This apparatus consists of a main shaft locked with three identical discs with different surface fixed on to it. One disc is plain (fine machined surface) the second is the same but has a tub underneath that can be filled with a grease or liquid lubricant and the third disc has a rough finish. The main shaft has a pulley fixed on the end to which an effort load can be applied to overcome the normal force between the contacting surfaces.

The apparatus has a braking lever which can be positioned over one of the testing discs at a time. The braking lever has the capacity to hold a variety of test samples made from different materials as well as a roller bearing that is supplied with the unit. Load can also be added to the lever to vary the braking force.