Automated manual transmissions (AMTs) have come to dominate the on-highway trucking segment, but they’re also gaining acceptance in vocational applications. Once shunned by drivers who preferred the reliability and versatility of their traditional stick shift, today’s AMTs can do more than ever. They’re no longer pigeon-holed into the on-highway segment, and they now have the smarts to make even the most fuel economy-challenged drivers perform like the best in any fleet.
Schneider is one of the mega-fleets that is in the process of converting its entire fleet to AMTs, a process that should be finished sometime this year. It is even hiring drivers who only have experience operating an automated transmission.
“We have been testing various versions of automated transmission tractors since 2007, so we had a lot of experience behind us when we made the decision in 2015 to start transforming the fleet,” said Rob Reich, Schneider’s vice-president of equipment, maintenance and driver recruiting. “Ever since then, we have been very impressed with the dependability of these tractors. In fact, we’ve had fewer maintenance issues with them than we’ve seen with the manual transmission tractors, which is not what we expected. We’re extremely pleased with the performance of these vehicles – and more importantly, so are drivers.”
I’m a big fan of automated transmissions, especially the newest versions, which perform beautifully and simplify driving. Here are some transmission trends I’ve noticed in recent years.
Mastering slow speeds
One of the knocks against early generation AMTs was that they were sloppy at ultra-low speeds. This is part of the reason they were slower to catch on in vocational applications. Volvo’s I-Shift now comes in a 14-speed version with two crawler gears, to effectively address this criticism.
My opportunity to first drive the 14-speed I-Shift with crawler gears came at Volvo’s Shippensburg, Penn., off-road test site. The gears allow the truck to move smoothly at speeds right down to 0.6 mph – even up and down a 21% grade. This makes the transmission capable of slow jobs such as pouring cement or conquering logging roads.
Magnus Koeck, vice-president of marketing and brand management, predicted the addition of crawler gears will all but eliminate manual transmissions in vocational applications within five years.
“The I-Shift we have now with crawler gears can do all the work the customer needs,” he said.
Mack has also brought two additional creeper gears to its mDrive AMT. The announcement, made at Truck World in 2016, gives customers in vocational applications an alternative to the Allison fully-automatic transmission.
Eaton also offers improved low-speed maneuverability with its Urge to Move and Blended Pedal features. Urge to Move allows the truck to crawl forward slowly when the brake pedal is released, and Blended Pedal allows the driver to control clutch engagement at engine idle through accelerator positioning and enables movement at varying speeds.
The Eaton Endurant – and its Paccar-branded sibling – brought some new developments to the automated transmission segment, in the form of the first purpose-built automated transmission. Instead of automating a manual transmission to handle the shifting, the Endurant was a clean sheet design. This enabled Eaton to take about 200 lbs out of the transmission, compared to its UltraShift Plus AMT.
“With an AMT, you started with a manual gearbox, so you had constraints where the shift pattern had to make sense to the driver,” explained Matt Erdmann, manager of program management with Eaton. “With Endurant, we said we are not holding onto any preconceived anything. We started with a clean sheet of paper and did what made sense. So, it took a
lot of restrictions off our engineering team.”
Linear shift rails allow for quicker gear changes. It also comes loaded with a Gear Logic shift schedule program, which changes from 12th gear down to 11th when rolling down secondary highways, to enjoy the benefits of direct drive, improving fuel economy.
The Eaton Endurant was the first transmission made under a joint venture with Cummins, dubbed Eaton Cummins Automated Transmission Technologies.
The Paccar-branded version of this transmission was calibrated to work optimally with Paccar MX engines. Aside from software programming and exterior branding, the two transmissions are the same.
All AMTs in the market are now available with some form of predictive shifting. This allows the transmission to select the best gear to take advantage of the truck’s momentum when ascending, cresting or descending a grade. How this is achieved varies by model.
The Volvo I-Shift and Mack mDrive must first “learn” the route they’re traveling. As the truck travels the country it remembers the road profile, and in the future, will take advantage of what it has learned to maintain momentum on grades.
The Detroit DT12, on the other hand, comes pre-loaded with GPS maps that tell the transmission when to shift based on the road profile. This means the DT12 is delivering the performance benefits from its very first run.
Detroit’s IPM6 (intelligent powertrain management) is the feature that provides predictive shifting. The road network that is now loaded onto the DT12 has just recently been increased by 35%, to nearly a million road slope miles. Many of the additions came in central Canada.
Paccar officials say their predictive cruise feature can reduce the number of gear changes made by as much as 20%. It also says fuel economy can be improved by up to 1%, thanks to the feature.
Servicing automated manual transmissions has become easier, thanks to vertical integration and their coverage under the various manufacturers’ remote diagnostics platform.
Transmission fault codes can be identified remotely and the best course of action to remedy them can be offered to the fleet manager or maintenance provider. In a sense, the transmission is able to tell a maintenance manager what’s wrong with it, so that the problem can be fixed immediately (if necessary) or during its next scheduled servicing (if it’s not an urgent fault).
It’s just another way the latest AMTs have gotten smarter.
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