NASA Technical Memorandum 86958

e i

i

' Lubrication and Performance of High- ,

d

Speed Rolling-Element .Bearings "i

L

- {_ASA-TM-66958) 10BRZCATICN IND PRRPORMA_CE N85-21658

OR HIGB-SP_D RCLZING-RL_BEN2 _IEZNGS

-; (liPS,) 19 p BC AO2/B_ E01 CSCL 131 I ',

-_ _ Oncla= I ,

_ _ G3/37 14528

i

-' Erwin V. Zaretsky, Fredrick T. SchuUer,

_i and Harold H. Coe "

" : _ Lewis Research Center i

_.,. Cleveland, Ohio

lit Prepared for the

1985 Annual Meeting of the ,,,r,,r-_- ._,

Anzerican Society of Lubrication Engineers _"." _ ' '_-''.

Las Vegas, Nevada, May 6-9, 1985 /_. A0_7es_ L&
+' '1i

I

LUBRICATIONANDPERFORHANCEOF HIGH-SPEEDROLLING-ELEHENTBEARINGS

i

Erwln V. Zaretsky, Fredrlck T. Schuller, and Harold H. Coe

i NatlonalAeronauticsand Space Admlnlstratlon

Lewls Research Center

r

Cleveland, Ohto 44135

ABSTRACT

_I Trends tn alrcraft engtne operating speeds have dtctated the need for

rolling-element bearings capable of speeds to 3 m1111onDN. A review of highspeed rolling-element beartng state-of-the-art performance and lubrication ts

_ presented. Through the use of under-race lubrication and "Bearing Thermal

i : c_0_ Management"beartng operation can be obtatned to speeds of 3 mtllton DN Jet

_i - , m0_1 lubricated ball beartngs are 11mtted to 2.5 mt111on ONfor large bore stzes and

:: _ to 3 mt111on DNfor small bore stzes Current computer programs are able to

predtct beartng thermal performance.

t

INTRODUC1ION

r

Current production engtne beartngs generally operate at speeds less than

c,ii 2.3 mtllton DNm and at temperatures generally less than 490 K (425 °F).

Because compressoror turbtne blade ttp speeds and dtsk burst strengths begin

; to 11mtt the maxtmumspeed of rotattng components, a bearing speed of 3 mt111on i

ON Is _qulvalentto the practlcalllmlt of alrcraftenglneoperation. Conventtonal lubrication methodology generally 11mtted bearing speeds to less than

,i 2 mt111on DN.

_i A problem associated wtth operating bearings at htgh speed ls the need to

adequately cool the beartng componentsbecause of relatively high heat generai ', tton. One method used successfully to 3 mtllton DN Is to apply cooling lubrt-

; cant under the race (ref. 1). Lubricant ts centrifugally ln3ected through the

z : spllt Inner race and shoulders of an angular-contact ball beartng through a

plurality of radtal holes. As a result, both the coollng and lubricant function ts accomplished.

:_ Reclrculattng 3et lubrication ts most commonlyused on atrbreathtng turboJet engtnes today. There have been many studies conducted to determine optimum

lubricant Jet arrangements -stngle-, multiple-, and multtp!e-opposed Jets

! (ref. 2).

Research (ref. 3) wtth 30-mmbore ball beartrJgs studted the effect of cage

locatton as well as 3et lubrication to speeds up to 3 mt111on DN. Unless significant cooltng was provided, bearing failure was due to overheating at htgh

speeds. Beartng 11mtttng speed was dependent on bearing destgn, Jet arrange-

. ment, and otl flow rate and veloctty (ref. 3).

Tapered-roller beartngs are being used tn somehelicopter transmissions

to carry combtnedradtal, thrust, and momentloads and, tn particular, those

ION ts a speed parameter defined as the beartng bore tn millimeters

multiplied by tts speed tn rpm.
loads from bevel gears such as high-speed input pinions (ref. 4). Taperedroller bearings have greater load capacity for a given envelope or for a given

bearing weight than the combinations of ball and cylindrical roller bearings

commonlyused in this application. Speed limitations have restricted the use

of tapered-roller bearings to lower speed applications relative to ball and

cylindrical roller bearings. The speed of tapered-roller bearings is ltmtted

to approximately 0.5 million DN (a cone-rib tangential velocity of approximately 36 m/s (7000 ft/mtn) unless special attention is given to lubricating

and designing the cone-rib/roller-large-end contact. At higher speeds centrt..

fugal e;fects starve this critical contact of lubricant (refs. 4 and 5).

In 1959 NASAbegan a research program to encompassthe pro3ected speed

requirements for large-bore ball and roller bearings. In the 1970's NASA

expanded its program to encompasstapered-ro_ler, and small-bore ball and roller bearings. The reported work is a review of high-speed rolling-element

bearing state-of-the-art performance and lubrication with emphasis on NASA

contributions.

LUBRICANTSELECTION

The criteria for a ltqutd lubricant to function in a rolling-element ;_

bearing are that (a) it be thermally and oxtdattvely stable at the maximum _

bearing operating temperature, and (b) it form an elastohydrodynamlc (EHD) film ,_

between the rolltng surfaces. The EHDfilm, which is generally dependent on

lubricant base stock and viscosity, is 0.1 to 2.5 wm(5 to 100 win) thtck at

htgh temperatures (ref. 6). Whena sufficiently thick EHDfilm is present,

: rolllng-elementbearingswill not usuallyfall from surfacedistress. Instead,

they fall from rolllng-elementfatiguewhich usuallymanifestsitself,in the l

early stages, as a shallow spall with a diameter about the sameas the contact

width.

