[ NOTE: I omitted the first 6 pages of this paper, which contain a tedious technical discussion of friction in the cylinders of steam engines. What follows is a discussion of "self-acting" lubrication devices. ]

... It is, therefore, highly necessary that all users of steam-power should fulfil the condition by having recourse to an efficient steam lubricator, of which there are several now before the public.

Having thus briefly glanced at the question of economy of fuel and the best means of effecting it, and having shown that steam lubrication is an indispensable condition, it remains to be seen that steam engines not built on economic principles are benefited by it. There is now scarcely an ordinary engine, using tolerably dry steam and cutting off at about three-fourths of the stroke, but which has some method of lubricating the steam in the cylinder. The ordinary means of lubrication consist of a grease cock on the cylinder, whereby the contents of a cup filled with oil or tallow are occasionally emptied into the steam. The effect of leaving a piston dry for a long time, and then injecting a quantity of tallow, has often been noticed. The engine instantly takes a start and materially increases both in speed and power. This goes to prove that the lubrication of the steam is good for something. It therefore only remains to be seen which is the best way of lubricating. Shafting is generally lubricated by self-acting means, such as the slow capillary action of a wick, or by the needle lubricator. No one would prefer to empty the contents of the oil cup into the bearing at once. And yet that is precisely what is done in the case of the grease cock on the cylinder, with this difference, that the latter probably detracts far more from the economy of fuel than the former.

The subject of steam lubrication has of late years acquired some prominence, and locomotives are now generally fitted with self-acting means for continuously greasing the steam before it enters the valves. The principle also makes headway with stationary and marine engines. Those who have considered the subject argue that if they can save about 40 per cent. of the tallow that the common grease cock consumes, and at the same time have the additional and possibly far more important advantage of diminishing friction and wear and tear, why should they not do it? Fifty per cent. of fuel can be saved if engines are properly constructed, and a good price paid for them, but to save about 2 per cent. in friction, which means fuel, besides from 30 to 50 per cent. of tallow or oil used for piston and slide valve lubrication, is a far easier matter, and involves an outlay of a mere trifle. We have ingenious governors and heavy fly-wheels and counterweights for the crank and connecting rods to equalize the speed of the engine, let us not lose sight, of a point which may appear trifling, but which in reality has something to do with the steady and even working of the engine, as experience has shown. It would be both superfluous and tedious to enumerate all the lubricators proposed or used for greasing the moving parts in the steam cylinder, the more so as all these appliances are now advantageously superseded by lubricators acting on the principle of continuously greasing the steam before it enters the slide valves. One of the first lubricators of this class is that invented by Mr. Ramsbottom, the locomotive superintendent at Crewe. Fig. 1 shows the form in which this lubricator is used upon locomotives. The principle on which it acts is the following:—A swan-neck pipe being in communication with the steam in the steam pipe, causes a steady flow of steam into a sphere which is filled with tallow to the top of the inner pipe. The steam continually condensing, especially when a current of air is sharp against it at high speed, causes it to fall to the bottom as water, because it is heavier than tallow in the proportion of 5 to 4. A certain amount of tallow is thus continually displaced and forced to overflow into the steam pipe, where it mixes with steam entering the steam cylinders; the steam is thus continually greased. There are no means of regulating this action, but this is not found so very requisite for locomotives. The case is, however, different when we come to apply this lubricator to stationary or marine engines. For such purposes it is necessary to lead the steam to the lubricator (seen at Fig. 2), through at long pipe in the engine room, that pipe then supplying the necessary condensing surface, or better still, to place the lubricator in a cool place outside the engine room. The apparatus, however, does not seem very well adapted for engine room purposes, though it answers for locomotives.

