Environmental regulations all over the globe and the demand on fuel efficient engines have increased bearing loads dramatically over the last 20 years, especially in small and high speed Diesel engines. Lead containing Bronze bearings, often with a Lead based overlay have become a standard in the automotive industry and are used over decades. Due to the harmful and poisonous effect of lead on the environment the European Union has set up the Vehicle end-of-life Regulation to reduce use of lead, also in tribological products. In order to fulfill the high load capability and the necessary tribological behavior of engine bearings new approaches in fatigue, temperature stability and Tribology has to be taken.
Basic investigation of the tribological working principles in bearings combining short term failure mechanism and long term behavior were carried out to understand the interaction of materials, layers and lubrication. Design guidelines for different bearing types were set up based on these investigation results and a range of different bearing families combining new lining materials and different coatings have been developed. A special validation program representing standard bearing loading as well as extraordinary events like starvation or dirt shocks have been set up to prove the new bearing families. Tribological testing, bearing testing on bearing test rigs with special programs as well as engines were part of this release program. The complete range of lead free bearing types serving all engine slide bearing locations based on Lead Free Bronze lining with electroplated Tin based overlay, Al based sputtered overlay and/or Synthetic overlay shows extraordinary performance in relation to standard Bronze bearing types.
The new publication give a detailed picture of the development work starting with the tribological basics, bearing development as well as bearing validation. Bearing performance judgment will be allowed by references to well known standard bearings. Engine test results will conclude the presentation.