A requirement for long-term high temperature bearing operation is that the i

EHDfilm thickness, h, divided by the composite surface roughness, ': :

(07 + a_) 1/2, equal 1-1/2 or greater, where o1 and 02 are the surface fin- j _

tshes of the raceway and rolltng elements, respectively (ref. 6). The EHDfilm i

thickness ts a function of several lubricant and bearing operating variables

(ref. 7). However, as a general rule, the minimumviscosity required of a

lubricant is 1 cSt at operating temperature (ref. 8). Thts same research

indicated that the ester based lubricants (table 1) meeting the MIL-L-23699

specification could provide the necessary lubrication requirements to 490 K

(425 "F) in an air environment. While other base stock lubricants could gtve

satisfactory operation to 590 K (600 °F) (ref. 8), they were precluded from

further consideration because of their cost and/or commercial availability.

Further, at temperatures above approximately 500 K (450 °F) a low oxygen

environment would be required _o minimize lubricant oxidation for most of the

lubricant types studied (refs. 8 and 9).

LUBRICATIONMETHODS

Jet Lubrication

For aircraftenginesand transmissions,where speedsare too hlgh for

greaseor simple splashlubrlcatlon,_et lubricationis used to both lubricate

2

:
I

and control beartng and gear temperatures by removing generated heat. In _et i

lubrication the placement and numberof nozzles, _et velocity, lubricant flow

rates, and removal of lubricant from the beartng and Immediate vtclntty are

all very important for satisfactory operation.

The placement of _ets should take advantage of any natural pumpingability

of the bearings. This Is Illustrated In figure 1 for a ball bearing with

relieved races and tor a tapered-roller bearing. Centrifugal farces aid In

moving the oll through the bearing to cool and lubricate the elements

(ref. 10).

Directing _ets In the radtal gaps between the races and the cage Is beneficial. The design of the cage and the lubrlcatlon of tts surfaces sliding on t_

the shoulders of the races greatly affects the high-speed performance. The t;

cage has been typically the first element to fall In a hlgh-speed bearing wlth

improper lubrication, i

It has been shown(ref. 3) that wlth proper bearing cage design, nozzle

placement, _et velocities, and adequate scavenging of the lubricant, Jet lubrication can be successfully used for small-bore ball bearings at speeds to ii

3 mtllton ON. For large (120 mmbore) ball bearings (ref. 11), speeds to

2.5 million ONare attainable. For large (120.65 mmbore) tapered-roller

bearings, 3et lubrlcatlon was successfully demonstrated to 1.8 mtllton ON

(ref. 5), although a high lubricant flow rate of 0.0151 m3/mtn (4 gpm) and a _

relatively low oil-Inlet temperature of 350 K (170 "F) were required.

Under-Race Lubrication 1

A more effective and efficient meansof lubricating rolling-element beartngs ts under-race lubrication. Conventional 3et lubrication fatls to adequately cool and lubricate the Inner-race contact as the lubricant ts thrown

centrifugally outward. Unfortunately, increased flow rates add to heat generated from oll churning. An under-race lubrication system used tn turbofan

engines for ball and cyllndrlcal roller bearings Is showntn figure 2. Lubricant Is directed under the inner race and centrifugally forced out through a ,j

plurality of holes In the race to cool and lubricate the bearing. Somelubrl- i

cant may pass completely through under the bearing for cooling only as shown

In figure 2(a). Although not shown tn the figure, someradial holes may be

used to supply lubricant to the cage side lands.

Thts lubricating technique has been thoroughly tested for large-bore ball

and roller bearings up to 3 mtllton ON(refs. 1 and 12 to 14).

Under-race lubrication has been applted to tapered-roller bearings to

lubricate and cool the crttlcal cone-rib/roller-end contact. As described tn

reference 15, 88.9-mm (3.5-tn) bore tapered-roller bearings were run under

combined radial and thrust loads to 1.42 mtllton ONwith cone-rib lubrication

• (the term used to denote under-race lubrication In tapered-roller bearings).
JI RESULTSANDDISCUSSION

; _ Angular-Contact Ball Bearings

large bore. - A parametric study was performed wtth AISI R-5O 120-mmbore

" angular-contact ball bearings havtng a nominal contact angle of 20°. The

' _"_ bearings either had an inner- or an outer-race land riding cage. Lubrication

i _: was by rectrculattng oll 3ets. The otl 3ets either had a single or dual orl-

_*!_......./L;#_.......:,,:_ were ftce. comp Thrust aredwload, ith those speed,obtained and lubricfromantbeafloriwngsrateof wtheeresame variedesign d. Test whichresults were

*! under-race lubricated but run under the sameconditions. 3et lubricated ball

bearings were ltmlted to speeds less than 2.5 mlllton ON. Bearings having

i Inner-race land riding cages produced lower temperatures than bearings wtth _

_,I outer-race land rtdtng cages. For a given lubricant flow rate dual ortftce

3ets produced lower bearing temperatures than single orifice 3ets.

