Deep Thinking: Eaton-Cummins tech right for the times
Posted: November 6, 2018 by Jim Park
The Endurant is a clean-sheet design conceived as an automated transmission. It’s a 12-speed twin-countershaft unit weighing just 657 lb. Direct drive is in 11th gear, with 12th gear offering a 0.77:1 overdrive.
JAMESTOWN, N.Y. — Cummins and Eaton have been integrating components for years. In 2013 they announced an engagement of sorts with the launch of the SmartAdvantage powertrain. Last year, by launching the Endurant transmission through the Eaton Cummins Automated Transmission Technologies joint venture, the last two independent major component suppliers figuratively tied the knot.
Before the end of this year we will see a new suite of performance features for the X15/Endurant powertrain that integrate engines and transmissions more tightly than ever before. In my opinion, this pairing is as tight as any of the vertically integrated OEM powertrains.
Back in June I went to the Cummins plant in Jamestown, N.Y., to hitch a ride on a Kenworth T680 equipped with the new powertrain. At that time, some of the calibrations were still being developed and not all the features had been named, so I couldn’t very well write about them in a test drive. You’ll soon officially hear what the engineers have been up to. In the meantime, I can tell you it will be worth the wait.
As a reminder, the Endurant was introduced to the market in October 2017 as a clean-sheet design conceived from the beginning as an automated transmission, not as a manual with add-on shift actuators. It’s a 12-speed twin-countershaft design weighing just 657 lb. Direct drive is in 11th gear, with 12th gear offering a 0.77:1 overdrive.
Our test drive took us along I-86 between Jamestown and Erie, Pa. That stretch has loads of rolling hills and a couple of climbs long and steep enough to prompt a downshift or two in some cases. The engine model was an Efficiency Series X15 450 SA, delivering 450 hp with 1550/1850 lb-ft of torque at 1000 – 1400 rpm. It also had the full Adept feature suite, including SmartTorque 2, SmartCoast and Predictive Cruise Control — a pretty typical fleet spec’ powering a pretty typical 65,000-lb. Gross Vehicle Weight load.
As innovative as it is, Endurant is still just a box full of gears until it’s programmed and bolted to a Cummins engine. I’ll get to the latest feature updates shortly, but first, here are my basic driving impressions of the X15/Endurant powertrain.
If previous generations of Eaton automated transmissions left a bad taste in some mouths, the Endurant is like a bottle of mouthwash. The closer ratios between the 12 gears allow for more skip-shifting opportunities and much smoother shifts to boot. It launches very smoothly, whether the driver is kind to the throttle pedal or just stomps on it. The level of acceleration changes with the “aggressiveness” of the throttle application, but it’s all carefully managed to not push the engine out of its optimum operating range. The new calibrations favor using as few gears as possible while accelerating, based on weight and grade, and are actually more inclined to skip up through the gears if the driver is firm on the pedal.
My first few runs through the gears were fairly gentle — in keeping with my driving style. I think I skipped two gears on the way from 2nd to 12th. My guide and instructor, Mike Hicks, a vehicle systems integration and calibration engineer at Eaton Cummins Automated Transmission Technologies, suggested I try driving it the way most drivers would, and sure enough, all the odd-numbered gears seemed to disappear. On one launch from a stop sign, I floored the pedal and we hit 6th gear on the second shift and then went right to 8th. I went from 2nd to 8th in two shifts and the engine revs were never carried away.
I hate to admit it, but I think my driving style has gone out of fashion. The team that put this calibration together recognized that many of today’s entry-level and junior drivers are going to drive this truck the way they drive their cars, and they have wisely tuned the calibration to that driving style. It responds really well to an aggressive throttle application, and when cruise control is set it settles into a more “seasoned” driving style basically invisible to the driver.
Cummins’ X15 for 2018 offers several calibration updates that improve drivability and performance when paired with an Endurant transmission.
New features and calibrations
The quick-shifting, fast-accelerating performance is new to the product, thanks to two new features. The first, Engine Assisted Shifting (EAS), uses the turbocharger as an exhaust brake of sorts, using exhaust backpressure to slow the engine for faster upshifts. That process also preserves boost pressure, so there’s no lag time while the turbo spools up after the shift. This helps drivers get up to speed more quickly without driving more aggressively.
On top of EAS, Performance Shift Optimization allows for higher engine revs in fourth gear and above, encouraging skip shifting and getting the truck up to speed more quickly with no fuel consumption penalty. The fuel savings come from fewer gear changes through the lower, less-efficient ratios.
Because Hicks had his computer connected to the electronic control module, he was able to turn these features on and off for demonstration purposes. The difference was obvious.
I noticed another of the new features almost immediately, even though I wasn’t initially aware of it. Launch Control Tuning all but eliminates the lag time as the clutch engages at launch. The truck literally starts moving the moment you depress the accelerator pedal. This is sure to be a hit with drivers.
The above-mentioned features are standard with the latest calibration and software update, which is backwards compatible with the first models released earlier this year. I also tried out two optional features that expand on technologies now available in the Adept suite: Accelerator Coasting Management and Predictive Gear Shifting.
Accelerator Coasting Management allows the transmission to coast in neutral on slight downhill grades even when the cruise control is not engaged. Protections are baked in to keep the truck from going above a customer-selected speed, where the transmission re-engages and the engine brakes activate. Coasting takes advantage of vehicle momentum without the parasitic losses from engine friction.
Predictive Gear Shifting uses look-ahead data from the Predictive Cruise Controls’ GPS and terrain maps to pick the right gear for an upcoming hill. It reads engine load, vehicle weight and grade to match engine output with the right gear to reduce or eliminate downshifts while climbing. This one confused me a little because it caused the truck to perform in ways I wasn’t expecting, like downshifting early — or what I would call early. We did in fact climb the grade without shifting on the hill. We just shifted before we got to the hill.
As I mentioned earlier, my driving style was somewhat at odds with this setup. Once I accepted the fact that it was calibrated for a different driving style, it all made more sense. The Eaton-Cummins joint venture will sell thousands of these powertrains to fleets with legions of exactly the type of driver to which this calibration will appeal. However, drivers like me can still order a calibration that will suit their driving style, too. That’s the nice thing about electronic controls — you can take the same pile of hardware and make it perform exactly for its intended market. Basically, this powertrain will appeal to everyone who likes red engines, because you can get it the way you want it.