The next lubricator is Roscoe’s, which is shown at Fig. 3. It acts by condensation of the steam and the consequent displacement of the tallow. It consists of a small hollow vessel with a steam connection on one side, tallow inlet at top, and waste cock at bottom. The opening is surmounted by a metal cup with open top, having a lid for filling the tallow; a bridge across the same with a screwed hole in it takes the screwed spindle of a jam valve, which fits a seat in the partition between the lubricator itself and the filling cup. A tube is fixed to the end of the screwed spindle, and reaches to within about two inches of the bottom of the lubricator. The inventor also claims a peculiar function for the central pipe, for he says that when the engine is running down an incline with the steam shut off, the heat causes the air in the tube to be rarefied, and thus obtain a certain pressure which again forces the tallow into the steam pipe and thence into the engine. The action of this pipe does not seem very clear, the more natural course seems to be that the whole of the lubricator when steam is shut off, and while running at any speed at all, should get comparatively cold, and the tallow have a decided tendency to stop where it was. However that may be, these lubricators are extensively used on the Midland Railway and on several others, as well as on many stationary and marine engines, and, the author believes, give satisfaction. The means of regulation, it will be observed, consist in controlling the amount of steam entering by the screwed jam valve opposite the steam pipe on the apparatus. That the inner pipe, as claimed by the inventor, should prevent the water at the bottom of the apparatus from freezing in the coldest climates when the engine is at work seems claiming too much, for the very small quantity of air contained in it which is compressed to a volume of the size of a thimble, if there at all, can have no influence on the quantity of water continually entering. The capacity for heat is much larger in water than in air pound for pound, and the quantity of air contained in the inner tube of a No. 3 lubricator containing about a pint of tallow is only about 1 cubic inch, and with 5 atmospheres pressure only 1/5th of a cubic inch, weighing 1/400th part of a pound.

The Wilson lubricator, shown at Fig. 4, has three different tallow levels each with corresponding ports or holes in the cock and its shell, thus giving three sizes of condensing surface, a means of regulation perhaps sufficient for some cases; but in practice something closer is generally required, and that must attained by throttling the steam inlet through the regulating cock. It acts on the same displacement principle as most of the others in common use. A jam valve with screwed stem serves as blow-off. Should the place where it is fixed be too hot so as not to condense sufficiently fast, a globe is attached to the steam supply pipe, as shown in Fig. 5, which will afford the requisite condensing surface. This ingenious and simple remedy is not mentioned in Mr. Wilson’s patent, and will no doubt answer for other lubricators constructed on similar principles when placed in a very hot position. One fault attached to the instrument made with a water gauge is that the latter does not at all times indicate the true level. The bottom of the gauge is connected to the lower part of the lubricator, but the top is in connection with the steam space above the two lower tallow levels, and any variation in the quantity of tallow and water contained—which, of course, when the instrument works, are continually changing—is not indicated, because the water locks the tallow in the glass. It is only by blowing the glass out and wasting the tallow that the true state of this instrument can be ascertained, as while the glass shows full tallow, there may be little or none left. This is not an oversight of the inventor’s, but is inherent in the construction because of the three different tallow levels the gauge only shows when working at the upper one, the one having the smallest condensing surface. In these lubricators a quantity of tallow can be let in at once, namely, all the tallow contained above the centre of the regulating cock, but the instrument then wants refilling again up to its ordinary tallow level.

Clements’s lubricator is of simple construction. A pipe from the engine steam pipe conveys steam up through the lubricator, entering from the bottom and discharging over the tallow level, also provided with a cock for regulating the supply of steam to the apparatus which acts on the displacement principle. Another inside vertical pipe, which must reach to and determine the tallow level, carries the tallow away to the engine steam pipe or slide jacket. This pipe is also provided with means for regulating. The steam is supposed to pass through the tallow and carry it along with it. A gauge glass is provided in the larger sizes. A blow-off cock is provided for discharging the condensed water or foul tallow. These lubricators seem to give satisfaction, and are simple enough; the fitting them on is more troublesome, as they require two steam connections.

A very ingenious lubricator was patented last year by Mr. Schauwecker. It is fixed on the cylinder, and consists of a cup with an outer jacket to keep it warm. A central pipe enters from the bottom, and reaches nearly to the top. Near the bottom this pipe is in communication with a capillary pipe or passage, too small for the oil to force itself through except when at the latter part of the stroke the pressure gets lower in the cylinder than in the top of the grease cup; at that moment a small quantity of grease is injected. A filling cup is provided as in the old-fashioned grease cups.

Storer’s lubricator, patented in 1866, deserves some notice, because it has been brought prominently before the public. The lid of the lubricator is fixed by means of a bayonet joint. A screw passes through the lid, and its end is tightened down on a soft metal seat; this is for shutting off the lubricator. A strainer or cage fits over the bottom outlet, which has a cock below for regulating the quantity of steam coming in and grease passing out. Supposing this grease cup be filled with suet, which is the material it is worked with; the suet will first melt, and the light oil which is present in it will be brought forward and in a profuse quantity enter the cylinder. This is an operation requiring but very little time; but the suet will remain in the grease cup for many hours after that, but only the gelatinous part of it, which partakes of the nature of glue and is gradually being distilled off, and is of no use to the cylinder but rather does it harm. We then see that the action of this lubricator is very imperfect, very irregular, and in point of fact nearly as barbarous as the old grease cup; nevertheless it has been brought widely into use, and maintains its position on account of its cheapness and simplicity.

