Mack: New Powertrain Products Save Fuel, Cut Emissions

April 22, 2016, by Tom Berg

2017 Mack MP-8 TC uses a second turbo to send extra power to the crankshaft and save fuel. Photos: Mack Trucks
2017 Mack MP-8 TC uses a second turbo to send extra power to the crankshaft and save fuel. Photos: Mack Trucks

Mack Trucks picked Earth Day in Austin, Texas – said to be one of the country’s most “green” cities – to announce its 2017-model powertrain products designed to save fuel and reduce carbon emissions.

The products include improved diesel engines, a more compact and easier-to-service exhaust aftertreatment apparatus, predictive cruise control, and 13- and 14-speed versions of its automated manual transmission for vocational use.

They continue in the tradition of the Mack brothers, who started the company in 1900 and early on “saw the powertrain components they were purchasing from others weren’t up to the task, and they began designing and building their own,” said John Walsh, the current-day company’s marketing vice president.

Mack was the first North American truck maker to use vertical integration and continues to evolve its products to satisfy the needs of customers and, by meeting increasingly stringent government mandates for emissions and fuel economy, to protect the environment – the essence of Earth Day which originated in 1970.

Guard Dog Connect telematics – over-the-air monitoring of engine and truck performance – is now being employed to help keep trucks running and on the road, increasing efficiency and earning revenue, Walsh said.

Mack’s 2017 engines feature the 10.8-liter MP-7 and 12.8-liter MP-8 diesels, which have been refined and upgraded to deliver greater fuel efficiency and emit fewer oxides of nitrogen, thus meeting government economy and greenhouse-gas requirements, said Stu Russeli, highway and powertrain manager. 

Principal changes include a common-rail fuel injection system, replacing the current unit-pump method, to lower parasitic losses and achieve more precise injection events. “Wave” piston tops have indents into which injectors spray fuel, which results in better combustion.

A two-speed water pump on the MP-7 also reduces energy required to move coolant. And turbo compounding on an MP-8 model adds up to 50-hp otherwise expelled as exhaust heat, reducing the load on the engine and cutting fuel use.

The turbo-compounded MP-8 TC will be rated at 445-hp, a popular version for regional and long-haul operators who are especially conscious of fuel economy, Russeli said. A new 425-hp rating for the MP-7 delivers “13-liter power in an 11-liter engine” while reducing weight by about 400 pounds for bulk haulers and other weight-sensitive operators.

An assembled tubular camshaft with attached lobes replaces a forged shaft now used, saving 27 pounds in both engine series. Redesigning engine blocks has trimmed additional weight.

The new MP-8 goes into production in October at the powertrain plant in Hagerstown, Md., that also produces engines for sister company Volvo as well as axles and transmissions for both divisions. The new MP-7 will enter production in January.

13-, 14-speed mDrive

Rear section just ahead of the bell housing contains creeper gears for 13- and 14-speed vdersions of Mack's mDrive HD. 
Rear section just ahead of the bell housing contains creeper gears for 13- and 14-speed vdersions of Mack's mDrive HD.

Mack’s mDrive automated manual transmission will get a new predictive cruise control that will save fuel for on-highway operators, Russeli said. It uses Global Positioning Satellites to note a truck’s location as it travels and records terrain profiles, then remembers the profile the next time the truck driver over that route.

It helps the truck efficiently climb and descend grades because it “knows” what’s coming and adjusts the throttle accordingly, adding power to climb hills, easing off at crests, then cutting power  and putting the transmission into coast mode as the truck rolls downhill, he explained.

The 12-speed mDrive HD vocational automated transmission will additional ratios through a new back section with creeper gears for enhanced startability for heavy loads and on steep grades, said Roy Horton, director of strategy. The 13-speed mDrive HD will have a 19:1 low-range gear while the 14-speed will have that and a low-low gear with a 32:1 ratio. The low-low ratio will also be useful for very low-speed concrete pouring and maneuvering in tight quarters.

ClearTech One

ClearTech One assembly contains CO catalyst, diesel particulate filter and urea dosing chamber. DPF element can be easily pulled for servicing, Mack says.
ClearTech One assembly contains CO catalyst, diesel particulate filter and urea dosing chamber. DPF element can be easily pulled for servicing, Mack says.

A new exhaust-aftertreatment apparatus saves weight and space and will be easier to service, Horton said. Called ClearTech One, it combines an oxidation catalyst, diesel particulate filter and urea dosing chamber into a single unit. The DPF element is positioned so it can be easily removed through an access cover. An entire canister need not be removed from the chassis, as is now the case. This cuts servicing time by 50%.

Exhaust gases flow through components via gentle curves and, when fully treated, flows through an outer chamber to preheat equipment so operation is more efficient. This helps reduce the number of DPF regenerations that might otherwise be needed, further saving fuel.

Treated and spent exhaust gas then leaves the unit, and is so clean that remaining pollutants can barely be measured. Thus, with advances made elsewhere in the industry and in society, future Earth Days should be even greener, Mack executives suggested. ClearTech One will be available in August on Mack Pinnacle and Granite models.

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