Abstract: An articulated tractor (10) for towing an aircraft comprising a front section (10A) including an engine means (18) and a rear section (10B) pivoted to the front section (10a), the rear section (10B) defining a nose wheel clamp means (34) for engaging and raising the nose wheel (36) of an aircraft. In another embodiment the clamping force applied to the nose wheel (36) by the nose wheel clamp means (34) is proportional to the mass of the nose wheel (32). Still in another embodiment the nose wheel clamp means (34) are provided with relief valve means to relieve if the raising force applied to the nose wheel (36) increases beyond a predetermined limit.