Conclusions And Observations

Based on our tests so fair conclusions and observations are as foilows:

1. In dry tests the titanium carbide, chrome carbide pair was a poor wear combination, whereas the chrome oxide pair was exceptional. The Hohman-A9 tests correlated well with Cameron Plint (TE77) results, and were in gualitative agreement with engine test results.

2. The lubricated tests demonstrated lower wear and friction as expected. Significant improvements in the control and definition of operating parameters are needed in order to produce quantative test results in this area.

3. Much additional work must be done to establish correlation between bench testers and running engines. Such work includes development of standard bench test procedures, parametric evaluations. and more sophisticated surface analysis of wear samples.

Overall it is felt the Hohman-A9 tester is a promising bench test device for evaluating ring. liner. lubricant combinations for low heat rejection diesel engines. While it will probably never be practical to eliminate engine testing completely, the Hohman-A9 should make the screening of wear materials much more efficient and less costly.

strain caces variable speed s stroke bfl 1 ows loadisc strain caces variable speed s stroke bfl 1 ows loadisc

Fig. 1 Sketch showing essential mechanics of Hohman A-9

reciprocating' liner and piston ring tester.

Fig. 3 Proficorder trace of liner-baseline engine materials, worn.

Fig. 3 Proficorder trace of liner-baseline engine materials, worn.

CHEOflE S!KS ON LUBBITE 78 LB/IN

Fig. 1 Sketch showing essential mechanics of Hohman A-9

reciprocating' liner and piston ring tester.

Fig. 4 Friction coefficient during test - baseline engine materials, lubricated.

fig. 2 Friction coefficient versus crank angle - base engine materials.

Ti Carbide ring on C? Carbide, non lubricated

Ti Carbide ring 011 Cr Carbide, Synthetic A oil l.BBj .98-; .88;; .78-; .68;: .58;; .48;; .38-; .ZBT .18*

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