On Thursday, 31 October 2013 at 19:45:17 UTC, Walter Bright wrote:
On 10/31/2013 7:57 AM, H. S. Teoh wrote:
You don't know how thankful I am for having learnt the concept
of
pumping the brakes, ABS or not. I'm afraid too many driving
instructors
nowadays just advise slamming the brakes and relying on the
ABS to do
the job. It doesn't *always* work!
Pumping the brakes is not how to get the max braking effect.
The way to do it is to push on the pedal to about 70-80% of
braking force. This causes the car to push its weight onto the
front tires and load them up. Then go 100%. You'll stop a lot
faster, because with more weight on the front tires they have
more grip. (I think this is called 2 step braking.)
You lose about 30% of braking force when the tires break loose.
The trick is to press the pedal just short of that happening,
which can be found with a bit of practice.
The downside of just slamming the brakes on and letting the ABS
take care of it is you lose the 2-step effect.
There are also cases where you *want* to lock the tires. That
case is when you're in a skid and the car is at a large angle
relative to its velocity vector. This will cause the car to
slide in a straight line, meaning that other cars can avoid
you. If you don't lock the wheels, the wheels can arbitrarily
"grab" and shoot the car off in an unexpected direction - like
over the embankment, or into the car that was dodging you. The
car will also stop faster than if the wheels suddenly grab when
you're at a 30 degree angle.
But yeah, I'd guess less than 1% of drivers know this stuff.
And even if you know it, you have to practice it now and then
to be proficient at it.
I still think that, although software can help to make things
safer, common sense should not be turned off while driving. If
it's raining heavily, slow down. Sounds simple, but many drivers
don't do it, with or without software.
