Powertrain engineers believe more fleets will shift to fully automatic and automated mechanical transmissions because all such gearboxes throw a three-punch combination that's hard to beat: They can be more easily integrated with engines; are more adaptable to specific applications; and above all, they make driving a truck easier and safer. “Look at where people who operate delivery trucks come from — from driving cars, not trucks,” points out Anthony Nigro, a powertrain integration engineer with DaimlerChrysler.
Nigro notes that shift quality with automated and fully automatic units is much better — with every shift being a “good” shift. “That helps you get better component life,” he says. “With a manual, you make a bad shift, drop the clutch a little bit hard, and you've got that shock going all the way through the driveline, every u-joint, going through the axle, the hubs, and the wheel ends. That can be pretty damaging over time.”
“We like to sell productivity,” says J.K.S. ‘Joe’ Johansson, Allison Transmission senior applications engineer. “When you get into extremely poor conditions with a manual, when you have to shift, you have to release the powertrain — and then when you get back into gear, the power digs into the drivetrain. You don't get full power through the shift. You don't have that problem with an automatic.”
“Driver training issues are significant,” points out Jim Devore, senior product engineer for ZF, which produces the automated ZF Meritor FreedomLine. “Given that learning on a shift without a synchronized transmission is one of the hardest things there is to do in terms of driving a truck, abuse is a significant issue; a lot of clutches and parts get replaced because they're being driven incorrectly. While [automated] units can't prevent abuse, they certainly can reduce the opportunity for it.”
Curt Hutchins, Eaton's general manager for fleet transmissions, points out that the automated Eaton Fuller UltraShift helps improve overall safety because it “enables drivers to keep their eyes on the road and both hands on the wheel. Optimized downshifting and use of the Jake brake entering onto exit ramps also reduces chances of truck rollovers.”
According to Hutchins, the automated unit enables “controlled shifts made at ideal engine speeds that improve efficiency and performance.” He adds that manual “skip-shifting,” available as operating and load conditions allow, is a feature that provides “for optimum performance and fuel efficiency.”
Engineers will be working to boost automated and automatic transmissions over technological hurdles posed by emission regs and the push for powertrain integration. “I think a continuing challenge for us, as an industry, is future engine legislation and how that translates into additional heat,” says Allison's Johansson. “It's the nature of the beast in order to do what EPA requires. Some strategies require more heat to lower emissions, so we … must find ways to get rid of it.”
“Ten or 15 years ago, you had to change the hardware to change response times or shift parameters,” says ZF's Devore. “Now we can do that simply by altering the software. We try to make it so the transmission on its own reacts differently when conditions change,” he adds.
“A new value to consider,” says DaimlerChrysler's Nigro, “is offering a completely integrated powertrain. That can give you a better-engineered product; you have the luxury of engineering the whole system as a single unit. That helps the transmission, be it automated or automatic, operate more efficiently.”