t

i Research reported In references 14, 16 and 17 showedthat bearings could

be operated reliably for very long time periods at speeds to 3 mlllton ONwith

lubrlcatlon of the bearing through annular passages extending radially through

'-_!_i the bearing split inner race referred to as "under race lubrlcatlon" _

i...... (fig. 2(b)). The concept of "Bearing Thermal Nanagement"was proposed _

_,_-. (refs. 14 and 16) as the proper technological approach to high-speed bearing

operation. The basis of this Is the recognition that total and flexible

*_= thermal control over a11 the bearing componentsts essential to ach!eve a reliable high-speed, highly-loaded bearing. Results reported tn the previous sectton show that bearings operating with _et lubrication under certain conditions

are llmtted to speeds generally less than 2.5 mt111on ON.

1

,° Oata for both under-race lubricated and Jet lubricated bearings are presented tn figure 3. The under-race lubricated bearings were provided wtth

outer-race cooling. However, outer-race cooling generally had an Insignificant

" effect on the Inner-race temperature (ref. 14).

The results shownIn figure 3(a) indicated that at a11 operating conditions the under-race lubricated bearings had lower temperatures than the dualorifice 3et lubricated bearings. At 12 000 rpm (1.44 million DN) the

temperature difference was approximately 22 K (40 °F) and at 16 7DOrpm

, (2 mlllton DN), approximately 44 K (80 °F). Beyond2 million ONthe bearing

temperature wtth under-race lubrication increases only nominally, whtle the

....... temperature of the 3et lubricated bearings increases at an accelerated rate.

Hence, proper thermal managementusing 3et lubrication was not achievable tn

these tests at the higher speeds. Fromthe above It was concluded that underrace lubrication results tn lo_eer operating temperatures.

The data of figure 3(b) comparepower loss for the two different 1ubrlcatlon systems. As was reported tn references 14 and 16 power loss Is a function

of the amount of ]ubrlcant penetrating the bearing cavity. Thls ts due to

viscous drag and lubricant churning (ref. 18). Fromfigure 3(b) the power loss

wlth under-race lubricated beartngs ts higher than w_th the Jet lubricated

bearings. At 12 000 rpm (1.44 million ON) the under-race lubricated bearing

power loss was ~1 kW(1.2 hp) greater than the Jet ]ubrtcated bearings. At

° 16 700 rpm (2 mtlllon ON), the difference was -2.3 kN (3.1 hp). The power loss

with the under-race lubricated bearing with a flow rate of 4920 cm3/mln

(1.3 gal/mln) was equivalent to a 3et lubricated flow rate of -6812 cm3/mln

(I.8 gallmln). If bearingpower loss Is a functionof lubricantflowing

4 _.

'/1 ' i
through or In the bearing cavity, then It can be reasonably concluded that, i

for a given Jet lubrlLant flow, -70 percent of the lubricant penetrates the

bearing cavity at speeds to at least 2 million ON, At higher speeds thts

percentage probably decreases due to centrifugal force and windage effects.

Small bore. - Applying under-race lubrication to small-bore ball bearings

Is more difficult than with the larger bore sizes. Thts ts because of limited '

space available for grooves and radtal holes, the meansof getting the lubricant under the race. For a given ONvalue, centrifugal effects are more severe

with small bearings since centrifugal force varies with the square of the

speed. Heat generated per unit of surface area Is muchhigher and heat removal

Is more dlfflcult.

Parametric tests were performed on AISI R-50 35 mmbore angular-contact ,I

ball bearings (refs. 19 to 24). Figure 4 showsthe bearing configurations

tested and the meansof lubrication. The bearings had a nomlnal, unmounted

contact angle of 24° and either a single- or a double-outer-land-gulded cage.

The investigation included lubrication by oll 3ets or through passages tn the

bearing inner race. Nhen inner race lubrication was used, the otl was channeled through axial grooves and radial holes tn the bearing inner race. In i_

sometests, 50 percent of the oll supplied to the Inner race was introduced

" k

Into the bearing for lubrication and 50 percent cooled the inner race exterior

surfaces. In other tests the distribution was 25 percent lubrication and 75

percent cooling. In selected tests the bearing outer diameter was cooled wtth

a constant oll flow of 1700 cm3/mtn (0.45 gal/mln).

Test conditions included nominal shaft speed,; from 48 000 to 72 000 rpm,

a radial load of 222 N (50 lb) and/or a thrust load of 667 N (150 lb). Lubri- i cant flow to the bearing ranged from 300 to 1900 cm3/mtn (0.08 to ,

0.50 gal/mln) at an inlet temperature of 394 K (250 °F). All bearings were ]

successfully run at speeds to 2.5 million DN. Generally, Increasing the _

t lubricant flow decreased beartng race temperatures but Increased bearing power

loss.

Figure 5 shows significantly cooler Inner-race temperatures wtth under- _

race lubrication at speeds to 72 500 rpm (2.5 mtlllon ON) than wtth 3et lubrt- I :

cation. Lowest power loss was generally obtained wtth Inner-race lubricated

bearings having an Inner-race guided cage. The highest power loss of 327 kN

(4.39 hp) occurred at 72 500 rpm for a Jet lubricated bearing wlth outer-race

cooltng.

