As used in this article, the following terms shall have the meanings indicated:
Every self-propelled vehicle not designed or used primarily for the transportation of persons or property and incidentally operated or moved over the highways, including but not limited to road construction or maintenance machinery, ditch-digging apparatus, stone crushers, air compressors, power shovels, cranes, graders, rollers, well drillers, and wood sawing equipment used for hire.