Search Results

Several cases of rod bearing shells assembled in highly loaded engines have been reported to show premature wear of the sliding surface, more specifically the electroplated lead-tin overlay. To understand these phenomena and overcome such occurrences, an analytical method has been developed to simulate the operation of specially designed journal bearings featuring circumferential profiling of the sliding surface. The resulting computer program solves the Reynolds equation taking into account a non-circular bearing surface, thus allowing for a customized design which extends operational component life through minimum oil film thickness (MOFT) increase and peak oil film pressure (POFP) and bearing back temperature (BBT) reduction. Theoretical results show an effective way to prevent premature wear.

Lead free bronze substrate associated with a lead free electroplated coating has been the standard bearing material technology for medium size Diesel engines. However the increasing engine demands are driving this technology to the limit. With the increase of Peak Cylinder Pressure (PCP) to improve power density and reduce CO2 emissions, the bearings are subjected to higher loads which usually reduce their durability. The new operating conditions are more prone to wear and eventually scuffing occurrences. Therefore materials with higher scuffing and wear resistance without a significant cost increase are demanded. To meet the requirements of highly loaded Medium Duty Diesel (MDD) applications, a lead free material based on a high resistant bronze substrate associated with a polymeric coating was developed. The polymer is sprayed onto the substrate and cured on a high temperature to provide performance improvement and adequate thickness control.