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Eaton Stirs up Medium-Duty Market with Dual-Clutch Transmission

September 5, 2014

By Jim Park

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The Procision transmission was unveiled at Eaton's Marshall, Mich., proving grounds on Sept. 4. Photo: Jim Park
The Procision transmission was unveiled at Eaton's Marshall, Mich., proving grounds on Sept. 4. Photo: Jim Park
GALESBURG, MICH. -- Eaton is bringing a new transmission to the medium-duty market that boasts car-like drivability with full-manual performance, a design of 10 years or 400,000 miles, and 8-10% better fuel economy than a torque-convertor-equipped automatic transmission.

The new 7-speed transmission, called Procision, features a dual-clutch design and electronic shifting that uses grade, vehicle weight and throttle input to provide optimal fuel efficiency and smooth, continuous delivery of torque to the drive wheels under all shift conditions.

The Procision transmission will be available for order in mid 2015, Eaton says.

Eaton's senior vice president and general manager of Commercial Vehicle Transmission business, John Beering, says the target customer of this transmission wants a truck he or she can climb into, turn the key and drive away, while still meeting the unique needs of the multitude of applications that use such a product.

"Procision is a clean sheet of paper," Beering told a press gathering in Galesburg this week. "We took a hard look at what we had done in the medium-duty space in the past and we listened to the voice of the market that told us there were gaps they wanted addressed. This new dual-clutch technology addresses those gaps."

The Procision 7-speed, dual-clutch transmission was designed to suit a multitude of medium-duty applications, including pickup and delivery, rental fleets, school buses, towing/recovery and more. Photo: Jim Park
The Procision 7-speed, dual-clutch transmission was designed to suit a multitude of medium-duty applications, including pickup and delivery, rental fleets, school buses, towing/recovery and more. Photo: Jim Park
The transmission itself is a 7-speed set up rated for up to 660 pounds-feet of torque with direct drive in 5th gear. The overall ratio is 10.13:1, with a ratio of 6.5:1 in first, right up to 0.64:1 in seventh. It weighs 364 pounds and will be available in 26,000- and 33,000-pound ratings. It also offers right, left and rear PTO positions.

The key to the Procision transmission is the dual-clutch shifting technology. Eaton says the torque path to the drive wheels is not interrupted by the gear change, so the driver never feels any lag in power as he or she would with a traditional manual transmission -- even an automated manual. To the driver, it feels like a torque-convertor equipped automatic transmission. But the benefits of maintaining a constant gear mesh throughout the shifting sequence improve fuel economy significantly, especially in stop and go situations.

There are two input shafts and two clutches, explained Jeff Carpenter, engineering manager for the Procision transmission. "Think of input shaft A linked to clutch A, and input shaft B linked to clutch B. While the transmission is in a particular gear, the next gear path is preselected in the unused clutch and input shaft. The shift is executed by transferring the torque path from one clutch and input shaft to the other, and that transfer of power is seamless. The driver will barely notice. From that gear, the next gear is preselected and the torque path shifts back to the first clutch, and so on. It's a closed-loop control system that significantly reduces slip and steady state losses associated with torque converter automatic transmissions.”

The dual clutch module is fully contained within the transmission, hydraulically controlled and oil cooled for extended life. A five-spring damper is used to control torsional vibrations.

The electronic controls are mounted on the transmission to reduce wiring and connector complexity, and the entire unit is fully sealed to eliminate contamination.

The hydraulically actuated clutches switch the torque path from one input shaft to the other, seamlessly shifting torque through the geartrain so the wheels never lose driving power, even during a gear change.
The hydraulically actuated clutches switch the torque path from one input shaft to the other, seamlessly shifting torque through the geartrain so the wheels never lose driving power, even during a gear change.
Drivability Features

While the base transmission remains the same, it can be electronically programmed to meet the specific demands of dozens of different applications, from a typical pickup and delivery operation or rental truck fleet to tow trucks and school buses.

