When the first semi-automated manual transmissions began appearing on the market more than 20 years ago from Eaton and Rockwell (which later became Meritor), few would have imagined the popularity automated manuals enjoy today.
At the time, automatic transmissions were popular in vocational and medium-duty applications but were almost unheard of in linehaul, mostly because of the premium price and the limited range of gears.
It’s been a bit over a decade since true AMTs really came into the market, when in 2006 Eaton introduced the UltraShift and Volvo Trucks announced it was bringing its I-Shift to North America. Since then, Eaton and Volvo have both improved their offerings, Mack adapted a version of the I-Shift tuned to its trucks, and Daimler entered the market with the Detroit DT12 AMT.
Fast-forward to today, and the success rate of these transmissions has been unprecedented, thanks in part to their fuel-saving abilities.
A decade ago, reports that AMTs enjoyed take-rates of around 75% on new truck builds in Europe raised a lot of eyebrows in North America. Drivers here were different, everyone said; North American drivers were devoted to manual gearboxes as a point of pride, while North American fleets would be unwilling to shell out the higher price for AMTs. Even the most optimistic analysts predicted a very slow climb to 50% of the market in a decade or so. Maybe.
Those experts were wrong.
Today, commercial vehicle OEMs consistently report take-rates for new long-haul/over-the-road builds solidly around the 75% mark, with Daimler Trucks North America and Volvo Trucks North America eyeballing sales north of the 80% mark. Class 8 vocational sales initially lagged behind the on-highway market segments, but have been rapidly gaining ground the past couple of years.
Automatic transmissions are not new, of course. Units designed for trucking applications have been available for decades. But unlike conventional torque-convertor automatics, AMTs saved weight and cost by simply adding electronic control modules to existing heavy-duty gearboxes. This approach kept weight and costs down while ensuring durability in tough operating conditions.
Initial OEM and supplier marketing efforts focused on AMTs as a solution to driver fatigue and ergonomic issues, ensuring smoother and consistent shifting day in and day out. These attributes went hand-in-hand with improved fuel economy. While really good drivers can beat an AMT on fuel economy when they’re on top of their game, AMTs never get tired or distracted. So over the long term, fleets that ran AMTs would see marked fuel efficiency increases.
AMTs benefited from some unforeseen industry forces as well. Chief among them was the sudden spike in fuel prices in 2008-2009, leading to a new-found and unrelenting focus on fuel economy. On top of that was the ongoing driver shortage and the influx of new, often younger drivers into the industry – many of whom didn’t even know how to operate a passenger car manual transmission.
Building on these trends, two more remarkable developments occurred. For starters, grizzled older drivers, who’d sworn to never abandon their trusty manual gearboxes, decided in large numbers that in terms of safety and comfort (as well as cab space) AMTs lived up to the hype. Widespread – and often automatic – resistance to the transmissions melted away with surprising speed.
Perhaps more importantly, OEMs realized that the functionality of AMTs, combined with their adaptability and barely tapped potential for electronic engine and powertrain control, were the perfect vehicle to begin spec’ing fuel-efficiency-focused powertrains. Today, it is no exaggeration to say that in terms of powertrain control, downspeeding, active safety systems, and adaptive/predictive cruise control, all arrows point to the AMT. In an astonishingly short amount of time, these units have become the brain and nerve center of a modern commercial vehicle.
Given their remarkable success across all fronts, it begs the question: How much more powerful, capable and efficient will the next generation of AMTs be?
Smarter, faster, safer and more connected
Allison Athey, Volvo Trucks product marketing manager, transmissions, says that since its introduction in 2007, the company’s I-Shift AMT has gone through at least three different generations, with each one increasing the transmission’s flexibility and capability. Today, she notes, a standard I-Shift is a 12-speed transmission. The I-Shift with Crawler Gears, introduced for 2017, is available with 13 or 14 gears, allowing for more precise tailoring of the I-Shift for specific jobs, like heavy-haul or curb-pouring.
“In addition to performance enhancements to the current Volvo I-Shift, this generation also allows for over-the-air Remote Programming of software and parameter updates,” she adds.
Looking farther ahead, Athey thinks the next generation of AMTs will most likely be an evolution from units available today, making them better in terms of both overall performance and functionality as well as expanding application-specific solutions. “As computer hardware and software continue to evolve, so will the ability to control additional vehicle functions,” she explains. For instance, Volvo’s recent release of I-See predictive cruise control allows Paver Assist and Auto Neutral functions for its VHD model, all of which are supported by specific software.
Facing the potential for lost market share to these new, more efficient, integrated powertrains, Eaton and Cummins Engine worked to develop their own version, dubbed the SmartAdvantage. The two companies recently formed a joint venture, Eaton-Cummins Transmissions, to focus on bringing new technology and transmission products into trucking with an emphasis on safety, connectivity and fuel economy. Mario Sanchez-Lara, director of on-highway communications for Cummins, says deeply integrated powertrains and downspeeding will become the standard vehicle configurations in linehaul applications.
