US2262526A - Lubrication - Google Patents

Description

Nov. 11, 1941. M. FAIRLIE E'rAL LUBRICATION Filed July 15, 1938 4 Sheets-Sheet 1 t Zr 2 llllllllllll, ,llilllllil l All] 111411 im Zwan? l ATTORNEYS Nov. l1, 1941. M. FAIRLIE ETAL.

LUBRICATION Filed July l5, 1938 4 Sheets-Sheet 2 ganar eare Y 2 ATTORNEYS Nov. l1, 1941. M. FAIRLIE ETAL LUBRICATION Filed July l5, 1938 4 Sheets-Sheet 5 6 4 2 0 8 6 L. 2 1. 1.. 1. L 0. 0. Q 0.

Nov. 11, 1941. M, FAIRLIE ET AL 2,262,526

LUBRIGATION Filed July 15, 1938 4 Sheets-Sheet 4 ATTORNEYS Patented Nov. ll, 1941 LUBRICATION Matthew Fairlie and Leonard E. Beare, Hammond, Ind., assignors to Sinclair Refining Company, New York, N. Y., l. corporation 'of Maine Application July 15,

8 Claims.

This invention relates to lubrication and lpar-` and inhibit the attack of such oils upon metalsparticularly alloy bearings such as cadmium-silver, copper-lead, etc. v

In general, the presence of `soaps of the alkaline earth metals in lubricating oil improves the lubricating quality of the oil and improves its thermal stability, i. e., its power to retain its4 lubricating quality under conditions of elevated temperature or pressure, or both. An example of a lubricating oil containing soap of an alkaline earth metal is that described and claimed by Arnold C. Vobachy in United States Patent 2,081,075, granted May 18, 1937. Such oil contains calcium phenyl stearate with or without calcium stearate or phenyl stearic acid. The` amount of calcium phenyl stearate plus calcium stearate or phenyl' stearic acid in the oil preferably ranges from 0.5% to 2.5% of the oil, the

latter being of petroleum origin having a viscosity upwards of 50 to 70 seconds at 100 Fahrenheit, Saybolt Universal.

Lubricating oils of petroleum origin and containing calcium soap or the soaps of barium or strontium are distinguished by good performance characteristics under severe operating conditions, for example, the conditions in the Diesel type of engines in which lubricating oils are subjected to extremely high temperature and pressures. Un-

der such conditions,\petroleum oils containing alkaline earth metal soaps and particularly petroleum oils lcontaining the phenyl stearate of calcium or strontium are notable for their high thermal stability and reduced tendency Vto form insolu`1e` sludge. In addition, oil containing phenyl stearate of calcium or strontium has the properties of rendering deposits of sludge and carbon in' an engine soft and friable rather than hard and coherent, and removing such deposits as an incident to the normal operationof the engine. However, under severe operating conditions, oils containing such soaps do deteriorate eventually and, although their operating life is langer than that'of most other lubricants under like conditions, it is desirable to still further prolong such life.

Although the principles oflubrication, that is to say how a given substance acts as a lubricant and what factors contribute to its lubricating 193s, serial No. 219,456 (o1. 12a-19s) qualities are notcompletely understood, it has been observed that increases in the viscosity,

sludge content and acidity of a petroleum oil dur- .ing service in an engine are indicative of de- 5 terioration of lubricating qualities. Moreover, the gradual formation of tar or asphaltenes in petroleum oils during service, due to polymerization or other chemical action is accompanied by diillculty in properly supplying the lubricant to metal surfaces and in maintaining cleanliness of reciprocating parts. Furthermore, many petrov leum lubricating oils after a period of service manifest some tendency to corrode metal. In the \case of oilscontaining alkaline earth metal soap l5 in service at elevated temperatures and in contact with certain types of metals, the tendency toward corrosion is marked. This tendency is relatively mild when the oil is new, but increases after the oil has been in servicefor some time at 2o elevated temperatures, probably due to the formation of oil acids or"'other oxidation products. Certain special alloys, such as the cadmiumsilver and copper-lead alloys now vused extensively as bearings in internal combustion engines, are particularly susceptible to corrosion by oils containing soaps of the alkaline earth metals at relatively elevated temperature.

