Lubrication

“ The experiments with lubrication were useful rather as comparing the various lubricants one with another than as representing, by a mere process of multiplication, what would be the behaviour of the ship on her cradles, because, for the reason already pointed out in the case of wooden sliding-surfaces, the lubrication would be more and more rubbed away as more of the cradle passed over it ”

“ In the lubrication of the cylinders and valves of steam, gas and oil engines, the lubricant must possess as much viscosity as possible at the working temperature, must not evaporate appreciably and must not decompose and liberate fatty acids which would corrode the metal and choke the steam passages with metallic soaps; for gas and oil engines the lubricant must be as free as possible from tendency to decompose and deposit carbon when heated. ”

“ The coefficient μ is a variable quantity, and bearing in mind that a properly lubricated journal is separated from its supporting brass by a film of lubricant it might be expected that μ would have values characteristic of the coefficient of friction between two metallic surfaces, merging into the characteristics properly belonging to fluid friction, according as the oil film varied from an imperfect to a perfect condition, that is, according as the lubrication is partial or complete, completeness being attained by the use of an oil bath or by some method of forced lubrication. ”

“ The lubricating device may either be a gravity or force-feed oiler system with pipes leading to the various bearings, or the chief lubrication may be by the splash system, where a reservoir of oil is kept under the crank case from which it is pumped to oil pans under the cranks, being splashed by projections which dip into the oil and throw it all over the inside mechanism. ”

“ If possible, lubrication by oil should be substituted by grease lubrication through screw caps.
Particular attention should be paid to the back of the machines. None but the individual in charge of engines should be allowed to lubricate the machines, and he should be held responsible for any excess of lubricant.
As a rule oil-marks are restricted to the edges or the proximity of the edges of crepe, but sometimes the streak is to be found in the middle of the length. In such a case it is almost certain [227] that the oil or grease has been picked up by the rubber in the tray. ”

“ The lubrication of a gasoline engine must be carefully looked after, as on its thoroughness depends the continued delivery of power. The most usual method of lubricating the piston and cylinder walls is to keep the crank case filled with oil to such a point that the end of the connecting rod dips into it in turning. ”

“ The differential equations for the equilibrium of the lubricant are what the differential equations of viscous fluid in steady motion become when subject to the conditions necessary for lubrication as already defined— (1) the velocity is below the critical value; (2) at the surfaces the velocity of the fluid is that of the solid; (3) the thickness of the film is small compared with the lateral dimensions of the surfaces and the radii of curvature of the surfaces. ”

“ Lubrication above all things spells life to the motor-car, and the lack of it must result sooner or later in disaster. Therefore see before starting for a drive that all the bearings of the car are properly lubricated, and also be sure during the drive that the lubricator to the engine is working satisfactorily. ”

“ In watchwork therefore, and other fine mechanism, it is necessary both to keep the bearing surfaces small, and to employ a thin and limpid oil for the purpose of lubrication, for the resistance caused by the viscidity of the unguent increases with the amount of surface, and the amount of surface is relatively greater in the smaller class of works. ”

“ The cylinder jackets were made of welded sheet steel so fitted around the cylinder that the head was also water-cooled, and the jackets were corrugated in the middle to admit of independent expansion. Even the lubrication system was duplicated, two sets of pumps being used, one to circulate the main supply of lubricating oil, and the other to give a continuous supply of fresh oil to the bearings, so that if the supply from one pump failed the other could still maintain effective lubrication. ”

“ Oil holes are apt to get choked by gumming, which is that the oil in time forms into a brown gummy substance that fills the oil hole. Perfect lubrication does not imply wasteful lubrication by any means, but a wasteful use of oil is probably less expensive than insufficient lubrication. ”

“ The rational theory of lubrication does not, however, depend solely on the viscosity within the interior of fluids, but also depends on the surface action between the fluid and the solid. In many respects the surface actions, as indicated by surface tension, are still obscure, and there has been a general tendency to assume that there may be discontinuity in the velocity at the common surface. But whatever these actions may be in other respects, there is abundant evidence that there is no appreciable discontinuity in the velocity at the surfaces as long as the fluid has finite thickness. ”

“ Insufficient lubrication may be caused by imperfect operation of the lubricators, or, particularly during cold weather, by too great a viscosity or congelation of the oil. If a lubricator be imperfect in its operation, the condition of its regulating mechanism should be ascertained, if it has any, and an examination made to discover any obstruction in the oil-ducts. Such obstructions are very likely to occur in new devices which have been packed in cotton waste or excelsior, with the result that the particles of the packing material often find their way into openings. ”

“ Lubrication of Machines.—It must always appear to those inexperienced in engineering matters that existing methods for lubricating rubber machinery are distinctly crude, when [167] one considers the delicacy of the material to be prepared. Many existing machines are still lubricated with oil, which has to be administered in generous quantities. Generally, such machines have been so designed that the excess of oil may find an easy passage into the tray which receives the rubber. If not, it drops just outside the tray to the floor, and is washed away in great gouts. ”

“ In cold weather a light grade of oil having a low cold test is absolutely essential for the proper lubrication of the car. Graphite should not be used as a lubricant in the engine or the transmission as it will have a tendency to short-circuit the magneto. ”

“ For all ordinary machinery, ranging from the light ring spindles of textile mills to the heavy shafts of large engines, mineral oils are almost universally employed, either alone or mixed with fatty oils, the general rule being to use pure mineral oils for bath, forced or circulating pump lubrication, and mixed oils for drop, siphon and other less perfect methods of lubrication. Pure mineral oils of relatively low viscosity are used for high speeds and low pressures, mixed oils of greater viscosity for low speeds and high pressures. ”

