M. Nosaka et al., TRIBO-CHARACTERISTICS OF CRYOGENIC HYBRID CERAMIC BALL-BEARINGS FOR ROCKET TURBOPUMPS - SELF-LUBRICATING PERFORMANCE, Tribology transactions, 40(1), 1997, pp. 21-30
Experiments were conducted to investigate and compare the self-lubrica
ting performance of two types of modified 25 mm-bore ball bearings: a
hybrid bearing with Si3N4 ceramic balls, and an all-steel bearing The
modified bearings had a single outer land-guided retainer with ellipti
cal pockets and a narrow axial pocket clearance to reduce wobbling of
the retainer. The bearings were tested under high thrust loads to 2840
N and at speeds up to 50,000 rpm in liquid hydrogen (LH(2)), liquid o
xygen (LO(2)), or liquid nitrogen (LN(2)). Testing showed that the bea
ring torque of the modified all-steel bearing was drastically decrease
d to about one-half that of the conventional double outer land-guided
bearing at a speed of 50,000 rpm in LH(2). Furthermore, the hybrid bea
ring had relatively stable variation of bearing torque and better load
capacity than those of the all-steel bearing in both LH(2) and LN(2).
However, in LO(2), the all-steel bearing exhibited excellent performa
nce with high load capacity at high speeds, contrasted with poor self-
lubrication by the hybrid bearing.