Tribological behaviour of paper friction plates for wet clutch application investigated on SAEII and pin-on disk test rigs.

The friction behaviour of wet clutches for automatic transmission applications strongly influences the dynamic behaviour of the entire machine or vehicle including the transmission. The wear, but also the friction curve, determines the lifetime of the clutch. The role of wear is obvious. The friction coefficient of the material couple friction plate/separator plate decreases with number of engagement cycles. As a result, the possible torque of the transmission decreases with time. Under a certain threshold, the clutch has to be revised. But because manufacturers tend to oversize their clutches the decrease in friction coefficient does not yield a limitation to the lifetime of the clutch. In this paper, both SAE#II and pin-on-disk tests are used to investigate the wear and friction characteristics of the friction material. Although the pin-on-disk tests fail in correctly reproducing the wear rate of the SAE#II tests, they can be used for a qualitative analysis of the influence of material parameters and operating conditions on both friction coefficients and wear rate. © 2001 Elsevier Science B.V. All rights reserved.