Chapter 3

Mr. Jabez Oldfield, of Glasgow, has the reputation of making the best and most reliable link belt in Great Britain. He has also the reputation of being the originator of these belts. This is, however, an error, the credit of the invention belonging, as we have said, to Mr. Roullier.

Mr. Oldfield, nevertheless, has invented many useful machines for cutting and assorting the links. He has also introduced improved methods for putting the links together.

For more than twenty years after Mr. Roullier's visit, nothing was done with leather link belting in this country.

In 1882, however, Mr. N.W. Hall, of Newark, N.J., patented a link belt, composed of leather and steel links. His method was to place a steel link after every third or fourth leather one, in order to strengthen the belt. In practical use this belt was found to be very defective, because the leather links soon stretched, and thus all the work had to be done by the steel links. The whole strain coming thus upon the steel links, they in course of time cut through the bolts and thus broke the belt to pieces. So this invention proved worthless.

In 1884 a Chicago belt company obtained a patent on another style of link belt. In this belt all the little holes in the links were lined with metal, similar to the holes in laced shoes. This produced an effect similar to that produced by Hall's patent. The metal lining of the holes cut the bolts into pieces by friction and thus ruined the belt. Therefore this patent proved a failure also.

After all these failures it fell to our lot to improve these belts so that they may now be worked successfully on our American fast running machinery. During the past two years we have made and sold over five hundred leather link belts, which are all in actual use and doing excellent service, as is proved by many testimonials which we have received.

Our success with these belts has been so surprising that we think we have found, at last, the long looked for "missing link," not in "Darwinism," however, but in the belting line. We prophesy a great future for these belts in this country.

How have we attained such success? First: We found that Roullier made a mistake in using leather offal, as, in the links of an _iron chain_, if one link is weak or defective, the whole chain is worthless, so in link belts, if one or two links are weak or made of poor material, the whole belt is affected by them. It is therefore of vital importance that only the best and most solid leather be used in making the links; second, the leather must be made very pliable, but at the same time its toughness and tenacity must not be injured, or it will stretch and break.

These things are of great importance, and are the principal reasons for the failures of all former efforts. The leather which Roullier used was stiff, hard, and husky. He believed that the harder the link the greater its tensile strength, but upon actual test this was found to be a fatal error.

Our leather links are saturated with a mixture of tallow, neatsfoot oil, etc. This makes them very pliable and increases their toughness, so that they will stand a strain three times as great as a piece of hard rolled sole leather.

In manufacturing this belt, the joining together is important. The links must be accurately assorted as to thickness, and the outer links countersunk, to admit the bolt. Then the most valuable improvement of all is our "American joint" (see Fig. 1).

By close inspection you will observe that it is absolutely necessary to use half length bolts for the width of wide leather link belts.

Examine Figs. 2 and 3. In the latter you will notice one length of bolt placed on a round faced pulley. That belt must either bend or break, and in any case it will not give satisfaction; but, on the other hand, examine Fig. 2; here two half length bolts are used, and ingeniously joined in the center. It gives just pliability enough to lay the belt flat upon the pulley. We experimented for some time before perfecting this important improvement.

We also took out four patents for different methods of joining, but abandoned them all and adopted the "American joint" system (Fig. 1) as the most efficient, simple, and reliable. It gives the belt an unbroken flat surface and is far superior to anything so far introduced for that purpose.

We have not stopped at _flat_ link belting, but have turned our attention to manufacturing round solid leather link belting, and believe that we have almost attained perfection in that line. As the illustrations clearly show, there is quite a demand for inch and upward solid round belting, and the difficulty always has been to join such a belt together. All steel hooks, etc., do not seem to satisfy. This, our new invention, is so simple that it hardly needs explanation. A belt of this kind can be taken apart in a short time, and shortened or lengthened at pleasure.

Now, Mr. President and gentlemen, I shall be glad to answer any questions in reference to these link belts, or give any further explanation you may desire.

Question.--Can these link belts be used on dynamos for electric lights?

Answer.--Yes. In England they are used almost exclusively on dynamos. However, they run only 700 revolutions per minute there, whereas our slowest dynamo runs 1,100.

Quest.--Would you advise link belts for high rate of speed?

Ans.--No; they give better results on slow running machinery.

Quest.--Have these belts any special advantage over flat leather belting?

Ans.--Yes, decidedly. When belts are run half crossed, or what is termed quarter turn, it is very hard to make flat belts lie perfectly even on the pulleys. These link belts, however, cover the entire face of the pulley (see illustration), and therefore are superior for that purpose.

Quest.--Why do they give better results when run slow?

Ans.--Partly because of their great weight over ordinary belting, also their grip power is stronger when run slow. No belt is superior to them for slow, hard working machinery.

