A coupling unit for a semi-permanent connection of two wagons of a rail vehicle, which has a first housing and a second housing, which is pivotably and rotatably coupled to the first housing. A bearing outer ring with a hollow spherical inner bearing surface is fastened to the second housing and is guided in sliding fashion on a bearing inner ring with a spherical outer surface. The bearing inner ring is seated with an inner bore on a shaft fastened to the first housing. The shaft has, on a first end, one or two flattened portions and, on a second end, one or two second flattened portions. At least one clamping piece is provided which bears against one of the flattened portions and an opening region in the first housing, thereby preventing the shaft from rotating.