As a result of our investigations, we have discovered a method of and apparatus for prolonging the life and lubricating properties of petroleum-base lubricating oils containing alkaline earth metal soaps even under severe operating conditions and for inhibiting the corrosive effect of such oils upon metals with which they come in f contact. We have discovered that the tendency of such oilstn increase in viscosity and acidity and to form sludge during service is inhibited by bringing the oil` periodically into contact with an alkaline earth metal (calcium, strontium or barium) or an inorganic compound thereof. Thus, calcium, strontium or barium in elemental form or as inorganic compounds, for example the cai-hides, carbonates, oxides or hydroxides, act to inhibit an increase in the viscosity, acidity and sludge formation of oils containing calcium soaps. Moreover, such treatment results in a marked reductionin the amount of gum" and sludge deposited on important reciprocating parts during service and at the same time reduces the corrosion of bearings and other metal surfaces lwith which the oil comes in contact. Oddly enough, magnesium and its inorganic compounds, although like calcium and its corresponding compounds in many respects is not useful in the 55 practice of our invention.

\ Generally speaking, the tendency of petroleum-base lubricants to deteriorate during service increases as the temperature of service increases. However, we have found that this is not the case with petroleum-base lubricating oil containing an alkaline earth metal soap, provided that during service such oil is brought periodically into contact with an inorganic solid containing calcium, strontium or barium in elemental or combined form. Under such circumstances, an increase in temperature of the oil, within limits, by providing increased and optimum temperatures of contact of the oil with the inorganic mass, actually decreases the tendency of the oil to deteriorate and lose its lubricating qualities. For example, the useful life of oil containing calcium phenyl stearate islonger at temperatures of 250 F. than at a lower temperature, say 225 F. provided that during service the oil is circulatedin contact with an inorganic solid containing calcium, strontium or barium in elemental form or as a compound.

We have found, moreover, that' at relatively low contact temperatures, i. e., substantially below 140% F., the favorable effect exerted by the alkaline earth metals (in elemental or combined inorganic form) upon oil containing soap of the alkaline earth metals is/not marked. Hence, it is advantageous to bring the oil into contact with calcium or the like under conditions of relatively elevated temperatures. The precise temperature at which the eiect of the alkaline earth metal is optimum is dependent upon the form in which themetal or metal compound is used. In the case of calcium hydroxide in contact with an voil containing calcium phenyl stearate the opti- 4mum contact temperature is in the neighborhood of 250 F., to 275 F. and in general such temperature is optimum. However, good results are obtained up to a temperature of about 300 F.

In the operation of an internal combustion engine in accordance with our invention, the oil containing a soap of an alkaline earth metal preferably is brought to optimum treatment temperature, either by heating or cooling. case of Diesel type engines and the like, oil in the lubricating system may attain a temperature above the optimum, in which case it is desirable to cool the oil before or during its contact with the solid containing the alkaline earth metal (-i. e., the contact mass). On the other hand, oil

in the lubricating system of automobile engines and the like usually will not attain the optimumf temperature for treatment as a normal incident of operation. Hence it may be desirable in the application of our invention to an automobile engine, to heat the oil or the contact mass containing the alkaline earth metal or both, so that treatment of the oil with the contact mass takes place under optimum conditions.

The Contact mass containing the alkaline earth metal in elemental r combined form preferably is porous and relatively finely divided, the oil being circulated through it. Optimum conditions of treatment may be attained by enclosing this mass in a jacket through which a heating or cooling medium is passed. In the case of automobile engines and the like, in which optimum conditions require the addition of heat, the latter may be supplied by passing the exhaust gases fromv the engine through the jacket. Where cooling is desirable, cold water or cool air or other cool fluid may be passed through the jacket.

Our invention therefore contemplates passing a liquid petroleum-base lubricant containing a In the terposed between flange and top to insure a tight soap of an alkaline earth metal periodically during service in contact with a solid containing calcium, strontium, or barium in elemental or combined inorganic form, for example, metallic calcium or the hydroxide or carbide thereof. Preferably, the treatment of the oil with the compound is conducted at elevated temperature. the optimum temperature being that at which the organic acidity is substantially continuously neutralized and the resultant soaps are dissolved in the oil. Generally speaking, the temperature of treatment should lie between F. and 300 F.

