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This paper will describe the development of an accelerated testing methodology for an off-highway vehicle rotary oil seal system. There are two typical field failure mechanisms associated with off-highway input pinion shaft oil seals: 1) excessive abrasive wear of soft seal lip and hard shaft surface due to abrasive environment; 2) excessive heat and degradation of the seal lip due to lack of lubricity and wear of the shaft surface run against this seal. The accelerated testing of the rotary oil seal consisted of a combination of the following factors; shaft run-out, eccentricity, testing temperature, rotation and reciprocal motion of the seal lip relative to the shaft surface. The combination of these factors especially reciprocal motion reproduces the same failure mechanism, i.e. shaft wear grooves and oil seal lip wear observed on the field usage samples with 6,300 hours service in only 350 hours of accelerated testing.

In spite of being a popular topic in technical publications, scuffing between a piston ring face and the cylinder liner is an extremely unpredictable and hard-to-reproduce phenomenon that significantly decreases engine performance. The scuffing phenomenon described as the transfer of cylinder liner particles to piston ring surfaces due to inadequate lubrication and high temperature at top dead center could significantly decrease engine performance. The mechanism of scuffing origin and subsequent catastrophic seizure usually is evaluated by coefficient of friction measurements. The purpose of this paper is (1) to examine the usefulness of acoustic emission RMS measurements generated during testing that results from the friction between piston ring and cylinder liner segments and (2) to establish the relationship between such signals and different levels of the scuffing phenomenon.

Vehicular suspension ball joints can be categorized in the family of tribological systems which can reduce useful service or working capacity through malfunction or breakdown. Detailed metallurgical analysis of the friction and wear mechanisms on typical ball joint bearing surfaces point to a Teflon-based woven fabric, self-lubricating liner as the best bearing material for the joint. Laboratory functional testing was conducted on modern, 4-axis test equipment simulating the applicable loading and motion conditions typically encountered in use. The self-lubricated bearing liner woven with Teflon thread demonstrated higher sustained load capacity, less rotating friction, excellent torque retention qualities and extended life in comparison to existing components utilizing greased metal-on-metal and/or “plastic” bearing materials.