The apparatus consists of a main shaft with three identically dimensioned discs fixed on to it. The variable between the discs are their test surfaces. 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 breaking 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. With the breaking force set the effort hanger’s mass is increased until the pulley starts to rotate and the masses fall at a constant rate. From this, forces can be calculated and a friction coefficient for the brake material or other material and disc surface can be represents as a graphical representation or calculated.