These and other aspects of our invention Will be moreI completely understood in the light'of the following detailed description of presently preferred practices of our invention taken in conjunction with the accompanying drawings, in which:

Fig. 1 illustrates a form of lter containing contact mass for use in the practice of our invention;

Fig. 2 illustrates a second form of iilter for use in the practice of our invention;

Fig. 3 illustrates a jacketed lter for use in the practice of our invention when it is desired to raise the temperature of the oil to attain or approximate optimum treatment conditions;

Fig. 4 illustrates a jacketed filter for use in the practice of our invention when it is desired to lower the temperature of the oil to attain or approximate optimum treatment conditions;

Fig. 5 is a graph of results obtained as to the viscosity and percent asphalteness of oil containing calcium phenyl stearate during 50 hours of service in a Waukesha four-cylinder gasoline engine, the results obtained while using a calcium hydroxide contact mass being compared with those obtained under identical conditions except that the contact mass was not used;

Fig. 6 is a graph of results obtained as to thev saponication number and acid numberof oil containing calcium phenyl stearate during the test of Fig. 5;

Fig. 7 is a graph showing corrosion of certain alloy bearings during the test of Fig. 5;

Fig. 8 is a graph showing the corrosion of copper-lead and cadmium-silver bearings during a 200 hour test in a Waukesha engine with oil containing calcium phenyl stearate circulated through a calcium hydroxide contact mass, as compared with results obtained under identical conditions, except that the filter was not used; and

Fig. 9 shows a calcium hydroxide lter in place on the oil circulating system of the engine employed in the tests.

Passing now to a consideration of the drawings, the fllter of Fig. 1 comprises a cylindrical metal shell III having a cover plate II bolted to a ange I2 around its top with a gasket I3 injoint. Disposed concentrically within the shell is a canister I4 made from perforated Monel metal screen or other pervious corrosionresistant material. The canister is annular in form with an enclosing top portion I5 so that it surrounds a space I6 immediately above an outlet pipe I1. An inlet pipe I8 is provided in the outside of the shell, and the space in the* shell around the canister is lled with cotton wool I9. The inside of the canister is filled with a pervious mass of an inorganic solid 20, containing calcium, strontium or barium in elemental or combined form. Thus the canister may be packed with twisted calcium foil, but for economic reasons it is desirable to fill the canister with pea-size or finer meshed lumps of say 8-14 or 14-30-mesh of calcium hydroxide or calcium carbide or a mixture of the two. Oil to be treated is introduced into the filter-through the inlet, and forced through the cotton wool and the packing of alkaline earth metal or inorganic compound thereof to the outlet.

The tendency of the contact mass to escape from the filter is relatively slight. Lumps of calcium hydroxide are relatively friable in the air, but when once wetted with oil there is little tendency for them to break apart. 'I'he cotton wool is provided as a safeguard against the passage of calcium hydroxide, etc., into the en gine. The cotton also serves to distribute the oil through the filter and thus prevents channeling. A conventional filter may be placed in the systemfollowing the filter of our invention as an additional safeguard.

As a further precaution against the escape of the packing into the engine, it isadvisable to soak it with oil prior to installing the lter on the engine. This may be done conveniently by pumping oil through the filter, so that fine particles which tend to lescape from the4 contactmass or packing may be removed prior to placing it in service in the lubricating system of the engine.

The lter of Fig. 2 is similar in principle Ato that of Fig. 1, but is somewhat moreV elaborate. As in the case of Fig. 1, a cylindrical metal shell 2| having a side inlet 22 and a bottom center outlet 23 is provided, the shell being sealed by a cover 24 and a gasket 25v held to an annular flange 26 on the shell by bolts 21. The interior structure of the lter of Fig. 2 is, however, so constructed that the cotton wool 23 and the packing 29 containing the elemental alkaline earth metal or its inorganic compound are retained in a single canister so that both may be removed together. Thecanister'is a perforated cylindrical shell of Monel or the like having a lid 3| which is held on by a spring leaf 32 that bears against the edges ofthe lid and against the center of the outer cover. Within the canister is a central upright felt-covered perforated discharge pipe 33 which is coupled to the outlet. around the pipe is the packing 29 in the form of an annular pervious mass, preferably made by molding relatively coarse calcium hydroxide particles or pellets with a small amount of binder such as plaster of Paris. I'he cotton wool is packed in the canister inside and outside the pervious mass. The canister is raised slightly from the bottom of the shell by means of an upset annularzridge 34.

