Mr. Tom Steinkamp

Hawkeye Truck Equipment

5800 2nd Avenue

P.O. Box 3283

Des Moines, IA 50316


Dear Mr. Steinkamp:


This responds to your e-mails, addressed to Jeff Woods of the National Highway Traffic Safety Administrations (NHTSAs) Office of Vehicle Safety Standards, about this agencys regulations concerning trailers. You asked whether certain trailers that you sell are classified as full trailers or semi-trailers. Your question is addressed below.

By way of background information, NHTSA does not provide approvals of motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act, now codified as 49 CFR Chapter 301, it is the responsibility of the manufacturer to ensure that its vehicles and equipment comply with applicable requirements. As such, we would also refer you to the individual manufacturers of the subject trailers for information about classification and their basis for compliance.

Turning to the information about the trailers you have provided to NHTSA, you describe the trailers as pup trailers. The average empty weight of the trailers is approximately 8,500 pounds, and they have two axles. There are three versions of the trailers, which vary by axle spacing. There is a 50 axle spacing trailer, an 81 axle spacing trailer, and a 10 axle spacing trailer. The gross vehicle weight ratings range from 34,000 pounds to 40,000 pounds. Each of the trailers is connected to the towing truck by a long tongue. (The tongue appears to be similar in length to the main part of the trailer.) You stated that the tongue is solid and would not slide from side. You also stated that if the trailer is unhooked from the truck, a jack is needed to hold up the tongue.

In addressing your question, we believe it is necessary to consider the definitions of full trailer and semitrailer together. These terms are defined in 49 CFR Part 571.3, for purposes of the Federal motor vehicle safety standards, as follows:

Full trailer means a trailer, except a pole trailer, that is equipped with two or more axles that support the entire weight of the trailer.

Semitrailer means a trailer, except a pole trailer, so constructed that a substantial part of its weight rests upon or is carried by another motor vehicle.

As you know, a distinction is made between these types of trailers for safety reasons and, as such, each designation carries with it attendant requirements in terms of safety-related features. Most significantly, the full trailer requires a more enhanced braking capability because its axles support the full weight of the trailer. Full trailers are required to have ABS on at least one front and rear axle to avoid an instability that may result from lockup of either a front or rear axle. Semi-trailers, by contrast, are supported in the front by another motor vehicle. They are only required to have ABS on one axle.

In applying the definitions of full trailer and semi-trailer to the trailers at issue, we distinguish between the weight of the main portion of the trailer and the tongue. The tongue on these trailers, while unusually long, is essentially a device for connecting the trailer to the towing truck. It is our view that if the full weight of the main portion of the trailer (the portion not including the tongue) is supported by the trailer axles, the trailer is a full trailer. However, if a substantial part of the weight of the main portion of the trailer is transferred via the tongue to the towing vehicle, the trailer would be a semi-trailer. We are unable to offer you further guidance as to the specifics of the trailers you ask about given the information we have received, yet we hope this analysis is helpful.

If you have any further questions, please feel free to call Edward Glancy of my staff at (202) 366-2992.


Anthony M. Cooke

Chief Counsel