"tractor truck" . "Semi-tractor" . "semi-tractors" . "truck tractor" . "towing engine" . "Heavy equipment transporter" . "tractor modification" . "semi-trucks" . "semi-tractor" . . "road tractor" . "driving vehicle" . "prime mover" . "tractor cab" . . . "semi-truck tractor" . . . . . . "traction units" . . . "vehicles" . "Tractor unit" . "Tractors" . "rig" . "Tractor head" . . . "truck" . . "traction engine" . "semitractors" . "Tractor unit" . "semi tractor" . "auto-transport" . "trucks" . "Tractor" . . "Prime mover" . "powered vehicle" . "heavy utility vehicle" . . . "semitractor" . "Tractor trucks" . . "road tractors" . "tractors" . . . "lorry" . "tractor_unit" . "heavy trucks" . "tractor units" . . . . "tractor/cab" . "tractor unit" . "tractor" . . "semi-truck" . "Semi-tractors" . . "40T truck tank transporter" . "truck-tractor" . "prime movers" . "cab and drive axle portion" . "bobtail" . "Prime Movers" . . "tractor-unit" .