The apparatus of Fig. `3 is similar to thatv of Fig. 1, except that a jacket 35 is provided outside the filter shell through which exhaust gases, or other hot fluid may be passed from an inlet pipe 36 to an outlet pipe 31 to raise the temperature within the filter. Similarly, the" apparatus of Fig. 4 is identical with that of Fig. 2, except for a jacket 33 through which a cooling fluid (say, water) may be passed from an inlet pipe 39 to an outlet pipe 40. l f

` Avconvenient method of handling the contact mass is to have the desired quantity made up in a light cloth, canvas, or metal mesh bag, so that 'when exhausteditmay be quickly removed en cating system of an internal combustion engine is shown in Fig. 9, in which an engine 4| is lubricated by means of oil forced into its crank case 42 through a pipe 43. The oil is withdrawn from the crank case through a line 44, and conducted into a filter 45 suchvas those shown in Figs. 1 to 4. After passing through the filter, the oil returns to the crank case of the engine through a pipe 46 which joins the pipe 43 at a T 41. Extending from the T is a rate checking line 48 provided with a valve 49. A valve 50 is provided in the line 43. y

A valved by-pass 5I connects the pipes 44 and 46 and a pressure gauge 52 is attached to the line 44 between the crank case and the filter. Gases from an exhaust manifold 53 of the engine may be conducted through a jacket 54 on the filter to heat it to optimum temperatures, the gases passing from the exhaust manifold to the jacket through a line 55 and being exhausted from the jacket vthrough a second line 5B.

vIn operation, the oil is circulated substantially continuously through the crankcase and the filter at the rate of about 3000 cc. per minute and at a temperature between 250 and 300 F. The rate of circulation required to keep the oil noncorrosive is, however, largely dependent upon the v per minute is dependent also upon the severity of I the engine service with respect to oxidation,'a

quantity between 25 per cent and 100 percent of the crank case `contents should be contacted per minute. In the example cited, approximately Disposed masse 'and -another unit installed. This is much percent of the crank case contents are circulated per minute. The crank case holds about 5000 cc. of oil.

In a 50 hour test of lubricating oil containing about 1.33% of calcium phenyl stearate, this oil was circulated through a Waukusha engine of the` type shown in Fig. 9'for a period of 50 hours. At intervals of ten hours, samples of the oil were withdrawn and `subjected to analysis. Fig. 5 shows the results obtained when the oil was circulated through a filter containing a contact mass of calcium hydroxide as illustrated in Fig. 1, these` results being contrasted with results obtained under exactly similar conditions, except that no contact mass was present in the filter.

The engine was run at 1000 R. P. M. The temperature of the oil in the crank case was about 250 F. Results obtained with the oil used in conjunction with the calcium' hydroxide filter are shown with Adotted lines, as contrasted with results obtained without the calcium hydroxide filter which are shown in solid lines. It will be observed that the use of the contact mass of inorganic alkaline metal solid (in this case, calcium hydroxide), was very effective in inhibiting the increase in viscosity yof thevoilduring service. Thus, during 50 hours of service, the viscosity of the oil at F. increased but slightly when the contact lmass was used, but increased markedly when the mass was not used. Similar effects were observed in the case of viscosity measurements taken at 210 F.

`Analysis of the oil for asphaltene content showed that there was practically .no increase in the per cent of asphaltenes when the calcium hydroxide contact mass was employed, while service without the mass brought a very great increase in the content of asphaltenes in th oil.

The saponication number and the acid number of the oil were also determined by analysis at the end of each ten hour interval of the abovedescribed tests. Saponication numbers and acid numbers are indicative of the amount of deleterious decomposition products accumulating in the lubricant during service. The dotted lines in Fig. 6 indicate results obtained with the calcium hydroxide contact mass, while the solid lines indicate the results obtained Without the use of calcium hydroxide. It will ce observed that the use of the calcium hydroxide contact mass hada marked eiect in inhibiting the increase in acid number and saponicati'on number of the lubricant as contrasted with the case in which no such mass was employed.

The engine used in the above-described tests was equipped with cadmium-silver and so-called Satco bearings, so that the corrosion-inhibiting effect of the contact mass with respect to such bearings could be determined. The cadmiumsilver bearings contained approximately 99% cadmium and 1% silver. The approximate composition of the Satco bearings was 95% lead, 3 to 4% sodium or calcium, and 1-2% of other metals as impurities.

The bearings were weighed at the beginning of service, and at the end of 25 hours and 50 hours, respectively, of service. Fig. 7 shows the results obtained, the solid lines indicating the extent of corrosion when no contact mass was used, as contrasted with the results obtained when a calcium hydroxide contact mass was employed., The results show that with either cadmium-silver or Satco bearings 'there is practically no corrosion when an inorganic alkaline metal contact mass is employed, whereas without such mass the corrosion is excessive.

The temperature of the oil in contact with the bearings during the tests, as indicated above, was about 250 F.

