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The parameters of a well designed vehicle steering system include a consistent torque effort at the steering wheel, a crisp and symmetric return to the straight ahead position, and a pleasing on-center feel. Historically, these features were more easily attained with a straight-line placement of the steering column relative to the gear connection. The trend toward vehicle downsizing, along with new vehicle requirements for crush zones and tighter package restraints, have necessitated the incorporation of multiple universal joint steering systems, thus making the features above more difficult to obtain. Moreover, operating angles continue to increase with the reduction of packaging space and imposed government motor vehicle safety standards.

Reliability research in hybrid ceramic bearings involves life testing of hybrid bearings and ceramic specimens. New materials for bearings like advanced ceramics have emerged for evaluation in recent years. In fatigue testing to determine the stress-life relationship, the number of sample size in life testing can be limited by consideration of cost and testing time. In the testing of ceramics, some researchers have relied on the use of a stepwise multiple loading approach to increase the failure data points. In this paper, a maximum likelihood method is applied to test data with multiple loads to estimate the stress-life exponent. This method treats the data at different loads or steps at once. Test data from three fatigue experiments using silicon nitride materials have been analyzed to obtain the stress-life exponents. Also, Weibull plots of the ‘equivalent lives' have been presented for all test specimens tested at different loads and load steps.

This paper presents a method of measuring the actual load distribution within a rolling element bearing. This method has been used successfully to measure the load distribution in both cylindrical and tapered roller bearings, with accuracies of 15% or less when comparing the applied load with the computed resultant load. An example using a tapered roller bearing is given.