On-Site Magazine

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June 28, 2012 by James Menzies

Mack Granite
Mack Granite

The construction truck market – particularly in the US – has been mired in a lull for several years now, which has given the folks at Mack plenty of time to come up with ways to improve their popular Granite model.

Over the past several years the company has made continuous improvements, including adding four inches to the cab’s interior, offering a stylish button-tuck ceiling at no extra cost and improving the HVAC system. They’ve also recently added a tilt steering wheel, ergonomic foot pedals, extra power outlets and an improved body builder interface.

I recently drove a Mack Granite with MP8-425 Maxidyne engine and Allison 4500 RDS six-speed automatic transmission at Mack’s Customer Center in Allentown, Pa. If you’ve never been to Mack’s Customer Center, opened in November 2010, it’s worth checking out. It’s a tribute to all things Mack, featuring a sprawling museum with an impressive collection of Mack trucks and other artifacts as well as a track on which customers can drive various Mack models.

It was on this track that I drove the Granite. It’s no ordinary circle track; the course includes a 12-per-cent grade and an off-road section with simulated railway crossings, cobblestones and other obstacles set up to give the truck a good shake. I was especially impressed with how little rattling took place inside the cab while I hammered it over top the roughest surfaces available – and this was unloaded.

Mack has a new automated manual transmission dubbed mDrive, which so far is offered only in its Pinnacle highway model. The transmission isn’t yet offered with the Granite, but there’s little doubt it will be eventually. The mDrive has a feature called Grade Gripper, which will hold a loaded truck on a steep incline for several seconds without rolling back as the driver releases the foot brake and reaches for the accelerator. It’s a great feature to have in any construction truck.

I stopped the Granite halfway up the 12-per-cent incline and tried the same maneuver with the Allison automatic and was surprised to see it held its position pretty well – but again, we were empty.

The Granite is a hugely popular dump truck and part of the reason for this is that the cab is seated high enough to afford an excellent view and ample ground clearance, yet low enough to easily climb in and out of the cab.

The truck is available in two interior colours, each designed to coordinate with some commonly hauled material. The slate gray interior is aimed at asphalt haulers while the sandstone is a better match for those hauling dirt and sand. It may seem funny to design an interior that matches the commodity hauled, but it goes a long way towards maintaining a clean-looking interior.

Customers seem to love the Mack MP7 and MP8 engines, available with 325-505 horsepower and also the wide variety of Allison automatic transmissions offered. Curtis Dorwart, vocational marketing product manager with Mack, told me about 25 per cent of Granites sold today are being spec’d with Allison automatics.

Mack’s popular MP engines provide ample low-end torque and are efficient to operate.

Mack also offers a lighter-duty Granite MHD (Medium Heavy-Duty) powered by the Cummins ISL engine for less rigorous construction applications hauling lighter loads. But the true Granite – or what is affectionately known internally as Mother Granite – is the real workhorse of the family. The dump truck I drove would be ideal for industrial or residential construction or roadbuilding. It’s available in either a set-back (SBA) or set-forward axle (SFA) configuration. The SBA will give you a tighter turning radius on crowded job sites but the SFA offers some additional flexibility in managing weight distribution. Dorwart told me the axle back version is more popular in Canada.

More improvements are coming to the Granite before the end of the year; little things such as a dead pedal footrest to give the left foot a comfortable resting place and an improved body builder console that will allow body companies to install controls more cleanly.

It’s clear that while the construction market has been sluggish, the folks at Mack have not been. They’ve been tweaking the Granite so that when the market rebounds, they’re ready to hit the ground running with an even better work truck than before.

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