The Frictional Stability of Wet Clutch Friction Materials Investigated on a Small Scale Test-Rig

The work presented in this paper is part of a European project (COST 532, project E2) to study clutch shudder and its influences, together with wear testing of clutch materials. The relation between the friction force and the relative velocity, and the dynamics thereof are investigated for typical wet clutch materials (oil lubricated paper/steel contact) on a small scale test rig, using a ground and polished steel ring onto which a coupon from a friction clutch plate was slid. The results clearly show that although momentarily the relative velocity of the sliders vs. the rotating ring reaches zero, no stick episode ensues. The mechanical parameters (stiffness, damping and normal load) of the test-rig were varied and the influence thereupon on the friction during sliding was investigated.