Automotive Engine Lubrication - ACS Publications

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INDUSTR141, A N D ENGINEEIUNQ CHEMISTRY

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btresc figureti there a n c e r t i d y be no cluestion as to which ively type of oil is best. Of course, ill ears which dilutc ex IS oil cent,-evon the noniiil u t ing ty ctory, biit it is Iielter than any ordinary nsed, and sucb ex< ive dilutions are

Vol. 18, No. 5

gradually being climiilnt(d by better design and inore int & w t operrttimi. If the automobile industry can keep dilution 11elow say 20 per ocnt the recommended oil nhoitld certaitily give almost, ideal lubrication automatically thinning down a lirtle i n \viittm m i l tlrirkrning up in summer.

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Automotive Engine Lubrication' By A. W. Pope, Jr. lV.i,

Kllll.i

Il,iTi,R

co.,W a o K i i s i l n , \Vi*

This paper aims to set forth the pertinent facts pertaining to modern practice of automotive lubrication. The splash system is most widely used today, but because of certain shortcomings when used for heavy-duty high-speed work the pressure system is coming into increased favor. The pressure system also has its disadvantages, but a combination of t h e pressure and splash systems has been worked out to give satisfaction for general automotive use. The only part of a n automotive engine giving any real dificulty in lubricating is t h e piston and piston rings. This difficulty has been overcome by certain changes in construction arid t h e development of the fresh-oil or sidewall lubrication system. Oil purification by elimination of solids from t h e oil and control of dilution is discussed and t h e need for better cold-weather performance is expressed.

that a plain bearing rotnting in its journal has nil inlierent pumping action, t,ending t o take oil in through tlie slack side and delivering it from t,he load side of tlie bearing. It might at first appear feasihlc to develop this inlierent pumping action to a point where it would siipply suflicient quantities of oil to it.s hearing. However, the rnasimom theoretical pressure available to form oil into the hearing by this method would only be atmosplterir. Present racing-car prastice includes oil pressure in excess of 200 pounds per square inch Sor lubricating and cooliirg connecting-rod bearings. So t,he impossibilit,y of ever liaridling the situation with no more than atmosplrcric pressure is apparent.

Splash System

OD4Y the sjilasli system of lobrication is used oil Sar the ar est number of units. lt has somo fontores that are T 1 very g favorable to t.hesat.isf:ict.ory operation of an engine. It fills the arcas within the eugine with a uniform, concentrated, heavy oil mist, which pervades all spaces open to the crank case. This assures a supply of luhricatit to all moving parbs within tliesc spaces. Corrosion difficulty appears to be tninimizcd with the use of tho splash system, probably owing to the following influences: (1) A n iinmediate supply of lubricant is available after starting under all conditions of temperature. This reduces dilution and protects hearings which are suddenly put into operation with corroded surfaces. i%i The heavv of oil mist in the crank case ...... ~.. rmiccntration .~ may be suficient'to produce an oil film on the bearing surfaces which will resist the oxidizing influence of the attacking add collected in the oil. (3) The fine mist farmed by the splash system is more suited for the elimination of the rust-producing products from the oil: that is, contact of this fine oil mist with the cylinder and hot niston heads tends to keeo down the nercentare of harmful k c n t s in the oil. \_,

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Piston and cylinder lubrication with a splash system is very satisfactoiy. There is a iiiiiforrn supply US oil to all pistons during the life OS tho engine, which is not. influeiiccd by t.he viscosit,y of the oil. In addition to this uniformity of supply, the great density of the mist produces a desirable cooling effect on the piston. These same points apply to all other parts wllich are dependent upon the splash for their supply of lubricant. The weakness in a splash system is its inabi1it.y to create tl. hydraulic oil pressure within a rotating beitring which is great enough to prevetit metal-to-metal contact of the surfaces under heavy loads or with large clearaiices. It is true I Prceented by T. C. Coiemliii andX. W. Pope, Jr.. ueder tile title "A Study of Cylinder l\~dlLuhrieafion.''