Attwood’s tallow pump, patented in 1864, was a step in the right direction; though it has since been superseded by better means, it well deserves a notice. The body of the pump is provided with a steam jacket to keep the tallow hot, otherwise it is fitted like an ordinary pump with valves and piston, which latter is worked up and down by being connected to some reciprocating part of the engine. The point of attachment is made variable, to regulate the quantity of tallow injected. This apparatus ranks intermediately between the old-fashioned way of injecting the whole contents of the grease cup every two hours or so, and the modern way of continuously greasing the steam. It would even now be useful were it not for the often troublesome matter of keeping the valves in proper order and of arranging its connection to the engine, and for the circumstance that the engineer in charge is too apt to forget all about the tallow pump. Finding that it gives too much tallow if always at work, he throws it out of gear, and often forgets to throw it into gear till too late. Engineers in charge of flour mills and other works where the power is variable, sometimes say that a tallow pump is the right thing or else the old grease cup, because the engine often labours hard when the stones are pressed together a little too much, and a sudden injection of tallow is apparently beneficial, the engine at all events recovering its speed; a little consideration has, however, persuaded many of them that this view of the case is quite wrong. If such a quantity of tallow is required all at once, and does produce such a marked effect, what must be the state of the piston and other internal parts? The answer is, “very much too dry.” But this would never happen were the steam properly lubricated. There is no surer way of clogging the piston rings, &c., nor a more likely way of starting red-lead joints than by injecting a quantity of tallow at once. If a mill engine labours occasionally, the power is not large enough to overcome the resistance, and it is the wiser plan to improve the condition of the engine and thus increase its actual power, than by dosing it with what might be likened to a strong dram of neat spirits—all very well in extreme cases, but very bad taken habitually.

It will have been observed that all the lubricators hitherto described are regulated more or less by throttling the steam admission to them, a consequence of which is that the least dirt is apt, as experience has shown, to stop their action altogether. Within the last two years another lubricator, acting on the displacement principle, but yet working in a different way to the others, has been introduced. It is the invention of Mr. Gamble. The principle of this lubricator, shown in Fig. 6, is as follows:—The steam enters from the steam pipe, passes over the surface of the tallow, which it absorbs and retains in the shape of vapour charged with tallow; this is true as regards part of the steam, but the other part condenses and falls to the bottom. There is consequently a continuous charging of the entering steam with tallow, a continuous condensation of entering steam, and a consequent tendency to rise in the level of the tallow floating on the water. To restore store the equilibrium one of three things may take place. There may be a continuous return flow of vaporized tallow from or near the surface back into the steam pipe, and thence into the cylinder, or a continual flow of condensed water if it could be siphoned out from the bottom, or a continual flow of a mixture of both. In his latest modification Mr. Gamble has contrived a simple means of accomplishing the object, and at the same time making it a perfect means of regulation. The steam enters from one side through a pipe, and rises into the steam space; part of it falls to the bottom as water, while part of it may flow back as greased steam or vaporized tallow. The steam pipe, at its termination at the centre of the apparatus, has a small hole at the tallow level for the entering of the steam and the egress of the greased steam. The steam pipe has a siphon pipe screwed into its bottom reaching nearly down to the bottom of the lubricator. Into the inside top of this siphon pipe a small pipe, the regulating pipe, is screwed, which has a small hole in its side and has plenty of play round it when it passes through the steam pipe. If this pipe is screwed down so as to have the hole in its side at the same height as the steam or tallow hole, then singularly enough, no doubt owing to the capillary attraction, the water will take the preference and will continue to be siphoned out from the bottom as fast as it comes in and condenses, so that little or no lubrication takes place. On the other hand, if the regulating pipe is screwed up so that its hole comes somewhat over the steam or tallow hole, then no water will be siphoned out from the bottom, and a very plentiful lubrication with tallow takes place. In any intermediate position partly tallow and partly water will overflow into the steam pipe. This can be regulated to the greatest nicety. In one case, for instance, the engineer in charge said that if the lubricator emptied itself in ten hours, it would do. It was set to do it, and did it. He found that he had more tallow on his rods than he wanted. It was regulated accordingly, and then used its tallow in fifteen hours. He found that he had got more than enough lubrication even then, and it was accordingly set so as to empty itself in twenty-two hours. As the mill works twenty-two out of the twenty-four hours, that just suited him; he fills the lubricator once a day while oiling round, and does not trouble himself further about it, for it will just use its tallow by the time he has done. These lubricators will work in very hot engine rooms without special means for condensing the steam; the means of regulation are such as not to offer temptation for meddling, for the jam screw must be taken out of the top after the steam has been shut off; a small crutch key is fitted into the top of the regulating pipe, and by turning it a trifle up or down more or less tallow is fed into the steam. But there is no regulation by throttling the entering steam by means of the steam cock, and neither is there any regulation by contracting the opening for the overflow of the tallow. These lubricators are simple in construction, and they have no working or wearing parts that require looking after, or setting, or renewing; and when once regulated they are always set, no further trouble being incurred than to draw the condensed water off and fill afresh with tallow. As soon as the engine has started, its action begins at once. They are now working successfully on marine engines, locomotives, stationary and portable engines, and are made in suitable sizes for all purposes.

