The invention is directed to a positive-engaging coupling between a drive part and a driven part. The positive-engaging coupling includes an insert portion defining a first noncircular cross section and formed on the driven part. The drive part defines a receptacle for accommodating the insert portion therein and the receptacle has a second noncircular cross section corresponding to the first noncircular cross section. The insert portion and the receptacle conjointly define an intermediate space when the insert portion is inserted into the receptacle. An elastic insert is inserted into the receptacle for filling out the intermediate space when the insert portion of the driven part is disposed in the receptacle. If an overload occurs, the elastic insert is destroyed and the insert portion rotates freely within the receptacle.