Rip Tare

Bob Miskelly had a 12,000-pound weight problem. As distribution manager for Praxair Canada, he’s responsible for moving carbon dioxide 45 miles from Ferndale, Wash., to Vancouver as efficiently as possible. “In the perfect world, there would be a seamless border and there would be no weight differentials between our two countries,” Miskelly says. “But the U.S. allows us to haul 12,000 pounds less, so we have to work smart to reduce the impact of the weight restrictions.”

When Praxair bought the Vancouver carbon dioxide business from rival Liquid Carbonic six years ago, the deal included the company’s trucks. The Kenworth T800s were made with Canadian weight laws in mind — their double steel frames and 46,000-pound rear ends were more than capable of hauling 96,000 pounds of CO2. But on the run back from Ferndale, they were always less than full due to the state’s 80,000-pound weight restriction.

“We were weighing-out before we were volume-full,” says Miskelly. “We had to get the weight down. In our situation, every pound we could shave off the tractor was a pound we could add in payload.”

A bigger payload is a hefty bonus for any truck operator, whether you’re the manager of a large private fleet or an owner-operator paid on a percentage-of-revenue basis. For Miskelly, the target was a 3,000-pound tare cut: he figured a 14,500-pound tractor pulling 80,000 pounds gross would make 110 fewer border crossings a year compared with the T800s Praxair inherited from Liquid Carbonic. The savings in fuel and other running costs aside, fewer trips meant 150 fewer hours per year, per tractor, that would normally be spent sitting in border traffic.

The quest to trim weight started with Miskelly and Praxair technology specialist Bob Hammond sitting down and defining precisely what they needed their equipment to do. Their length of haul is short — Ferndale is just 12 miles south of the border, with gentle grades all around. The GVW is a strict 80,000 pounds. “Those old T8’s had big sleepers and Caterpillar C15 engines,” says Hammond. “We have strict performance and safety requirements, but we don’t need that much truck, and we certainly don’t need that much power on that run.”

When you lose the sleeper and drop to a more practical engine for the application — in Praxair’s case, a 435-horsepower C12 — you can make serious headway when you tip the scales. But once you’ve looked beyond the obvious, wringing tare out of a tractor is a pound-by-pound process, 50 here and 25 there.

One strategy is to spec lightweight components where you can — aluminum air tanks, fuel tanks, and wheel hubs, composite front springs, and centrifuse drums, all of which are part of the Praxair spec. But the new trucks also have aluminum frame rails and crossmembers — seldom seen on power units. They’re more common on trailers, especially flatbeds, where a deep-sectioned rail is possible.

Hammond included the aluminum frames at the urging of Peter Roy, the national accounts manager at Paclease Canada, which provides and maintains the tractors. Roy, a former fleet manager at industrial gas provider Air Liquide Canada, made a convincing argument. “Peter knew us and our application well and had done extensive work with aluminum frames, enough to give us the confidence to go down that road,” Hammond explains.

When all was said and done, Praxair signed a full-service lease for two T800s that weigh 14,343 pounds each, about 3,000 pounds less than the previous trucks, right on target. “It’s been nearly a year, and these trucks are bulletproof,” Hammond says. “Light, strong, and efficient.”

Lightweight components may work well at 80,000-pound gross weights, but are they worth their weight when you’re tipping the scales with a B-train? Ask Tom Kenny, who watches pounds with the alacrity of a wrestler making weight before a match. Kenny is general manager at Westcan Bulk Transport in Sherwood Park, Alta., one of Canada’s largest dry and liquid bulk truck fleets. He loads his B-train combinations to the limit — 63,500 kilograms in Alberta and Saskatchwan and 62,500 throughout the rest of Western Canada. At those gross weights, he says, using lightweight materials involves striking a balance.

“Our Mack day cabs, with a product pump, full of fuel, chains on, and a driver inside, weigh 17,500 pounds,” says Kenny. That includes 46,000-pound rears, a 460-horsepower engine, 18-speed transmission, and a heavy-duty driveline. Put a 42-inch sleeper on that and the weight comes in at 18,430 pounds for a tractor that can take one of the most demanding operating environments you’ll find in Canada..

