Design and Stress Analysis of Extraterrestrial ... - The Black Vault

Friction and wear in such a bearing are very low. However, the
expenditure of power on the circulation of the lubricant is rather
high (special pumps are necessary). The supply of liquid to the
bearing ;should begin before the start of rotor rotation,
The use of a liquid-metal lubricant can damage the bearing
and shaft material,
Erosion can be the result of the incompatibility
of structural materials with the liquid-metal lubricant or can be
caused by the washing of the surface of parts by the flow of highdensity
lubricating material, for example, mercury. This is connected
with the low viscosity of liquid-metal lubricant, as a consequence
of which the flow can be turbulent despite a small clearance.
Turbulent flow gives rise to the onset of' a high dynamic pressure
for the lubricant on the surface of the part and to the washing out
of material with the fluid flow.
Fig. 3.10. Diagram of a I
hydrostatic thrust bearing.
A-
To reduce the effect of turbulence, it is necessary to increase
the purity of the working parts of the bearing (by polishing). To
reduce wear, obviously, special coatings are useful.
Fluid-friction bearings, in addition to their load-lifting
capacity and the expenditure of a working liquid are characterized
by stiffness, vibrational stability, and sensitivity to the direction
of the external load. By the stiffness of' the bearing we mean the
ratio of the variation in magnitude of e'xternal load to the variation
in eccentricity. Invest-tgations have shuwn that stIffness of a
hydrostatic bearing is h-gher than that of a hydrodynamic bearing.
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