The effect of outer-race cooltng wlth the 35-mmbore ball bearings ts

shown In figure6. Outer-racecoollngfor both oll-flowdistributionand for

the Jet lubrlcatedbearlngsresultedIn a substantlaldecrease!n outer-race

temperaturebut had a mlnlmal effecton Inner-racetemperature. The same

effectswere obtainedwlth the large bore angular-contactbearings.

Cylindrical Roller Bearings

Early NACA(now NASA)research (refs. 25 and 26) was conducted on Jet

lubricated 75-mmcyllndrlcal roller bearings. The maximumDN value reached was

1.65 million at which speed the Inner-race riding cage falled. The general

trends tn temperature wlth otl flow reported herelnabove for the ball bearings

w_re reported for these 75-mmroller bearings. For all values of otl flow and

5
L

4 all oll-_et diameters investigated, the outer, race maxlmuhltemperature

increased linearly with an increase tn 9N value; however, the Inner-race temperature increased with DNvalue at a rate sllghtly greater than ltnear.

For the oll-_et positions investigated, the inner- and outer-race bearing

temperatures were found to be at a minimumwhen the otl was directed at the

cage-locating surface perpendicular to the bearing face.

Parametric tests were conducted In a high-speed bearing tester on an AIS[

R-50 118-mmbore roller bearing wlth a round outer rtng (refs. 27 and 28).

Test parameters were radial loads of 2200, 4400, 6700, and 8900 N (500, lO00, _i

1500, and 2000 lb) and nominal speeds of 10 000, 15 000, 20 000, and 25 500 ,i

rpm. The oil-Inlet temperature (for both the lubricating and the cooltng o11)

was 366 K (200 eF). 0tl was supplted through the inner ring for lubrication i

and Inner-ring cooltng at flow rates from 1.9x10 -3 to 10.2x10 -3 m3/mtn (0.5 to /

2.7 gal/mtn). Outer-ring cooltng flow rates were 0 to 4.3x10 -3 m3/mtn (0 to

1.13 gal/mtn).

The ll8-mm bore roller bearing ran successfully to 3.0xlO 6 DNwtth radial u

loads of 2200 to 8900 N (500 to 2000 lb) and no outer-ring cooling. At a maxtmumtotal flow rate to the inner rtng of 9.5x10 -3 m3/mtn (2.5 gal/mtn) and

no outer-ring cooltng, the maximumbearing temperature was 466 K (380 *F). !

1

i No cage sltp occurred at 3.0x106 DNprimarily because of the tight

clearance or even sltght interference within the bearing at thts htgh speed.

Bearing temperatures varied Inversely with cage slip for all conditions. There

was no effect of luad on either bearing temperature or cage slip as load was _

varied from 2200 to 8900 N (500 to 2000 lb) over a speed range of 10 000 to

25 500 rpm.

! !

Cooltng the outer ring decreased tts temperature but increased the innerrtng temperature. Ntth no outer-ring cooling, bearing temperatures decreased

wtth increasing total oll flow rate to the inner ring. Outer-ring temperatures

were always higher than Inner-ring temperatures over the shaft speed range of

10 000 to 25 500 rpm. Heat re3ected to the lubricant (power loss within the

bearing) increased with both shaft speed and total otl low rate to the inner

ring.

TaperedRoller 8earlng

Tapered-rollerbearingshave been restrictedto lower speed appllcatlons

than have ball and cyllndrlcalrollerbearings. The speed limitationIs prlmarllydue to the cone-rlb/roller-endcontactwhich requlresvery careful

lubrlcatlonand coollngconslderatlonat hlgherspeeds. The speed of taperedroller bearings ts 11mtted to _0.5 mtlllon ON(a cone-rtb tangential veloctty

of -36 m/s (7000 ft/mtn)) unless special attention ls given to lubricating and

designing this cone-rib roller-end contact. At higher speeds centrt6ugal

effects starve this crlttcal contact of lubricant.

The technique of under-race lubrication has been applied to tapered-roller

bearings to lubricate and cool the critical cone-ribroller-end contact. As

described tn (ref. 15), 88.g-mm (3.5 ln) bore tapered-roller bearings were run

6
'; under co

mbined radial andthrust loadsto 1.42million DNwith cone-rib lubrication (the term used to denote under-race lubrication in tapered-roller

bearings)• A co

mparison of cone-rib lubricationand Jet lubricationwas reported tn

reference5 for 120.65-mm (4.75tn) bore tapered-roller bearings under combined

radial and thrust loads• These bearings were standard catalog bearlng design

exceptforthe large endof the roller, which hada different spherical end

radius to provide more favorable contact with the cone rib (ref. 29). Those

bearings that used cone-rib lubrication also had holes drtlled throughfroma

:__antfold inthe cone bore tothe undercut at the large end ofthe cone

ii (fig. 7).The resultsof reference5show very significant advantagesof cone-

rlblubrication (fig. 8).At 15000rpm (1.8 mtlltonON)thebearingwlth

cone-rib lubricationhadaconefacetemperature 34K (62 °F) lower than one

_.' with Jet lubrication. Furthermore,reference5 showsthatthetaperedroller

bearingwould operate at15 000rpm withcone-rib lubrication at lessthan half,

the flowraterequiredfor Jet lubrication atthat speed

¥

Furtherwork has shownsuccessful operationwith large-bore tapered-roller

; bearingsat evenhigher speeds. Long-termoperationof107.94mm(4.24 in) ! bore tapered-roller bearings under pure thrust load to 3 million DNwtth a co

m-

:!btnatlonof cone-rtb lubricationandJet lubricationwas reportedtk, (ref. 30). i i

