Driving a new fully-loaded Mack Granite dump truck near Allentown, Pa., I was reminded that there’s something special about the rolling Pennsylvania backroads. I was following State Road 309, running south from West Hazelton toward Tamaqua. It’s something like 350 years old – a pleasant reminder of how much transportation has changed.
The old farmhouses are so close to the road that in many cases you could stand on the porch and spit on the traffic. Often, the house sits on one side of the road and the family barn on the other. It’s something you see only in the Eastern United States.
Mack engineers say the 13-liter MP8 diesel delivers ample torque and horsepower in a more compact, lightweight design. The company has championed smaller-displacement diesels for years.
Mack has deep roots in this area. The Mack brothers hammered out their first bus 112 years ago and 80 miles away in New York City. The brothers relocated to Allentown – not far from the big-city action but with the benefit of being close to Bethlehem Steel Works.
My Granite test drive began at the company’s Customer Center – a combination museum, product and technology showcase and test facility. Curtiss Dorwart, Mack’s vocational products marketing manager, explained how Mack’s expertise can be found everywhere on a Granite. Take the fuel/diesel exhaust fluid tank arrangement: The 111-gallon diesel tank is D-shaped in contrast to the usual circular design. Dorwart says Mack engineers found this configuration enhances the tank’s structural integrity while adding capacity. It also allows the use of stronger and safer J-brackets to hold the tanks in place while seamlessly incorporating the DEF tank.
Touches such as this show why the Granite is so well-suited for the often-brutal conditions of dump work. Dorwart calls this design philosophy “application excellence.” Mack’s Granite is tough, well-designed and intelligently conceived: a blend of power, performance and elegance.
The truck was fitted with an Allison 4500 RDS six-speed automatic transmission, so there was a silver bulldog standing tall on the truck’s nose, signifying a powertrain other than all-Mack, which would merit a gold bulldog.
Given Mack’s reputation for toughness and power, I was surprised to find a Mack MP8 13-liter diesel under this Granite’s hood since 16-liter power is available. Dorwart explains that Mack has been leading the industry charge toward smaller-displacement diesels for years now. One reason Mack is so passionate about this shift, he says, is that size no longer automatically equals power. This truck’s MP8 churns out 425 horsepower, which – thanks to the Allison 4500 RDS – is plenty for moving heavy loads across a jobsite and down the highway.
“The conventional wisdom for dump trucks has always been a bigger hammer under the hood to make sure you can get the job done,” Dorwart says. “That was then. This is now. Today we can offer our customers up to 505 horsepower with our MP8 engine. You get a lot more power with a lot lower weight.”
On the road, this Granite proved him right. We started out down Interstate 81 unloaded at 29,200 pounds, easily accelerating to highway speed. After loading up to 72,660 pounds at a local quarry, I was pleased to discover that the “little” 13-liter engine remained in its comfort zone.
On both the interstate and sleepy Pennsylvania backroads, the Granite’s handling was outstanding. It doesn’t wander around in the lanes, and views to the front and rear are enhanced by clean sightlines and the aggressively-sloped low-profile hood. Gauge and switch placement is logical, everything right where you need it and within easy reach.
Behind the wheel of a Granite, long days getting bounced around in the cab and deafened by the overwhelming road and engine noise are ancient history. Mack engineers have added serious sound and vibration dampening to the chassis. One can carry on a conversation in normal speaking tones, even when starting out at full throttle. Once you reach cruise speeds, this remains as quiet a cab as you’re likely to find.
The interior blends class and common sense. Nice touches like chrome-accented bezels and button-tuck upholstery on the seats, door panels and ceiling are hallmarks of the Champion interior. The floor mats deliberately are earth-colored to hide the inevitable grime that makes its way into the cab. Even better, the Granite’s floor plan and mats have been designed specifically for easy cleaning; there are no little nooks or crannies to trap dirt when you’re trying to sweep it out.
Spec’s as tested:
Engine: Mack MP8, 425 hp, 1,570 lb.-ft. torque
Transmission: Allison 4500 RDS 6 SP
Gross combination weight: 80,000 lb. maximum
Wheelbase: 226 in.
Engine brake: Mack Powerleash
Front axle: Mack FXL18, 18,000 lb.
Front axle tires: 425/65R22.5 L Bridgestone M844F
Front axle brakes: Meritor S Cam 16.5-by-6 in.
Front suspension: 18,000 lb. taperleaf
Tandem rear axle: Mack S440, 44,000 lb.
Rear axle tires: 11R22.5 G Bridgestone M726EL (drive only)
Rear axle brakes: Meritor Cam 16.5-by-7 in. Q Plus
Tandem rear suspension: Mack SS440 multileaf
Rear axle carrier ratio: 4.50
Power divider lockout: In-cab manual air valve