Separate sectors for each lobed area of the bearing are assembled into the bearing housing individually and bolted tightly against the housing inside diameter. The center of a grinding wheel and the center of the housing are offset, resulting in the desired inner radius and tilt of the sector

Schuller, F. T.

English

NASA Technical Reports Server

Bearinç 
Grindin 
Center 
(lop Lc r-1JuIl ly ¼_el ILCI 
September 1970 	 BrieF 70-10143 
NASA TECH BRIEF 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage commeriat 
application. Tech Briefs are available on a subscription basis from the Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Low Cost Lobed Bearing 
High-speed, lightly loaded rotors running in plain 
journal bearings lubricated with low viscosity fluids, 
such as water or air, are inherently unstable. Instabil-
ity here refers to self-excited fractional-frequency 
whirl, or the tendency of the shaft center to orbit the 
bearing center at an angular velocity about half that 
of the shaft around its own center. 
Figure 1. One-Piece Three Lobed Conventional Bearing 
A number of self-acting-bearings of fixed geometry 
that exhibit good stability characteristics have been 
studied. One of these is the lobed bearing. Conven-
tionally, this type of bearing is made in one cylindrical 
piece, (See Fig. 1), and is lobed at the midpoint of each 
lobe arc. 
This new technique, shown in Figure 2, utilizes 
separate sectors for each lobed area of the bearing. 
During fabrication, each sector is assembled into the 
hearing housing individually and bolted tightly against 
the housing inside diameter by two hold-down screws.
Hold-Down 
Screw	 Bearing Sector 
Bearing 
Housing 
' l	 /' "	 '.	 ,,/Hosin Grinding Too	 Center Center  
(Top Sector)	 Shaft 
Bearing Sector 
Figure 2. Lobed Bearing 
The center of a grinding wheel and the center of the 
housing are then offset from each other to result in the 
desired inner radius and tilt of the sector. When the 
first sector is finish machined, it is removed and the 
next sector is mounted in place and machined using 
the same initial setup. This is repeated for the remain-
ing sectors that make up one bearing. Additional 
sectors can be made at the same time to be used for 
replacement parts. When all desired sectors have been 
completely machined, they are installed in the housing 
to make one complete bearing. A circumferential SUN 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19700000331 2020-03-17T00:42:16+00:00Z
face trace can be made of the assembled bearing in-
side diameter to insure that each sector has the desired 
profile. 
With the multisector lobed bearing, replacement 
of excessively worn or failed parts is simple. If ex-
cessive bearing wear , or failure occurs, replacement 
requires only removing the hold-down screws that 
hold each sector to its housing, and replacing the worn 
or failed sectors with the pre-machined extra parts 
at hand. Removal of the bearing housing and reboring 
of the bearings are unnecessary. 
Rotors 1-1/2 inches in diameter by 1-1/2 inches 
long were tested in lobed bearings having three sep-
arate sectors that were tilted at the trailing edge of 
the sectors. Tests were run in water at speeds to 9000 
rpm with stability thresholds in excess of those for 
herringbone-grooved bearings in some cases.
Notes: 
1. This bearing innovation can be used to support 
rotating shafts where bearing stability is critical 
or where simple and economical replacement of 
the bearing is desired. 
2. No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
2100013rookpark Road 
Cleveland, Ohio 44135 
Reference: B70-10343 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546.
Source: F. T. Schuller

Lewis Research Center

(LEW- 11076) 
Brief 70-10343	 Category 07


Low cost lobed bearing

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