Current Design Trends of Sleeve Bearings and Thrust Washers in Passenger Car Automatic Transmissions

A study of 10 current production passenger car automatic transmissions with respect to environment, bushing and washer material, journal and thrust runner materials and finishes, loads and speeds, and grooving was conducted to compare results with an earlier study made in 1961. A second objective was to present results of a test program to determine effect of bushing and shaft surface finish on performance of copper-lead, babbitt, and aluminum bushing materials.

Test results showed load capacity is largely dependent on shaft and bushing surface roughness. Also, that babbit and copper-lead bushings are preferred for applications in which edge-loading and marginal lubrication are encountered.