RUAN Designs 20,000 lb Tractor & Trailer

Sept. 1, 1997
The goal was simple: Build a tractor and trailer combination light enough that it could haul a 60,000 lb load and still conform to the 80,000 lb gross

The goal was simple: Build a tractor and trailer combination light enough that it could haul a 60,000 lb load and still conform to the 80,000 lb gross weight limit. This weight restriction was met by the use of 19.5" wheels and tires as well as a smaller diesel engine, the Cummins C8.3 ( an unusual combination for over-the-road applications.

This lightweight rig was designed for a can manufacturing customer of the Aluminum Company of America. Alcoa manufactures extra-large coils in Alcoa, Tennessee, that are 4' 8" wide, 6' 8" in diameter, and weigh 30,000 lb. Approximately 450,000 beverage cans can be produced from one coil this size, which allows longer operating periods and less scrap materials, resulting in increased plant productivity.

Due to the weight of the coils, delivery to the customer would require one coil per truck, approximately 44 loads per week at 300 miles per load. In an effort to reduce transportation costs, Alcoa approached Ruan Transportation Management Systems for a delivery solution.

In order to maximize efficiency, Ruan needed to create a vehicle that could haul two of the 30,000 lb coils and remain within the 80,000 lb gross weight limit. Bill Giles, Ruan vice-president of research and engineering, worked with Freightliner, Cummins and Reinke Manufacturing in researching all available sources in order to make this vehicle a reality.

The result is a pair of tractor/trailer combinations that are among the lightest vehicles in their class in the United States. The units have been in service since July 1994. "The trucks have proven to be very strong and reliable vehicles," says Ralph Stapleton, Ruan service manager.

Every aspect of the truck was designed with weight conservation in mind. The Freightliner tractor is 6 x 2 as opposed to the regular 6 x 4. It is equipped with only a driver's seat and 70-gallon fuel tank and has no sleeper unit. Although the tractor was fitted with steel frame rails, the crossmembers are aluminum. The single drive axle truck was fitted with a tag axle.

The aluminum flatbed trailer has a scale weight of 7,320 lb without the landing gear, but the landing legs were later added when it was determined that the tractor and trailer would not be "married." Then two extra trailers were ordered so that the trailers could be preloaded with coils for pickup on the weekend. Trailer length of 44' 8" represents the optimum length for the bridge formula, and the rear suspension is spread 10' 2" for maximum loading flexibility.

The trailer's main I-beams have a 30" maximum depth with 7/8" x 6" flanges and are made of 6061-T6 high strength aluminum. Crossmembers are 6" aluminum I-beams on 24"centers, but the heavy-duty floor design is equivalent to a 16" crossmember spacing. That is, the 1 7/16" thick floor planks of treated yellow pine alternate with extruded aluminum hat sections for increased strength. Extruded aluminum side rails are 8" deep. The trailer also has 13 pairs of in-floor chain tiedowns.

Lightweight options were specified throughout the trailer, including aluminum hubs and wheels. Truck-Lite LED lights and a Blue Seal harness were specified.

Use of the 19.5" wheels on the tractor results in a 40" fifthwheel height. The upper coupler is a half-inch aluminum plate. Trailer deck height is 55" front and 51" rear. The lightweight trailer has Hendrickson HT-230 air suspensions. The dump valve on the rear axle is controlled from the cab, as is the dump valve for the tag axle. Reinke rates the trailer at 80,000 lb distributed or 50,000 lb concentrated in 10 feet.

The lightweight rig requires three tire sizes(Michelin 265/70R 19.5 XZT drive axle tires, 285/70R 19.5 XZA steer tires and 265/70R 19.5 XZA tires for the trailer.

"We originally tried highway treads on the rear of the tractor but they became worn very quickly. We switched to the lugs and they performed much better," says Stapleton. "With the tag axle there is a little more tire wear. It tends to wear out the drive axle tires faster. In response, we rotate these tires back and forth , from the tag axle to the drive axle, because the tag axle doesn't do any pulling, it just rolls. We use a wider tire on the steer axle because of the weight on the front axle.

The tractor and trailer are equipped with larger 15" x 8 5/8" brakes. The trailer baking system uses a load-sensing valve that reduces air pressure when the trailer is empty.

Since they've been put into operation, the two trucks make two round trips a day, five days a week, plus one trip on Saturday. Maintenance is performed on Sunday.

"We've had good luck with them," notes Stapleton. "I think one of the units has 421,000 miles on it, while the second unit has 362,000 miles. We have definitely seen better utilization of our time and drivers since these units have come on-board, saving money for all parties involved."

The lightweight vehicles are the only trucks dedicated to the can manufacturing plant in Rome, Georgia. The other 25 tractors of Alcoa's Rigid Packaging Division make runs to Atlanta and Forest Park, Georgia; Jacksonville, Florida; Columbus, Ohio; Chicago, and Bradley, Illinois. The Rome container facility is the only plant that handles the 30,000 lb coils. The remainder of the coils delivered range in weight from 12,000 lb to 23,000 lb.

Cummins C8.3 Engine The Cummins C8.3, rated at 300 hp, has been a major contributor to the success of the Alcoa lightweight trucks. " I had my doubts when I first saw it," said Stapleton. "Initially I thought that 100,000 miles would be the best we would get out of the engine, but it has proven me wrong."

The C8.3 combines power, strength and reliability ( all of which contribute to its versatility. Its big pulling power, great horsepower-to-weight ratio, and fuel efficiency make it suitable for a wide range of applications.

In developing the "C", Cummins took into consideration the power requirements of a broad range of vehicles. Its compact design means it can adapt easily to varied vehicle configurations. This engine can be found in mixer, delivery, dump, and refuse vehicles as well as fire and transit vehicles. Simple by design, the C has 40% fewer parts, which results in a reduction in repair time if a problem does occur.

The engine is mated to a Fuller RT-8609 nine-speed transmission through a Valeo 14" ceramic clutch. Trucks are serviced and oil changed every 8,000 miles because of the heavy loads being pulled by the small-bore engine.

Weight of the FLD112 tractor was reduced further by spec'ing aluminum air tanks, aluminum carrier housing, aluminum bumpers, Centrifuse brake drums, a single 5" cab-mounted exhaust, and two 12-volt batteries. Tractor empty weight is under 12,000 lb dry.