William A. Yahraus

Bio: William A. Yahraus is an academic researcher. The author has contributed to research in topics: Bearing (mechanical) & Plain bearing. The author has an hindex of 1, co-authored 1 publications receiving 1 citations.

Improving Sleeve Bearing Fatigue Life - A New Design Concept

Abstract: Peak oil film pressure is cited as the parameter controlling a sleeve bearing's fatigue life. Improvements in sleeve bearing fatigue life are achievable through alloy strengthening or reduction of peak oil film pressure; unfortunately, the "soft" properties required of a bearing generally limit metallurgical alterations which could accomplish alloy strengthening. Theoretical calculations show that the most effective way of reducing peak film pressure is to reduce the bearing clearance, but this technique tends to sensitize the bearing to "off" conditions and can lead to excessive operating temperatures. By incorporating unequal walls in upper and lower shells, fatigue life improvement can be realized without the penalty of higher temperatures. Tests conducted in both engines and bearing fatigue machines confirm the validity of the unequal wall theory. Several diesel builders are conducting tests on their own engines. By reducing the peak oil film pressure developed in a halfshell bearing, the unequal wall design offers longer bearing life in existing engines, higher load capacity for equivalent bearing life, potential for returning to a nominal 0.001 inch (or thicker) overlay in high-output diesel bearings, maintenance of acceptable peak oil film pressure values in lower-speed high-torque-rise engines, and possible lift/drag reduction to save space and weight and/or improve crankshaft reliability by allowing the use of larger fillets.