Bench Tests

An extensive series of bench wear tests were conducted on standard material couples and on couples involving silicon nitride (ceramic). The test equipment used was a Fa lex No. 1 Block-on-Ring wear tester. Only the most interesting results from the matrix tested will be summarized here. One parameter which was shown to have a significant effect on wear rates was the condition of the engine oil. So all material combinations were tested in high quality new engine lubricating oil and then in deteriorated, dirty (used) engine oil.

One series of tests involved crosshead and rocker lever materials. Stellite blocks (crosshead pad) were run against hardened ductile iron rings (rocker lever nose) — this combination being the standard production materials. An experimental combination was then tested — ceramic blocks (crosshead pad) against ductile iron rings. The results of the standard and experimental combinations were then compared in the following table.

Experimental Parts Wear

As A % of Standard In New Oil In Used Oil

Block Wear 10% 40%

Ring Wear 85 50

In both engine oil conditions the experimental combination using the ceramic block had significantly less wear than the standard combination.

A second series of tests involved ball and socket materials. Hardened steel blocks were run against hardened steel rings — this combination being the standard ball-socket production combination. Two experimental combinations were then run — stellite blocks against hard steel rings, and ceramic blocks against hardened steel rings. A comparison of relative block wear follows:

Block In New In Used Wear Oil Oil

* We were unable to even complete a test with steel-on-steel in used oil at the standard test conditions due to extremely severe wear. ** Mechanical problems with the Falex machine prevented our running additional combinations to add to the results shown.

Again it was clear that the combination involving the ceramic block was much superior in the used oil.

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