Major Structural Tests on GTB-40 PHEV Hybrid Bus
Successfully Completed
Innovative chassis design easily exceeds structural load requirements.  

Troy, Michigan – On September 11, 2008, Fisher Coachworks announced the successful completion of a major engineering milestone, as the first GTB-40 chassis easily surpassed load test requirements set by a Department of Energy research program for the development of the next-generation hybrid transit bus.
A funding milestone for the $2.5 million DOE program to build the first GTB-40 PHEV transit bus was completed today with the successful load testing of the chassis.  The test included loading the passenger compartment with a simulated 30,000 pound live load to check for structural deflection and possible deformation.  The test load represented 2.5 times the anticipated maximum loading; the equivalent of 200 passengers standing between the front and rear wheel wells.  The load was applied repeatedly over several days as testing equipment measured maximum deflection of the NitronicTM stainless steel monocoque chassis.

“Applying such a large load uniformly over the floor was an engineering challenge in itself,” commented Bruce Emmons, Fisher Coachworks Chief Technology Officer. “In lieu of utilizing hydraulic actuators or dead loads, we employed a more novel approach using atmospheric pressure to apply the load. Our test rig was comprised of a large vacuum chamber fabricated below the bus between the front and rear wheels.  The chamber was attached to the smooth underside of the bus floor with a special gasket material, and then we applied a precise vacuum to the chamber which uniformly loaded the floor to a pressure of 1.35 PSI.  Applying the test load just between the front and rear wheels actually represented a much higher loading factor, because evenly dispersed passengers would have placed offsetting moment leverage both fore and aft of the structural wheel housings. The resulting load of 30,000 pounds caused a maximum elastic deflection of just 3/8”; with no measurable permanent set.”

“I had no doubt that the bus would excel in structural testing,” commented Griffin Burgh, Chief Operating Officer for Fisher Coachworks, “but it was just as impressive to see another excellent example of Bruce’s engineering innovation.  Implementing such a carefully controlled test procedure at a traditional vehicle OEM could have been a very expensive exercise for this one-time test.  Our lean and innovative engineering approach continues to generate substantial savings while helping to drive creative problem-solving at all levels. Adding further substance to this, a recent visitor commented that the GTB-40 confirmation prototype would have required an investment of well over $25 million, or nearly 10 times our investment, using a traditional prototyping approach. I believe they are correct, and we will take this same lean, innovative spirit forward as we ramp-up our assembly operations in 2009.”

Earlier this year, the same GTB-40 chassis also completed vibration or “modal” testing to investigate the onset of possible harmonic resonance at various frequencies and amplitudes.  The testing was successful and data recorded will contribute to further chassis tuning to achieve exceptionally low road noise under power.

Further testing for braking, suspension durability, bumper protection, passenger safety, and overall maintainability will be conducted in 2009 during federally subsidized evaluations at the Bus Research and Testing Center near Altoona, Pennsylvania.

 About Fisher Coachworks, LLC
Fisher Coachworks was formed in 2007 to manufacture advanced hybrids using a patented ultra-lightweight stainless steel unibody structural system and low-cost fabrication process.  The company’s launch product is the GTB-40 PHEV Transit Bus which began road testing in Summer 2008. Applying a total vehicle optimization engineering approach enabled the company to significantly reduce vehicle mass, achieving step-change improvements in fuel economy, emissions and operating cost efficiency.  Currently based in Troy, Michigan, the company will soon be relocating to a larger manufacturing facility to prepare for ramped vehicle production beginning in 2009.

NitronicTM is a trademark of AK Steel Company.

For more information about Fisher Coachworks please contact:

John VanAlstyne
VP Marketing
Fisher Coachworks LLC
1150 Stephenson Highway
Troy, Michigan 48083
313-483-3700 x7702
jvanalstyne@fishercoach.com