As already mentioned in Sect. 1.3 , many components are fastened to the frame along with the large assemblies, such as the cab, body, axles and drivetrain (that get their own booklets in this series). Cab, body and fifth wheel, in the case of a tractor, are sitting on top of the frame. Most other attachments to the frame are mounted sideways. Figure 4.1 shows some example of attachments to the frame.