Search Results

A copper based bushing alloy is used under boundary lubrication for the sliding part of a fuel injection pump etc. for automotive diesel engines. Lead is added to a copper based alloy bushing, because seizure resistant property is an important factor under boundary lubrication. However reducing the use of lead, an environmental pollutant, is required from environmental concerns. Therefore, a lead free bushing alloy was studied in this paper. Concept of material design is to prevent adhesion between a bushing alloy and a mating shaft leading to less wear under the boundary lubrication. The tested material is basically copper-based alloy to which low melting metal instead of lead, hard particles and solid lubricant are added. Tribological and mechanical properties of the material were evaluated in terms of seizure resistance, fatigue strength, conformability and cavitation resistance.

Properties of engine bearings were investigated with different bearing materials and different HTHS viscosity oils by means of both an engine test and a rig test. The rig test well simulated the bearing wear which occurred in the engine test. Lead-bronze bearings with lead-tin-indium overlay gave the least amount of wear in operating under high speed and heavy load conditions even with low HTHS viscosity oil. Aluminum bearings without overlay gave good wear resistance in the case of no seizure occurrence. The wear amount of bearings were well correlated with HTHS viscosity, not with kinematic viscosity.