cut-off; diameter of drivers, 673"; area of throttle valve, 14 sq. in.; Allen valve, outside lap, 1"; inside clearance, 3.

Vertical lines at end of diagrams show volume of clearance.

a tachometer attached by belt to back axle.

Speed taken by

Engine 355, same as 476, with following exceptions: Lead," in the 20" cutoff; diameter of drivers, 573"; area of throttle valve, 28 sq. in.

SYNOPSIS.

The single-exhaust nozzle shows a better smoke-box vacuum than the double nozzle, but it also shows more back pressure, owing to steam passing over into the other cylinder.

The economy of working engine with short cut-off and wideopen throttle is clearly illustrated, showing a saving of twentythree per cent. for the short cut-off.

The efficiency of the Allen valve is very apparent, it showing a gain in power of twenty-eight per cent., in 6" cut-off, over the plain valve, with a slight gain in economy. In this comparison the Allen valve is at a disadvantage, as engine 476 had less lead and a very small-throttle valve.

CCCXLVII.

BITS OF ENGINE-ROOM EXPERIENCE.

BY LEWIS F. LYNE, NEW YORK CITY.

(Member of the Society.)

ABOUT the middle of the year 1888 I had charge of a Buckeye engine, in which a mysterious pounding noise one day appeared. It proved upon examination to be in the cylinder, and was caused by the packing-rings striking against a shoulder which had been

worn at each end of the bore. How this occurred will be quite clear from an inspection of Fig. 161, which represents a longitudinal section of the cylinder of an 18" x 36" Buckeye engine. The shoulder is represented at AA, and it was formed in this wise: The piston packing was of the type shown in Fig. 162, where A represents a cross-section of the cylinder and B the piston. The two piston packing-rings were cut to break joints, and occupied a groove 7" wide in the center of the piston, as shown at C. It will be seen at once that these rings do not travel the entire length of the bore, but stop in this case 1" short at each end, as shown by the dotted line D.

From the center, E, upward, this shoulder was worn quite sharp, while from E downward the shoulder was less marked, for the reason that the pistou wore the bottom of the cylinder, as shown by the dotted line extending from E downward. An exaggerated case is shown by the dotted lines in the cross-section of cylinder, A. The Buckeye company, I am glad to learn, have abandoned this style of packing, and now use spring rings similar to those that I put in place of the kind removed. These rings were " square, and traveled over each end of the bore", as shown by the dotted lines FF. To put this packing in, the shoulder shown at AA had to be removed. It was a comparatively easy matter to file off the

shoulder at the back end when

Fig. 162.

the head was removed; but to file off a belt of cast iron 14" wide, " thick, and 56.70" long, in the crank end of an 18" x 36" cylinder, is not such an easy job. This engine had to run every night, starting at 4.30 P.M. and stopping at 6.30 A.M.; so it will be understood that the cylinder did not have time to cool make the interior a very desirable place to work in. The way we did it was this: A rod, B, of "round iron was provided with an eye turned on one end, to slip over the offset file-handle C., generally used by machinists for filing flat surfaces. This rod was left sufficiently long to reach outside the cylinder as shown, so that a workman standing close to the end of the cylinder, at D., could work the 14" bastard file which was used on this occasion.

sufficiently to

I used what is known as a safe-edge file, on account of its having a broad end, thus giving more surface for cutting. I had an old rubber spring which was cut in two; then, with a tenpenny nail, one half of this spring was fastened to the end of a broomstick, as shown at E. The broomstick was sawed of a proper length, so that, when placed across the cylinder inside, a sufficient pressure could be thrown upon the end of the file. We were now ready for business; so a sperm candle was placed in a 3" hexagonal nut, and after being lighted was placed close to the head of the cylinder. A rubber hose was attached to a common bellows, and supplied fresh air through the stuffing-box. In just two and a half hours from the time of commencement, the shoulder at this end of the cylinder was removed. Any one who has ever undertaken to work a file

inside of an 18" cylinder can readily appreciate the pleasure I experienced in lying inside that cylinder and guiding the file, while the workman outside furnished the motive power. To be sure, the temperature inside was high; but we all get used to that in working around steam-engines and boilers. The engine was ready to start on time, so no delays occurred in consequence of the work we had to do. Most people would have bored out that cylinder; but it did not need it, as the bore was in fine condition but for the shoulders at the ends.

While I am on this subject, I cannot refrain from condemning all forms of piston packings which do not wipe over the entire ends of the bore, to avoid the slightest possibility of wearing a shoulder.

I remember an instance that happened on a tugboat in 1882, where a 20" cylinder was split the entire length because the pistonrings wedged against a shoulder worn at the end of the bore. The engineer had been taking up the main-rod brasses the day before, and in so doing the rod was lengthened so that the packing-rings, which were of the old-fashioned spring type, being stuck fast, split the cylinder as described. If the rings travel over the end into the counterbore there is no possibility of such an accident. I never could ascertain why any engineer could design cylinders so that shoulders could be worn at the ends. I mean this to apply to pumps of all descriptions, and air compressors, as well as to steamengines; for I have met and remedied this same difficulty time and again in overhauling various kinds of machinery. I remember on one occasion, where the cross-head gibs on a certain steam-engine were adjusted when the piston stood at half stroke, there was a shoulder worn on each end of the guides, so that, when the engine started, the cross-head was split open when it reached the shoulders. So it will be seen that this principle applies not only to cylinders, but to guides as well. In short, where there is reciprocating motion, great care should be taken to have the gibs or slides wipe over, to prevent the formation of shoulders. To be sure, such instances are becoming more rare, on account of the better diffusion of practical knowledge through our technical schools; but there are hundreds of steam-engines and pumps where these shoulders should be taken off and recesses cut in their places. I visited a machine-shop the other day, and saw a newly designed automatic cut-off steam-engine in which the cylinder had no counterbore at all, the bore being straight through from end to end. I asked the designer why it was, and he gave an evasive answer,

treating the matter as of little consequence. While I am so near the stuffing-box, let me say that since there are people in this world who will still persist in using fibrous packing-why cannot we have a good, respectable-sized stuffing-box to put the packing in? There are many steam-engines in the market to-day which are well designed otherwise, and represent the crystallized practice of many years, and yet are almost destitute of stuffing-boxes. Some people argue that, with large stuffing-boxes, ignorant engineers will fill them with packing and screw them too tight, thereby losing work through unnecessary friction. Grant it; but if people will persist in hiring ignorant engineers to take care of their engines, should they not bear the consequences? and is this a sufficient reason why the intelligent engineer should be deprived of a properly proportioned stuffing-box? Engines should be designed so that intel. ligent men will not be compelled to put less than one-half the packing required into a stuffing-box, then screw it up until the piston-rod, after a week's run, more resembles a fluted column than anything else. This is no exaggeration; for it was only the other day that I saw a new engine in which the valve-stem had to be packed every week, when it ought to run at least two months.

A common mistake is made in turning valve-stems of a uniform diameter throughout, so that, after they have been in use a year or so, one has to either throw away the stem and get a new one, or resort to some such wrinkle as I am about to describe. The valvestem, as it wears, assumes the form shown in Fig. 163, so that it is. entirely out of the question to keep it tight except at each end of the stroke, where it jams so tightly that one is in danger of tearing some of the valve motion apart. I once knew a locomotive rockarm to be sprung" out of its original shape by screwing the packing too tight on a badly worn valve-stem.

A valve-stem of the kind first described became badly worn upon an engine under my direction, and its shape very much resembled Fig. 163; so I put it in a lathe and trued it up, letting the