contact between the thermally conducting element 16 and the rotor 8 is prevented so as not to have an adverse effect on the rotation of the rotor 8 the thermally conducting element 16 has a cutout 24 in the manner of a cone as shown in fig4 on the inside starting from the end surface 18 in the direction of an end face 22 the cutout 24 on the one hand represents a saving on materials and also serves to enlarge the surface of the thermally conducting element 16 allowing more heat to be emitted to the surroundings a drive roller 12 in the assembled state in which a roller drive 2 with two thermally conducting elements secured to its end face is disposed within a roller tube 14 is shown in fig5 because the diameter d w of the thermally conducting elements 16 corresponds to that of the rotor 8 the diameter d w is only a degree of tolerance smaller than the internal diameter d i of the roller tube 14 a very small gap is thus formed between the thermally conducting element 16 and the roller tube 14 by way of which gap heat from the thermally conducting element 16 is emitted in the form of thermal radiation to the roller tube 14 the length l w of each of the thermally conducting elements 16 in this exemplary embodiment is roughly 30 of the length l 1 of the roller drive 2 the thermally conducting elements 16 thus represent an extension of the roller drive 2.