Complex sentence: The use of cardan joints within the Thompson Coupling reduces the wear, heat and friction which is present in Rzeppa type constant velocity joints-cardan joints utilise roller bearings running circumferentially, whereas Rzeppa constant velocity joints use balls which roll and slide axially along grooves.
Split into simpler sentences: The use of cardan joints within the Thompson Coupling reduces the wear, heat and friction when compared with Rzeppa type constant velocity joints. Cardan joints, including Thompson couplings, utilise roller bearings running circumferentially, whereas Rzeppa constant velocity joints use balls which roll and slide axially along grooves.