The invention provides an improved tractor. According to the improved tractor, stress ofrotating shafts in the rotating process is well balanced, it is ensured that the tractor operates stably for a long time, meanwhile, sealing and moisture preventing of a motor are ensured, and time and labor are saved in the installing process of a stator. A tractor base comprises a first shell and an end cover. The first shell comprises a radial end face and an outer ring. The outer ring is arranged on the radial periphery of the radial end face. The outer ring is arranged in the axial direction, and the outer ring and the radial end face are combined to form a periphery ring. Theend cover is packaged to the end face, away from the radial end face, of the outer ring to form a closed installing cavity.The portion, located in the center of the closed installing cavity, of the end cover is provided with an inner ring installing side protrusion protruding axially. An installing distance is reserved between the opposite end faces of the inner ring installing side protrusion and the radial end face. Corresponding bearing locating holes are formed in the radial end face and the center position of theend cover correspondingly. The rotating shafts protrude laterally after being located in the corresponding bearing locating holes through bearings to form the first exposed end and the second exposedend.