Fresh Oil Pump and Distributor Assembly Showink AdJustin$ Screw and Delivery Pipe Conrlectiuns

When using a splash system it is necessnry to muintain close bearing clearances with consei~ucntclose manufacturing limits to maintain quieti1 This also means that only small amounts of wear are permissible before the machine will become very noisy. Pressure System

It is the general recogrtit,ion US these sliortoomings of the splash system whicli has brought the pressure system into almost univcrsal use for heavy-duty high-speed work. The trend is toward the pressure system. h e a t i n g hearings are operated nrosi sur:i:wsSully where lubricant is supplied to them under pressure. The necessary lubricant pressure is a direct function of the bearing load and speed. I n connecting-rod and crankshaft-bearing work the lubricant serves the triple pitrpose of lubricant, cushion, and coolant. If sufficient oil is supplied under suitahle pressure, cornparat.ivcly large bearing clearances can he used.

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I N D U A W R I A LAND EIVGINEERISG' CHEMISTRY

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the h e . Under tliese iircssures there will be some . passam -

OiI Purification

passage of oil, howc~cr,occut%a t the point in the cycle where the ring trailsfem from tile top of the groove to the bottom of t,he groove. To overcome this oil-pumping action it was necessary to put holes in the bottom of the lower ring groove and to furnish passages in the ring or in the lower edge of the ring groovc to permit the oil to pass hack of the ring and so through the holes into the crank ease. Any compression leakage past the upper rings tends to blow the accumulated oil in the lover ring groove through these holes back to the crank case. Tlie use of such an oil-control ring permits flooded lubricatiou of tlie piston and cylinder with only uniform small amounts passing

The outstanding developments in the lubrication system which are in progress today are in connection with the purification of the oil. This can be divided into two classifieatinns--elimination of solids from the oil and control of dilut,ion. The most important phase is the elimination of the solids or abrasives. This is accomplished by placing air cleaners on the carburetor air and filters, settling chambers, or centrifugal cleaners in the oil line. Some systems place the oil elaaner in the main oil passage and ntliers only shunt a portion of the oil through the cleaner.. Anything which eliminates foreign matter from tlie luiwicant is a great help in prolonging the life of the engine. Fuel dilution of the o i l i n itself is not harmful. Reduction of the oil viscosity to a point where metalt o - m e t a l contact is permitted is the chief d a n g e r . The introduction of water and sulfur into the oil is t h c d a m a g i n g byproduct of dilution. From this anglc, therefore, it is desirable to control the dilution within cert a i n l i m i t s . There Vlew of O*cUlatln0 PIstm Mechanism are many devices on on Fresh Oil Pump t,lie m a r k e t which remove the dilution from the oil by heating. The heat is derived from the exhaust gases of the engine. However, there are indirect methnds of controlling dilution. High cylinder-wall temperatures obtained with steam cooling reduce dilution to a point where it offers no trouble. Warin crank cases are also a great help. Cylitirler barrels wltich ' o the crank case are effective i n this respect. ngine can easily be doubled or trebled by the

of oil ketween the rini and cylinder rail. The greatest

consists of a separate reciprocating p u m p and d i s t r i b u t o r rnourited on the regular oil-pump housing. It receives fresii oil from a t m k outside the engine and distributes it^ a few drops per minute to a groove in each cylinder wall which is located just below the upper piston ring at the bottom of it.s sbroke. The pump has no spring loaded valves. The required viilve timing is secured by oscillating the ported piston. It is capable of building up pressures of 2000 pounds per square inch if ohstructions should lodge in the delivery line. Tlie advantages to be derived from this system accrue from the fact that the piston and this much overworked upper compression ring are always lubricated with clean, fresh oil. Tests have shown slight improveme in power, economy, oil consumption, dilution, quietne reduced dcionation. and carbon deuosit. Any of these Fresh 011 pump and Dbtrlbmtor Mounted on Slde of Maln Oil Pump Houslng

Id-Weather Performance

tdav lubricaiit is its

Constitutionality of Flexible Tariff Law to Be Tested 1. W. Hamnton, Jr., & Co., the "rotestants in the case, have

lhe United States Court of Customs Aoueals. in WGhinRton

preme court Thxs issue, ~nvolvmgthe rate of duty on tzicd before Board One of the appraisers

posed of Judges McClelland, Sullivan, and Brown

Cleliand wrote a lenathv majority opinion, in which Judrr

of legislative ~ o w f fand taxinr

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to ex&utlve authontv.

k customs &raising officers at the rate n accordance with the proclamatmn of

May 27, 1924, snd authori Act of 1922 (T.D. 40,216).

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