds" doesn't even come close.

In fact that's more like normal driving on Indian roads, isn't it?

My ABS cut in the other day, braking sharply on a wet road (nearly missed seeing a red signal, blush). First time in about 16 months of owning this car, and I was wondering if it worked.

Imagine saying "Brrrr" on a cold, frosty morning... it's that fast. For those lucky enough never to have seen a cold frosty morning (ok, ok, it does have its charms, yes!) remember being a kid, pretending to have a machine gun, making that noise; ABS is faster than that!

Last edited by Thad E Ginathom : 27th October 2008 at 23:54.
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Old 28th October 2008, 08:29   #29
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The issue is not whether we can match the speed of ABS braking and releasing the brakes, but whether we as drivers can try hard braking - releasing the brake etc to gain control. i.e simulate the functionality of ABS in non ABS cars as the title suggests!

Yes you can. Please practise this on an empty road or playground. slot second gear accelerate hard, brake hard, the steering becomes ineffective, then releasing the brakes makes you gain steering control.

This is what ABS does in milliseconds, hence the wheels actually dont lock up but are on the verge of locking up.

In panic situations, while one is already braked hard and is holding onto dear life, noticing that his vehicle is going at a trajectory, releasing the brakes momemtarily and braking again will make the car change direction if correct steering inputs are given.

But, please practise this technique at a playground first before trying it on roads. Excessive steering inputs could have the vehicle fish tailing as well.
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Old 28th October 2008, 09:01   #30
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I saw a documentary on Discovery/National Geographic Channel, the name has slipped of my mind, however in that they actually test ABS and non ABS vehicles on slippery surfaces. And ABS reduced the braking distance by a HUGE margin.
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