Three support friction surfaces with a total of four different surfaces.  Force measuring unit: force gauge and adjustable air damper. Force measuring unit height-adjustable. Lines of action of friction force and tensile force always parallel. Friction body stationary, support friction surface in a moving carriage. Carriage driven by cable pulley and motor. Two driving speeds via a graduated cable drum. Mechanical friction between two solid bodies. Two friction bodies each with two different surfaces.
Adjustable air damper - with damping: Measurement of a mean friction force adjusted by disturbances, without damping: Slip/stick effects measurable. Box to house the components.