MARSHALL, Mich. — Eaton has introduced North America’s first dual clutch automated transmission for medium-duty trucks, claiming it can net 8-10% better fuel economy than torque converter-style automatics. They call it the Procision. It could be called the Allison Assassin.
The dual clutch transmission replicates the strongest attributes of a torque converter-style automatic – notably its smooth shifting and robustness – yet still offers the relative simplicity of an automated manual design.
How it works
As the name implies, a dual clutch transmission incorporates two clutches and actuators, which alternate shifting responsibilities so that one of the two clutches is always engaged. This allows for “powershifting,” which eliminates the power interruption that traditionally occurs when a non-torque converter transmission shifts gears.
The Eaton Procision dual clutch transmission.
While the transmission is in third gear, for example, the second clutch pre-selects fourth and then the transmission seamlessly changes gears when an upshift is required. The other clutch will then pre-select fifth gear so it’s ready to complete the next upshift.
“This allows for the smooth, continuous delivery of torque to the wheels under all shift conditions,” explained Jeff Carpenter, engineering manager, Procision.
Powershifting also occurs with downshifts.
The seven-speed transmission is comparable in weight to a fully-automatic, yet Eaton claims it’s more serviceable. The transmission control module has been mounted onto the transmission itself and three PTO apertures are offered: one on each side and another at the rear.
On-road and dynomometer testing has indicated medium-duty applications using the Procision will yield an 8-10% fuel savings compared to torque converter automatics, and there’s potential for even greater savings in duty-cycles with frequent starts and stops or plenty of grades, officials said.
“A dual clutch transmission is more efficient than a torque converter and the more you have that torque converter out of lockup, the greater the benefits of the dual clutch,” Carpenter explained.
In developing the Procision, Eaton consulted with its customers to find out what they liked and disliked about currently available medium-duty transmissions. Many indicated they found the Allison to be a robust product, but costly and difficult to repair when necessary. Eaton felt it had to make the Procision more serviceable and reliable than existing products and so it was designed for a 10-year, 400,000-mile life. Even the clutches are expected to last that long. The Procision was built with all-aluminum enclosures, clutch housing, main case and rear case. It can go 150,000 miles between service intervals, meaning many medium-duty operators will be able to run three or four years before servicing their transmission.
How it performed
A number of trucks equipped with the Procision, and some fitted with competitive products, were made available for a full afternoon of driving activities at Eaton’s Marshall Proving Grounds. This is where the advantages of the dual clutch design became obvious.
Two Freightliner M2 extended cab chassis with identical Cummins ISB 6.7 engines were made available. One was equipped with the Procision and the other with a Gen 5 Allison 2000-series automatic with FuelSense features enabled, including load-based shift scheduling and vehicle acceleration controls. This was the baseline vehicle against which Eaton conducted its fuel economy testing. Both trucks were loaded up to 26,000 lbs.
The Procision outshone the Allison in several areas, most notably its performance on the grades, which ranged from 3-20%. A Hill Helper feature will hold the Procision-equipped truck in position on a grade of up to 8% with no rollback, allowing the driver sufficient time to apply the throttle.
Whether on flat ground or steep grades, the Creep Mode feature will move the truck forward or in reverse at a slow, steady speed, allowing the driver to feel in control of the vehicle at all times. The Allison-equipped truck freewheeled down the larger grades while the Procision descended in a more controlled manner.
Low-speed maneuvers such as backing were also easier to perform with the Procision.
The Procision also shines during acceleration, charging quickly through the seven gears without the momentary power loss normally felt between shift-points. Fuel no longer has to be spent to recover the momentum that was lost during gear changes and in this respect, the performance between the Procision and a torque converter automatic, or for that matter your passenger car, is very similar. The Procision and its Dynamic Shifting features can be synched up with Cummins Vehicle Acceleration Management, to ensure drivers aren’t wasting fuel while accelerating, by providing them only the power they truly need.
The tall first gear ratio of 6.50:1 allows the truck to get up to speed in a hurry and yet, Eaton officials claim it’s also consuming less fuel while doing so than the Allison. Eaton engineer Ed Magner said the Allison uses about twice as much fuel as the Procision when accelerating up to 30 mph. The Procision also saves fuel while idling in gear, by reducing the torque applied at idle, Magner explained.
Another nice feature is the Tap Down shifting, which allows the driver to downshift with a tap of the brake pedal, assuming conditions are right for a downshift. A Manual mode is still available, allowing drivers to shift gears themselves, but protection characteristics have been built into the transmission, which won’t allow the driver to cause damage. In fact, you can even shift from Reverse to Drive without coming to a complete stop without damaging the transmission.
Drivers of medium-duty trucks are often not professional drivers. Their truck is a tool that’s required to conduct their primary business. The Procision will be a great fit for these drivers as it’s easier to operate than existing products, giving the driver a greater level of comfort and confidence when operating the vehicle.
When it will be available
The Procision will be launched with an unnamed OEM next July, initially targeting the pickup and delivery, towing and recovery, beverage and school bus segments, which collectively comprise about 70% of the medium-duty market, according to John Beering, senior vice-president and general manager, commercial vehicle transmissions with Eaton. However, there are 200-plus other medium-duty applications that could eventually see the Procision. There’s also the potential to scale the technology up to Class 8, or down to Classes 4/5 vehicles, though Eaton officials said at the product launch they’re initially focused on the medium-duty applications identified above.
“We have a lot of customers coming to us from a variety of segments, both in North America and other regions, that are asking for this product,” Beering said. “We have constrained the team initially to stay focused on launching the core product, but there’s a growing list of folks lining up to talk. I’m quite bullish that following this, there will be much more to come.”
The Procision will come in two models, with or without Park Pawl. A new synthetic transmission fluid will be required.
Eaton’s John Beering unveils the new Procision dual clutch transmission.
The Eaton Procision dual clutch transmission.
James Menzies is editor of Truck News magazine. He has been covering the Canadian trucking industry for more than 15 years and holds a CDL. Reach him at firstname.lastname@example.org or follow him on Twitter at @JamesMenzies. All posts by James Menzies