The apparatus consists of a wall mounted fixed pulley with a loaded belt. Four different pulleys are supplied with different vee groove angles; flat rim, 120°, 90°, and 60°.
A load is added to one of two hangers until the rope just begins to slide. This is the datum condition. Loads are now added to both sides of the rope to cause very slow sliding of the rope. This enables the coefficient of friction to be obtained.