An experiment is performed with a pin-on-disk tester to evaluate the shear strength of a lubricant. The

experiment involves sliding of a spherical pin of hard steel against a copper plate of hardness equal to 120

kgf/mm2 . Both specimens are immersed into a bath of the lubricant and slide under a low speed (boundary

lubrication regime). The radius of the pin is 2 mm and the width of the wear track produced from sliding is

0.5 mm. Strain gages attached to a cantilever beam supporting the pin indicate that the total coefficient of

friction is 0.2.

Determine (a) the shear strength of the lubricant and (b) the reduction of the work of adhesion in the

presence of the lubricant. Clearly state any assumptions you make.

Ball Weight Arm Track w (rpm) Engine axis Specimen