Heavy Duty Trucking

AUG 2014

The Fleet Business Authority

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test drive i 36 HDT • AUGUST 2014 www.truckinginfo.com continuous power flow — "power shifting" similar to fully automatic Allisons and other lighter-duty truck products. Power flow in the TC10 alternates among the counter- and main shafts, depending on what gear it's in, Allison reps explain. The TC10 has no dry clutch that contacts the flywheel, but it does have wet clutches — five in the main 5-speed gearbox and two in the 2-speed range box. The range box also uses planetary gears and a synchronizer. The resulting feel is like an automatic transmis- sion, but with less "slush." There is inherent smooth- ness that competitors' automated manual products can't quite match, advanced though they are. They definitely can't duplicate the Allison's continuous power flow, because they need a pause in engine output to make each gear change. Allison says that pause requires an engine to work a little bit harder each time to regain momentum, and that costs fuel. It's been two years since we first reported on a drive of an early TC10 automatic transmission. Since then, the innovative product has undergone more testing and development and has entered production at Allison's plant in Indiana. The time it took to get it exactly right allowed competitors to field new or improved automated transmissions, but the TC10 stands out as the only true multi- speed heavy-duty automatic. So far, the TC10 is available from only one builder, Navistar. You can buy a TC10 today in the International ProStar, which represents the exact type of vehicle the transmission is aimed at: short- and regional-haul tractors that run on-highway but see a lot of gear shifting, as well as some vocational tractors that don't go off road. Its fuel economy advantage over manual and even some automated gearboxes, said to be a solid 5%, would make it valuable in long-haul tractors, as well. "TC" in the name means Torque Converter and Twin-Countershaft gearbox, as the product has both. The combination provides very smooth start-ups, and quick shifting that's done under Tom Berg Senior Editor This 10-speed brings continuous power to a crowded field of smooth self-shifters test drive Allison's TC10 automatic transmission Allison's demo rig included a ProStar sleeper- cab tractor and a 34-foot Vanguard trailer with GCW of about 56,000 pounds. Navistar's tractors, driven later, pulled longer, heavier flatbeds with GCWs well into the 70,000-pound range. PHOTO: TOM BERG

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