Truck bodies on a diet

  • 31-Mar-2009 01:36 EDT
Reading’s Aluminum II bodies weigh only 600 lb (272 kg), nearly half the weight of steel.

­Truck body designers are responding to the economic downturn with cutbacks that are more often associated with post-holiday resolutions: They are working to slash pounds. Weight is becoming a central element in truck body designs, driving a transformation as aluminum and composites replace steel.

Though fuel prices have declined from record highs, weight reduction was a hot topic throughout the recent Work Truck Show in Chicago. Much of the focus was on body materials, but even truck makers noted that whenever a vehicle is redesigned, its weight is closely examined.

Introductions on the show floor spanned the gamut of vehicle styles. Dodge highlighted a new interior when its redesigned Heavy Duty Ram 2500/3500 was unveiled. Though a number of upgrades were made to attract buyers, the total interior weighs 20 lb (9 kg) less than on previous models.

Mass reduction also drove changes in the pickup’s body. Dodge took an unusual tack to cut mass, extending a steel structure to replace a plastic addition.

“In the past, we added a plastic flare to the pickup box. Now it’s all steel, with less overlap and a reduced geometry,” said Scott Kunselman, Vice President of Product Development at Dodge’s Truck Products group. “We measure weight in grams. Even a plastic push pin adds weight.”

Though the pickup box uses steel, aluminum and composites are rapidly replacing steel in larger bodies added to truck chassis. Step vans, delivery trucks, and other trucks began adopting these lightweight materials during the tumultuous period of high gas prices.

Aluminum is more readily available, so it is seeing the fastest uptake. “Our ratio of aluminum sales has gone from 5 to 15% in the past year,” said Richard Sippola, Vice President of North Coast Truck Body.

The lightweight metal helps in companies’ green movement because it is recyclable, but its real attraction is that it increases fuel economy and payloads by slashing weight. In a van, Aluminum Classic II service bodies unveiled by Reading Truck Body weigh only 600 lb (272 kg), well below the 1100 lb (500 kg) of similar steel bodies. In a service van, 1400 lb (635 kg) are trimmed from the 2500 lb (1135 kg) of steel bodies.

Other suppliers are touting new aluminum products as well. At Warner Bodies, partially recycled aluminum is being used to cut weight to half that of steel bodies. It can also improve strength.

Aluminum can be bent so only one piece is needed for walls that had seams when they were made with steel, noted Warner Bodies President Mark Boice. Those seams could be a weak point, he said.

There is also a huge shift in the shelving used in these trucks. Sortimo of North America is supplying honeycombed aluminum shelves that reduce weight by 60% compared to the steel shelves now in widespread use.

Morgan Olson is rolling out aluminum shelving that has no holes, improving strength without reducing adjustability.

Going forward, aluminum will have increasing competition from composite materials. Though composites have been around for years, production costs and manufacturing techniques have evolved rapidly in recent years, making the material viable for trucks. Many of those production improvements stem from use in aircraft, proving that the material offers strength and long-term reliability. That means composites can be used for both walls and flooring.

“Composites provide a dramatic weight savings vs. the aluminum walls and plank floors we used before,” said Robert Burnham, Vice President of Engineering for Morgan Olson. “We can save 500 lb.”

Composites can be used for the entire body, reducing the need for plank flooring. On Morgan Olson's composite concept vehicle, the walls are 20 mm (0.8 in) thick, while floors expand to 30 mm (1.2 in) to provide extra support. Putting a composite body on a lightweight chassis from Freightliner can reduce the total weight of a step van by 20%, Burnham noted.

The weight savings of composites will be even greater for customers who replace steel bodies.

“A 4 x 8-ft sheet of ¾-in composite will weigh about 112 lb, while the same size piece of 7 gauge steel will weigh 258 lb,” said Craig Bonham, Sales Director at America's Body Co. (ABC), acquired by Reading last fall.  

Some body makers are dipping their toe into the composite world in small steps. That gives them experience in manufacturing while still providing some reduction in fuel consumption.

“We’ve gone to composite corners instead of using aluminum, saving 3 or 4 lb," said Mark Beer, Supreme's Vice President of Sales.

Marketers noted that there are other benefits. Composites are also recyclable and repairable, and most offer improved thermal characteristics.

“Composites have less than 2% thermal conductivity, which is important when you’re carrying plants or other products that can be damaged by large temperature swings,” Bonham said.

Other nonmetallic solutions are being used to trim pounds. Utilimaster recently began shipping a polystyrene core with fiberglass skins, offering it as an alternative to aluminum sheets or fiberglass-reinforced panels (FRPs).

“On a light-duty truck, it’s about 600 lb less weight than aluminum or 700 less than FRP,” said Steve Campbell, Commercial Sales Director at Utilimaster.

The reductions offered by both aluminum and composites do not come without cost. With Utilimaster’s composite body, costs roughly double, jumping from $5600 to $11,000. However, Campbell noted that increased payloads and reduced fuel costs provide a quick payback.

Longer lifetimes are one of the paybacks for body designers who adopt aluminum. “Aluminum costs more but it has twice the life,” North Coast’s Sippola said.

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