The same principle is carried out in a different way by another arrangement, shown in Fig. 7. As steam users sometimes ask for a lubricator with which they can at any time vary the supply of tallow, the inventor contrived this arrangement; the author contends, however, that this is quite unnecessary, except in very few cases. As before explained, if an engine is constantly and properly lubricated, there is practically no need for constant regulation of the tallow supply. It is made in the shape of a hollow plug cock passing vertically through the lubricator; the plug has several small ports with corresponding holes in the plug shell, which is fitted with a siphon pipe leading to the bottom of the lubricator the same as the others. To vary the respective vertical heights of the tallow overflow and water overflow, the plug has a slanting slot corresponding with a horizontal slot in the shell; and by turning the cock to any of the pointer divisions on the outside of the lubricator neck, these levels can be varied to such an extent as to cause the same action as above explained with reference to the former of Gamble’s lubricators. The same objection may, however, with justice be urged against this last arrangement as against some of the lubricators by other inventors which have been previously described, namely, that any cock arrangement in course of time gets out of order by constant wear.

The author has now, it is hoped, shown that steam lubrication is a subject well worth taking into account in steam engine economy; also that the continuous system is the only correct one, and ought to be more generally introduced wherever the old-fashioned and wasteful intermittent system has been found better than no lubrication at all. It is therefore important that engineers should more generally take notice of these facts, which form small links in the large chain of steam economy.

DISCUSSION.

Mr. P. F. Nursey said that in the paper which had just been read lubrication by means of condensed steam was credited originally to Mr. Ramsbottom, of Crewe. In 1858, Mr. Stirling, then of Kilmarnock, but now of Doncaster, read a paper before the Society of Scottish Engineers, in which he described a lubricator acting upon the same principle. The objection to the apparatus described by him was that there were no means of regulating the supply, and also that it required replenishing several times when the engine was running a journey. Next in the order of date came Mr. Ramsbottom’s lubricator, which was patented in 1860. In that, as Mr. Jensen had observed, Mr. Ramsbottom claimed the principle of lubrication by condensed steam. Now, it was quite clear that Mr. Ramsbottom could not claim anything of the kind, inasmuch as Mr. Stirling, whilst engineer to the Glasgow and South-Westem Railway, had some two years previously to Mr. Ramsbottom’s patent described a lubricator worked by condensed steam. Looking at Ramsbottom’s lubricator as represented in Fig. 1, it appeared to him (Mr. Nursey) that the objections to it were that it was partially inefficient, being constructed upon the same principle as that described by Mr. Stirling was, and it was open to the same objection—that there were no means provided for regulating the supply. The practical result of that was that sometimes the contents of the lubricator were emptied at one stroke. Following on, then, in the order of the paper, the next lubricator was Roscoe’s. That was fitted with a regulator and also with a central tube, which Mr. Jensen did not sufficiently explain. The air in the tubes was acted upon by the steam passing through the valves, and when the engine was running the action of the air imparted a constant motion to the lubricant and to the water beneath it, and so preventing it either stagnating or freezing. Then, when the steam was shut off, supposing the engine to be running down an incline, the sudden expansion of the air would drive some portion of the lubricant out of the chamber into the steam pipe and cylinder, and so afford a means of lubrication whilst descending the incline, when the steam would be shut off. There was a lubricator which had just come under his (Mr. Nursey’s) notice, and which was the invention of a Mr. Kessler. It was patented in 1866, and a wick was introduced into it, but it would only answer when the steam was shut off, as it was only to be used during that time. Mr. Kessler argued that no lubrication was required when steam was on, steam being a sufficient lubricant in itself. He (Mr. Nursey) thought, however, that the high-pressure steam used in the present day was so dry and so heated that it certainly required lubricating when the steam was on as well as when the steam was shut off—possibly more under the former condition. He (Mr. Nursey) therefore failed to see the great efficiency of Kessler’s lubricator. Gamble’s lubricator appeared to be—taken generally—a very efficient one; but when the author of the paper stated that inquiries were constantly being made for those lubricators—but they were required to be fitted with regulators—it appeared that there must be some inefficiency in the apparatus when worked without the regulator. It was either too delicate in its construction, or else it was too incomprehensible in its action; therefore the very fact of a regulator being required appeared to him to show that there was no great superiority in Gamble’s over Roscoe’s lubricator. With regard to the lubricator shown by Figs. 4 and 5, that seemed a little complicated and went back to the old principle. With respect to the entrance of dirt, he did not see why there should be any fear of that in Roscoe’s lubricator; in practice, he was not aware that the objection bad been raised. It was used on some thirty lines of railway in Great Britain and on a great number of railways on the Continent, and in America and Australia. Amongst other lines, he believed it was used on the North London Railway, and he hoped their President would be able to tell the meeting whether it was efficient or not—whether dirt entered it or not. In that lubricator the principle of regulation appeared to be very nicely adjusted. The engine driver could use either large or small quantities; and unless they opened the regulator to an unnecessary extent, there was no fear of the whole contents blowing off at once, as in some other lubricators.