Quest.--Are they more expensive than ordinary flat belting?

Ans.--Not when compared to the work they can accomplish.

Quest.--Can they be run in wet places, such as mines, etc.?

Ans.--Yes; by waterproofing the leather, no cement being used as in flat belts. The links can be made positively waterproof. We have furnished paper mills, tanneries and bleacheries, and other exposed places with waterproof link belts, and all have been entirely satisfactory so far.

Quest.--Can they be run on ordinary flat pulleys?

Ans.--Yes; our "American joint" link belt can be run on any straight or rounded pulley, whether made of iron, paper, or wood, and being all endless they run much smoother than other belting.

Quest.--How are they made endless?

Ans.--By a very simple process (see illustration), and takes almost less time than lacing a flat belt. All that is necessary is to take both ends and interlock the links, then pass the bolt through and rivet it, and when you wish to shorten the belt proceed likewise: File off the end of the bolt and take out, or add rows of links at pleasure and rejoin it again.

Quest.--What is the relative strength of a link belt compared to flat belting?

Ans.--Nothing definite has yet been ascertained. We are preparing a table showing results, and so far we can report that they can stand about twice the strain of double flat belts. A four inch link belt one inch thick is able to do the work of an eight inch flat double belt.

Quest.--Explain the advantage of your American joint over the English hinge.

Ans.--The American joint gives a perfect unbroken surface of entire width of belt, whereas the English hinge joint makes two half widths, and whenever a sudden change of power occurs and the belt runs half way off the pulley, it will catch at the edge and tear everything to pieces.

Quest.--Have you a table or schedule of their weight per square foot?

Ans.--Yes. The following is as near as we can estimate the weight of leather link belting per square foot:

1 inch thick, about 5 lb. per sq. ft. 7/8 " " " 4½ " " " 3/4 " " " 4 " " " 5/8 " " " 3½ " " "

Upon motion a vote of thanks was passed, and the paper read ordered to be printed.

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A NEW PROCESS OF CASTING IRON AND OTHER METALS UPON LACE, EMBROIDERIES, FERN LEAVES, AND OTHER COMBUSTIBLE MATERIALS.

[Footnote: Abstract of a paper read before the Franklin Institute, April, 1887.--_J.F.I._]

By A.E. OUTERBRIDGE, JR.

The art of making charcoal--if, indeed, so crude a process is worthy of being dignified by the name of an art--dates back to a remote antiquity, and has been practiced with but little change for hundreds of years. It is true that some improvements have been recently made, but these relate to the recovery of certain volatile by-products which were formerly lost.

Every one is familiar with the appearance and characteristics of ordinary charcoal, yet I hope to show you this evening that we still have something new to learn about its qualities and the unexpected practical uses to which it may be applied.

We commonly regard charcoal as a brittle, readily combustible substance, but we have before us specimens in which these qualities are conspicuously absent. Here is a piece of carbonized cotton sheeting, which may be rolled or folded over without breaking, and, as you see, when placed in the flame of a Bunsen burner, the fibers may be heated white hot in the air, and when removed from the flame, the material shows no tendency to consume. Here, again, we have a piece of very fine lace, which has been similarly carbonized, and displays the same qualities of ductility and incombustibility.

These carbonized fabrics may be subjected to much more severe tests with impunity; and when I tell you that they have been exposed to a bath of molten iron without injury, you will readily admit that they possess some qualities not ordinarily associated with charcoal. When removed from the mould in which they were placed after the iron casting had cooled, not a single fiber was consumed, but _upon the face of the casting there was found a sharp and accurate reproduction of the design, thus forming a die_. This die may be used for a variety of purposes, such as embossing leather, stamping paper, sheet metal, etc., or for producing ornamental surfaces upon such castings.

Some of the carbonized fabrics displayed upon the table are almost as delicate as cobwebs, and one would naturally suppose that when a great body of molten metal is poured into a mould in which they are placed, they would be torn to fragments and float to the surface even though they were unconsumed, yet such is not the case. I have found in practice that the most delicate fabrics may be subjected to this treatment without danger of destruction, and that no special care is needed either in preparing the mould or in pouring the metal.

By the aid of the megascope, the enlarged images of some of these castings, showing the delicate tracery of the patterns, will now be projected upon the screen, and you can all see how perfectly the design is reproduced.

In these experiments, the mould was made in "green sand" in the ordinary manner, and the fabric laid smoothly upon one face, being cut slightly larger than the mould, in order that it might project over the edge, so that when the moulding flask was closed, the fabric was held in its proper position. As the molten metal flowed into the mould, it forced the fabric firmly against the sand wall, and when the casting was removed, the carbonized fabric was stripped off from its face without injury. In this way several castings have been made from one carbonized material.

