the pivot links 10 and 14 on the connection link 11 the aligned connection apertures 12 13 and 14 are penetrated by a connection element 15 in the form of a connection bolt or connection pin this is relatively thick for improving the wear resistance and for preventing bending while the spacing and the diameter of each connection aperture 12 of the guide links 9 and the connection aperture 14 of the connection link 11 can be selected in such a way that both sit on the connection element 15 with an interference fit so that they cannot pivot it is possible to select the diameter of the connection apertures 13 of the pivot links 10 somewhat larger so that they are held in a clearance fit on the connection element 15 here the spacing can be selected somewhat smaller so that the inner wall contacts a point on the connection element 15 a corresponding construction is shown in the enlarged detail view in fig4 from which it is visible that the two pivot links 10 and the connection link 11 are significantly wider than the guide links 9 preferably twice as wide in order to realize the largest possible tooth contact surface which is especially possible then at a considerable degree when the connection link 11 u2014 following the teaching according to de 10 2005 024 747 u2014 is also provided with a toothed profile preferably the pivot links 10 and.