Mr. Schonheyder said that the question of steam piston friction had been raised by the author of the paper; but he had not been able to make any actual experiments on friction; and although he (Mr. Schonheyder) did not doubt the accuracy of the author’s calculations as to the friction of the various parts of the engine, yet he thought it was a calculation which was very difficult to make and liable to very great errors. The state of the lubricant and the amount of friction in each case might be very different from what was assumed, and the result arrived at would therefore be very erroneous. It seemed to him that if the question was to be settled, the steam ought to be put upon one side of the piston, and apparatus upon the opposite side, by which the direct pressure required to move the piston could be measured. Without that they could not arrive at any accurate knowledge of the friction of various pistons. The author stated in his paper that the friction varied directly as the diameter, which was correct; but the author also stated that it varied as the width of the ring, which was not correct, for the friction varied as the total pressure upon the rings, because friction was independent of surface; in fact, so far it was independent of diameter, as the friction depended upon the total pressure upon the rings, and not upon the surface; and he did not see why it should be twice as great in a piston that had a 2-inch ring as in one that had a 1-inch ring, although the surface was twice as great, unless the pressure was twice as great also. Mention had been made of Ramsbottom’s packing rings, of which he (Mr. Schonheyder) had had some experience, and he found them wear exceedingly badly in some cases. In a great many instances the would not work for more than two months, in which time they were worn completely through. It was a difficult matter to set and adjust them so that they would wear equally. On the other hand, with a few engines, they lasted a great number of years. In one 16-inch cylinder engine they had lasted five years, working twelve hours a day; and in large engines, with about 52-inch cylinders, they had lasted as long as eight years. The great fault was that they were made too light, and their name was deceptive. They were made too light commonly called steel rings, but they were nothing of the kind, or at least it was a very peculiar steel; it would not harden if it was immersed in water after being heated to a bright red, and it would bend like soft iron. With respect to lubricating, it was the right thing to do, to grease the steam continually. Those lubricators that required a very fine adjustment were liable to be stopped up. He thought it was an advantage in Gamble’s lubricator that whichever way it was adjusted, all the passages were large, and none of them were diminished by the adjustment, and therefore they were not liable to choke. The grease ought to be introduced into the centre of the steam pipe, not on one side of it, so that it was at once enveloped in the steam, and carried away in a body.

Mr. Hodge said that the best method of lubricating stationary engines was to carry the oil in two cups, one on each side of the cross-head, and inject the one for one half the day and the other for the other half. A small tap was bored through the crosshead by which the consumption of oil could be regulated. He objected to the use of tallow, because it accumulated in the cylinder, and had to be removed from thence in a condition resembling glue, but which was really stearic acid, which became hard and choked up the cylinder and steam passages, the oleic acid being driven off by the steam pressure. A lubricating material had been introduced from America which answered well with high-pressure steam. It was a mixture of paraffin and common oil. He considered the best packing to be that made of Babbett’s metal in rings, which he had used with great success.

Mr. Olrick said that within the last few weeks a new material had been introduced for making friction surfaces, and by which means lubricators were dispensed with. He did not know the composition of the material, but it was stated that an engine with gudgeons of that material made 5000 revolutions a minute, and no lubricant whatever was used or required.