Better late than never ...
I'll not discuss ABS systems which limited brake force to the wheels, as they are too old for me to care, rarely found here in Amerika, and nearly extinct. The ABS systems I'm familiar with respond to a locked wheel by immediately releasing that wheel's brake for one to two tenths of a second before resuming old fashioned brake function, which would lead to that wheel locking again, which repeats the process until the vehicle either comes to a stop, or the driver releases the brakepedal sufficiently.
I owned a Cadillac Fleetwood with 4 Channel ABS, which was capable of shorter ABS panic braking distances than my present Chevy Caprice Estate with 3 Channel ABS. Since they both weigh within 100 lbs of each other, I assumed, and later determined for a fact, that either rear wheel locking takes that bit longer for 3 Channel ABS to unlock, resulting in longer braking distances for the Estate.
Corporal Ed Sanow, of the Benton County Indiana Sheriff's Dept, wrote:
ABS brakes got off to a bad start with a lot of law enforcement officers when they were first put on police cars in 1991. It was assumed that police officers understood how ABS brakes worked, including the pulsating pedal. While Mercedes-Benz, BMW, and other European cars have had ABS for a long time, it was totally new to most cops. They had to be taught that the ABS brakes would not lock, taught not to pump the brakes during emergency stopping, taught that the pedal would pulsate and even kick back a little when activated, and taught that the pedal would be lower before maximum braking.
This was a lot to teach every police officer in the U.S. Over the next few years, with both Ford and GM active in educating the police on the characteristics and advantages of ABS, cops got up to speed [on ABS brakes].
ABS had a controversial start, but is now a widely understood and accepted safety device.
This is not the case with the general public.
Some people misunderstand [and possibly fear] the kickbacks. Upon feeling the pulsations, they come to believe that their brakes are malfunctioning, and either begin pumping, or partially releasing the brakes to 'calm' the pedal. Either action increases braking distances to potentially dangerous effect.
(I'm nearly convinced this is the biggest reason why Panic Brake Assist was invented; the other reason being that some people simply won't step on any brake pedal hard enough for fear of locking, or fast enough, for pretty much the same reason.)
Some people believe that ABS brakes allow a car to stop in a shorter distance than a non-ABS car. While an ABS panic stop should outperform four locked wheels in any case, that was never their raison d'etre. This assumption, or at least its miscalibration, is also potentially hazardous.
A well calibrated ABS system should perform within 16% of a theoretically perfectly executed panic stop. This isn't always the case. Depending on the quality of the ABS calibration, it may take longer.
I personally rate ABS systems by how close they come to my average threshold braking distance on dry and wet surfaces; all through the nineties, most cars' ABS panic stops gave up more than 20% to my average performance, meaning 'thumbs down'.
I also find fault with ABS systems that overreacted to bumpy roads, measured by deactivating the ABS and changing lanes in the bumpy area.
ABS' purpose was to preserve their ability to continue steering the vehicle [with the steering wheel instead of the brakes], thus to give drivers another way to avoid crashing into stuff. The finding that ABS is ineffective is misleading for one reason:
It is the drivers who were ineffective, because they - unlike the average police officer - STILL haven't been trained in either the use of ABS brakes, or the steering wheel.
[rant]I've said this before, and I'll say it again:
Untrained drivers deserve more training, not more gadgets. If a person spent the money to buy ABS, Traction Control, Stability Control/Roll Control, etc on themselves, THEY'D have equipped themselves, and thus carry the benefits to every car driven, instead of paying over and over again.[/rant]
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