A tipper body is a large container or vessel mounted on the back of a truck that can be mechanically tilted. This allows its contents, typically soil, gravel, sand, cement, waste, or other materials, to be emptied, or "tipped," from the rear without having to manually unload the material. https://articlescad.com/tipper-body-a-versatile-attachment-for-transportation-of-bulk-materials-97139.html