These castings are as sharp as electrotypes, whether made of soft fluid iron or of hard, quick-setting metal. This peculiarity is owing to the affinity between molten iron or steel and carbon. The molten metal tends to absorb the carbon as it flows over it, thus causing the fabric to hug the metal closely. It is somewhat analogous to the effect of pouring mercury over zinc. You know that when mercury is poured upon a board, it runs in a globular form, it does not "wet" the board, so to speak; but when poured upon a plate of clean zinc, it flows like water and wets every portion of the zinc, or, as we say, it amalgamates with the zinc. So when molten iron is poured into an ordinary sand mould, which has been faced with this refractorily carbonized fabric, it wets every portion of it, tending to absorb the carbon, and doubtless would do so if it remained fluid long enough, but as the metal cools almost immediately, there is no appreciable destruction of the fibers.

The casting which I shall now exhibit represents a very interesting and novel experiment. In this case, the piece of lace, having open meshes a little larger than a pin's head, instead of being laid upon one face of the mould, was suspended in it in such a way as to divide it into two equal parts. Two gates or runners were provided, leading from the "sinking head" to the bottom of the mould, one on each side of the lace partition. The molten iron was poured into the sinking head, and flowing equally through both runners, filled the mould to a common level. The lace, which was held in position by having its edges embedded in the walls of the mould, remained intact. When the casting was cold, it was thrown upon the floor of the foundry and separated into two parts, while the lace fell out uninjured, and the pattern was found to be reproduced upon each face of the casting.

The question naturally arises, Why did not the iron run through the holes and join together? The answer may be found in the fact that the thin film of oxide of iron, or "skin," as it is popularly called, which always forms on the surface of molten iron, was caught in these fine meshes, and thus prevented the molten metal from joining through the holes. I have repeated the experiment a number of times, and find that the meshes must be quite small (not over one fiftieth of an inch), otherwise the metal will reunite.

I think that this observation explains the cause of many obscure flaws found in castings, sometimes causing them to break when subjected to quite moderate strains. We frequently find little "cold shot," or metallic globules, embedded in cast iron or steel, impairing the strength of the metal, and it has long been asked, "What is the cause of this defect?" The pellicles have been carefully analyzed, under the supposition that they might be alloys of iron and nickel, or some other refractory metal, but the analysis has failed to substantiate this theory. Is it not probable that in the process of casting, little drops of molten metal are sometimes splashed out of the stream, which immediately solidify and become coated with a skin of oxide, then falling back into the stream of rapidly cooling metal, they do not remelt, neither do they weld or amalgamate with the mass, owing to this protective coating, thus forming dangerous flaws in the casting?

The process of carbonizing the delicate fabrics, leaves, grasses, etc., is as follows: The objects are placed in a cast iron box, the bottom of which is covered with a layer of powdered charcoal or other form of carbon, then another layer of carbon dust is sprinkled over them, and the box is covered with a close fitting lid. The box is next heated gradually in an oven, to drive off moisture, and the temperature slowly raised until the escape of blue smoke from under the lid ceases. The heat is then increased until the box becomes white hot. It is kept in this glowing condition for at least two hours. It is then removed from the fire, allowed to cool, and the contents are tested in a gas flame. If they have been thoroughly carbonized, they will not glow when removed from the flame, and the fibers may even be heated white hot before consuming.

Of course, the method employed to carbonize the materials is suspectible of variation, but the scientific principles involved are unchangeable, viz.:

(1) Partial exclusion of air and substitution therefor of a carbon atmosphere.

(2) Slow heating to drive off moisture and volatile elements.

(3) Intense and prolonged heating of the partly charred objects to eliminate remaining foreign elements, and to change the carbon from the combustible form of ordinary charcoal to a highly refractory condition.

NOTE.--Fig. 1 is photographed from a white iron casting made upon carbonized coarse lace; the lower portion of the plate shows the lace embedded in the iron. Fig. 2 is a casting in gray iron upon lace laid on an iron plate. Fig. 3 is a casting in hard iron upon lace laid on dand. Fig. 4 is a casting in gray iron upon a piece of thin summer dress goods with machine embroidery.

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RECENT PROGRESS IN GAS ENGINEERING.

At the recent meeting of Scottish gas managers Mr. A. Macpherson, of Kirkcaldy, the chairman, said:

THE REGENERATIVE SYSTEM OF RETORT FIRINGS.

For me to attempt, with the time at my disposal, to do full justice to many important points which have cropped up since our last meeting, and which will, no doubt, have been engaging your individual attention, would be impossible. But I think there can be no doubt that, although at our last meeting we had a very full and interesting discussion on the different systems of regenerative retort settings, still we might very profitably spend a little time to-day in hearing the experience of those who have had some of the systems introduced into their works since then, or who may have gained further experience with the system they were then working, or have introduced improvements or modifications thereon.

