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Antilock-breaking (ABS) vs Stabilty Control (ESP) vs Traction Control Video

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SeraphimLabs:
Well speak of the devil. Ruptured a brake line this morning.

Overshot slightly on a turn and hit the brake harder than usual to try and stick it anyway. Instead I get halfway into the turn, the brake goes soft, and I feel the car sliding sideways. Well riding it out was easy enough, it slid clear over into the other lane because of some loose stone and I had no problems correcting. Course when I reached the next stop sign I had a wait what moment- because my brakes weren't there.

Now if my car actually had ABS, that right there is where the automation would fail. It would sense that a line has ruptured and shut down in order to avoid wasting the remaining fluid. If you weren't used to driving without relying on the ABS, your brakes would suddenly become next to unusable. Fortunately I am familiar with utilizing engine braking to slow a vehicle with poor brakes, greatly reducing how much braking I have to perform. But again that's something most people don't do, that leads to accidents because they don't. They just rely on the car to work right all the time, which it won't.

IainB:
Scary. The only time I ever read of the actual hydraulic brake-line rupturing was when it got damaged on a loose stone road (a rally driver's curse), or in a minor shunt, or corroded. Do you inspect/check (or get checked) your vehicle every 6 months or so?

CWuestefeld:
A defective brake caliper about 25 years ago grabbed my disc and ripped itself off its mounting, thus opening the hydraulic line. That's the only time I've ever experience such, or heard of it happening.

It was quickly clear what had happened to the brakes. But note:

* Once this happens, any rational person is going to drive very slowly and cautiously to the nearest service station, if not stop entirely. If at this point you get yourself into a situation where ABS would be required, you're beyond stupid.
* When this happened to me, I still had partial braking. That's because car designs anticipates such a failure. You'll have two independent hydraulic "circuits", probably governing opposing wheels. So loss of pressure in one loses only half of your braking potential. I suppose that if I'd needed to drive more than 2 miles to get to service, the master cylinder might have run dry trying to push fluid into the broken line.
* The vast majority of people today drive cars with automatic transmissions, which don't really afford a good means of engine braking.

SeraphimLabs:

* The vast majority of people today drive cars with automatic transmissions, which don't really afford a good means of engine braking.-CWuestefeld (June 23, 2014, 11:30 AM)
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Have to disagree with you on this point.  Most automatic transmissions are provisioned to allow the driver to manually set it to a certain gear. That provision is meant for pulling trailers- and for engine braking. Just very few people know about or utilize that capability because engine braking is not taught in the normal driver's courses. I know about it from working farm tractors where engine braking is practically required due to the brakes on the tractor being too small for the tonnage behind it, but most people I talk to who haven't operated heavy equipment or big trucks have never heard of it. My current car has an automatic transmission, and not only have I heard it performing engine braking on its own while in cruise control, but I was successfully able to perform it using the manual override this morning to keep my speeds down and compensate for the loss of braking power.

I paid $1000 cash for this car about two years ago. Right from the start it needed new brakes, and one of the brake lines got changed at that time because I had to cut the line to get the caliper hose off. But for the most part the only time I even look at the underside of it is when I think there is something odd happening, and having the brake lines rot out and pop like this happens every couple years. I'm sure people who actually put money into their car to begin with would take the time and money to have it checked and repaired on the posted schedules, but most of the people I know don't bother - if it isn't broke don't fix it.

They do indeed use two circuits, but when you have a ruptured pipe every time you stroke the pedal you are shooting fluid onto the ground. So yes you can still stop, but you only can stop a couple of times before the shared reservoir has allowed all of the fluid to leave both systems. Driving it with a ruptured line should be avoided as much as possible for this reason.

Edit: And like clockwork, the line that I had to move aside to replace the one that failed just ruptured as well. Fortunately this one was in the driveway, pumped the brakes up real nice then rolled forward about 20 feet and stomped on it- squish as all the fluid runs out again. I hate cars so much.

Stoic Joker:
I've been trying to find the time to finish this post for over a week!

So I took my car down a rocky gravely road, and tested ABS -- which kicked in easily on that surface.  It wasn't particularly dramatic but i'm glad to know what it feels like so if it happens in real driving it won't startle me.-mouser (June 15, 2014, 04:09 PM)
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That in itself is probably the most important - takeaway for you - part of the test. Because the last thing you need in an emergency situation...is more surprises.


I also tried to get it to trigger on a regular road, but a hard stop at 35mph did not trigger it -- despite giving me whiplash and throwing baby cody from the back seat to the front seat, and so i gave up on that.-mouser (June 15, 2014, 04:09 PM)
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Okay, I'm going to go out on a limb here, and assume you just gave the brake petal a good stomp to effect that reaction...yes? While it is excellent for testing purposes, It is also the exact type of problem behavior I was initially eluding to when one - fortified with ABS - takes the expression "Panic Stop" a bit too literally.

The reality of it is that in "normal" driving, if you really have to suddenly clamp down on the binders ... You weren't really paying attention. Otherwise, you'd have had other accident avoidance (e.g. escape) options available. And yes, after 35+ years of street riding this is where my motorcycling elitist background tends to bleed through rather quickly. Because for most people it's "just a fender-bender", but or me it could quite easily be a fatality ... Mine! ...So I tend to take that and the whole defensive driving thing quite seriously.

Now here is the part that people seem to have difficulty grasping. We've already had much discussion about ABS being able to stop a vehicle faster ... but the problem is - from a truly holistic defensive driving stand point - that's irrelevant. Because the real reason that ABS was originally explored as an option for cars, was to resolve an issue with steering control during hard breaking. Once the wheels lock due to excessive braking the ability the steer the vehicle is completely lost. That! is the one and only reason for ABS to ever be explored as a possible safety feature in an automobile. The fact that it also happened to make the cars stop faster by properly regulating break pressure was and still is a completely accidental (pun intended) fringe benefit.

Want proof, simple ... There are 2 wheel and 4 wheel designs for automotive ABS systems. Now for the 2 wheel only systems - on a 4 wheeled vehicle - which 2 wheels get the advantage of ABS control? I'll give you a (a slight misdirect) hint. Due to weight bias under breaking, the front wheels provide 70% of a vehicles stopping power. The ABS btw... goes on the back wheels. Why??? Steering control pure and simple. This configuration is actually most common in pickup trucks which when traveling empty and having no weight in the rear, have a very bad reputation of locking the rear wheels and sliding sideways.

Faster breaking...not so much. Safer breaking, yes ... But that - in defensive driving - is not necessarily always faster breaking. You see in defensive driving, the person who stops the fastest, is frequent also the first person to get killed in (if not the cause of) a chain reaction crash. First rule of defensive driving is in an emergency...look for a soft place to land.

Motorcycles stop faster than cars do - it's simple weight ratio physics. So I have always been able to stop much quicker then the folks in the cars around me. However... If the guy behind me can't stop as quickly as I'm about to...then who's fault is it really if he just so happens to run my stupid ass the fuck over? Hm..? Not really a trick question is it? I have to maintain steering control so I can swerve to some out of the way place - so as to politely and defensively allow him to proceed to continue and finish crashing into the idiot/obstacle that I just avoided. Otherwise to be brutally honest it is quite simply my own fault that he ran over my ass.

Now sure, Florida law says that if you rear-end someone, then the accident is automatically your fault. So according to 'The law' I would be completely blameless. However in any defensive driving classes you take the term applied to this type of situation is called being "Dead Right". Yeah, sure you're "right"...but you're also dead. Pyric victory anyone?

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