_i Successful operation of optimized design120.65mm(4.75 tn) boretapered-

, roller bearings under combined radtal and thrust loadwith under-racelubrlca- i i tlon to both large (cone-rib) and small ends to speeds up to 2.4 mtlllon ONwas

:._ reported tnreferences 31to 33

• ! i :li C

OMPUTERANALYSISi

]

"I

_Therearecurrently severalcomprehensivecomputerprograms that are,

i capableof predictingrolllng-elementbearingoperatingand performancechar- i actertsttcs. These programs generally accept input data of bearing internal

geometry(suchas sizes, clearance,and contactangles),bearing material and

lubricant properties,andbearing operating conditions(load,speed, and;

ambienttemperature). Theprograms then solve several setsofequations that

_,characterizerolling-element bearings. The outputproduced typically consists

of rolling-element loads andHertz stresses, operating contact angles, compo-

'.i: nen

t speeds, heat generation, localtemperatures, bearingfatigue ltfe, and

power lossThe critical assumptionscurrently necessarytn theuse of these

programsare theformof the lubricant tractionmodel and the lubricant volume

percent (the assumedvolume percentof the bearingcavity occupied by the lubricant). These programswere used to predict the performance of the 120-mm

angular-contactba]l bearings (ref. 34)and the ll8-mmcylindrical roller

bearing(refs. 27and 28)discussedtn the prevlou_ sections• Representative

data are shownfor the ball bearing infigure9 andfortheroller bearing in

figure 10 asa function of lubricantflowrate. The correlation between the

prediction and experiment Isreasonably good for these bearings.

Another correlationof predicted and experimental dataforcylindrical

roller bearings is shown in reference 35. Experimentswere performed with

124.3mmbore bearings at speeds up to3 million DN, andthe resultswere com-

pared withanalysis using the computer program described in reference12.

Predictions of both heatrejection totheoil and outerrace temperaturewere

within I0percentofthe experimentalvalues.

7
use ofAsthese was mcomputer entioned aprog bove, ramsonels ofthethelubcri ricticantal volu assump me petions rcentnecessary on the bearin In theg

cavity. Bearing heat generation and temperature are dependent on thls factor.

The lubricant percent volume varies wtth bearing type, size, design, lubrication method, lubricant flow rate, and shaft speed. An equation was derived for

the lubricant percent volume In the bearing cavity as a function of lubricant

flow rate through the cavity, shaft speed, and bearing pitch diameter

(ref. 36). The predicted bearing heat generation, inner- and outer-race temperatures, and otl-out temperatures agreed very well with the experimental data

obtained from three sizes of ball bearings (35-, 120-, and 167-mmbore) over a

speed range from 1.0 to 3.0 million ON.

The equation derived appears to be valid over the range of shaft speeds

and lubricant flow rates for the three bearing sizes investigated. The predicted trends of increasing temperature and heat generation with increased

shaft speed and of decreasing temperature and increasing heat generation with

increased lubricant flow rate were verified by the experimental data.

SUMMARY II

Conventionallubricationmethodologygenerallyllmltedrolllng-eiement

bearing speedsto less than 2 million DN. Jet and under-racelubricationwere

applledto ball, roller,and tapered-rollerbearingsIn order to definebearing

performance and speed limitations. Bearing bore sizes ranged from 35 to _1

120 mm. Lubricant flow rate and distribution together wlth bearing load and t

speed were varied wtth temperature _nd power loss determined. Experimental

results were comparedto computer predictions. Operating speed limitations !

were defined, t

The following results were obtained: ; i

i

1. Through the use of under-race lubrication and "Bearing Thermal Managemerit." reliable highly-loaded bearing operation can be obtained to speeds of

3 million ON. i,

2. 3et lubricated ball b_arlngs are limited to 2.5 million P4 for large

bore sizes and to 3 million ONfor small bore sizes.

3. Current computer programs are able to predict bearing thermal perform- ,J

ance. An equation was derived for the lubricant percent volume In the bearing T

cavity as a function of lubricant flow rate through the cavity, shaft speed,

and bearing pitch diameter.

(

REFERENCES )

I. Holmes, P.N., *Evaluation of Ortlled Ball Bearings at ONValues to Three

Million. l; Variable 0tl Flow Tests." NASACR-2004: "2; Experimental

Skid Study and Endurance Tests." NASACR-2005, 1972.

2. Macks, E.F. and Nemeth, Z.N., "Lubrication and Cooltng Studtes of

Cylindrical-Roller Beartnqs at Hlgh Speeds," NACATR-1064, ]952.
,J'

3. Mlyakawa, Y. Sekl, K, and Yokoyama,M., "Study on the Performance of Ball

Bearings at Hi ' gh DNValue, " Natlonal Aerospace Lab., Tokyo (Japan), NAL-TR284, 1972. (NASATT-F-15017, 1973).

