Abstract: A centrifugal expansion roller (1) for sanding machines, particularly floor sanders, of the type consisting of a metal core (3) with an outer elastomeric annular cover (4). The entire surface of the cover is provided with a plurality of longitudinal slits (5, 8) extending into the annular cover along non-radial planes. The slits (5, 8) are formed along trajectories which have opposite ends that are inclined in opposite directions in respect of a longitudinal generatrix of the surface of the cover.

Abstract: A tracking device for endless belts moves on a pair of rollers--a driving roller (RM) and a tension roller (1)--especially for an emery cloth belt (TS) moving on the cantilevered rollers (1, RM) of a belt sander (S) for wooden floors. The tension roller (1) is formed in two parts: a minor portion (3), close to a support (5) of the roller shaft (2), mounted--rotatable but not inclinable in respect of said shaft--onto an eccentric rotary sleeve (11), its part closest to the support (5) being of frustoconical shape; and a major portion (4), mounted revolving on a bush (12) coaxial to the roller shaft (2) and inclinable on a ball joint (13) but not rotatable in respect of the shaft. A unilateral contact ball constraint (15) is moreover provided between the sleeve (11) and the bush (12), and at least one spring (16) is provided to cause the inclination of the bush (12) in respect of the roller shaft ( 2) in the direction allowed by the constraint (15).