Truck bodies with solid walls are a mandatory requirement for the transport of bulk cargo. This applies regardless of whether the cargo is loaded via a wheel loader from the side via the wall, through a funnel, via a filling tube from above or via a rear door. Also when unloading there are the options to excavate from above, off-load via a rear door, or push or tip out in one or more directions. Over the years, heavy goods vehicles have become increasingly specialised with such options to accommodate various bulk goods and loading conditions.

What they all have in common is the fact that unlike all other truck roofs, the tarpaulin must be designed to be laterally elastic in order to accommodate the shape of the wall for reliable operation under all conditions.