You can go with lighter components and still have trucks that are tough, capable of handling heavy gross weights, Kenny says. “We just can’t be out there sacrificing reliability and long life for tare alone. We’ve tried that with certain components and found it’s just not worth it.”

For instance, when you talk about lowering weight one of the first items on the list is aluminum wheels, which Kenny specs at all positions. Compared with steel dual wheels, a five-axle tractor-trailer outfitted with aluminum duals will weigh about 600 pounds less, savings that are compounded on a B-train setup.

But Kenny says there are reasons other than weight to consider aluminum wheels — true running, sharp appearance, and durability among them. Yes, on a per-pound basis, aluminum is expensive, Kenny explains. “But if something helps me exchange 1,000 pounds of tare weight for 1,000 pounds of payload,” he says, “I’ll try it.”

That pound-for-a-pound idea works for Miskelly, Hammond, and Kenny, where the consignee can take every drop or ounce the rig can legally carry. They can justify the higher price of lightweight components compared with those made of more workaday materials. If you’re not grossing out all the time, calculate how many actual trips you can make fully loaded to determine the payback of lighter, more expensive components, says Hammond.

“If cost is still an issue, you can make sensible compromises without compromising safety or performance,” he adds. Among them:

Wheels: Use aluminum on the steer axle and steel disc wheels at most other positions but spec aluminum hubs. Aluminum hubs will save 110 pounds per tandem in the case of a lightweight Meritor product.

Tires: If you’re still using 24.5-inch tires and wheels, you’d better have a good reason. You’re rolling hundreds of extra pounds compared to 22.5-inch assemblies.

Sleepers: A long wheelbase with a fully dressed condo out back looks good, but it’s going to be heavy. If you or your drivers don’t live in the truck for days on end, maybe a basic 42-inch bunk is a better choice than the 500-pound heavier 60-incher, for example. Indeed, the sleeper box alone may weigh 1,500 or more pounds. If you can haul that much more product in a tanker or on a flatbed most of the time, the cost of an occasional motel room may be cheap.

Aerodynamics: Aerodynamic fairings may not be worth it in weight-sensitive operations where the rig is standing a lot. Fairings are made of fibreglass or plastic and don’t weigh much.

But their supporting brackets are typically steel, and they contribute heavily to the 500 to 1,000 or so pounds a full fairing package will add to the weight of an over-the-road tractor.

Fuel supply: Diesel fuel weighs about 7.5 pounds per U.S. gallon (depending on temperature-induced density), so topping off at a cheapie fuel stop may mean carrying around a ton of fuel you don’t need. As you gain experience on certain routes, look for ways to limit what you carry in fuel and haul payload instead.

Powertrain: If you can afford the drop in power, spec a smaller engine. Just be sure to choose a clutch/transmission/driveshaft combination able to take higher output if you buy an electronically controlled engine that can be uprated later for higher resale value.

If you need a tandem rear axle, and your spec can handle it, consider a 6×2 configuration. It eliminates a second drive axle, along with the interaxle differential and the short driveshaft. Together, this can save about 1,000 pounds.

Traction shouldn’t be a problem in most applications, because the single drive axle can be fitted with a locking differential. (Lifting the dead axle slightly will transfer traction-inducing weight onto the driving axle.)

Drawbacks to the 6×2 include lower life for tire tread in the drive position (all torque now goes through half the usual number of tires), plus possible lower resale value (most buyers still believe the 6×4 with twin-screw axles are superior).

Like most things, you’re looking at a trade-off when you go for a lighter weight component, explains Praxair’s Hammond. “Sometimes you know right away whether you’ve made a good choice, sometimes it takes years to find out,” he says. “You have to be willing to work with your suppliers and look at different concepts. Otherwise, you won’t know what kind of savings you’ve been missing.”