Large-bore, liquid hydrogen-cooled, ultrahigh-speed, rolling contact bearings of an optimum design allow optimization of large rocket engine turbopumps in which bearing speed is a limiting factor. Optimum design for the bearings resulted from an application of liquid hydrogen used as a coolant

Butner, M. F.

Wagner, D. A.

English

NASA Technical Reports Server

Load 
Pisto, 
Piston Pre 
Pc
d Hydrogen 
Seals 
rid 
,gen 
let 
Liquid 
Hydrogen 
Inlet	 Test Bearings 
Figure 2

Bearing Tester Schematic 
A large, extra light series bearing was designed 
having a 200-mm bore chosen on the basis of require-
ments of a large liquid hydrogen pump. A design goal 
of 15,000 rpm (3.0 lOb DN) and a design life of one 
hour were established for this bearing. 
For design purposes, a steady-state load of 5000 
pounds was established for the bearing with require-
ments for a peak transient load of 15,000 pounds. The 
5000-pound load, applied by a compliant preloading 
device, represents the load required to obtain reason-
able radial stiffness for shaft critical speed control. 
Dynamic geometry and stress and life curves were 
calculated for a 200-mm bore bearing. 
Results of bearing tests under axial loads from 1000 
to 8700 pounds at speeds from 3750 to 15,000 rpm 
for 5 to 60 minutes at liquid hydrogen flows of 60 to 
June 1969	 Brief 69-10178 
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. 
Design and Testing of Liquid Hydrogen-Cooled,

Ultrahigh-Speed Ball Bearings 
.
22 30 025R 
-	 TYP) 8 Places
0015 
4813 -0 000 R 
(TYP) 8 Places 
4693 
(TYP) 8 Places 
UM	 8 Slots Equally Spaced Section A-A	 A	 As Shown 
Figure 1
Bearing Design 
Use of large-bore, liquid hydrogen-cooled, ultrahigh-
speed, rolling-contact bearings of an optimum design 
allows optimization of large rocket engine turbopumps 
in which bearing speed is a limiting factor. Extensive 
information is now available on these bearings. 
Optimum design for the bearings resulted from 
extension of knowledge based on previous work. Butner 
and Rosenberg (Note I) in 1962 reported that liquid 
hydrogen can be used as a rolling contact bearing 
coolant. Ball bearings of 45- and 60-mm bore were 
operated at high loads for rocket engine design life 
durations at speeds from 1.0 to 1.6 x 10" i DN. (DN = 
bore of bearing in mm multiplied by speed in rpm). 
Subsequent tests demonstrated some performance 
limitations for 150-mm ball bearings operating in 
liquid hydrogen at speeds in excess of 2.0 x 10 DN.
Icoittirtued oserleal I 
This document was prepared under the sponsorship of the National	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States	 will be free from privately owned rights.
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274 gpm were successful. This indicated that the opti-
mization procedure was feasible. 
Figure 1 shows the bearing design. This bearing 
has a bore of 7.8740 in., outside diameter of 11.0236 
in., and width of 1.4961 in. The ball diameter is 0.875 
in.
For optimizing the bearing for high speed operation, 
the effects of variations in internal geometry were 
determined and the best , compromise was selected 
based on results of varying ball size, race radius, and 
contact angle. This involved establishing minimum' 
operating diametral clearance and selecting the design 
displaying minimum heating with adequate fatigue 
life. 
Special bearing design features for improved cool-
ing, i.e., cooling slots in the outer race, and thin-
section cage were effective in achieving high speed 
capability. 
Vacuum-melt American Iron and Steel lrstitute 
440C steel was employed for races and balls because 
of its corrosion resistance, high hardness, and maxi-
mum fatigue life capability. Generous cross sections 
in the 440C steel bearing races were required to avoid 
cracking problems arising from extreme brittleness of 
the cooled material. 
Mandrel-wrapped, glass fabric-supported polytetra-
fluorethylene was used for the cage material because 
of its low friction coefficient, high strength, and ability 
to withstand severe service conditions without failure. 
Figure 2 shows a schematic of the bearing tester. 
Mounted on the tester shaft are two test bearings, one 
loaded axially against the other, with axial load applied
by pressurizing the piston with gaseous helium. Trans 
mission of the axial load is through bearing No. I to the 
shaft and through bearing No. 2 to the housing. Care-
ful balancing of the tester shaft in place assures ob-
servation of no sign of unbalance in the test bearings. 
Utilization of small-diameter liquid hydrogen seals 
maintains rubbing speeds at conservative values to 
avert seal problems. The test fluid enters the tester, 
flows through both test bearings, and exits near the 
load piston. 
Notes: 
1. M. F. Butner and J. C. Rosenberg: "Lubrication of 
Bearings with Rocket Propellants," Lubrication 
Engineering, ASLE Paper Vol. 18, 17-24 (1962). 
2. Documentation is available from: 
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Price $3.00 
Reference: TSP69-10178 
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: M. F. Butner and D. A. Wagner of
Rocketdyne
a Division of
North . American Rockwell Corporation 
under contract to
Marshall Space Flight Center 
(MFS-18453)
. 
. 
Brief 69-10178 
1
	
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Design and testing of liquid hydrogen-cooled, ultrahigh-speed ball bearings

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