“The next generation of AMTs we are working on now will be lighter but more robust and able to leverage very high torque loads at low RPMs for downsped drivetrains,” Sanchez-Lara explains. “Once you start to add other systems to the equation, such as predictive cruise control, for example, we feel that next-generation powertrains will easily offer fuel economy increases from 2% to 4% from where we are today. In and of itself, a next-generation AMT’s alone can only deliver about a 1% fuel economy increase. But it’s the AMTs role as the enabler for the entire drivetrain that makes it invaluable in delivering these efficiency increases and will allow us to bring powertrain speeds drop another 100 to 150 RPM in the near future.”
AMTs are the central “brain” unit controlling most of the functions in ZF’s Innovation Truck, a concept vehicle unveiled by the company in Germany last summer. Frank Discher, technology and communications manager for ZF, says the trend lines today definitely show movement toward more fully integrated and connected vehicles. And AMTs will be critical in processing all the information associated with the many tasks these systems will enable and in ensuring seamless operation in all driving conditions.
“My point of view is that we will soon start looking at commercial vehicles more as one, complete, functioning system, instead of many different components and systems working together,” Discher says. “So right off, I think we will see substantial increases in the electronic capabilities for the next generation of AMTs. We will see them become ‘smarter,’ and more connected. They will start to integrate data in new ways. Everything from blending electronic drivers’ logs with GPS terrain mapping to provision-based shifting and throttle inputs using real-time and predictive terrain mapping for maximum fuel economy.”
Downspeeding will certainly be a priority for next-generation AMTs, agrees Steve Slesinski, director of product planning for the commercial-vehicle market at Dana Inc. He notes that downspeeding puts considerable stress on all drivetrain components. And AMTs will be key for managing power and protecting driveline components while delivering optimal performance and fuel economy.
“Increased torque impacts axle and driveshaft size much more than transmission design does,” Slesinski explains. “An engine running at lower rpms requires faster axle ratios to maintain the same vehicle speed and performance in all driving conditions, and it generates significantly higher torque-induced stresses in the driveline.”
However, as AMTs undergo additional refinements to allow for even lower engine rpms and closer transmission gear steps, don’t expect size, weight, or packaging of the transmission, axle and driveshafts to change greatly.
“As new physical products are released, I always expect some reduction in weight,” says Patrick Dean, chief engineer for Kenworth, but “current transmissions are already fairly optimized in terms of packaging and weight, so these changes will not be significant.”
As far as gearing goes, Dean says current 10- to 13-step transmissions have proven to be ideal for over-the-road operation with a good balance between efficiency and cost. “From a driver perspective, next-generation AMT improvements in drivability will mainly be seen in low-speed maneuverability. An example is Eaton’s urge to move that engages the clutch automatically when the service brake is released, creating a very car-like feel.”
Increased fuel economy will be a prime design consideration for future AMTs, too. And not just for over-the-road trucks. One important factor that will affect future AMT design are the Phase 2 greenhouse gas emissions regulations, says Gerard DeVito, vice president, technology, for Eaton’s Vehicle Group. “These are very aggressive targets that are really thinly disguised fuel economy goals,” he says. “And OEMs will be required to meet them across all vehicle platforms. This will lead to more AMTs moving into vocational applications, as well as putting new features in AMTs such as the ability to decouple road speed from engine speeds and PTO options. The planning process, as it happens now, is taking these factors – and many others – into account by over-planning the next generation of ATMs in terms of memory and data-processing capacity.”
Another important consideration will be connectivity, and vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) capability. This will be vital for autonomous or advanced driver assistance technologies and enhanced efficiency — both in terms of fuel savings and in vehicle utilization. Volvo’s Athey says these higher levels of vehicle integration, of which AMTs are a part, will be the enablers to provide customer efficiencies realized by V2V and V2I.
“In particular,” she says, “the more automation provided in the system increases the system efficiency. Imagine a V2 giving information to a vehicle with a manual transmission. The only help that may be offered is a signal to the driver to change speed, the driver processing that info and then the driver causing the change – do I shift gears, apply more fuel, among other things. Communicating to [an integrated engine and transmission] is quicker to act and therefore more efficient.”
There is no doubt that vehicle connectivity will continue to grow, says Melissa Sauer, executive director, corporate affairs and communications, Allison Transmission.
“Assuming that the security issue is solved and there is a secure connection through a telematics service provider or other means, the capability of remote diagnostics and programming presents fleets with opportunities to reduce vehicle downtime, to tailor their vehicles for their specific duty cycle, and better manage driver productivity,” Sauer says.
Thanks to increases in computing power and the corresponding leaps in safety, efficiency, and ergonomics that will accompany that trend, it appears AMTs will be a vital — perhaps even indispensable —tool for fleets competing in a faster and more complex operating environment.