OCT 2018


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OCTOBER 2018 52 CompositesWorld WORK IN PROGRESS » Proterra Catalyst battery-electric buses already have logged more than 4 million miles of zero-emission and — no small benefit — foul-fume-free service in public and commercial transit duty. Behind that green success is a structural design by Proterra Inc. (Burlinghame, CA, US) with TPI Composites Inc. (Warren, RI, US), in which all loads are supported solely by a monocoque composite structure. Minus the conventional steel frame, the buses are lightweight enough to offer operators a nominal range of 350 miles on a single charge. Composites technology enables performance goals "A transit bus can log hundreds of miles each day for 12 years up to 20 years, so we needed high strength, low weight and dura- bility," says Joshua Stewart, Proterra director of customer engi- neering. "e composites technology enables those goals." Catalyst boasts an acceleration from 0 to 20 mph in 4.5 seconds (an important asset for a bus merging into traffic); a curb weight of 26,000- 33,000 lb (11,793-14,969 kg), claimed to be the lightest in its class; and a climb gradeability of 15.5%, or 8°. (Gradeability refers to the percent of slope, or the steepest incline, the vehicle can climb from a standing start.) Further, the composites design offers unmatched corrosion resistance. Stewart notes that another substantial benefit of composites is safety in a collision. Automotive composite pioneer Gary Lownsdale, now owner of consulting company TransTech International Inc. (Loudon, TN, US), tells us how it works: "ough the damage mechanisms comparing metals Monocoque composite body designed to support all bus loads. A clean technology for clean, zero-emissions buses By Donna Dawson / Senior Writer Emeritus FIG. 1 All-electric buses with composite bus bodies A Foothill Transit (West Covina, CA, US) Proterra Catalyst 40-ft bus in its docking station; the charging arm connects with the contacts on top of the bus to recharge it. Foothill plans for all-electric buses by 2030 on its routes carrying 14 million people annually over 300 square miles, serving 22 cities plus downtown Los Angeles in Southern California's San Gabriel and Pomona Valleys. Source | Foothill Transit

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