LOCOMOTIVEFIREBOXES.

Paper read before the Institution by Mr. SMITH MANNERING, Member, Brighton, December 9th, 1916.

DISCUSSION. Mr. W. A. Lelean: \Ye haxe all listened with the greatest interest to this very practical paper. It will be a most useful contribution to our proceedings. The paper contains such a number of matters for discussion that I am anxious not to take up any of the time of the meeting at the outset and at once, therefore, invite any remarks or criticisms. Mr. R. P. C. Sanderson: Gentlemen,-I would like first to have heard from the English railway men before saying anything myself, because the paper deals largely with cop- per boxes, but in the sixth paragraph of Mr. Mannering’s very interesting paper on firebox construction and main- tenance, he refers to fusible plugs and apparently is desirous of learning other people’s experience. Perhaps I may be able to give some information of interest from my past experience in railway service in the United States. Years ago it was almost universal practice to use fusible plugs in all locomotive crown sheets. Several cases of burned and dropped crown sheets occurred with plain evidence of “ no water,” where the fusible plug was found still intact (un- melted) in the sheet. In the course of the following in- vestigations it was ascertained that :- The new plugs melted at the right temperature and quickly. The old plugs were reasonably clean, the records showing that they had been periodically removed, cleaned and replaced. The melting point of the metal in the old plugs was very high (as I recall it a little above a dull red heat in some cases). Other plugs removed showed varying melting points ranging from normal upwards. Examinations for the muses of this last, made by our

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 IAOCOMOTIVE FIREBOXES-MASSEHI~O. 37 chemist, at first showed no sufficient reason for the varying melting point, but on closer analysis it was found, if I remember correctly, that the zinc in the alloy was oxydized and that the oxide or mixture containing the oxide had a higher melting point than the alloy. The lesson learned from this, confirmed by the experience of others, was that fusible plugs to be effective can only remain in service a certain length of time, or until this-let us say-change of nature in the zinc ingredient of the alloy begins, after which the plug is no longer reliable for its intended purpose and should be removed. The old alloy should then be melted or drilled out and replaced with fresh alloy. I would like, amongst ourselves, to say further, that at thAt time I held the position of Division Master Mechanic of a railroad, and, in trying to discipline the men for neglect of duty in allowing the crown sheets to be bare, I was met first by the committees with the response that, because the fusible plug had not melted the crown sheet could not have been bare, and, in other cases, because the fusible plug did melt and the crown sheet did not come down, that the water was still there; they used it both ways. The use of fusible plugs was gradually discontinued, partly for the above reason, coupled with the difficulty involved in the constant replacement and supervision, but partly also because of the danger connected with their use. In locomotives with large boilers having grates above the frames-I am speaking now of boilers with grates of any- where from 50 to 80 square feet-therefore having shallow fireboxes and large grate areas, the fusible plug when it does “go” does not put the fire out, but the steam (not water-the high pressure water flashes instantly into steam) produces a plenum in the firebox and blows the fire out 01 the fire door into the faces of the men who are working to extinguish it. If, to prevent this, they put on the blower, this serves to foan the fire that they are making every effort to extinguish. It was my privilege to conduct a long series of tests with various forms of fusible plugs and low water alarms. Attempts were made to utilise a cupshaped plug so that when the water level dropped below the rim of the cup, the water contained in the cup would rapidly evaporate, baring the fusible metal in the bottom of the cup. It was hoped that this would blow before the water was lost off the crown sheet, and the rim of the cup would hold back what water there was, thus giving time to extinguish the fire. Other tests were made with fusible devices arranged so that when

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 38 JOURNAL OF THE INST. OF LOCO. ENGINEERS. the cup emptied itself, melting the fuse, an alarm whistle or jet of steam in the cab manifested itself before the crown sheet was actually bared. As a result of about a year's continuous work, every device of the kind proved unreliable under necessary conditions of hard service and all were abandoned. As in American practice it is almost universal custom to slope the crown sheets back from three to six inches, ac- cording to length, fusible plugs in the back would be of no service whatever. The arched crown sheet with radial stays is safer than the flat crown sheet when the water is allowed to get too low. A flat crown sheet is bared all together, and becomes overheated over a considerable area simultaneously, and " lets go " altogether with more or less explosive violence even when sloped backward. In the case of an arched crown sheet, also sloped, the crown of the arch at the front becomes overheated, " letting go " before too large an area of the sheet is overheated, so that the damage is localised, with results of a less dangerous character. Some mechanical men made a practice of distributing amongst the button head crown bolts a number of bolts with small hammered heads, the intention being that these would let go on being overheated, before the bolts with the larger heads, thus giving warning and relieving the pressure with- out explosive violence. It was then found easier to straighten up the crown sheet in place by the use of heat and clamps. So far as the endurance or life of fireboxes is concerned, I do not know anything of the life of copper fireboxes, because during my whole railway experience, from 1882 up to 1910,I never saw nor knew of one being used in the United States. The life of steel fireboxes varies very mn- siderably, largely depending on the character of the water used, but always affected also by the original design and the care in maintenance. In very bad artesian deep well water districts, I have known fireboxes to require renewal in six to eight months. In good water districts, with proper care, I have known fireboxes that were in service over twenty years with' original flue sheets. Certain engines recur to my mind that retained their original fireboxes in a bad water territory, in good working condition, although patched, for about sixteen years ; while many of the other engines of the same lot, built of the same materials at the same time and precisely of the same design,