Tests of copper-lead and cadmium-silver bearings in service in the engine of Fig. 9 at a crank case temperature of 250 F. and for a period of 200 hours confirm the results shown in Fig. '7, and show further that the rate of corrosion of bearings continues to be almost negligible over a period of long and severe service provided that the lubricant is passed repeatedly in contact with a solid containing an alkaline earth metal either in elemental form or as an inorganic compound. Fig. 8 shows graphically the amount of corrosion resulting when cadmium-silver bearings containingl approximately 99% cadmium and 1% silver and copper-lead bearings (typical analysis 43% copper, 57% lead) were placed in service in the hereinbefore-described engine for 200 hours at a crank case temperature of about 250 F. and lubricated with the hereinbefore-described oil containing calcium-phenyl-stearate, which was circulated through a contact mass of calcium hydroxide at a rate of about 3000 cc. per minute. The extent of corrosion is shown'- by the heavy lines. Both in the case of cadmium-silver and copper-lead, the corrosion was practically negligible. For purpose of comparison, the test results obtained with cadmium-silver bearings without the use of a calcium hydroxide contact mass (as described in conjunction with Fig. "1)v earth metal in elemental combined inorganic form is less marked, While tests conducted at higher temperatures, say up to 300 F., indicate an improvement in the corrosion inhibitive effect of such contact masses.

It is apparent that the beneficial results obtained through circulating oil containing a soap of an alkaline earth metal in contact with a contact mass containing an alkaline earth metal in elemental or combined inorganic form are not to be explained solely on the ground that acids originally present or formed in the' oil during service are neutralized. This is shown by the fact that corrosion is inhibited by the elements themselves and by compounds thereof such as the carbides which are neutral or acid in reaction. On the contrary, it would appear that the alkaline earth metals in elemental or combined inorganic form under certain conditions of operation exert a catalytic effectto reduce the rate of oxidation of oxidizable constituents in the oil with resultant decrease in the amount of sludge and oil acids formed. This may be explained by reference to the following analyses of new oil containing calcium phenyl stearate (test l), this oil after 24 hours service at 250 F. in a lubricating system equipped with a calcium hydroxide contact mass (test 3), this oil after 24 hours service at 190 F. in a lubricating system equipped with a calcium hydroxide contact mass (test 4), and this oil in service for 24 hours without benet of contact with calcium hydroxide (test 2).

Test numbers Rate of passage through contact mass b 30 Temp. of oil entering contact f ma 250 190-200 Temp. of oil leaving contact mass, 210 i60-170 A. S. T. M. insolubles 70.6 1.4 3.1 Viscosity at 100 F 579 742 882 Viscosity at 210 F... 57. 9 68. 2 59. 9 63. 0 Neutralization number. 0. 213 3. 62 0. 718 1. 40 Saponiticaton number... 1. 98 17.8 5. 04 6. 63 Calcium content, per cent. 0. 067 0.06 0. 0.116 Added titre 2. 88 1. 37 Actual reduction in neutralizationnumber 2.90 2.22 Actual reduction in saponflcation number 12.8 11.2

In each instance inspection of the contact mass after service indicated that it had not picked up appreciable sludge or soap.l Hence, the results indicate that. the calcium hydroxide contact mass brought about a lessening insludge formation and viscosity rise, as compared with the case (test 2) in which the mass was not employed. The lessened sludge formation (A. S. T. M. insolubles) and the lessened viscosity rise indicate that the lcontact mass causes a decrease in oxidation rate of constituents in the oil.

Morecogent ev'idence that the benefits of the,

service in test 3, since this increased alcium content would only be suicient to brin about a de crease of 2.88 in saponification number. In test 3, and likewise in te'st 4, there was an actual decrease in the rate at which saponiflable oxidation products formed, and this we attribute to the catalytic eiect of the contact mass.

The beneficial effects obtained through the use of contact masses of elemental alkaline earth metals or inorganic compounds thereof apparently are peculiar to these substances. Thus magnesium and its inorganic compounds: do not exert such an effect, nor do the hydroxides of iron, chromium, nickel or aluminum. Moreover, tests conducted with oils containing aluminum soaps (employing as a contact mass aluminum or an inorganic compound thereof) showed, surobtained as crystals and lose water at relatively low temperatures. For use in the practice of this invention, these hydroxides should be dehydrated at about 400 F. The resulting dry powders may then be briquetted in a mold by compression under a steam hammer and thereafterV chipped and screened to size. Calcium hydroxide for use in the practice of the invention should be treated by making it into a thick paste with water. The paste is then dried, preferably in an atmosphere free from CO2, ground in an ice chipper or the like and screened to size.

