Although slowed by existing federal regulations, the U.S. trucking industry is moving toward adopting advanced braking technologies, according to officials at Meritor Automotive. Meritor Heavy Vehicle Braking Systems briefed trucking media this spring on progress toward electronic braking systems (EBS) and other refinements.
Current federal regulations call for combination vehicles to stop in 355 feet, compared to 194 for passenger cars. Pressure is mounting to have FMCSA reduce the distance somewhat for cars, and to reduce it significantly for trucks. To help meet the challenge, Meritor has an operable electronic braking system (EBS) and a line of air disc brakes (ADBs), now standard equipment on top-of-the-line European tractors and trailers. Any new government mandate for shorter stopping distances may drive us to accept ADBs and EBS.
A new concept that may prove equally important to electronic braking systems is "friction coupling." EBS will cut the time interval between the moment you hit the pedal and the moment the brakes activate, and will make up for differences in brake torque between individual wheels. Friction coupling can work on all types of brakes: S-cam, wedge and disc.
Friction coupling involves matching the material and structure of the brake surface, disc or drum, with properties of the friction lining or disc pad. It can be done by coating the surface or by re-engineering materials using ceramics, new alloys or composite structures.
Friction materials will be developed that work best with each particular surface. With friction coupling, brakes and linings can be engineered according to vocation. The technique maximizes the transfer of vehicle energy, while it minimizes wear on both the friction material and the drum or disc. Meritor believes that friction coupling, using new composite matrix materials, can be available within five years.
The ultimate stopping system will likely be one in which an electronic control unit (ECU) receives input from sensors all around the vehicle. When you press the brake pedal, the ECU measures the speed of pedal movement and the force applied. It then decides which combination of actions is best for the situation: reduce fuel to the engine, activate the retarder, shift the automated transmission, and, of course, apply the friction coupled brakes.
Until the day comes when computers monitor all our systems, we still need to check our brake linings and drums, grease our automatic slack adjusters, and do four or five consecutive hard stops every month or so, just to put the automatic slack adjusters back in balance.
Meritor recently released its new CamLaster automatic adjusting cam brake technology, currently an exclusive available only for Freightliner tractors. Meritor will soon make the CamLaster available for trailers. It should make S-cam brakes virtually maintenance free over the five-year, 500,000 mile product warranty period.
Meritor is now the world's largest supplier of brakes for heavy commercial vehicles. Its product line runs from the familiar S-cam brakes to a full range of wedge brakes and air-operated-disc-brakes, and now encompasses brake drums, slack adjusters, air dryers, hubs and wheels, ABS brake control systems, friction materials and even brake valves. This total systems approach can simplify truck and trailer manufacturing.
Know Before You Slow
If your tractor is ABS equipped and you must pull a non-ABS trailer, be very careful when braking on less-than-ideal road surfaces. Check your mirrors often when applying brakes. If you see the trailer start to come around, ease off on the brakes.
Hopefully, you will have enough room to slow or stop while maintaining control of your trailer. Otherwise, you may have to decide on the lesser of two evils: the damage from rolling into what lies ahead, or from wiping out what lies to your side. That's not a decision any of us wants to make. There have been a number of fatal crashes due to ABS on the tractor only.
Find out if your trailer has ABS, and drive it accordingly. And remember, the best way to stay out of trouble is to avoid it in the first place by staying alert, looking ahead and leaving adequate stopping distance.
