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Radioactive tracer technology (RATT™) is an important tool for measuring real-time wear in operating engines and other mechanical systems. The use of this technology provides important wear information that is not available by other, more conventional wear measurement methods. The technology has advanced to the point where several components can be interrogated simultaneously, and new methods have extended the method to materials that are normally not amenable to radioactive tracer evaluation. In addition, sensitivity has increased so that the onset of wear can be detected long before practical with non-tracer methods. This improves the ability to measure and determine cause and effect relationships, thus providing a better understanding of wear responses to specific operating conditions and to changes in operating conditions. This paper reviews the radioactive tracer process and recent improvements that have extended its reach in both automotive and non-automotive applications.

Radioactive tracer technology is an important tool for measuring component wear on a real-time basis and is especially useful in measuring engine wear as it is affected by combustion system operation and lubricant performance. Combustion system operation including the use of early and/or late fuel injection and EGR for emissions control can have a profound effect on aftertreatment contamination and engine reliability due to wear. Liner wear caused by localized fuel impingement can lead to excessive oil consumption and fuel dilution can cause excessive wear of rings and bearings. To facilitate typical wear measurement, the engine's compression rings and connecting rod bearings are initially exposed to thermal neutrons in a nuclear reactor to produce artificial radioisotopes that are separately characteristic of the ring and bearing wear surfaces.

System contamination caused by contaminates or small particles built-in, self-generated, or inhaled from environment presents severe problems. The problems include but are not limited to the malfunctioning of valves, pumps, seals and injectors or lock-up of these components; increased wear of bearings, piston rings, and other friction components; and degradated machine performance. In general, system contamination changes a deterministic system into a stochastic system and shortens machinery service life. In this paper, these contamination problems are discussed in categories and associated analysis, testing and computer modeling methodologies are also discussed.

Physical wear plays an important role in engine performance and longevity, with the vast number of engines alone indicating the extent of the poten-economic impact. Nevertheless, engine wear is often treated subjectively in terms of understanding the critical wear mechanisms caused by external and internally generated contamination or by the many transients encountered during an engine's duty cycle. In fact, in few other areas of engine design is quantitative data so limited. Consequently, there is a definite need to obtain quantitative, real-time data on engine wear, in general, and to establish correlations between engine wear and inlet air contamination, in particular. This paper discusses laboratory research designed to investigate these concerns.

Recent legislation, including the California Clean Air Act of 1988 and the Federal Clean Air Act Amendment of 1990, includes off-road engines, equipment, and vehicles as targets for new exhaust emissions regulations. The Santa Barbara County Air Pollution Control District in cooperation with EXXON USA is conducting a major Low NOx Demonstration Program including mobile sources, construction equipment, and offshore equipment. As a part of this program, an existing backhoe has been retrofitted with a low NOx engine and demonstrated in the field. This paper discusses the work performed to allow Case model 580 backhoes to be retrofitted with Cummins 4BTAA3.9 on-highway turbocharged diesel engines. A standard production conversion kit can be used to mount the new engines in place of the older existing JI Case engines in some models while other newer models already have 4B3.9 engines. In addition, an air-to-air aftercooler and associated plumbing was designed and installed.

Systems for controlling automotive exhaust particulates, especially lead particulates, are discussed and a suitable method for determining automotive particulate emission levels during on-the-road vehicle operation is presented. Data is presented for a large number of vehicles. The evaluation system is suited for use with a large variety of vehicles during all modes of vehicle operation. A total emissions control system, capable of meeting the strict 1978 statutory gaseous emissions levels with virtually zero particulate emissions, is also discussed. This emissions control system is compatible with leaded and unleaded fuels. The economic implications of lead additive restriction, as a means of reducing lead airborne particulates, are briefly considered. It is concluded that the reduction of airborne lead, by trapping it in the exhaust system, is more cost effective and energy conservative than is reduction by regulation of the fuel supply.