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

With a low shaft rotation rate the bearing touches and dry
friction appears. In order to eliminate misaiignments and noncoaxiality
(which also leads to metal-to-metal contact and dry
friction), it is advantageous to use self-adjusting bearings.
The working medium is used as the lubricating liquid in the
bearings of ERE turbogenerators, i.e., the same liquid-metal heat
carriers as used in the main system. A number of difficulties arise
with the use of common oils, in-the first place, in creating gaskets
capable of preventing, over a long period of time, the break-through
of working medium vapors into the cavity of the bearings or the
flow of the lubricant into the -cavity with the working medium, as
well as lubricant leakage.
As we know, the viscosity of liquid metal is very low (absolute
viscosity of liquid-metal heat carriers is approximately 10-100 times
less than common lubricating oils). Therefore, the working
clearances in the fluid-friction bearing should be approximately
10% of the clearance in common oil bearings. In order to prevent
the metal-to-metal contact which is destructive to the bearing,
erosion, and the phenomenon of fatigue, we must strictly maintain
this clearance during the operation of the turbogenerator.
Figure 3.8 shows the construction of a hydrodynamic bearing
which handles liquid-metal lubrication. The bearing is a bushing
wJth a ring groove installed in a spherical seat. To prevent the
turning of the bushing, a pin has been installed. A bushing without
a pin (the floating type) is also possible. The clearances between
shaft and b.•aring and also between spherical ring and housing are
set by selection.
The bearing and uhe housing are made from an alloy of molybdenum
with tungsten and titanium.
Pressed to the shaft is a bushing of tungsten carbide. The
lubricant feeds through the opening in
the housing, falls into the
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