Quote:
Originally Posted by ShadeTreeMech
I now recall the van would lock up at less than 15 mph. But as it was a steep hill, it got over 15 mph easily, then the ABS held me at about 15 mph so long as I let off the brakes long enough to get the wheels turning. If it slowed down too much I had to let up or go into a skid. And it was on glare ice--this was after the ice storm a few years ago that made national headlines.
With as sophisticated as cars are getting, I wonder if the more high tech systems can "learn" the amount of available traction and ease on the brake pressure instead of locking up/unlocking constantly.
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My experience is pretty similar; ABS works better at higher speeds. The more expensive systems have speed sensors at each wheel and when an individual wheel is turning slower, it reduces braking pressure at that wheel. As your speed approaches zero the threshold between turning and stopped gets narrower. You can only vary brake pressure so much, thus, your performance near a stop is poorer. With that said, how many of those accidents were over 15mph in the video? Probably few were over 10mph, where ABS works the worst.
In every situation where I've been on true glare ice, I've ended up having to take back control after all four wheels locked. At the same time, we're being told not to pump the brakes and let the ABS do its job. That's all well and good if it does, but I'd really encourage everyone to get out and play in the snow in a nice, big empty parking lot and learn what the abilities and limitations are and how to get the best performance out of your brakes. I was an FTO with a small sheriffs office about 20 years ago and I would always head to the ski area parking lots at night just to run the new officers through their paces on packed snow and ice. Everyone sucks the first time they go into a skid, but after only a handful of times, your reflexes develop and you start making more precise adjustments to your steering and braking.
Far better to practice with no one around than to hit your first icy road of the year with wall to wall commuters.