Quarryside Classics: Mack R-Series – Rock Solid Since 1966

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– Posted on April 13, 2024

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(first posted 4/7/2013)    I recently rented a little three-yard dump truck and used it to pay several visits to one of the local quarries–partly to haul gravel, but also as an excuse to pay homage to the dwindling number of Mack R-Series still on their roster. It’s hard to imagine a time when these toughest of trucks ever built will no longer be prowling our streets; but then, I felt the same way about their predecessors.

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The last time I was doing some building, a bit over ten years ago, this lineup was exclusively R-Series. Now, more recent Macks, as well as some white Kenworths, have infiltrated the ranks. If it’s any consolation, on the way out I did notice another batch of Rs in a different parking area–but one of these decades, they’ll all be gone.

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And then the only one left will be this one, a spiffed-up display model out front by the freeway. Well, at least one was saved; are the rest still working hard in some rural outpost in Mexico?

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Or maybe they’re in the hands of a small local operator, like the one that was still using the R-Series’ predecessor, the B-Series, when I caught him on the street a couple of years ago, blowing out a spectacular black cloud.

mack ac triplesimage: hank’struckpictures

The Mack bulldog legend was earned the hard way. Since the early days of the century, the Mack brothers had been building buses, and later, trucks, which were already developing quite a rep for superior quality and reliability. But the mighty Mack AC of 1916 imprinted that reputation indelibly. Unlike the many truck manufacturers that assembled trucks with components from various suppliers, Mack developed and built the whole unit from stem to stern–and the AC’s unbreakable ruggedness was in a league of its own.

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Regardless of the job, from the hauling of vital supplies during World War One to building America’s infrastructure during the booming 1920s, the AC was the most desirable truck for the toughest jobs. And it stayed in production until 1936, despite having only a 75 hp, four-cylinder engine and old-school chain drive.

mack b61

I’m not going to cover all the Mack models, but actually there weren’t all that many. Before being eclipsed by the R-series,  the B-Series was the iconic Mack truck of my younger days. Pennsylvania-based Mack was particularly dominant in the eastern half of the country. During the ’60s and ’70s, the roads and highways there were dominated by these handsome machines with their growling Thermodyne diesels. I have vivid memories of seeing bright-orange flames dancing on top of their exhaust stacks as they slowly hauled nighttime loads up the grades of the Pennsylvania Turnpike: nature’s thermal reactor.

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In 1966 the S-Series arrived, with a drastically improved cab that must have felt like a greenhouse compared with the claustrophobic B-Series. The S-Series was built in a staggering variety of configurations, for a vast array of purposes.

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The long-hood Superliner targeted the West-Coast market, which didn’t have length restrictions.

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R-Series trucks were specialized to do all sorts of off-highway jobs, including logging, working the oil fields, military usage, house moving and construction: Whenever and wherever there was an extra-tough job to do, you’d inevitably find a Mack doing it.

Mack R series U Cab

Another popular variant was the U-Series; essentially an R-Series with an offset cab, for better visibility in-close range maneuvering and such. Popular with the transfer, garbage, and certain other urban-oriented uses.

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And they went about doing those jobs in a fairly radical (for the time) new way: The R-Series also marked the premiere of Mack’s innovative Maxydyne engine. It had a dramatically widened power band, with maximum torque coming on at 1,200 rpm, as well as a flat horsepower curve between 1,700 and 2,100 rpm, all accomplished with stronger internal components and changes to the fuel delivery and turbo boost systems.

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With their much narrower torque rises, other truck engines needed 12- to 15-speed transmissions, but the Maxydyne could readily do its job with just five speeds– a boon to vocational drivers like dump and garbage trucks and cement mixers. Of course, some jobs called for more gears, but the Maxydyne was noted for its ability to need less shifting (if you ever listen to one accelerate, that becomes quite obvious). Pulling hard from around 1,000 rpm, the sound is quite distinct–more like a bulldozer than a truck.

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I don’t know exactly what engine or transmission is in Delta’s fleet of various R-series.

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This one is a Value-Liner; others are RS600Ls. But they all have that distinctive, low-rpm growl as they pull their double-loads of gravel, dirt or whatever around town.

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So here’s the famous bulldog, which has become quite the icon in its own right.

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The bulldog on the display truck out front has even been dressed up.

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The last example of the R-Series was made in 2005, 40 years after the first one rolled off the lines. But its successor, which is now called the Granite, has been around even longer–and of course, Mack has been owned by Volvo (since 2001) following 11 years of ownership by Renault.

For a long time, the Mack approach to vertical integration (making their own drive-train components) was unusual; in fact, Mack was the only major truck company practicing it. Nonetheless, their approach turned out to have been ahead of its time, once again becoming the industry trend (one which has squeezed independent engine makers like Caterpillar out of the over-the-road market). The big truck makers are consolidating into a few global giants and increasingly controlling which components go into their trucks. I don’t know just how well Mack is doing these days, but they’re still around, although perhaps without the unique reputation they once enjoyed.

In any case, though, it’s likely we’ll keep seeing R-Series chuffing away on our streets for quite some time to come.

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