4. Orago, R., "Heavy-lift Helicopter Bring Up Drive Ideas," PowerTransmission

Des__._J.1.66, gp_ln, pp. 49-62 (1974).

5. Parker, R.J. and Signer, H.R., "Lubrication of High-Speed, Large Bore

Tapered-Roller Bearings," J. Lubr. Technol,, 100, pp. 31-38 (1978).

6. Talltan, T.E., Chlu, Y.P., Huttenlocher, D.F., Kamenshtne,J.A., Stbley,

L.B., and Slndllnger, N.E., "Lubricant Films in Rolling Contact of Rough

Surfaces," ASLETrans., _, pp. 109-126 (1964). _

I

7. Zaretsky, E.V., and Anderson, N.J., "EHD Lubrication," Mach. Des., 40 (26)

pp. 167-183 (1968).

8. Zaretsky, E.V., and Anderson, W.J., "Preliminary Determinations of Temperature Limitations of Ester, and Hydrocarbon Base Lubricants tn 25 mmBore

Ball Bearings," NASATN-D-4146, 1967. i

9. Bamberger, E.N., Zaretsky, E.V., and Anderson, W.J., "Effect of Three

AdvancedLubricants on Htgh Temperature Bearing Life," J. Lubr. Technol.

92, pp. 23-33, (1970).

10. Parker, R.J., "Lubrication of Rolling-Element Bearings," Bearing Oeslqn -

Historlcal Aspects, Present Technology and Future Problems, ed. by

W.J. Anderson, ASME, NewYork, 1980, pp. 87-110.

11. Zaretsky, E.V., Stgner, H., and Bamberger, E.N., "Operating Limitations of i

High-Speed Jet-Lubricated Ball Bearings," O. Lubr. Technol. 9_88,

pp. 32-39, (1976). !

i

12. Brown, P.F., Dobek, L.O., Hslng, F.C., and Miner, J.R., "Malnshaft Hlgh

Speed Cylindrical Roller Bearings for Gas Turbine Engines," Pratt-Whitney

Aircraft Group, PWA-FR-8615,Apr. 1977. (AD-A052351). ,'

13. _chuller, F.T., "Operatlng Characteristics of a Large-Bore Roller Bearing

to Speeds of 3xlO6 ON," NASATP-1413, 1979.

14. Zaretsky, E.V., Bamberger, E.N., and Stgner, H., "Operating Characteristics

of 120 mmBore Ball Bearings at 3xlO° DN," NASATN-D-7837, 1974.

15. Lemanskt, A.J., Lenskt, Or., O.W., and Drag,, R.J., "Design, Fabrication,

Test, and Evaluation of Spiral Bevel Support Bearings (Tapered Roller),"

U.S. Army Aviation Materials Research and Development Lab., USAAMDL-TR73-16, June 1973. (AD-769064).

16. Stgner, H., Bamberger, E.N., and Zaretsky, E.V., "Parametertc Study of the

Lubrication of Thrust Loaded 120 mmBore Ball Bearings to 3 Million DN,"

J. Lubr. Technol., 95, pp. 515-525 (1974).

17. Bamberger, E.N., Zaretsky, E.V., and Signer, H., "Effect of Speed and Load

on Ultra-High Speed Ball Bearings," NASATN-D-7870, 1975.
18. Townsend, D.P., Allen, C.N., and Zaretsky, E.V., "Study of Ball Bearing

Torque Under Elastohydrodynamtc Lubrication," J. Lubr. Technol., 9._6,

pp. 561-571 (1974).

19. Schuller, F.T., Pine1, S.I., and Signer, H.R., "Operating Characteristics

of a H_gh-Speed, 3et-Lubrlcated 35 mmBore Ball Beartng with a StngleOuter-Land-Guided Cage," NASATP-1657, 1980.

i

20. Schuller, F.T., Ptnel, S.]., and Signer, H.R., "Effect of Cage Destgn on

Characteristics of High-Speed-Jet-Lubricated 35 mmBore Ball Bearings,"

NASATP-1732, 1980. !i

21. Schuller, F.T., and Signer, H.R., "Performance of 3et- and Znner-Rtng- ,i

Lubricated 35 mmBore Ball Be_rtngs Operating to 2.5 H1111on DN," NASA

TP-1808, 1981.

22. Schuller, F.T., "Lubrication of 35 mmBore Ball Bearings of Several Designs

i to 2.5 Htllton DN," AdvancedPower Transmission Technoloqy, ed. by it

G.K. Fischer, NASACP-2210, 1983, pp. 221-237.

23. Schuller, F.T., Ptnel, S.1., and Stgner, H.R., "Operating Characteristics :

of Four Different Design 35 mmBore Ball Beartngs at Speeds to 2.5 Hlllton

_: DN," (Proposed NASATP).

24. Schuller, F.T., Ptnel, S.I., and Signer, H.R., "Effect of Two Inner-Ring 1

0tl Flow Distribution Schemeson the Operating Characteristics of a t

" NASATP-2404, 1985. . t 35 mm-BoreBall Bearing to 2.5 Million DN, _

"Investigation of 75-Hllltmeter-Bore _ i

ao

25. HCyllndrlcal acks, E.F., Roller and Nemeth, BearingsZ Nat, Hlgh Speeds, I - Inltlal Studles, " NACA ;

:- TN-2128, 1950.

