Self-acting, partial-arc, pivoted-pad bearings in which the bearing-to-journal applied load is pneumatically controlled are used in the operation of a radial flow gas generator where shaft speeds are on the order of 38,500 rpm

Six, L. D.

English

NASA Technical Reports Server

October 1967
	 Brief 67-10364 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Resilient Bearing Supports Are Gas Controlled 
The problem: 
In the operation of a radial flow gas generator 
where shaft speeds are on the order of 38,500 rpm, 
rotor dynamic stability requirements place a high 
premium on bearing performance. Conventional cy-
lindrical journal bearings cannot accommodate even 
the slightest rotor radial misalignment at such speed.
The solution: 
Self-acting, partial-arc, pivoted-pad bearings in 
which the bearing-to-journal applied load is pneumati-
cally controlled. A hydrostatic pad lift-off flotation 
system assists in starting and stopping. 
How it's done: 
Each bearing consists of three bearing pads en-
compassing 100 degrees of arc per pad. The pads are 
(continued ovciieai) 
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supported by ball and socket joints riding in control 
members equipped with flexible diaphragms. The con-
trol member diaphragms are exposed at their rear sur-
faces to a source of pneumatic pressure. A hydrostatic 
source is connected to each ball and socket joint and 
to each pad bearing surface through drilled passages. 
Air pressure through the pneumatic line to the con-
trol member diaphragms applies an effective force to 
the bearing pads. When bearing loads increase due to 
shaft growth from thermal and centrifugal effects, 
bearing loading is reduced by means of a feedback 
loop involving capacitance probes mounted in quadra-
ture, with respect to the rotor axis, on each bearing 
member. The hydrostatic lift-off system operates dur-
ing starting and stopping to unload the pads and is 
automatically released when the rotor reaches oper-
ating speed.
Note: 
This system is further described in NASA CR-706, 
"Design and Fabrication of a High-Performance Bray-
ton Cycle Radial-Flow Gas Generator," February 
1967, available from the Clearinghouse for Federal 
Scientific and Technical Information, Springfield, Vir-
ginia 22151; price: $3.00. Inquiries may also be di-
rected to:
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B67-10364 
Patent status: 
No patent action is contemplated by NASA. 
Source: L. D. Six 
of the Garrett Corporation 
under contract to 
Lewis Research Center 
(LEW-10109) 
Brief 67-10364	 Category 05


Resilient bearing supports are gas controlled

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