Natural gas, suspensions and powertrain receive attention from Mack

by James Menzies

ALLENTOWN, Penn. — The construction truck market remains mired in a slump, but Mack Trucks hasn’t been sitting on the sidelines, waiting for it to recover. The company outlined several new product developments at a recent press event, which have kept Mack engineers busy.

One of them is the company’s strength in the natural gas truck market. Curtis Dorwart, vocational product marketing manager, noted Mack has been offering natural gas trucks since the early 90s. Over that time, it has built several hundred natural gas trucks and many of them remain in service today, Dorwart said.

UPS has been a notable customer of natural gas-powered Mack Pinnacles. The company ran a CH model since 2001 and that truck was recently retired to the Mack Museum in Allentown.

“That truck worked out so well, it postured us for additional orders from UPS,” Dorwart said. Mack is offering the Cummins Westport 12L spark-ignited natural gas engine, which produces up to 400 hp and 1,450 lb.-ft. of torque. It works well for regional haul applications and can run off either liquefied or compressed natural gas.

On the refuse side, the Mack TerraPro can also be ordered with a natural gas engine. Dorwart said this offering has allowed Mack to strengthen its West Coast presence.

Also new to Mack, and currently in production, is the Twin Y air suspension, which highway product marketing manager Jerry Warmkessel vowed will “revolutionize” the Class 8 truck suspension industry.

The Twin Y provides a smoother ride and has proven in real-world applications to extend drive tire life by 25%, Warmkessel said. Unlike traditional air suspensions, the Twin Y is designed to position the axle entirely on the air bag. It also saves significant weight. At 630 lbs, it weighs 70-500 lbs less than other suspensions currently in the market, including 110 lbs less than Mack’s previous lightest-weight option, the MaxLite 40 EX.

The Twin Y is lube- and maintenance-free and the axle seats don’t have to be re-torqued, Warmkessel said. It also produces little torque reactivity when the driver is on the throttle or brakes, resulting in a smoother ride. The simple design includes a Y blade assembly, spring hanger bracket and upper and lower axle seats. Elastomeric bushings are designed to last a million miles.

“We’ve had 13 customers put on three million miles with this and they all came back and said the same thing, that the suspension got 25% better tire wear on the rear axles,” Warmkessel said.

On the construction side, Stu Russoli, construction product marketing manager, spoke of the new mRide spring suspension. It’s a six-rod suspension designed for extreme articulation and greater ground clearance.

The mRide is available in 40,000-, 46,000- and 52,000-lb weight ratings on the axle-forward Pinnacle, Granite, Titan and TerraPro. Stiffness can be controlled by choosing from between two and 11 springs, and shock absorbers on all four corners of the suspension provide a smooth ride, Russoli said. The rubber center bushings don’t require lubrication and the mRide weighs about 300 lbs less than a conventional camelback suspension.

Russoli acknowledged that some applications are still better served by a camelback, but “we see this taking a big chunk of that business.”

Speaking to improvements in powertrain design, David McKenna, director of powertrain sales with Mack, talked about the Econodyne+ and SuperEconodyne packages.

The Econodyne+ allows customers to get 15-litre-type power out of a smaller, more efficient 13L engine, McKenna said.

“Up till now, power and fuel efficiency have been two mutually exclusive items,” he said. “If you wanted to boost power, it generally cost us fuel economy. The idea was to take some modern technologies and apply them and optimize our powertrains.”

In the past, engineers were generally able to get 20-25 hp for every litre of displacement.

“Now we can get engines that are more like 39 hp per litre,” McKenna said.

The Mack MP8 Econodyne+ engine can produce 505 hp and now offers 1,860 lb.-ft. of torque when it’s needed. Normally, the engine would offer 1,660 lb.-ft. at cruise, but when the driver needs some extra power, the engine will increase torque by 200 lb.-ft., allowing the driver to remain in top gear.

“The greater amount of time you spend in top gear is directly proportionate to how good your fuel economy is going to be,” McKenna said.

The Super Econodyne is an all-Mack powertrain, including the engine, transmission and axles. It incorporates downspeeding to reduce rpms and improve fuel economy. The package features the mDrive automated manual transmission in overdrive configuration and drive axles with 2.54, 2.66 or 2.83:1 ratios, allowing the engine to cruise at 1,150 rpm.

The efficiencies derived from the Super Econodyne are possible as a result of vertical integration, McKenna said.

“Our engine, transmission and vehicle ECUs are in constant communication with one another,” McKenna said. “They speak the same language and they share 100% of their information, 100% of the time.”

In some cases, the mDrive transmission takes control of the engine. For example if a driver is trying to accelerate while going downhill and exceeding the maximum road speed, the transmission will intervene, perform a downshift and maybe even generate some engine braking.

McKenna said sales of the Super Econodyne are slowly picking up. The key is getting fleet owners to give it a try.

“We can give you 450 or 500 hp in a 13-litre package,” McKenna said, noting the 13L is 500-700 lbs lighter than a 15L, providing some fuel savings.

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