But the truck didn't fall onto the outrigger because the system sensed what was happening, and quickly cut power and applied the brakes. I took the mixer into one turn faster than the demo's prescribed speed and the tandem's inside wheels left the ground. Not that the anti-rollover system will guarantee a truck's safety. The price might be somewhere between $2,000 and $3,000, which would pay for itself many times over if the system saved just one $150,000 mixer truck. Mack has not yet announced a price for the Road Stability Advantage system, but Tom Kelly, senior vice president for marketing, said it'll be a lot less than what some customers who previously saw the demo said they'd be willing to pay. Last August, Volvo showed off its version of the Bendix stability system for tractors during a truck show in Dallas. If the trailer is an older one without ABS, the system on the tractor sends pulsing pneumatic signals back to the trailer brakes, effectively turning them into ABS-controlled units, said Randy Howe, Bendix's northeast regional sales manager who works with Mack and its sister company, Volvo Trucks. On a tractor, the stability system sends signals that are read by the trailer's ABS, whether it's Bendix's or another manufacturer's. Brake applications vary at each wheel, depending on the direction of the turn and the dynamics being experienced.
The stability system and ABS then take appropriate action, cutting power and applying brakes.
#BENDIX ABS TOO PLUS#
The system shares a more powerful electronic brain with ABS it reads inputs from sensors on wheel ends, plus more sensors on a truck's steering column, chassis and braking system, and compares the severity of the turn to road speed. But the truck's braking action was nowhere near the violence of a real rollover.Įlectronic stability control is an enhancement to the anti-lock braking system now required on all air-braked trucks and tractors. Braking action seemed smoother on the tractor-trailer rig than on the truck, maybe because the semi's total wheelbase is far longer.
#BENDIX ABS TOO DRIVER#
The trailer begins to roll first and there's no seat-of-the-pants feel it's usually past the point of no return by the time the driver sees it in his mirrors, if he looks at all. The start of a roll is apparent to the driver of a straight truck, but not to the driver of a semi or other combination vehicle. The system reacts in microseconds to a rollover situation and acts before a driver might be aware that he's in trouble, the Bendix people said. In the sharp turn and lane-change maneuvers, the system simultaneously cut power and applied the brakes. RSA cut power on me several times as I made sharp right turns at the other end of the parking lot I was driving too slow for it to apply the brakes, but it knew that the truck was still moving too fast into the turns for its own good. What I couldn't feel until I drove the truck is that although the accelerator was floored, the system told the engine to cut back on power, which also helped with deceleration. The truck's wheels stayed on the pavement and we finished each run at about 10 to 15 mph slower than when we began. As the truck barreled into the sharp turns at 25 to 30 mph, the brakes came on swiftly and slowed the vehicle to a safe speed. Ross flicked a switch on the dashboard to turn on the system and went through the coned courses again, first entering a tight-radius right turn and then a sudden double lane-change maneuver. With RSA switched off, I was jostled a bit as the truck tried to roll over, then plopped back onto all its tires when he hit the brake pedal. Bendix test driver Charlie Ross took it through the coned courses while explaining what he was doing. The Bendix-made system will be available later on air-braked straight trucks from other builders.įor the demonstration, the Granite mixer's drum was loaded with 12 tons of pea gravel to simulate concrete. And they are preparing systems for dump and tank trucks, which also carry heavy, high-centered loads.
Engineers are programming RSA for other mixer configurations, including multi-axle chassis with forward-set steer axles, Romanchok said. But Mack claims to be first with an anti-rollover system for vocational trucks, and its three-axle Granite mixer chassis with a setback front axle is the first to be fitted with RSA. Some truck builders already offer stability control on tractors. Engineers must study each vehicle type and program the stability system accordingly, explained Kevin Romanchok, director of electronics for Bendix Commercial Vehicle Systems. The inherent instability of loaded mixers makes them far harder to deal with. But tractors like the Vision are relatively easy to equip with an electronic stability system, because most semitrailers they pull don't vary too much in mass and center of gravity, said Bendix engineers working on what Mack calls its Road Stability Advantage, or RSA.
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