Advanced hybrid rolling element bearings for the Space Shuttle Main Engine high pressure alternate turbopumps

Bursey, R.; Chin, H.; Olinger, John B.; Price, J. L.; Tennant, M.; Moore, Lewis E.; Thom, Robert; Moore, James D.; Marty, Dave

doi:10.2514/6.1996-3101

Cited by 2 publications

(2 citation statements)

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“…Microcracks on the balls were probably generated due to rupture of the transfer film at the trace contacting against the outer raceway under severe contact stress (above 2.0 GPa) increased by high centrifugal load accompanied by insufficient cool-ing conditions. (5) Decreasing the outer-race stress to 2.0 GPa by a limited race curvature of 0.51 in conjunction with sufficient cooling through a narrow outerland clearance prevented the propagation of superficial thermal microcracks.…”

Section: Discussionmentioning

confidence: 99%

“…For these ultrahigh-speed turbopumps, hybrid ceramic bearings consisting of Si 3 N 4 balls and steel rings have been used. Also, for the improved high-pressure LO 2 /LH 2 turbopumps of the reusable space shuttle main engine (SSME), hybrid bearings with Si 3 N 4 balls were used instead of conventional all-steel bearings in an attempt to reduce serious bearing wear 5) .…”

Section: Introductionmentioning

confidence: 99%

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Improvement of Durability of Hybrid Ceramic Ball Bearings in Liquid Hydrogen at 3 Million DN (120,000 rpm)

et al. 2010

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The durability of a hybrid ceramic 25-mm-bore ball bearing having a single outer land-guided retainer was evaluated and improved in liquid hydrogen at speeds up to 120,000 rpm (120,000 min -1 ) (3 million DN) by comparing the propagation of superficial thermal microcracks on Si 3 N 4 balls at various speeds. To select a tough Si 3 N 4 ball capable of restraining crack propagation, bearing tests were conducted for three kinds of the Si 3 N 4 balls with different jet-cooling systems. The test results showed that the Si 3 N 4 ball having high fracture toughness as well as high thermal shock resistance could restrain the propagation of wide-ditch microcracks. With regard to the jet-cooling system, four nozzles were better than two nozzles with increasing jet speed. Furthermore, the jet flow aimed at the retainer was superior to that aimed at the inner race, and its result indicated that microcracks might be generated at the trace in contact with the outer raceway under insufficient cooling conditions with a large centrifugal force. Thus, decreasing the maximum contact stress of the outer race to 2.0 GPa by a limited race curvature of 0.51 could restrain the propagation of superficial microcracks.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%