Experimental Study on Reciprocation Rolling-Sliding Contact with Spin

―Study of the Contribution of Lubricants―

Abstract

Machine elements in rolling contact operate under severe loading condition associated with repetitive pure rolling or rolling/sliding contacts. Such a severe loading condition can promote fatigue accumulation in the surface and subsurface layers leading to a fatigue flaking failure known as rolling fatigue. In our previous report, a novel test rig to simulate flaking of constant velocity universal joints, CVJs, was developed and preliminary tests using this test rig showed that various modes of failures can occur in CVJs depending on the test condition. This study is to evaluate flaking prevention of greases using this test rig under a test condition in which flaking is caused by the development of subsurface comb-shaped cracks. The results confirmed that the occurrence of the flaking is significantly affected by the type of thickener used. The flaking and cracks were initiated at the stroke end at a relatively low speed suggesting that the thickener contributes to extended flaking life by thickening a boundary film in the low-speed range.