Scuffing and lubricant film breakdown in FZG gears Part I. Analytical and experimental approach

This paper presents the influence of the base oil viscosity and of the pitch line velocity on the scuffing load of a spur gear. Standard FZG A/8.6/90 tests, and constant temperature tests for several pitch line velocities, were performed, for three mineral paraffinic base oils, with different viscosities. These tests were complemented by the analytical evaluation of the most important operating parameters, such as the oil bath temperature and viscosity, the lubricant film thickness and the contact temperature along the gear contact path, for each load stage considered. The analysis of experimental and theoretical results shows a good correlation between the scuffing loads and scuffing temperatures and the lubricant film thickness, suggesting that a close relation exists between scuffing failure and lubricant film breakdown, for a base oil tested in the FZG rig. (C) 1998 Elsevier Science S.A.