We claim: Y

1. In the operation of a system for lubricating bearing surfaces with a petroleum base lubricating oil containing a soap of an kaline earth metal which involves repeated contacting of said oil from a body thereof with the surfaces to be lubricated and circulation of said oil through a treating zone, the improvement which comprises bringing the oil in said treating zone into contact with a solid selected from the group consisting of the alkaline earth metals and inorganic` compounds thereof at a rate suilicient to bring into contact with said solid an amount of oil equivalent to a substantial part of said body of oil per minute, and controlling the temperature of the oil in said.treating zone to maintainthe oil in contact with said solid at a temperature between about 140 F. and 300 F.

2. In the operation of a system forlubricating bearing surfaces with a petroleum base lubricating oil containing a soap of an alkaline earth metal which involves repeated contacting of said oil from a bodythereof with the surfaces to be lubricated and circulation of said oil through a treating zone, the improvement which comprises passing the oil in said treating zone through a contact mass containing exposed surfaces of a solid selected from the group consisting of the alkaline earth metalsv and the oxides, hydroxides, carbonates and carbides thereof at a rate sumcient to bring into contact with the exposed surfaces of said solid an amount of oil equivalent to a substantial part of said body of oil per minute, and controlling the temperature of the oil in said treating zone to maintain the oil in contact with said solid at a temperature between about 140 F. and 300"` F.

3. In the operation of a system for lubricating bearing surfaces with a petroleum base lubricating oil containing a soap of an alkaline earth metal which comprises repeated contacting of said oil from a body thereof with the surfaces to be lubricated and circulation of said"`oil through a treating zone, the improvement `which comprises passing the oil in said treating zone through a porous medium comprising a solid selectedV from the group consisting of thel alkaline earth metals and inorganic compounds thereof at a rate sufiicientto bring into contact with said solid an amount of oil equivalent to about 25%100% of said body of oil per minute while maintaining said medium at an elevated temp'erature. 4

4. In the operation of a system for lubricating an internal combustion engine with a petroleum base lubricating oil containing a soap of an alkaline earth metal which involves repeated contasting of said oil from a body thereof with the surfaces tobe lubricated and circulation of said loil through a treating zone, the improvement base lubricating oil containing a calcium soap' which involves repeated contacting of said oil from a body thereof with the surfaces to be 1ubricated and circulation of said oil through a treating zone, the improvement which comprises I passing the oil in said treating zone in contact with a porous mass comprising a solid selected from the group consisting of metallic calcium and inorganic compounds thereof at a ratesufiicient to bring into contact with said solid an amount of oil equivalent to a substantial part of said body of oil per minute and controlling the transmission of heat to the oilr passing through said treating zone to maintain the oil in contact with said solid at a temperature-between F.300 F.

6. In the operation of a system for'lubricating an internal combustion engine with a petroleum base lubricating oil containing a calcium soap which involves repeated contacting of said oil from a body thereof with the surfaces to be 1ubricated and circulation of said oil through a treating zone, the improvement which comprises passing the oil in said treating'zone through a porous mass comprising calcium hydroxide at a rate sufilcient'to bring into contact with said calcium hydroxide an amount of oil equivalent to a substantial part of said oil body per minute and controlling the temperature ofthe oil in said treating zone to maintain a temperature approximating 250 F.300 F.

7. In the operation of a system for lubricating bearing surfacesy of cadmium-silver-alloy with a petrole base lubricating oil containing a soap of an al line 'earth metal which involves repeatedco tacting of said oil from a body thereof with the surfaces to be4 lubricated and circulation of said oil during service through a treating zone, the improvement which comprises bringing to bring into contact with said solid an amount of oil equivalent to about 25%-100% of said body of oil per minute.

8. In the operation of a system for lubricating bearing surfaces of lead-copper-alloy with a petroleum base lubricating oil containing a soap of an alkaline earth metal which involves repeated contacting of said oil from a body thereof with the surfaces to be lubricated and circulation of said oil during service through a treatl.,

ing zone, the improvement which comprises bringing the oil containing said soap in said treating zone into contact with a solid selected from the group consisting of the alkaline earth metals and inorganic compounds thereof at a rate suiicient to bring into contact with said solid an amount of oil equivalent to about 25%- 100% of said body of oil per minute.

MATTHEW FAIRLIE. LEONARD E. BEARE.

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