New vision for blue bird: newest school bus designed for improved driver sight lines; first application for C7 ACERT in bus - on-highway vehicles

Diesel Progress North American Edition, Oct, 2003 by Mike Brezonick

Blue Bird Corp. has unveiled its new vision for transporting schoolchildren. You could also say that the company has developed a different view of engines as well.

For the kids, there's the new Vision school bus, a vehicle with a specially angled hood design that the company said provides the most unobstructed view of loading and unloading zones as any conventional bus on the market.

And for Blue Bird, there is the sight of a new preferred engine supplier. The Vision bus is powered by Caterpillar's C7 diesel engine with the company's Advanced Combustion Emissions Reduction Technology (ACERT). It is the first application of an ACERT engine in a school bus and the first Blue Bird application for the Peoria, Ill., headquartered manufacturer.

"It's a great pleasure for us to see, quite literally, Blue Bird's Vision become a reality," said Caterpillar Chairman Glen Barton, while visiting Blue Bird's Fort Valley, Ga., headquarters to mark the vehicle's formal introduction. "The Vision sets the standard in the industry and introduction of Caterpillar's ACERT technology into the North American school bus industry marks a significant milestone for our low emissions engine product line," Barton said. "Blue Bird is the leader in school bus technology and we're proud to be the engine supplier of choice."

The decision to use the new C7 was not taken lightly, according to Barry Hines, vice president and general manager, commercial bus at Blue Bird, who until recently served as director of engineering. "We had been predominantly using another engine," he said. "About three years, ago our engineering and sales and marketing went on a fairly indepth search to research everybody's technology.

"We looked at EGR. We looked at ACERT. We looked at the various other attempts and through that research--and it was about 9 to 10 months we visited all the engine manufacturers either at their facilities or here. We chose Cat.

"We think we got the way forward long term. Cooled EGR, we believe, is an interim step whereas Cat's philosophy was that this was the building block to the next step."

That, Hines said, was an important factor as it meant that Blue Bird wouldn't be required to make significant changes to the engine compartment down the raod to accommodate future emissions standards. "The Caterpillar it is very, very dean install," he said. "It is very, very similar to the 3126. So from a packaging perspective it is simpler to install--pretty much like repackaging a 3126 in any other product. There are some electronic changes, but we handled that through multiplexing. We multiplexed this chassis so it's a fly-by-wire chassis. Any electronics change we have needed to make, we go to a computer program to tie into the Cat program.

"As far as a typical engine install, this one was easy because we didn't have to deal with all the other externals of a new EGR system. We have put EGR on some other commercial products. As I've been able to compare the two installs, this is by far easier."

The C7 engine is rated up to 230 hp, depending on the size and configuration of the bus. The Vision is available with multiple floor plans accommodating as many as 78 passengers. Vehicle lengths range from 289 to 471 in. and wheelbases of 189, 217, 238, 252 and 273 in. Along with the Cat engine, the Vision's engine package includes a 175 amp Leece-Neville high output alternator; Valeo radiator/charge-air cooler; Horton fan clutch; Cooper air filter; Racor fuel/water separator; Wix oil filter; and diesel particulate exhaust filter.

The engine is mated to an Allison 2000 series automatic transmission that drives an ArvinMeritor rear axle rated 21,000 lb. through Dana Spicer lubed-for-life driveshafts. In front is an ArvinMeritor steer axle rated 12,000 lb.

The front axle incorporates Softek leaf springs and Hendrickson air ride suspension systems are available as options on both front and rear. The front axle design, combined with the power steering system, provides a 50[degrees] wheel cut, 5[degrees] better than the industry standard, according to Blue Bird. The Vision bus is also equipped with Bendix hydraulic antilock brakes. Michelin XZE 112R22.5 tires with highway treads are the standard tires.

The newly designed chassis frame includes heavy-duty reinforced cross members under the engine and front suspension. A 100 gal. fuel tank is positioned between the frame rails in the rear overhang. A 60 gal. tank is used on buses with wheelbases of 189 to 238 in. Overall structural strength is also enhanced by the company's trademark one-piece roof bow and unitized body construction.

As Hines noted, the chassis incorporates multiplex wiring for fly by-wire capability. The main wiring is run through a Commercial Vehicle Controls control module.

"There are a lot of new features on this bus," said Rich Maddox, Blue Bird's vice president and general manager. "There is better visibility for the driver and the dependability is through using components from the leading component manufacturers in the world, such as Caterpillar. It's our belief that working with suppliers like Caterpillar helps us build a better product. And we like the fact that, both companies have a longtime love of the color yellow."