John Kingsley knows a thing or two when it comes to driving trucks for a living.
A former owner-operator turned company driver with 22 years of over-the-road experience under his belt, Kingsley followed a path into the industry familiar to many big rig operators — starting right out of the U.S. Army — with his career split between flatbed and dry van operations.
Needless to say, after all this time, he knows intuitively how to shift gears to get the best possible fuel economy, a skill built on millions of miles of hard-won experience and one no machine could equal. That is, until he test drove a 2018 model Freightliner Cascadia equipped with a 15-liter Detroit engine mated to a 12-speed DT12 automated manual transmission (AMT), which is also sometimes referred to as an automated mechanical transmission.
“Overall, the truck continues to amaze me with its ability to handle shifting under just about every situation thrown at it,” he explained to American Trucker, following a two-week test run.
“The predictive cruise control, which uses a database of terrain mapping to adjust the speed of the truck as it crests a hill, and then allow it to coast as needed down the backside, works wonderfully in most situations,” Kingsley said.
“It does, however, require you to actively keep abreast of the speed going downhill on extended grades. In my truck’s settings, it will allow itself to exceed my company’s preset-governed limit by 5 mph before automatically applying the Jake brakes to slow the truck,” he noted. “Under conditions where the truck’s roll-out would exceed our governed speed, I do have to apply the [engine brake] manually to keep it within the set guidelines.”
Kingsley said he took his 2018 Cascadia on a run across Ohio and Pennsylvania along the full length of the Pennsylvania Turnpike and into New Jersey with a gross weight of 79,000 lbs. He then followed that run with a “really light load of aluminum cans” weighing only 6,000 lbs. that took him up into lower New York and then all the way down to Jacksonville, FL.
“So here were two extremes of driving situations: A heavy load on a route that involves endless hills and downgrades to keep you busy, plus a run that covers several hundred miles of the flattest Interstate driving in the country,” Kingsley noted.
“But I held on to almost 8 mpg on the run across Pennsylvania to New Jersey. And on the run down to Jacksonville, the truck averaged just shy of 11 mpg,” he said. “Yes, it was a light load and covered a great deal of extremely flat Interstate down I-95, but the truth is, that would’ve been quite a good number in my previous Cascadia, but as a bobtail. This truck, with all the aerodynamic improvements and the new engine/transmission package, continues to impress me.”
After two weeks and over 7,300 miles, Kingsley pointed out that his AMT-equipped 2018 Cascadia averaged 8.4 mpg, even with engine idle time included.
“The reset I just finished in the Dallas, TX, area chewed that down to 8.3 mpg, but that is still a really good number” in terms of fuel economy, he stressed.
Those kinds of fuel savings are just one of many reasons fleets — and now even owner-operators — are rapidly shifting over to AMTs in their truck specs, reasons that also include lessening driver fatigue, explained Kelly Gedert, manager of Detroit powertrain and components marketing for Daimler Trucks North America (DTNA).
“AMTs such as our DT12 are absolutely a benefit from a driver fatigue perspective because the transmission does the work for you and eliminates the need to repeatedly use a clutch for manually shifting gears,” Gedert said.
“Like for many of us, as drivers age, reflexes slow down, joints get stiffer, and muscles weaken,” added Kurt Swihart, marketing director for Kenworth Truck Co.
“Arthritis, which is common among older adults, can make it harder and often downright painful to shift gears, particularly after a full day of driving,” he explained. “Then there’s the traffic in and around metropolitan areas. Over the years traffic conditions there have become increasingly difficult and taxing on even the best drivers. And as the recent fire and collapse of an elevated part of U.S. Interstate 85 in Atlanta clearly demonstrated, such events can make navigating in and around those areas even more challenging.”
Swihart said that driving a truck with an AMT can make such scenarios less challenging to deal with.
“Often we’ve heard from our fleet customers who have chosen to equip their Kenworth T680s and Kenworth T880s with AMTs that their older drivers say how much they appreciate the ability to be more attentive to the traffic around them,” he said. “They don’t have to quickly gear down to stop or slow down or gear up to get back up to highway speed. They also like how much more relaxed they feel at the end of their driving shifts.”
But it’s the fuel efficiency benefits that really seal the deal, added Scott Kuelber, general manager of Detroit component sales.
“What AMTs do is bring your worst driver’s performance closer to your best driver,” he emphasized. “AMTs like the DT12 don’t have bad days. They can skip shift to get to top gear as efficiently as possible and ensure that you’re always in the most optimal gear. Cruise control usage plays a major role in fuel efficiency and, while in cruise, AMTs can leverage ‘predictive’ technologies to use the truck’s kinetic energy to limit fueling, shifting and braking.”
Kuelber noted that the DT12’s Intelligent Powertrain Management provides a 3% improvement in fuel efficiency on average over an AMT without such predictive technologies.
