A drive mechanism for a mobile imaging system comprises a main drive geared into a drive wheel for propelling the imaging system, including a base and one or more imaging components, across a surface. The drive mechanism can also include a scan drive that moves the drive mechanism and the one or more imaging components along an axis relative to the base to provide an imaging scan, and a suspension drive that extends the drive wheel relative to a bottom surface when the imaging system is in a transport mode and retracts the drive wheel relative to the bottom surface of the base when the imaging system is in an imaging mode. The drive wheel supports the weight of the imaging components, but does not directly support the base assembly, which can include pedestal and tabletop support. One or more casters located on the base can support the weight of the base assembly.