For the purpose of inducing a discussion on this subject, I will give you the result of the working of the bench of retorts which I erected three years ago on the Siemens system. As I stated last year, my experience up to that time had not been altogether a happy one, but one of sunshine and cloud alternately. I am glad to be able to say, however, that since then I have had nothing but the utmost satisfaction in the working of the regenerative settings. The chief difficulties I have before experienced were of a mixed nature--choked ascension pipes, entailing considerable loss of gas; the choking of the orifices from which the secondary heated air issued to join the producer gas; and the eating away, in a "scooped-out" sort of fashion, of the brick lining of the producers at the points where the primary air entered. These, I am pleased to be able to say, I am now completely clear of; and this has had the effect of converting what was before a considerable source of annoyance and anxiety into as perfect a working bench of retorts as any one could desire.

The results I have obtained have caused me much surprise, being far in excess of anything I ever anticipated; and the saving effected will materially assist in compensating for the greatly reduced value of residuals. I may state that I have used 30 per cent. of fuel on an average, saved from 25 to 30 per cent. on stokers' wages, and increased my production of gas per ton of coal; while the regularity of the heats was a pleasure to look upon.

As showing what I have been able to accomplish, I will give you a few details. I was able regularly to produce 10,000 cubic feet of gas per mouthpiece in 24 hours--the size of my retorts being 18 by 13 inches by 9 feet long, inside measure; and on a sudden dullness coming on, with an increase of first class cannel I produced from 33 retorts 357,000 cubic feet, or at the rate of 11,500 feet per mouthpiece in 24 hours. With 32 retorts I made as much gas as would have required 42 retorts to produce on the old system. But I know that even this can be excelled; and I am aware that there are works where, by the introduction of retorts measuring 21 by 15 inches, instead of 18 by 13 inches--and which, I may say, can be put quite easily into the same arch--a production of 12,000 cubic feet per mouthpiece can be obtained. This will, of course, still further reduce the cost of production.

With such an experience, gentlemen, I think it is almost needless for me to add that I am a strong advocate of the regenerative system. I have often heard it asked, "But can the system be profitably adapted to small works?" In answer to this, I will say I have proved that it can. During last summer the manager of a small gas works in my neighborhood called on me regarding the working of this system, and expressed a desire, if it was at all possible to adapt it to his present settings without much expense, to try it. I must say I admired his progressive spirit and pluck; and, after a somewhat lengthy conversation with him, during which I gathered the full details of his working and his requirements, I determined to encourage him in his desire to prove if it could be successfully applied to a works of the size mentioned. The present setting consisted of three [semicircle] retorts in one arch; and one of his stipulations to me was: "You must so contrive the setting that if it should prove a failure I can reconvert it into the old system in a few hours." I at once saw that the stipulation was reasonable, or he might be caught in a fix in midwinter. But, with true "Scotch caution" and forethought, he was, while anxious to experiment, determined not to be "caught napping." After some consideration, I prepared a sketch for him of how I thought it could be done, and at the same time comply with his stipulation; and having received full explanations, he set about it, and has had it working now for something like six months. His experience has been somewhat similar to that of most of those who have gone in for the new system. It did not answer very well at first. But after a little manipulation and experience in the proper working and management, it is now acting in first rate style, and is saving fuel, with better and more regular heats; and this although it is not constructed in such a way as to yield the best possible results, owing to the before mentioned stipulation having to be considered and allowed for in construction.

In answer to an inquiry I made the other day, the gentleman referred to informed me that he has now had this setting in operation for six months. He has three retorts, 14 by 16 inches, and 8 feet long, in an oven carbonizing 2 cwt. of coal every four hours; the heats are higher and more regular; and the retorts easier kept clear of carbon. The coke drawn from the top retort is sufficient for fuel. My oven would hold four retorts; and the same fuel would heat this number just as well as the three. I used only the coke from Cowdenheath parrot coal for this setting; but had to mix it with Burghlee coke for the old system of setting.

No doubt most of you will have noticed the satisfactory results obtained by Mr. Hack, of the Saltley Gas Works, Birmingham, and by Mr. McMinn, of Kensal Green, with the furnaces employed by them for gaseous firing without recuperation, whereby they are enabled to save fuel and carbonize more coal per mouthpiece than with the old system. Still they admit that the saving by this setting is only in fuel, with increased production, but without any economy of labor--one of the points in favor of regenerative setting being a saving of at least 25 per cent. in the latter respect. Even where regenerative settings cannot be had, I think the system of using gaseous fuel is well worthy the attention of managers; the expense of altering the existing settings to this method being very small.