Clutch System Evaluation and Failure Diagnosis: Chemical and Physical Effects

Wet clutch friction performance has historically been visualized by multiple graphs due to the number of temperatures and pressures required to characterize the system. However, this same friction performance can be visualized by a single graph using an alternative approach to map the friction data. Applying a method similar to that used to develop the Stribeck curve for journal bearings, a single system-level graph for wet clutches can be created. This paper will highlight how this visualization method, particularly when used to diagnose clutch failures, provides benefits in understanding the effects of both the friction material and the lubricant performance. We conducted extensive studies comparing ideal clutch systems with failed ones under a variety of conditions. Lubricant and friction material failures were independently studied, and durability tests were conducted to evaluate component failures. The effects of the friction material and lubricant can be seen in different regimes of this visualization, allowing us to assess the individual impact of the friction material and the lubricant. This new visualization method helps to characterize clutch system failures and provides key insights to improve wet clutch performance.