Quote:
Originally Posted by squirrel
I'm sure there's a good reason for ABS, but I don't know what that could be....
then again I've been driving old cars and trucks with manual drum brakes for a long time, and mostly I don't run into things, because I keep some room between me and the vehicle ahead. Although I did run into a garage door with an ABS equipped truck, the truck didn't believe that I wanted to stop, no matter how hard I pushed on the brake pedal, it knew I wanted the wheels to keep turning.
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Barring a component failure, in all likelihood it wouldn't have helped. The ABS detects the point at which your wheels will skid (where your braking force is limited by the friction of tires on road, instead of the friction of brakes on discs), and disengages the brakes momentarily to avoid that. In other words, it's finding the optimum conditions for maximum braking, and trying to keep the vehicle there. (This is the same principle as a PID loop on a FIRST robot's drivetrain, for those who are familiar with that technology.)
Incidentally, some trucks only have ABS on the rear wheels (individually or together). I suspect this layout was intended to avoid the lightly-loaded rear end of the truck from skidding, and destabilizing the vehicle. You may not have even had ABS on the brakes that were doing the most work (the front ones).
There's a common fallacy that ABS is less effective than ordinary manual braking. Implicit in that assumption is that a driver can maintain the car at the braking threshold continuously, without briefly over- or undershooting that point like ABS will do. Of course, it's very unlikely that a randomly selected driver will be able to do that at all. And even a well-trained driver will be unable to do it with anything approaching the repeatability and consistency of an ordinary ABS system, especially under changing dynamic conditions.
The other nice thing about ABS is that by preventing skidding, the steering still works.
And even if the technical rationale is unimpressive, there's always the appeal to authority: why would the engineers who design planes and F1 cars implement ABS if it wasn't useful?
Quote:
Originally Posted by Karibou
Just be warned, mine came with no ABS and no key fob. Don't just assume that ABS is standard on older cars, because apparently it's not.
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A GM car without ABS? That's strange. For many years, GM did not install airbags in their cars, but did install ABS as standard, feeling that a tradeoff between these two systems favoured the brakes. (I don't know the criteria they used; it may have been largely for commercial reasons.) The 1993 Buick Regal Custom I used to drive was so equipped—four-wheel disc brakes with ABS, but no airbags.