SIC 3713 Truck and Bus Bodies
SIC 3713
This industry is comprised of establishments primarily involved in the manufacture of truck and bus bodies. Some establishments also provide complete vehicles by assembling the bodies they make onto purchased chassis. Establishments engaged in the manufacture of vehicle chassis are classified in SIC 3711: Motor Vehicles and Passenger Car Bodies. Establishments primarily engaged in the manufacture of truck trailers and demountable cargo containers are classified in SIC 3715: Truck Trailers.
Other related motor vehicle classifications include establishments primarily engaged in the assembly of motor homes on purchased chassis, SIC 3716: Motor Homes; stamped body parts for trucks and buses, SIC 3465: Automotive Stampings; cabs for agricultural tractors, SIC 3523: Farm Machinery and Equipment; cabs for industrial tractors, SIC 3537: Industrial Trucks, Tractors, Trailers, and Stackers; and cabs for off-highway construction tractors, SIC 3531: Construction Machinery and Equipment.
336211
Motor Vehicle Body Manufacturing
Truck sales tend to be volatile because they are subject to cyclical changes in the overall economy. During the recessive economy of the early 2000s, trucking companies postponed new purchases to waylay costs and shore up demand. As the economy recovered during the mid-2000s the heavy truck industry saw a significant upswing in production rates as companies replaced older fleets. New emissions standards, with a deadline of full compliance by 2007, also were providing incentive for trucking companies to update their fleets. In 2003 total shipment values were $8.56 billion, up from $8.02 billion in 2002.
Established guidelines in the United States categorized on-road trucks and buses into one of eight classes according to their gross vehicle weight. As a group, Classes 1 through 3 were referred to as light duty trucks; Classes 4 through 7 were referred to as medium duty trucks; and Class 8 vehicles were referred to as heavy duty trucks. Light duty trucks included personal pickups, minivans, and sport-utility vehicles. Class 1 vehicles were those weighing up to 6,000 pounds; Class 2 vehicles weighed between 6,001 and 10,000 pounds; and Class 3 vehicles weighed between 10,001 and 14,000 pounds.
Medium duty trucks included service or local delivery vehicles, some types of construction vehicles, school buses, and refuse collection vehicles. Class 4 vehicles weighed between 14,001 and 16,000 pounds; Class 5 vehicles weighed between 16,001 and 19,500 pounds; Class 6 vehicles weighed between 19,501 and 26,000 pounds; and Class 7 vehicles weighed between 26,001 and 33,000 pounds. (Purchasers of medium duty trucks tended to be small to medium-sized businesses.) Heavy duty trucks, listed as Class 8, were the largest type of on-road vehicle sold in the United States. Class 8 vehicles weighed more than 33,000 pounds and were primarily purchased by large industrial manufacturers and interstate fleet operators.
Trucks and buses were made up of three primary parts—the chassis, the body, and the engine. The chassis contained the wheels, axles, and fuel tank, as well as all the structural elements necessary to provide support to the body and engine. Manufacturers often used one single chassis style with many different body types.
Truck and bus body makers provided a variety of body styles to meet different hauling requirements. Van bodies were used to transport enclosed cargo, and types of vans varied. For example, refrigerated vans were airtight, while livestock vans featured vents to allow for air flow. Tank bodies were used to transport liquids. Hoppers were a special type of tank used to carry chemicals, salt, wheat, and cement. Flat bed truck bodies were designed to carry large, heavy loads such as machinery, steel beams, and telephone poles.
Other factors also distinguished different types of trucks. "Straight" or "rigid" trucks were mounted on a single chassis, with their cab and load areas forming one unit. "Semi" or "tractor trailer" trucks were mounted on two chassis, with their cab and load areas forming two separate units. The units were attached with a device located behind the cab on the tractor called a "fifth wheel."
Straight trucks, semi-trucks, and buses were available in two basic configurations termed "conventional" and "cab-over." In conventional designs, the vehicle's engine was located under a traditional hood in front of the driver cab. In cab-over designs, the driver cab was mounted directly over the engine. The cab-over design permitted manufacturers to make shorter cabs. In areas where total vehicle length was limited by law, cab-over tractors permitted drivers to pull longer cargo trailers.
Another type of truck designation, based on numerical references, was used to describe how many wheels a vehicle possessed and how many of its wheels were powered by the engine. For example, a 4 x 2 truck was one with four wheels, two of which were drive wheels. A 4 x 4 vehicle had four wheels and all four were drive wheels. A 6 x 4 truck had a total of six wheels and four of them were drive wheels.
In the United States, many truck engines differed from automobile engines because they ran on diesel fuel rather than gasoline. Diesel engines, invented by Rudolf Diesel in 1897, were a type of internal combustion engine powered by the controlled explosion of fuel sprayed into a cylinder under pressure. Diesel engine design was simpler than gasoline engine design and required no spark plug. Diesel fuel also cost less than gasoline and did not burn as readily if spilled. Diesel engines, however, were more expensive to construct because they required heavier gears to accommodate a more powerful stroke. Because diesel engines were especially suited for heavy duty hauling and long distance running, they gained popularity in cartage vehicles in the United States.
Trucks developed in response to the need to transport goods. John B. Rae, automotive historian and author of The American Automobile Industry, wrote, "At the beginning of the nineteenth century the cost of moving goods thirty miles inland by road in the United States was as great as the cost of carrying the same goods across the Atlantic." Although steam locomotives helped to provide alternatives to animal power during the mid- and late 1800s, railroads could not offer "door-to-door" service.
As the emerging automotive industry began to supply people with self-propelled vehicles for personal transportation, enterprising innovators began to apply the technology toward the development of commercial vehicles. The popular Model T chassis, introduced in 1908, found itself used in a variety of applications. Ford Motor Company offered it as an ice cream truck, an urban delivery truck, and a farm vehicle.
One of the first types of specialty trucks was the twin boom wrecker, designed by Ernest Holmes in 1914. The truck's twin booms featured cables powered by the vehicle's engine. One cable could be deployed to rescue or lift a disabled vehicle; the other cable could be hooked to a tree to provide additional support. Other truck innovations made during the early decades of the twentieth century included four wheel drive, four wheel steering, and an improved clutch system.
With the coming of World War I, unfavorable front line driving conditions compelled truck designers to make other improvements and refinements. One popular truck developed during the war era was the...
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