26. Hacks, E.F., and Nemeth, Z.N., "Investigation of 75 mmBore Cylindrical

Roller-Bearings at High Speeds, II - Lubrication Studies - Effect of OilInlet Location, Angle, and Veloctty for Stngle..Jet Lubrication," NACA

TN-2216, 1950. ':

27. Coe, H.H., and Schuller, F.T., "Comparison of Predicted and Experimental

Performance of Large-Bore Roller Beartng Operating to 3.0 Htllton DN,"

NASATP-1599, 1980.

28. Coe, H.H., Schuller, F.T., "Calculated and Experimental Data for a 118 mm

Bore Roller Bearing to 3 H1111on DN," 3. Lubr. Techno1., 103, pp. 274-283

(1981).

29. wren, F.J., and Hoyer, C.A., "Understanding Friction and EHLFllms in Concentrated Contacts of a Tapered Roller Bearing," E1astohydrodynamlc

Lubrication: 1972 SymDoslum,Institute of Hechanlcal Englneers, London,

1972, pp. 55-60.

30. Orvos, P.S., and Oressler, G.J., "Tapered Roller Bearlng Development for

, Atrcraft Turbine Engines, Atr Force Aeropropulston Lab., AFAPL-TR-79-2007,

Mar. 1979 (AD-A069440).

10

z;
31. Parker, R.3., Pine1, S.[., and Stgner, H.R., "Lubrication of OptimizedDeslgn Tapered Roller Be_rlngs to 2.4 Nllllon DN,," NASATP-1714, 1980.

32. Parker, R.3., Pine1, S.[., and S_ger, H.R., "Performance of ComputerOptimized Tapered Roller Bearings to 2.4 H1111onON," 3. Lubr. Technol.,

103, pp. 13-20 (1981).

33. Parker, R.3., Signer, H.R., and Ptnel, S.I., "Endurance Tests N_th LargeBore Tapered-Roller Beartngs to 2.2 H1111on ON," 3, Lubr. 7echnol., 10__.2,

pp. 293-299 (1982).

34. Coe, H.H., and Zaretsky, E.V., "Predicted and Experimental Performance of

Jet-Lubricated 120 mmBore Ball Beartngs Operating to 2.5 Mtlllon DN,"

NASATP-1196, 1978.

35. Brown, P.F., Dobek, L.3., and Tobtasz, E.3., "High-Speed Cylindrical Roller Beartng Development," Pratt & Nhttney Aircraft Group, PNA-FR-12598,

Aug. 1980. (AFNAL-TR-80-2072, AD-A095357).

36. Parker, R.3., "Comparison of Predicted and Experimental Thermal Performance of Angular-Contact Ball Bearings," NASATP-2275, 1984.

TABLEI. - PROPERTIESOF TETRAESTERLUBRICANT

' Additives Antlwear, oxidation' _i,

_-- Inhibitor, antlfoam ,

Kinematic viscosity, cS, at:

311 K (100 "F) 28.5

372 K (210 OF) 5.22

477 K (400 OF) 1.31

Flash point, K (°F) 533 (500)

Autolgnttlon temperature, K (°F) 694 (800)

Pour point, K (°F) 214 (-75)

Volat111ty (6.5 h at 477 K

(400 "F)), wt_ 3.2

Spectflc heat at 477 K (400 "F),

31(kg)(K)(Btul(lb)('F)) 2340 (0.54)

Thermal conductivity at 477 K

(400 OF), J/(m)(s)(K)

(Btu/(h) (ft)(°F)) 0.13 (0.075)

Spectftc gravtty at 477 K (400 °F) 0.850

11
i

1

OUTERRING_.

INNERRING---"

OUTERRING--..

.J

" INNERRING-'"

": ]

CUP_

_ --2 ii

7

i CO_IE--"" ._,

_ Figure1. - '_lic_mentofJetsforIxlllWrings

withrell_l ringsandta_riKl..rollerbearing_

/7 _o,<o,sc.oE , i

,-OIL_, I_", _,

\JET J.XYC/,rOIL _ I ! \ ]..,_ i

* \_'_UNRADCEERI ,i

COOLINGGROOVES '

W)Cyllndrl=lrollerIxmrlng,

• ro,c=op

COOLINGHOLES

(b)BallthrustIxmring,

Figure2. - Under-ricelubricationsystemfor mainshaftImrlngs

onturbofanengine,
LUBRICANT

.J:LOWRATE,

m_Jmin tgpm)

0&3x10"3 (2,2)

&? (LS)

•_d3.4 (L O)

440r-_ poo!- UMITINGTEMPERATURE

_ _EARI THNRGLUSOA__I T -'.7---

240N />,',.'"

• _"""460 --(50GO)-_,

"'i t 420_-_ 22240(5000)

r;

_1Temperature,

16 --_.aUNDERRACE(NONJET)LUBRI_CA- ! 20 --_ TI_}NFL: OWRATE,4,9X10" -I ._ m Imln 11.39Pm) _.,.._"

-_: i =8- ._8- _"__ ..... ! 4_=1 l I. 1 1 _1

4- 10 12 14 15 18 20 ..,.0_

BEARINIGNNER-RACSEPEEDrp,m

(b)Powerloss, !

