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To simultaneously reduce wear and friction in automotive valve train systems, a technique for measuring the rotational speed of tappets by placing radionuclide markers in their surfaces has been developed. Using an electrically driven test rig, counting rate variation during camshaft rotation is traced, allowing a mean value of the tappet's rotational speed to be determined. Measurements were performed on a V6 Peugeot engine cylinder head for various geometrical combinations of the cam-to-tappet contact (crown radius of the tappet, cam taper angle), and the dependence of the tappet's rotational speed upon functional parameters (lubricant pressure and temperature, angular speed of the camshaft) was determined. Tappet rotation was found to be strongly affected by camshaft operating speed and the design of the cam-to-tappet contact, and less by lubrication conditions (off pressure and temperature).

SLA IS A METHOD for precisely measuring material loss due to wear, erosion or corrosion in mechanical systems. A marker layer is activated by exposure to a particle accelerator beam. The intensity of gamma rays from this marker is then monitored by a detector mounted externally to the operating system while wear occurs. The decrease in intensity after correction for natural decay half-life results in a direct measure of wear which can be repeated at arbitrary intervals while the system is on-line and operating. Recent applications have been in diesel, gasoline and gas engine components, in utility power plants measuring solid particle erosion and corrosive wear, in oil drilling and piping, in key components in the space shuttle, and in medicine measuring ion release corrosion from prosthetic implants. This paper describes recent efforts to extend the range of this approach to much shallower activation depths and thus improve accuracy.