ARGH!!! brake controller 104

They experimented with diagonal split brake systems and found them to be pointless. Having a single brake line to the rear also saves probably $5 per vehicle in manufacturing cost. The frequency of loosing half your braking system while driving at any speed is also incredibly low. Much higher probability that if a line is going to fail, it will do so on the first actuation of the day, likely when you step on the brake initially when releasing the mechanical parking brake. Even then, ruptured brake lines are quite rare and a pinhole leak usually appears and is detected first.

The rear axle load in a pickup varies considerably, the front stays more constant. Braking pressure that slows down the loaded truck moderately can lock up the rears when it's empty. On my 91 only the rear circuit has ABS which senses the average rear wheel speed at the differential ring gear. A diagonal circuit would require two separate controller channels, brake line solenoid valves and individual wheel sensors.

It isn't as good as later ones but I've tested it HARD on ice and it works pretty well to keep the truck pointed straight. The previous version was simply a weight switch that detected when the bed was light.

I was a test engineer on the 1975 version of ABS for big trucks, the industry's first attempt at mass producing reliable safety-critical electronics. They all failed miserably, so badly that Congress repealed the truck stopping distance requirement. However the young engineers hired for that project (and emissions controls) learned fast. Previously the only electronic item in a car had been the radio.

jsw

On Thu, 25 Mar 2010 21:49:21 +0000, the infamous Mark Rand scrawled the following:

With _great_ care, sir. Oh, and a bit of prayer and possibly a bit of urine and/or fecal release, depending upon the speed of entry, the degree of brake loss, and your current mental state...

Oh, that's right. You Brits did it differently, didn't you? Here in the States, we learn, at a young age, the subtle differences between 2 and 4-wheel drifts.

-- Challenges are gifts that force us to search for a new center of gravity. Don't fight them. Just find a different way to stand. -- Oprah Winfrey

Mark Rand wrote in news: snipped-for-privacy@4ax.com:

The same way that drivers managed the feat *before* 4-wheel brakes became "normal" in the 1930s. (The Rickenbacker had them in the 1920s but was attacked by "the majors" who claimed that "they are dangerous because they stop too quickly".)

BTW, braking should be done *before* entering the corner and is most efficiently accomplished by using the engine...

One of the differences I learned then was that my Honda Civic could out-corner my friend's MG Midget, mostly because the MG's suspension didn't handle bumps as well and spun out more easily. He was the better (or at least crazier) driver, too.

Both vehicles had a very small polar moment of inertia and were almost as tricky as a motorcycle to slide. Later he bought a BMW 2002 that drifted with excellent balance and control.

jsw

On 26 Mar 2010 03:17:16 GMT, the infamous "RAM³" scrawled the following:

True!

Which equates to the rear tires only on older cars, the front tires only on newer, front-wheel-drive vehicles. Luckily, just going around a corner scrubs off speed, so taking your foot off the gas immediately helps, and downshifting helps more. But if you're still going too fast, a light touch on the (broken) brakes can still help a bit. Hopefully, you still have the circuit that -isn't- helping via engine braking, or it may break you loose. In an empty parking lot, it's fun (Dad used to run the autocross and gymkhana circuit.) On the side of a mountain with a 1,500' sheer drop, it's Pampers Time.

-- Challenges are gifts that force us to search for a new center of gravity. Don't fight them. Just find a different way to stand. -- Oprah Winfrey