What does the official definition of a semi-trailer exclude?

What does the official definition of a semi-trailer exclude?

• A. It has axles only at or near its rear end
• B. It has axles either at its front or rear ends
• C. While being towed, it is supported at its front end by the truck tractor or the immediately preceding trailer
• D. When connected to the truck tractor or preceding trailer, it is connected by means of a kingpin and a fifth wheel

Answer: (B)

A semi-trailer is defined by having its own axles only toward the rear, with the front of the trailer being supported by the tractor through a kingpin and fifth wheel. Because of this design, if a trailer had axles at its front end, it would not fit the official definition of a semi-trailer. The front-end support by the tractor and the rear-positioned axles are what make it a semi-trailer, and the connection method is specifically via kingpin and fifth wheel. Therefore, the description that implies axles at the front end is excluded by the official definition.

A semi-trailer is defined by having its own axles only toward the rear, with the front of the trailer being supported by the tractor through a kingpin and fifth wheel. Because of this design, if a trailer had axles at its front end, it would not fit the official definition of a semi-trailer. The front-end support by the tractor and the rear-positioned axles are what make it a semi-trailer, and the connection method is specifically via kingpin and fifth wheel. Therefore, the description that implies axles at the front end is excluded by the official definition.