Abstract: When, according to the invention, a coupling is provided between a driving shaft (1) and a hub (6), the shaft (1) being configured with several sets of grooves (2, 3) in which an elastic cord (4) may extend, the cord (4) in the deep track (2) will have a slight or poor engagement with the hub (6), while the cord in the low track (3) will be pressed out into firm engagement with the hub (6).

Abstract: When, according to the invention, a coupling is provided between a driving shaft (1) and a hub (6), the shaft (1) being configured with several sets of grooves (2, 3) in which an elastic cord (4) may extend, the cord (4) in the deep track (2) will have a slight or poor engagement with the hub (6), while the cord in the low track (3) will be pressed out into firm engagement with the hub (6).

Abstract: With sanding or sanding machines with rotating sanding tools comprising sanding segments which are rotated in mutually opposite directions, according to the invention a more uniform sanding result and uniform wear on the tools is achieved with a method whereby the tools (10) which are rotated in the direction like a roller are rotated in the direction like a roller are rotated slightly faster than are the tools (1) which are rotated in the opposite direction. The necessary increase in speed has shown to be around 7%, since the individual segments under the increased influence of the centrifugal force will thus obtain the same sanding pressure and herewith a uniform sanding effect for all of the sanding tools regardless of their direction of rotation to thee item.