Background

This paper will review the successful component types: their function, the design approach, the environment in which they operate, the tests conducted to evaluate these components, the results, and the benefits derived.

In general, the effort has been focused on ball-socket joints and flat 'wear pad1 surfaces of components variously described as 'overhead' components or 'valve and injector train' components. The environment in which these components operate is high quality lubricating oil with EP (extreme pressure) additives at 200-250 degrees F.

The ball-socket joints are on the ends of straight links and pushrods which follow the eccentric motion of the engine camshaft. These components translate this motion to the reciprocating strokes which activate the valves and the diesel fuel injectors. In Cummins engines, these components operate at very high loads in order that the fuel injection is accomplished quickly and at high pressure as this leads to efficient fuel combustion. Furthermore, it is important that the precise control of the valve and fuel injection events be maintained over long periods of time without adjustment so that the power, fuel economy and exhaust emissions performance of the engine do not deteriorate over time. And as emissions requirements become more strict for heavy duty diesel trucks in 1991 and 1994, the need for even higher performance fuel injection systems working for long periods without wear will become even more important.

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