Paccar is the latest North American truck manufacturer to bring a proprietary automated transmission to market. Called the Paccar Automated Transmission, it’s a 12-speed, twin countershaft design that was designed from the ground up as an automated transmission. It’s not a manual box fitted with add-on shift-actuators. Paccar says it’s the lightest automated transmission currently in production. At just 657 pounds, it is nearly 200 pounds lighter than Eaton’s Advantage AMT.
The new transmission completes Paccar’s goal of a fully integrated proprietary powertrain. Paccar says it has been performance-optimized for MX-series engines and the new 40,000-lb drive axles that were unveiled in October 2016.
“Last year’s launch of the Paccar axle was certainly a statement to our customers that we were moving toward our own integrated powertrain,” says Kenworth Marketing Director Kurt Swihart. “We have spent a lot of time over the past few years working on proprietary calibrations for the transmission and the MX engines. The result is a deeply integrated powertrain that will deliver everything customers would expect from such a design.”
Swihart says the AMT take rate for the T680 has more than doubled since its introduction, going from 25-30% in 2013, to currently more than 70% of T680 on-highway builds. He calls that a rapid and dramatic change in customer preference, and he believes this new transmission will push the take rate even higher. “We think moving from the Eaton Fuller Advantage series transmission to the Paccar automated transmission will be a game-changer.”
Let’s dispense with the big question right up front: Eaton designed and will manufacture the transmission, but the calibrations and features are proprietary to Paccar and its truck brands Kenworth and Peterbilt.
Production is set to begin in October at Eaton’s San Luis Potosi facility in Mexico, which won the National Quality Award in 2014.
And to put the other big question to rest: Yes, Eaton’s Advantage 10-speed AMT will still be available from Paccar, as will the rest of Eaton’s manual and automated transmission lineup and certain Allison automatics. Kenworth says it has no immediate plans to make the new automated transmission the standard offering.
Development work on the Paccar Automated Transmission has been ongoing for the past three years, including testing ranging from standard line haul validation to summer and winter testing in extreme conditions.
“We benchmarked all the other great products out there and looked at what customers liked about those other offerings, and we found ways to incorporate and surpass the best design features that exist in the market today,” Swihart says. “Eaton, with its long history and expertise in transmission design and manufacturing, has hit a home run with this product.”
Nuts, bolts, and semiconductors
The transmission will hit the street geared with many features that Eaton customers are already familiar with, such as Urge to Move, Creep Mode and Blended Pedal. These offer better low-speed maneuverability in low and reverse gears, while the latter allows the driver to “slip” the clutch by varying foot pressure on the brake pedal.
Also baked into the Paccar Automated Transmission are several drivability enhancements, such as optimized gear selection, which selects appropriate starting gears and makes optimized shift decisions based on vehicle weight engine torque, grade and throttle position. More fuel-saving features are offered as options.
“If the customer specifies Predictive Cruise Control, then the GPS capability will integrate with the Paccar Automated Transmission. Also available is Predictive Neutral Coast, which uses GPS to shift into neutral earlier than the standard neutral coast.”
All the hardware is built into a lightweight all-aluminum enclosure, with an externally mounted integrated ECM. Wiring and sensors are enclosed within the case to protect them from the elements. The shifter mechanism was designed into the transmission rather than bolted on after the fact, and uses pneumatic actuators.
Finally, the Paccar Automated Transmission is equipped with a 430-mm (17-inch) clutch with diaphragm springs and cushioned organic facings. These are said to provide more even pressure on the plates and smoother engagement. Clutch engagement is managed by an electro-pneumatic linear actuator, which Swihart says “provides a more robust and responsive way to actuate the clutch.”
The Urge to Move and Creep Mode features will amp up clutch stress over time, which seems to be why Paccar and Eaton have engineered what appears to be a very robust clutch and actuator system. From what we know now, there’s very little maintenance required on the transmission, and there are heat sensors on the clutch that will warn drivers to go easy on the thing before any damage occurs.
The next biggest question after who makes the transmission would be, how does it perform? I had about two hours in dense Seattle to find out, and even that short drive put the transmission through its paces. Stop-and-go traffic means lots of shifting, and the hills and turns give the transmission lots of reason to be seriously engaged in the process. Running on flat open highway isn’t much of a workout for a gearbox.
My drive began with a few laps around the parking lot at Kenworth’s Research and Development Center in Renton, Washington, to observe the low-speed drivability. We were loaded to 65,000 pounds, enough to test the smoothness of the launch and few low-speed gear changes. I could feather the brake pedal at launch to make the truck creep back and forth very smoothly with no jerks or lurches. Even backing into a loading dock did not produce that cab-jarring torque surge as the truck smooched the dock pads.
Due to the transmission’s hard-wired determination to skip-shift whenever even remotely possible, some of the high-acceleration launches saw the engine revs getting close to 1,600 or 1,700 rpm coming out of second gear and heading for fourth, but on a gentle acceleration, I seldom saw 1,400 rpm when upshifting. Driving in stop-and-go was very pleasant and smooth, even starting on a hill. The transmission seemed happy enough to deliver the acceleration when I put my foot right into it, but that’s so counterintuitive for so many reasons that I can’t see many drivers doing much of that. It was a little torquey at those times, but so is any automated transmission, and this one seems less so than others I’ve driven.
Given the number of times it skip-shifted, they probably could have made it a 6-speed rather than a 12. I don’t think I ever saw 3rd, 5th or 7th gear while accelerating up to speed. Once up to speed and cruising in the 45-60 mph range, upshifts came at a comfortable and fuel-efficient 1,400 or 1,500 rpm, usually dropping the Paccar MX-13 engine down to 1,100 — and on several occasions a sultry 1,000 rpm. The peak torque range on that engine extends from 1,000 up to about 1,400; that’s where all the pulling power is and it’s also where the least fuel is consumed.
It’s pretty clear that the level of system integration between the engine and the transmission is pretty high. They are more than speaking the same language; they are singing from the same hymnbook.
Because of the traffic density, I only got into top gear once. There, I cruised at 1,000 rpm at 60 mph before having to get off the freeway at our exit back to the Research and Development Center. Much of the on-highway time was spent in 11th gear (direct) where cruise speeds were around 50 and 1,200 rpm or so.
At various times the engine brake came on based on my cruise control settings and did a good job of maintaining my set speed, plus or minus a few mph for a more comfortable and fuel-efficient ride. On a few of the hills where I figured Neutral Coast might have kicked in, it did not. I guess the hills were a little steep for the transmission’s conservative sensibilities. Best to err on the side of caution, I suppose.
I got a good mix of city and highway driving in during those couple of hours, and the transmission handled it all with finesse and aplomb. It’s as smooth-shifting as any of the best automated transmissions on the market right now, and vastly better than some. Having 12 gears rather than 10 provides more gear selection options for performance and fuel efficiency without the complexity of a multi-speed transmission, and the 17-inch clutch with its linear actuator (I still don’t quite understand how that works compared to a traditional actuator, but I’m learning) makes for a very smooth launch and stop.
Given that it’s a brand new product, albeit with three years of design, validation and durability testing behind it, some folks may be reluctant to dive right in, but my two-hour drive suggests there won’t be anyone holding out it because they don’t like the performance.
The new Paccar Automated Transmission performs like a veteran and will surely meet the driver satisfaction test. They have backed it with an extraordinary 5-year/750,000 warranty, and with its oil drain interval also at 750K, few fleets will find reasons to avoid it solely because of its maintenance requirements.
Originally posted on Trucking Info
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