Highly Extended Life of Transmission Bearings of "Sealed - Clean" Concept

A unique stress analysis method was applied to the study of premature flaking failures of ball bearings used in manual transmissions for passenger cars. The study determined that premature flakings were due to the abnormal surface-originating fatigue rather than the normal subsurface-originating type fatigue. Existence of fine ferrous particles of high hardness in transmission oil was the cause. Based on these findings, "Sealed-Clean" bearings have been developed which have special rubber seals on both side of bearings. Tests proved that "Sealed-Clean" bearings last several times longer than open-type standard bearings or special bearings having steel balls of extra-large size. Already 4.4 million pieces of "Sealed-Clean" bearings have been installed in 16 models of transmissions during the last six years. This stress analysis method has opened a new possibility of remaining-life prediction on ball and roller bearings. The "Sealed-Clean" concept is being applied to other usages including bearings for steel rolling mills with remarkable success.