The invention disclosed is a self-propelled aircraft undercarriage for driving an aircraft on the ground, comprising: an axle; a strut supporting said axle; at least one wheel rotatably mounted on said axle; and drive means for driving said at least one wheel; characterized in that said drive means is disk shaped and is external to said wheel. In one embodiment of the invention, said drive means is mounted on said axle between said strut and said wheel. In a second embodiment, said drive means is mounted on said axle, on the side of said wheel furthest from said strut.