Figure3,- BearingInner-racetemperatureandpowerloss

withjetlubricationasa functionofspeedforvaryingthrust

leedsandlubricantflowrates,Bearingtype,120-ram-bore

angular'_ontact ballbearing,lubricantjet, dualorifice,

numberofJets.2perbearing;oll Inlettemperature,_9_K

(250"F); contactangle.20".
,I

//-OUTERRING

(elDouble'_Jter-land-gulded cage.

Jetlubricated.

_.,_.,,/.OUTER RING

THRUST_...-'CAGE

OILjET./" _,,_-,,THRUST

L 1.._"-INNER RING

(b)Single-outer-lend-guided cage:jet

lubricated, , ,,-OUTERRING

THRUST,--._,-CAGE

RADIAL - _',"THRUST

LUBRICANT ,"" I _\{'-INNER RING

SUPPLYHOLE-' I,.AXIALOILGROOVE

(c)Slngle',outer-lancl-gulded cage'Inner-ring

lubricated,

Figure4, -Angular-contactballraring,

_.

l [3 INNERRACE

O OUTERACE

UNDER-RACELUBRICATION

370 _O *

.... JETLUBRICATION

I cf .." _,.f

270 -- 45000 5_000 6Ji000 7_000

SHAFTSPEED,rpm i

Fk3ur5eo- Effectofunder-racalubricationwltll_-mm-

, boreIngullr-con_ct1311b1arlngs. (Tolaoll l flowrate,

13ZllcmJImln(0._169pro)*oil , -Intmperature,_95K

(_0 °F),)

C
f

i 420 -- 490[--- _ NOOUTERACE

'_" 480_- COOLING i i 400 "t (_ ------ OUTERACE{;OOLING

6O0 10o0 1400 1800

_ TOTALOILFLOWR_,TETOTEST

BEARINGcm. 'lmln

I I I I I f

0 .l .2 .) .4 ._

TOTAOIL L FLOWRATETOTEST

BEARINGgal . lmin

_ Figure6.- Effectofouter-racecoolingonouter-race

, teml_atureof_"mm-boreballl_rlngs at72300rpn_

: Oil-intemperature. 3_ K(2_0OF).

: ! OILOUT CUPCOOLING

- OIJT IN rLUBRICANT

.... *'-CUP

.

: CONE_,_L__."_"_] I THERMOCOUPLE

{_T_. _LOCATIO_S

-l._JL' .

• oo_

d *

Fkjure1,- Tapered-roller Imrlngwith¢ont-rlbindlit lubrication.
70 _ 40

:Z_ 50

t

_ _ TOTA_ F_OW,

_i°'_ 20IiLi l:I°m3'°°1mln (9p'"m°)'

D ,0114 (3.0)

, 10 Zl . 0076 (2.0)

o o I I f I i

0 5000 10000 15000 20000

SHAFTSPEED,rpm

Figure8. - Effectofshaftspeedoncone-facetemperature

withJetlubricationminusthatwithcone-riblubrication

for120.6P-mm-bortaepered-rollerbearing.Oil-intemperature,_0 K(170°Fh thrustIoed.53400N (120(]0Ib):

radial:Dad,26700N (6000Ib).

O EXPERIMENTAL

• EXPERIMENTAL (CALCULATED

FROMHEATRANSFERTOOIL)

PREDICTED, SPLIT'LINEFLOWONLY

...... PREDICTEID. NCLUDINGHALFOF

LANDFLOW

J

_o ,. o'-..., o _0t-_

420 t I- _ _ _ 4ZO i I t I I

ia)Inner-racetemperature. (b)Outer-racetemperature. '

_o "'. _'= 1_1=z- _1 o .......:

o_o_ l0

3 4, ._ 6, 7x10 ,.... _ Pb___" 3 4 P 6 ?xlO3

TOTALUBRIC.ANT FLOWRATE, TOTALUBRI(;ANTFLOWRATE,

cm_/_/mln cm_/mln l I I ] L I I I

.5 1.0 1._ 2.0 .P 1.0 L_ 2.0

TOTALLUBRICANTFLOWRATE,gpm TOTALUBRICANFLTOWRATEgpm .

(c)OIl-_Jttemperature, td)TotalImrlrKjhint generation.

Figure9. - Predictedandexperimentather l malperformanceof120-ram-borebellI_rln9 asfunctionoftotal

lubricantflowrate. ThrustIDeal,22240N (POLIb): O oil-In temperature394 , K (;50UFI;shaftspeed.25000rl_.

_ _,.. _ -
SO0-- D TESTCALCULATED

m---- INNERRACE

_: 12 OUTERACE

"b",,o

44o . ,1 1 I I

(a)Racetemperatures.

z8

_, LI TEST CALCULATED

14 _ A A J

_ lo " I I I I

4 6 8 10 lZXlO"3

TOTAOIL L FLOWRATE,m31mln

(13H) eatransferredtolubricatingoil. |

Figure10,- CalculatedendexperimentalllS-mm-borerollerbearing

operatingcMracteristlcewithan Inputcolddlametreclear l anceof

0,09mmInthecomputeprogra r m- shaftspeed25, 500rpm, R_llil

IOIKlN. (2000Ib); lubricantvolume2, percent,