Kenworth’s Swihart echoed Kuelber’s perspective, noting that since AMTs can be more easily paired with predictive cruise control, it further reduces fuel consumption by the truck’s engine as it crests a hill, since GPS readings tell the system that it can use the vehicle’s momentum to maintain and increase speed on the downslope.
“AMTs can keep trucks operating at lower rpms particularly when they’re running in off-highway environments or in stop-and-go traffic,” he emphasized. “That can help drivers get the best fuel economy possible.”
Ken Davis, president of Eaton Corp.’s vehicle group, noted that automating the gearbox allows truck operators to spend more time focusing on road conditions and worksite tasks to help improve safety. The vehicle group recently formed a 50/50 joint venture with engine maker Cummins back in April dubbed the Eaton Cummins Automated Transmission Technologies specifically to foster wider adoption and sales of AMTs.
Davis also noted that Eaton’s AMTs are connected to the vehicle and engine through a high-speed data link so information is processed in real-time, allowing the transmission to optimize gear selection, engine torque, and clutch position.
“Shifting logic is developed to allow the powertrain to operate in the most efficient zone of the fuel map, enabling performance and fuel economy gains,” Davis explained. “[That] logic utilizes real-time road grade and vehicle mass estimates to adjust upshift and downshift points, just like an experienced operator would as [vehicle] mass or road grade profiles change.”
He added that Eaton’s AMT technology is also heavily integrated with cruise control and predictive systems, allowing optimized gear selection to efficiently maintain the desired speed range. These design characteristics help improve fuel economy and performance while providing a more comfortable and safer operating environment for drivers.
“With a smaller and smaller workforce available, having trucks equipped with AMTs can make fleets more attractive to perspective employees who don’t typically drive trucks,” noted Kenworth’s Swihart.
“AMTs provide them the opportunity to focus on the road and drive more confidently without much training or practice,” he added. “Even among more seasoned drivers, AMTs are becoming not only more widely accepted but also expected because they can make driving more relaxing. That’s why we’re seeing increased interest and demand for AMTs in the on-highway and vocational markets, and we expect to keep seeing that grow.”
Other truck OEMs say they are witnessing the same trend taking shape among their customer bases.
During a recent press conference, Roy Horton, director of product strategy for Mack Trucks, noted that the company’s mDrive AMT is now being spec’d in 80% of its Class 8 Pinnacle axle back highway tractor models, 60% of its Pinnacle axle forward tractor models, and 20% of its Granite conventional vocational trucks.The backlog for mDrive gearboxes spec’d in Granite trucks is now at 30% for 2017.
Overall, Horton said AMTs and fully automatic transmissions are now being spec’d across 80% or more of all Mack models, with only 15% to 20% of orders requesting manual transmissions.
The same is true for Mack’s brother company, Volvo Trucks North America (VTNA), which noted that spec’ing for its I-Shift AMT (originally designed for the European market in 2001) topped 90% on all of its truck models sold through the first five months of this year.
“Looking at the market today, AMTs lead to higher residual values and have for the past several years,” noted Allison Athey, VTNA’s product marketing manager for transmissions.
That’s a trend line Kenworth’s Swihart agrees with as well.
“Demand for trucks with AMTs continues to increase, both in the new- and used-truck market,” he said. “About two out of every three Kenworth T680s our dealers sell are equipped with AMTs. With a higher demand for trucks with AMTs, resale values are getting much stronger. Fleets are also telling us they are experiencing less damage and less clutch replacement when they [spec] AMTs. That can offer owner-operators lower operating costs throughout the truck’s life.”
With additional AMT features that provide low-speed maneuverability and functionality, AMTs are becoming, in Swihart’s words, “a very valid option” for vocational markets, too, like dump truck and ready-mix concrete chassis.
“And like trucks in the on-highway market, we anticipate those vocational trucks to maintain high resale values at trade-in,” he added.
“We have seen an increase of AMTs … entering the secondary market over the last 12-18 months, and they are holding a premium position over manual transmissions,” noted DTNA’s Gedert.
“Those worried about the higher price of an AMT should consider the benefits, like improved fuel economy, safety, reduced maintenance, [longer] clutch life, and the opportunity for a lower cruise speed rpm,” Gedert said. “These [AMT] transmissions will more than pay for themselves.”
Looking to the future, AMTs will remain key enablers of downspeeding and will continue to be to an even greater degree in the future, noted VTNA’s Athey.
“Adaptive cruise control is not limited to AMTs, while predictive cruise control is exclusive to AMTs,” Athey stressed.
On a different trend line, Wesley Slavin, on-highway product manager at Peterbilt Motors Co., noted that both fleets and owner-operators will continue to move toward AMTs and fully automatic gearboxes as a way to improve both driver retention and recruitment efforts.
“Driver retention is crucial as the driver workforce pool ages,” he stressed.