“Our customers had direct input on the features they want in a medium-duty transmission, and because of this real-world input, the Eaton Procision is smart from the word go,” said Joe Semaan, commercial vehicle segment director, Eaton’s Vehicle Group. “It is easy to tailor, which is key for fleet owners looking to put trucks on the road that best meet their business needs.”

Regardless of the application, the Procision transmission features several performance enhancements not currently available with traditional automatic transmissions.

Creep Mode allows controlled low-speed parking lot and loading dock driving without applying the accelerator. Forward and Reverse creep speeds are independently adjustable to allow a customized lower speed in reverse. Drivers can shuttle back and forth between forward and reverse without coming to a stop, and based on a brief test drive of the transmission, there's no hesitation when shifting between forward and reverse.

"The creep speed is controlled by clutch slippage, not engine idle speed," says Systems engineer, Tony Stasik. "Customers can select the speed they want for creep mode and we control the clutch engagement accordingly. We have designed the clutches to do this, so it's not placing any undue strain or wear on the clutch."

Because the engine and transmission are permanently linked, the truck won't free roll down a hill. And enough torque is transmitted through the clutch at idle, the truck can idle up a 5-8 percent grade without throttle application. This provides precise control for the driver in sometimes difficult terrain.  

Brake-pedal-actuated Tap Down Shifting gives the driver more control by downshifting on grades or other conditions without removing their hands from the wheel or eyes from the road.

In Low mode, Automatic Grade Braking downshifts the transmission to help slow the truck on long, steep grades and increase brake pad life.

“Because medium-duty customers rely on their truck day in and day out, reliability is key,” said Carpenter. “Our extensive reliability testing program takes into consideration a variety of geographies, vocations and duty cycles. We’ve put this transmission through things that an average customer would never experience.”

Smart features such as Eaton Dynamic Shifting allow the transmission to automatically switch between economy and performance shift schedules based on mass, grade and driver demand. Base shift results are modified dynamically based on available torque, engine acceleration and grade.

Economy and performance shift tables can be adjusted to tune an overall calibration to meet any customer’s specific needs. Eaton says the calibration flexibility is the most it has ever offered on a transmission.

Optional and adjustable Hill Helper technology prevents roll back or roll forward for up to three seconds while on grades of up to eight percent, allowing for a controlled launch. With Procision, these features can be turned on and off using Eaton’s ServiceRanger software.

Procision has three standard Power Take-Off openings. PTO functionality can be enabled via the ServiceRanger software by dealerships after purchase.

Photo: Jim Park
Photo: Jim Park

Fuel Economy Advantage

The Procision transmission features an optimized design that delivers 8-10% or greater fuel economy improvement over a torque converter automatic. The Procision is fully integrated with Cummins Vehicle Acceleration Management, which can be used in conjunction with Eaton Dynamic Shifting to reduce the impact of an aggressive driver on fuel economy. The optimized Urge to Move and Creep Mode provide an excellent balance of efficiency and performance. These features can be disabled for even greater fuel economy if desired. In addition, transmission load on the engine is actively reduced when the truck is stopped for increased fuel economy.

Service Life and Maintenance

Eaton Procision transmissions use a new synthetic transmission fluid which provides component protection while reducing maintenance costs. Maintenance intervals are extended to 150,000 mile lube and filter change intervals. The internal sump filter and electrical system do not require maintenance.

“With the fuel efficiency and low maintenance costs, Procision transmissions promise to deliver the lowest total cost of ownership for any medium-duty transmission in the commercial vehicle market today,” says Beering.

Eaton Procision transmissions carry a three-year/unlimited mile warranty, which covers the complete system including the dual clutch module, in commercial vehicle applications. School bus applications receive a five-year/unlimited mile warranty.

Procision transmissions under warranty can only be repaired by an OEM dealer or an Eaton authorized fleet, both of whom will benefit from the simplicity of the product and keeping service revenue in their shop bays, Eaton says.

“Customers told us that they wanted features that made their trucks easier to drive,” said Carpenter. “So we engineered a host of features that instill confidence and maximize efficiency for operators with routes on hilly, difficult terrain, or those who navigate tight turns and traffic as part of an urban route.”

For more information, click here.

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