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 LOCOMOTIVE FIREBOXES-MANNEBING. 39 had to have their fireboxes renewed in less than half the time. The cause of this difference lay solely with the washing. Some very remarkable results were once obtained by using an intermediate sheet between the firebox plates and the boiler shell-plates, thus dividing the side water spaces so that there was rapid up-rush of water and steam next the firebox plates and down-rush next to the outside. The firebox plates nemained remarkably free of deposit although particularly hard to wash and the fireboxes lasted unusually well. The experiment was never repeated because of the excessive staybolt breakage caused by the presence of the intermediate sheet. Many of the bolts were found broken in three pieces. So far as the influence of superheating on firebox endurance is concerned, it means in the last analysis that with the superheat one can do just so much per cent. more work per pound of steam; that is, per pound of water evaporated; consequently there is just that mich less sedi- ment and scale in the boiler to shorten its life. This should be far more noticeable in bad water districts than in good water territories. I can most heartily endorse what the author says con- cerning the favourable effect of pkcing the feed inlet to the boiler on the top and near the front. As far back as 1905 I began using Nathan double top check valves, which had been much used before that time by others. The results were so noticeably good that the practice was continued up to the end of my railroad service in 1910. We have as far as possible avoided all forms of internal feed pipes in American practice. Such pipes will get choked up, and this means more cost for maintenance. Also the cardinal principle of American locomotive design is " get- at-ableness." Nothing should be inside that can be placed outside. Staybolts and boiler stays in general in American loco- motive practive are very commonly made of high grade iron-steel is seldom used. We prefer a material for boiler stays that will fail as a wire rope fails, gradually, strand by strand, giving time for discovery before fracture is com- plete, rather than steel or homogeneous material wherc, when a fracture once starts, it extends through the entire section with a few bendings, giving way more suddenly. These iron stays are almost universally turned down between the sheets so as to promote flexibility and to avoid points for starting fractures or localisation of bending points. The flexible staybolt has, however, become a permanent feature of American locomotive boiler practice, and from

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 4" JOC'HNAL OF THE: ISST. OF 1,OCO. EXGINEERS person:il knowledge, covering many locomotives in bad and good water territories during many years, I can say that th,ere is no one thing that has done more to reduce the number of broken staybolts and the cracking of firebox sheets than the use of the hinged or flexible bolt, and I wonder that it is so little used in this country. The general practice in crown staying, whether for Belpaire or radial stayed crowns, is to use a Crown stay rod having a button head on the lower end associated with a taper thread in the crown sheet. The practice is to screw these in so that they should just come steam tight on the taper thread about half a turn or so before the button head comes up tight against the sheet. Then when given the extra half or three-quarters turn to bring the head home tight on the sheet a first class job is obtained. No copper or other washers are necessary, nor are nuts of any kind used on crown or firebox stays. Girder bars for crown sheet supports, except those specially designed as T-bars and flexibly slung from the roof for the first one or two rows of crown bolts to allow freedom for the tubeplate expansion upwards, are never used in modern American locomotive boiler practice. We con- sider it an obsolete method of crown sheet support that throws unknown strains on the boiler parts. As far as possible, boiler bracing should be designed so that each part will be strained in direct tension only and so that the strains imposed on any brace or stay can be calculated with reasonable certainty. While on this subject of firebox staying, I would par-. ticularly direct attention to the recently published results of extensive experiments on the New York Central Railways, conducted by Mr. D. R. MacRain, Superintendent of Motive Power, in which it was most clearly demonstrated that there was a distinct advantage in arranging for 1/32in. to 1/16in. slack in all the stays and braces supporting those parts of locomotive fireboxes most subject to expansion and con- traction. The art of oxy-acetylene and electric arc welding has also made ii wonderful difference in the maintenance of steeI fireboxes. Bad places, even up to half sheets, can be cut out of steel fireboxes and new pieces welded in without any seams, rivets, or double thickness metal, thus lengthening the life of fireboxes that otherwise would have to be entirely renewed. In the designs of some new fireboxes with long corn- bustion chambers, advantage is taken of this art of welding by oxy-acetylene or the electric arc, and the side sheets of

