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In recent years, engines equipped with idle reduction system for fuel saving have been increased in Europe and Japan. Because of the start-stop frequency increase, correspondingly crankshaft and engine bearing contacts also increase. The friction between shaft and bearing is significant to reduce fuel consumption, and besides it, engine bearing wear tends to increase. Therefore, lower friction with small wear engine bearings are expected. In this paper, new developed engine bearing with solid lubricant overlay and its frictional and wear properties are reported (1). As experimental result, a bearing with MoS2 solid lubricant contained polyamide-imide resin coated overlay proved 40% less coefficient of friction, 25% less starting torque and 65% less bearing wear against conventional aluminum alloy bimetal bearing without overlay under close to the start-stop lubrication conditions by testers. Also diesel engine bench test proved less FMEP.

The recent demands for higher performance and lower fuel consumption of automotive engines require the bearings to operate under severe conditions. One of the problems with conventional aluminum alloy bearings used under these conditions is the low wear resistance. A new aluminum alloy bearing that allows a higher wear resistance is developed by controlling Si particle size and lining hardness. The mechanism to upgrade the wear resistance are the concentration of enlarged Si particles on the sliding surface and to prevent falling off Si that are held by sufficient lining hardness. Wear resistance of this bearing is 4-5 times better compared with the conventional bearings and seizure resistance is two times better than the conventional bearings.