The ease of driving a truck spec’d with a fully automatic gearbox or AMT provides a more comfortable environment for “tenured” drivers, while on the driver recruitment and training front, they are both helpful in terms of making training easier.
“As younger, less experienced drivers are entering the workforce, the growth of AMTs and automatic transmissions increases,” Slavin noted.
It all makes the case that AMTs should remain the “hot” transmission of choice for truck drivers young and old, in either over-the-road or vocational environments, for the foreseeable future.
AMTs and automatics: Measuring the cost
So how much more does an AMT or a fully automatic gearbox cost versus a manual shifter?
As luck would have it, the global consulting firm Frost & Sullivan conducted a study last year to answer that very question for several different commercial truck segments as well as identifying some of the “ripple effects” from broader AMT adoption:
- The medium-duty truck premium for AMTs averages $600 to $3,000 per gearbox, increasing to between $1,000 and $5,000 for heavy-duty units.
- The medium-duty truck premium for fully automatic transmissions averages $3,000 to $6,000 per gearbox, rising to between $6,000 and $10,000 for heavy-duty units.
- With newer dual clutch automated transmissions (DCTs), the medium-duty premium averages $3,000 to $5,000 per gearbox, while the heavy-duty premium averages between $5,000 and $10,000.
- Those high incremental costs versus the potential to gain fuel savings is the primary factor presently inhibiting mass adoption of all three types of gearboxes, dubbed “electronically controlled transmissions,” or ECTs, as a group, the firm noted.
- Worldwide, AMTs are expected to experience the highest rate of adoption over the next decade, with a compound average growth rate (CAGR) of 12.5%, while fully automatic gearboxes will experience a CAGR of 7.7%.
- Downspeeding, engine downsizing, and the increasingly “vertical integration” of truck transmissions in North America, Europe, and Asia is “catalyzing” the adoption of ECTs. Truck OEMs in particular are using ECTs to meet the higher torque requirements downspeeding places on powertrains.
- European truck manufacturers already offer AMTs as “standard fitment” in both medium- and heavy-duty trucks; their market share topped 55.4% among European Union trucks last year.
- The manual transmission will still dominate in trucks with gross vehicle weight ratings exceeding 16 tons, Frost & Sullivan stressed, as the fuel economy benefits of ECTs aren’t as yet conclusively proven.
- The firm noted that manual transmissions as a group will still experience a decline in global heavy-duty truck market share from 81.4% currently to 65.5% by 2025.
- AMTs and fully automatic gearboxes will hit a compound average growth rate of 3.9% and 2.9% through 2025.
- By 2025, Frost & Sullivan expects the market share for manual transmissions among North American medium- and heavy-duty trucks will decline to 43.5%, while AMT market share will climb to 29.4%, with fully automatic gearboxes at 27.1%.
Downspeeding: What is it?
About two years ago, the North American Council for Freight Efficiency (NACFE) issued a report regarding the potential advantages of “downspeeding” a truck, which basically entails spec’ing faster gear ratios while lowering engine speed or its revolutions per minute (rpm). Lowering engine rpm is what improves fuel economy, with about a 1% gain in fuel efficiency per every 100 rpm reduction. That also lessens the need for horsepower, as a fleet used to 425- to 450-hp. engines would typically find a downspeeding-configured variant generating just 400 hp.
NACFE’s research indicated downspeeding can reduce commercial truck fuel consumption by 2% to 3%.
What does that mean in terms of cold, hard cash? Well, Mike Roeth, executive director at NACFE, explained that for a “classic” over-the-road Class 8 tractor accruing 120,000 miles a year, a 1% savings in fuel equates to roughly $700 annually. Thus a 2% to 3% fuel economy improvement returns anywhere from $1,400 to $2,100 per year.
But that’s with diesel prices pegged at $3.75 to $3.85 per gallon. As diesel prices have instead hovered around the $2.50 per gallon mark for several years now, that “return” from downspeeding needs to be cut by about a third, Roeth said. So this means that the fuel economy improvements generate about $1,000 to $1,500 worth of savings per year.
Yet the key that truly unlocks the benefit of downspeeding is an automatic gearbox that is far more precisely computer-controlled than ever before, he stressed.
That’s also critical because within a powertrain “optimized” for downspeeding, faster rear axle ratios are in use and much more engine torque is being delivered down the driveshaft. While that heavier torque load is easily managed in steady-state (read as “highway-speed”) operation, it becomes a big problem in start-and-stop applications.
“Torque is up significantly in downspeeding-configured powertrains and so there is the potential for driveline issues, particularly in day cabs operating part of the time in pickup and delivery applications,” noted Roeth.
In those situations, “more robust” components are available, he pointed out, but that can hike the cost of downspeeding-configured powertrains by $500 to $1,000.
According to NACFE’s research, about 25% of the truck “build” going on today encompasses downspeeding-configured powertrains, a level the group thinks could reach between 50% and 70% over the next three to five years just due to the fuel savings alone.
