Drive

Putting the heavy in Ford, GM and Chrysler's heavy-duty trucks

If you have a big job to do, chances are you’ll need a big truck. Heavy-duty pickup trucks usually look similar to their lighter-duty siblings, but they’re built to handle more stress.

“The difference is in their capability,” says Jeff Luke, executive chief engineer for General Motors’ full- and mid-size trucks. “Everything is upsized and stronger.”

Pickup trucks are designated by their payload capacity, which is the combined weight of passengers and cargo they can carry, measured in tons. A light-duty truck, which is badged as a 1500 or 150 depending on the manufacturer, is popularly called a half-ton.

Heavy-duty trucks are rated in three-quarter-ton (badged as 2500 or 250), and in one-ton (3500 or 350).

These “ton” names are actually out of date, and modern trucks can handle much more—GM’s new one-ton can carry more than three times that much. They were introduced back when trucks had far less capacity, and a half-ton could only carry 1,000 lbs., but the names have stuck. Buyers should look at the actual specifications for each truck to determine what they need.

Building a heavy-duty truck starts with the frame. While it’s basically the same overall dimension as on a half-ton truck, the sections are thicker to handle heavier loads. The axles are larger, the shocks are stronger, and the tires are built to take more weight. Some trucks have dual rear wheels, which spreads the load across four tires and allows for even more capacity.

Heavy-duty trucks will offer diesel engines, which provide the highest amount of torque—the low-end pulling power needed to move heavy loads or big trailers. The transmission and rear end have to be strong enough to handle the engine’s power as well.

When the engine is working hard, keeping it cool is an issue. “The radiator will be larger and heavier, and there will be more coolant,” Luke says. “These engines may have more oil in them, and there will be coolers for the oil and transmission fluid.”

There are larger openings in the bumper area so air can easily flow over the oil and transmission coolers, which look like miniature radiators. If these fluids aren’t kept cool, it can lead to premature wear or even component failure in the engine or transmission.

The down side is that because these trucks are heavier than a half-ton truck, they also get poorer fuel economy. “That’s just physics, so we try to offset it with aerodynamics,” Luke says. “On this new truck, the air deflector shape is taken from the Corvette so that air travels around it. Every little bit helps.”

Truck notes

  • Titanic trio. Currently, only GM, Ford and Chrysler make heavy-duty trucks. The largest Japanese pickup truck available is a half-ton.

  •  Be prepared. Any vehicle that regularly tows a trailer should be equipped with a transmission fluid cooler to avoid premature wear or damage.

  • Ratings. Trucks are rated on how much they can carry, and how much they can tow with a trailer hitch and with a fifth-wheel hitch, which attaches in the bed.

More on Metronews.ca