Mack Manufactured Axles are Back

Trucks with all-Mack powertrains proclaim their pedigree
 with a gold Bulldog hood ornament.

Mack this week announced it is back in drive axle production, opening up a 100,000 sq. ft. manufacturing and assembly operation in the Hagerstown, Maryland, plant. By returning to making axles in-house, Mack brings all components of the all-Mack powertrain under one roof in Hagerstown.

The actual start of production was in April, but Mack waited for the announcement until axles reached full production. Currently around 100 axles a day are shipped from Hagerstown to the truck assembly plant in Macungie, Pennsylvania.

Mack Trucks North America President Stephen Roy says the total investment of $30 million means 100 new jobs added to bring total headcount at Hagerstown to 1800, with 400 of these engineers working on Mack powertrain components.

In addition to the new axle, Hagerstown builds Mack MP7 and MP8 engines, manufactures and assembles the T300 triple countershaft manual transmission and the mDrive automated mechanical transmission (AMT). The base 11- and 13-liter engines and the AMT are shared with the Volvo side of the house.

The axles and the T300, though, are exclusively Mack products and both enjoy a reputation as bulletproof components that are popular in applications that demand high reliability and durability with potentially deep reduction.

Building the whole all-Mack powertrain in the same plant shortens supply lines, says Roy. Axles were previously produced under license to Mack designs by Detroit-based American Axle. The co-location of all of the Mack powertrain also brings engineers together and allows for developing interaction between the current and future powertrain electronic controllers.

Benoit Potin, director of the Mack axle product line says his engineers could see future electronics and sensors on drive axles that could well contribute to optimizing the whole powertrain.

Already axles are important in the fuel economy programs. The new differential carriers – the 125/126 – are capable of accommodating new tall ratios of 2.66 and 2.83 to 1. This enables downspeeding the engines in the Super Econodyne package, running at 1100 to 1200 rpm at cruise speeds. Not only does this give better fuel economy, but as the peak torque of the Mack engines is 1200 rpm, it gives good performance at the same time.

This, says Roy, is the integration that has been the cornerstone of Mack for 115 years. Component manufacture in the same location as the powertrain engineers enables the engineering of the most fuel efficient, durable and reliable powertrain, he says.

“Integration is extremely important − even more than 20 years ago,” said Roy in his address to the Hagerstown staff assembled in the production area to celebrate the event. “With the focus on fuel economy, we must focus on all components for maximum performance. Seamless communication between the components means fuel efficiency can be optimized.”

According to Roy, today nearly 70 percent of Mack production features the mDrive AMT. That share has increased recently with the heavy-duty vocational version of the automated transmission. And, he says, raising a cheer from the workforce, customers like the fact that Mack trucks are all-American manufactured and assembled. “And we commit to manufacturing to keep all lines running at full speed,” says Roy.

Hagerstown Manufacturing

Differential carrier is top-loaded into the drive axle.

The Hagerstown plant was built in 1961 and was originally a Renault plant. It was acquired when Volvo bought Renault’s truck business unit in 2000. Mack was purchased at the same time.

When Hagerstown was acquired, investment in the plant had been limited for some time. But during the last seven or eight years, investment in production facilities and plant improvement have been significant, says Roy. This latest $30 million has lead to further improvement and rearranging of work areas to include the location of Mack’s aftermarket core warehouse at the plant.

In the new axle manufacturing area, the cast carriers are machined and assembled with differential and gears, and then dropped into the axle casing. Like traditional Mack tandem axles, the new ones are top-loading with spiral bevel gearing. This design gives the axles 95 percent to 98 percent efficiency, says Potin, more than vendor axles and further complementing the fuel economy achieved through the integration of engines and transmissions.

Mack trucks with the all-Mack powertrain of MP engines, T300 or mDrive AMT transmissions, and Mack drive axles are referred to as Pedigree Powertrain vehicles and the trucks are identified by a gold Bulldog hood ornament. Trucks with vendor components such as Eaton transmissions, Dana and Meritor axles, have a chrome Bulldog. A very few refuse and natural gas trucks have Cummins engines.

The use of the Bulldog as a trademark goes back to 1922.  In 1932, Mack Chief Engineer Alfred Fellows Masury carved the first Bulldog hood ornament and every Mack since has featured the Bulldog on the hood.