US Patent 7445271 Truck sleeper

A truck cab and sleeper unit are extended using a preferred stepped aerodynamic roof which at a first ceiling level corresponds to the original sleeper unit ceiling height, and which at a second ceiling level corresponds to the original sleeper unit ceiling height plus the height difference between the truck cab height and the original sleeper unit ceiling height. The original sleeper roof may be used, or a new unitary roof may be fabricated. The apparatus and method of the invention preserve all or most of the components of an original sleeper unit, while enabling rapid conversion comparable to the full replacement of the prior art.