“ As the piston, piston rod, and valve slide on their respective surfaces with considerable pressure it is absolutely necessary that these parts receive ample lubrication. In practically all engines the oil is taken into the cylinder with the steam in the form of drops, the oil being measured out by a sight feed lubricator that is tapped into the steam supply pipe. In this device, the oil from the lubricator reservoir is fed through a regulating needle valve, drop by drop, up through a gauge glass so that the engineer can tell the amount of oil that he is feeding. ”

“ Every properly-lubricated portion of a motor either moves in a bath of oil or is connected with an oil reservoir so that a certain amount will be fed regularly to the rubbing surfaces. There is always some heat generated in a bearing, no matter how well it may be lubricated, and the continuous flow or circulation of the oil serves to carry off this heat that would otherwise tend to dry the lubricant if there were no fresh supply.
The proper lubrication of the motor is even more necessary than is the adjustment of the carburetor or the condition of the ignition system. ”

“ Practically every owner will fill up the oiler to insure engine lubrication, because that is a regular task; most men will remember to keep oil in the transmission case and the differential housing;40 probably a lesser number will put grease in the wheel bearings when needed. ”

“ It is not the intention of the author to treat of the proper shape of the teeth of wheels, [Pg 31] leaves of pinions, or the proportions of the escapements, the nature and scope of this work not permitting of it; but he will confine his remarks principally to the parts that involve lubrication. ”

“ Lubrication is faulty when the quantity of lubricant supplied is either insufficient or too abundant, or when the oils employed are of bad quality. It has already been shown that insufficient lubrication and the utilization of bad oils leads to the overheating of the moving parts. ”

“ I need not
illustrate so well-known a principle by experiment. Solid
friction disappears when the liquid intervenes. In its place we
substitute the lesser difficulty of shearing one layer of the
liquid over the other; and if we keep up the supply of oil the
work required to do this is not very different, no matter how
great we make the pressure upon the bearings. Compared with the
resistance of solid friction, the resistance of fluid friction is
trifling. Here under the skate the lubrication is perhaps the
most perfect which it is possible to conceive. ”

“ Some oils are very defective in this respect, and leave large quantities of carbon deposit on the metal walls of the cylinder and the valves; others again are gummy or too viscous even at high temperatures. Such oils must be avoided equally with those which lose their viscosity too much under heat.
Splash System of Lubrication.—One method of lubricating the working parts is known as the splash system. In this system oil is poured into the crankchamber and the moving parts dip into it, splashing it all over the interior of the crankcase and the lower portions of the cylinder walls. ”

“ No material thing, however polished, is quite smooth; every surface may therefore be considered as covered with irregular hooks or teeth, however flat and smooth it appears to the unassisted eye, and these catch and hold one another, producing the hang or drag called friction. Oil, being a fluid, fills up the spaces between these invisible teeth and levels off the surface; the office of lubrication is, therefore, to get between the contact surfaces and keep the hooks or teeth thereon from touching. ”

“ An oil having little viscosity is suitable for the escapement and lighter parts of the train, but is not a good lubricant for the bearings of the center pinion and barrel arbor and the mainspring, which require a more viscous lubricant ”

“ If some of the bearings need a small quantity of oil, being otherwise in such good condition—because of never having been used, in fact "new"—that it is unnecessary to take all the mechanism apart and clean it, it is very important that the operator know what kind, or variety, of lubricant has been previously used, in order not to "mix oils;" ”

“ The less the viscosity, consistently with the use of the oil under the maximum pressure to be anticipated, the less is, usually, the friction. The best lubricant, as a rule, is that having the least viscosity combined with the greatest adhesiveness. Vegetable oils are more viscous than animal, and animal more so than mineral oils. The fluidity of an oil is thus, to a large extent, a measure of its value. ”

“ The Variations of Viscosity of Oils in Varying Temperatures always create fluctuations of their friction reducing power; while the variations of fluid friction which result are also of great importance in horology. When it is known that the viscosity and lubricating power of an oil are usually (80) very closely related, it is seen that change of temperature has an exceedingly important effect upon oils, even for general lubricating purposes ”

“ For perfectly lubricated surfaces, were such attainable, assuming it practicable with complete separation of the surfaces, the laws of friction, according to Thurston, would become:
1. The coefficient is inversely as the intensity of the pressure, and the resistance is independent of the pressure.
2. The friction coefficient varies as the square of the speed.
3. The friction varies directly as the area of the journal bearing.
4. The friction varies as the temperature rises, and as the viscosity of the lubricant is thus decreased (80) . ”

“ We were then satisfied that, with proper lubrication and better adjustments, a little more power could [10] be expected. The completion of the motor according to drawing was, therefore, proceeded with at once. ”

“ With heavy machinery, as the hardness and degree of polish of the surfaces cannot be increased in proportion to their weight, the solid friction is so great that while the interposition of a lubricant between the surfaces adds fluid friction, it also reduces the solid friction ”

“ Fig. 4.—D. C. Stull's Watch Oil Factory, Provincetown, Mass.
[Pg 17]
11. Mineral Oils have of late years taken immense strides in the popular and merited estimation of consumers, for general lubricating purposes. Their application in horology will be discussed in another part of this volume. They are obtained from the residuum of petroleum distillation, and vary so greatly in their properties that many of them are not applicable to delicate mechanism ”

“ Porpoise Jaw Oil [13] and Blackfish Melon Oil have certain good qualities which have made them very [Pg 62] popular, particularly on this side of the Atlantic. When properly refined (4-6) they are no doubt very suitable for the work of reducing friction in small and delicate mechanism.
65. Sperm Oil (7) had been used to some extent as a lubricant for time-keeping contrivances; in fact, many tower clock experts still employ it on the heavier bearings. ”