A term defined in General Liability policies as land vehicles, including machinery and apparatus attached thereto, whether or not self-propelled, and (1) not subject to motor vehicle registration, or (2) used exclusively on the insured’s premises, or (3) designed principally for use off public roads, or (4) designed or maintained for the sole purpose of providing mobility for permanently attached equipment such as cranes, loaders, pumps, generators, or welding equipment.