OK you retro grouches in the back row, settle down… I know you drove a million miles in that old truck with no ABS or even brakes on the front axle and did just fine, though you’re still complaining about that jacknife and the flat spots on the trailer tires.

Maybe I got too techy with the discussion on stability control systems on 22 or more wheelers the other day, so time to back track with some discussion of just what these technologies is and isn’t. ABS is pretty simple, havin’ been around since the 1950s. Originally developed to prevent flat spotting on aircraft tires during landings, with the coming of semiconductors ABS had migrated to trucks by the 1970s. Initial prototypes showed a lot of promise- the Civic driving idiot that pulled in front of the ’73 Freightliner with experimental Kelsey-Hayes ABS survived unscaved because I was able to nail the brakes hard on that rainy day and stop straight with no jacknifing or fishtailing. But NHTSA got a little too optimistic about ABS and mandated ABS on all new air braked trucks… A ’78 Freightliner I drove with malfunctioning off brand ABS blew right through a red light with my foot pushing the brake pedal right to the floor. Fortunately I laid on the horn and everyone waiting to cross on green waited up a couple seconds more. A driver and several motorists on a downgrade into Salt Lake City weren’t so lucky- despite eyewitness accounts that the brake lights on the rig were lit up, the rig kept picking up speed and finally stopped in a multi fatality accident. That evidence caused the courts to throw out the ABS mandate, and the ABS designers went back to the drawing board, while us truckers taped over “ABS” idiot lights on our dashboards.

A decade later, ABS was back, and I again had a chance to sample a prototype on an ’88 Freightliner with a Bosch system that was so german that the diagnostic tool for it was labeled in german. A decade of advances in semiconductors and weatherproofing had made ABS safe and reliable, and by the mid 90s NHTSA again made ABS mandatory on new air braked trucks and trailers. Yup, there was some initial whining until mechanics and accountants noticed that jacknifes were going extinct and trailer tires were wearing twice as long.

Now an explanation of how ABS works is probably in order now before we get into the enhancements like traction control and such that have been piggybacked on ABS. ABS is stupid simple- usually just a toothed wheel on the axle or hub and a pickup that counts how many times those teeth have passed and thus calculating speed. That message gets sent to a pretty dumb computer that compares the signals from the various wheels and watches for huge differences in speed between wheels or sudden changes in speed, like would happen if a wheel locked up. If the computer detects lockup, it tells a modulator along the brake line to that wheel to back off the pressure until the wheel is rollin’ again.

Like I said, pretty stupid… Which explains why the manufacturers have been adding functions to these basic ABS systems. Heck, as long as you’ve got a system to detect locked wheels and get them rolling again, why not use the same system to stop wheelspin on accelleration? Thus was begot traction control, with the computer gently braking the spinning wheel and sending a message to the motor to cool it a bit. Too many rollover accidents? Add a g-meter or tilt detector and gently apply the brakes to slow the rig to below tipover speeds while the one week wonder behind the wheel soils his shorts. Rig slewing around in an evasive manuever? Take a signal off the steering draglink to see where the driver intends the rig to go, then apply brakes to steer the whole rig in that direction.

So we thus have an all singing, all dancing ABS and stability control system. Not exactly simple (the manufacturer needs some fancy test equipment to set the stuff up), but when your trying to get a hundred foot long double or triple trailer rig down the road in the intended direction and to stop on command, the technology is pretty handy. And we’re just getting started- for example, that signal off the steering drag link can be used to steer trailers or dollies so a near 200 foot long triple trailer rig can make it around the tightest cloverleaf loop. Add a converter mounted hybrid battery pack and motor, and we’ll probably be able to move twice the cargo with no more fuel than we’re using now while providing traction to get up slippery hills.

Meanwhile, some troglodyte will still be clipping ABS power wires and the “one week wonders” will find new and creative ways to put big trucks in the ditch…

 

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