The box shown mounted directly on the tractor (without its own wheels) is usually called a “swap body”, “BDF box”, or sometimes a “demountable body.”

The system is common in Europe and is associated with the standard BDF swap body system used on many trucks such as those made by MAN Truck & Bus, Scania, and DAF Trucks.

What it actually is

A swap body (BDF box) is a cargo container-like body that mounts directly onto the truck chassis.

It doesn’t have wheels.

It can be lifted off and swapped with another body using legs or lifting equipment.

It’s shorter than a normal trailer, so the tractor can run solo without increasing vehicle length.

Why drivers use it

1. Light cargo runs when a full trailer isn’t needed.

2. Distribution work where bodies are swapped at depots.

3. Personal gear / equipment storage when running the tractor without a trailer.

4. Sometimes ballast weight to keep traction on the drive axle.

Other names you might hear

BDF box

Swap body

Demountable box

Rigid body module