The following text may have been generated by Optical Character Recognition, with varying degrees of accuracy. Reader beware!

g = MARINE REVIEW. STEVENS VALVE GEAR FOR MARINE ENGINES. ITS ORIGIN AND USE IN THIS COUNTRY.--A VALUABLE CONTRIBUTION TO MARINE ENGINEERING HISTORY FROM THE VENERABLE FRANCIS B. STEVENS. A paper read at the recent meeting of the American Society of Me- chanical Engineers in New York deals with the origin and introduction of the Stevens valve gear for marine engines. It was thought that the ven- erable Francis B. Stevens would be present at the meeting, and there was general regret upon learning that he was unable to attend. The paper was by Andrew Fletcher of the W. & A. Fletcher Co. "It has been urged upon me" Mr. Fletcher says, "that the transactions of the American So- ciety of Mechanical Engineers should contain some record of the origin and introduction of the form of valve gear for beam engines which 'has grown to be so general in the side-wheel practice of the marine engine builders of the United States, and of which the firm with which I am con- vected has been for so many years an advocate. I have thought that this could best be dome by getting from Mr. Francis B. Stevens a communi- cation to me in which this history should be included, anid which I might illustrate by drawings from more recent practice. Accordingly the com-~ munication is appended herewith, and the drawings are self-explanatory. I may be permitted to add that Mr. Stevens is eighty-seven years of age, and is still an enthusiast upon steamers of all kinds. My own connection with his form of valve gear began forty-four years ago, with my first con- niection with the old firm of Fletcher, Harrison & Co., during twenty-seven Fig. 6. Toes:and' Wipers for Stevens Cut-off, {| Steamers Albany and New York. ~ ; 2 =u Abzig ---------- = <1" Position of Wy, . ciel ee : é : aaa a greater angular motion of the rock shaft, and consequently a shorter cut-off, could be obtairied. "We then agreed to take out a patent in our joint names, with the understanding that I was to have complete owner- ship of the patent. And in April, 1840, I made the drawing that accom. panied the patent, a copy of which, on a reduced scale, 1 annex. The patent was granted on the 25th of January following, the claims being as follows. First--Combination of an additional and separate eccentric wheel to work a rock shaft to raise the steam valves in combination with any of the several methods hitherto used for working the exhaust valves. Seconid.--The manner in which the toes are affixed to the rock shaft so that the shaft is made to vibrate during a certain interval, without either toe communicating motion to either valve. Third--The connection of the cog wheel and rack in the manner set forth, for the more completely effecting our object. This connection was never used, being found un- necessary. The patent was renewed in 1855 and expired in 1862. Its validity was never attacked, and none of its claims was infringed during the twenty-one years of its existence. Since it expired, separate eccen- trics for the steam and exhatist valves have been frequently applied in combination with the Sickels. the Allen and other cut-offs. In the course of the year 1840 I applied the cut-off to the engines of eight steamboats, namely, the Albany, Columbus, Rochester, De Witt Clinton, Independence, Swan, and two steamboats on the Delaware; and shortly afterwards I sold a half-interest in the patent to my father, James A. Stevens. In the year 1842 the Stevens cut-off was applied to the engine of the United States steamer Fulton the Second, and afterwards to the greater portion of the padidle-wheel vessels of war of the United States | Erg. 5. Toes and Wipcrs for Stevens ae K Steamers Albany and New Yor QO ») . SIZIN/Z 7 of : taal pes aMis eel ; U Hat + ; at i | | geet lye ; Ba s ee La > a > Wie ---_ aa : ti | i a eee ee : eo! WX oN years; W. & A. Fletcher for three years; and the W. & A. Fletcher Co., forthe past fourteen years.' The letter of Mr. Stevens to Mr. Fletcher follows: My dear Mr. Fletcher:--In answer to your request, I send this letter in relation to the Stevens cut-off. Previous to its introduction in the year 1840, the form of valve and valve gear in almost universal use on the' steamboats navigating the rivers and bays of the Atlantic coast was by poppet valves, operated by a single eccentric and a single rock shaft, the admission and exhaust of steam being coincident. Expansion was effected by a butterfly valve on the steam pipe worked by cams on the shaft, which was called the camboard cut-off. On the Mississippi, at the date men- tioned, the engines were the same as at present in use, having poppet valves worked by cams on the main shaft. In the latter part of the year 1839 I invented the Stevens cut-off, and early in the year 1840 I had the machinery for its application on the en- gine of the steamboat Albany made. This vessel was owned by my father, and the machinery was made by H. R. Dunham & Co., North Moore Street, New York, where you served your apprenticeship. As the work was not finished until after the opening of navigation on the Hudson, I" was unable to attach it to the engine until the following August, when the Albany was laid up for repairs at Cold Spring, opposite West Point. Anid in the interval I had similar machinery of smaller size made 'by the firm mentioned, anid put in operation on the engine of the steamboat Colum- bus, owned by my uncle, Robert L. Stevens. The engine of the Albany had a cylinder 65 inches in diameter and 9 feet stroke. That of the Columbus was 40 inches diameter by 12 feet stroke. The cut-off as first applied was essentially the same as at present. On the Albany, the length of the toes was 26 inches and the lift of the valves was 514 inches. On submitting to my uncle, Robert L. Stevens, my model of the cut- off, made on a scale of 1% inches to the foot, he proposed an improve- ment, by substituting a cog wheel for the arm of the rock shaft, by which navy. In 1845 it was applied to the steam frigate Missouri: The contract for it, made by my father and myself with the navy department, required that the cut-off should be made adjustable while the engines were in mo- tion. Tio effect this, devices made at the works of H. R. Dunham & Co. were applied to quickly change the angle of the toes, the position of the arm pin, and the lead of the eccentrics. This vessel was the flagship of Commodore Berry's squadron on the famous expedition to Japan in 1853- 04. And Mr. Daniel B. Martin, afterwards engineer-in-chief of the United States navy, reported that this adjustable cut-off worked perfectly during the whole cruise, lasting about two years. The cut-off has been made ad- justable on river steamers by this and other plans; but the advantage gained has not been considered equivalent to the increased complication of the machinery. Previous to and during the Civil War, the cut-off was on many large ocean steamers. The advantages gained by the Stevens cut-off over the camboard cut- off were: First, the saving of a portion of the steam in the space between _ the butterfly valve and the main valves; secondly, the use of two eccen- trics allowed the lead of the exhaust valve to be greatly advanced, by which a quicker exhaust was obtained, and also the reversal of the strain on the piston at the end of the stroke was more gradual and with less jar on the bearings. The Stevens patent, whether under the combined first anid second claims or under the first claim alone, can be said to have been in universal and exclusive use on all beam-engine paddle-wheel steam- boats in the United States since the expiration of the patent thirty-five years ago. Of late years the substitution of the screw, with its quick- moving engine and slide valve, has superseded the paddle and poppet valve on the ocean; and also in great part on the rivers of the Atlantic coast, and on the great lakes. I add the following account of the early use ot the expansion of steam and of the valves used on the Atlantic seaboard. Watt, the creator of the steam engine for uses other than pumping, was the first to conceive the idea of utilizing the expansive action of steam