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 LOCONOTIVE FIREBOXES-MANNERING. 4r the boxes are welded up so as to do away with riveted seams that would otherwise be apt to give trouble by wasting away or cracking. In some recent cases the entire fire- boxes have been welded along the caulking edges of the seams. Some railway engineers have recently required that the steel or iron boiler tubes should be welded into the tube- phtes. In such cases, of course, copper ferrules are not used and the subsequent use of the flue roller or tube ex- pander is entirely obviated. The purpose of all theso changes is to keep the engine in service and earning money instead of having her in the shops costing money. Just in conclusion, { notice Mr. Mannering mentions only one type, although a very good and largely used type of flexible bolt. While not interested in the sale of such things, I want to call attention to another type of flexible bolt that has recently come to the front, known as “The Flexible Rolt,” which has many advantages over the type of flexible bolt having separate bushings, caps, etc. I thank you for the opportunity of making these few remarks. Mr. J. Clayton: Mr. Chairman,-I have been ex- tremely interested in the very practical paper put before us this afternoon, which indeed does the author great credit, and I was more than interested, too, in the remarks thereon by the previous speaker. It is not often we get into touch in this country with people who have had actual experience of American practice ; and, just at the present time, Ameri- can practice in the use of steel fireboxes is coming very much to the front, owing to the great difficulty in obtaining, as easily as formerly, copper plates. It is good to hear that the steel firebox is really a practical proposition from one who has had actual close contact with them. I feel per- sonally somewhat relieved because we are concerned at the present time on the railways, in this country, with the installation of steel fireboxes, and it is comforting to know that it is really a safe proposition in America under a11 conditions. The question of fusible plugs has been raised, and, in this country, of course, we always say, ‘‘ Safety first.” Although the fusible plug has its shortcomings, it seems better to adopt it as being very little trouble to apply, and it may answer the purpose for which it is intended. It has often answered the purpose of calling attention to likely trouble, for if only well looked after-and that is the essen- tial point (neglect of which gives it a bad name)-and is regularly changed, say, every two months, it is generally reliable. The alloy, as the previous speaker pointed out,

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 42 JOURNAL OF THE IKBT. OF LOCO. ENGINEERS. deteriorates in service more or less rapidly, especially with some waters, so that the time it should be allowed to run varies. Another point, too, is that the fusible plug should not be allowed to project too far into the firebox, because then the metal gradually fuses from the inside of the firebox until there remains only a thin shell of the alloy which may readily melt due to no cause of overheating. If this point of putting these plugs in, so that they project the right dis- tance into the water space and into the firebox, is attended to, they can be relied upon, in my opinion, as a great safe- guard. It is a significant fact that in connection with the two last locomotive boiler explosions in this country, the fusible plugs would have been called into great evidence, but, in each case, I believe I am right in saying this, they could not be found. In one case, it was known for a fact that the plug had been stolen by someone very closely con- cerned with the accident, though no absolute proof was forthcoming. With regard to the point about superheated and non- superheated engines and the difference in the life of the fire- boxes, it was instructive to have that actual example put before us, of two similar engines, but there was one notable weakness in my opinion in the comparison. The superheat engine was pressed to 16olbs. per square inch, whereas the steam pressure of the saturated engine was 18olbs. per square inch. That 20lbs., I think, makes all the difference and nullifies the comparison very much. If we had only the mileage of each, one could perhaps have made a fairer comparison. I believe it is a fact that boxes, even with the same steam pressure, do stand better, as was pointed out, and the stays give much less trouble with superheated than with saturated engines, but that is largely due to the fact, I consider, that the engines are not necessarily pressed to the same extent. On the question of the fitting of the ends of super- heater tubes in the firebox, I have seen trials of both the ordinary screwed end and the superheater tube grooved on its outside and expanded into the firebox, and experience showed that the screwed end is no better than the other met hod. I cannot say anything about the point of partial beading. There may be soinething in that. Beading in small tubes, on some railways, I know, has been entirely given up; the scale seems to get behind the bead and then there is nothing but trouble, to be remedied only by withdrawing the tube. Re-expanding only seems to make matters worse. Screwed ends have recently been tried on one of our

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 LOCOMOTlVl*: FIREEOXI~R-JIASSlRlS~. 45 large trunk lines, and I have just learned that they have been entirely given up in favour of expanding and beading over, that is, the large steel flue tubes. Cracked Tubeplate Bridges.-I think a lot of this trouble would be prevented by the introduction of the reduced ended tube which gives you bigger bridges. I mean re- ducing the tube in the neck just at the firebox end, not a sudden reduction but la gradual reduction in two to three inches, sufficient allowance being left so that the tube can be driven up from the smokebox end as the ends burn off in the firebox; the tubes being left projecting +in. to %in. at the smokebox end for the purpose of driving up. The reduction of the tube at the firebox end gives, firstly, a much bigger bridge; secondly, the velocity of the passage of the gases through the neck of the tube is thereby in- creased at this point and also the water space is increased ; and thirdly, the tubes keep cleaner and stand altogether very much better. With regard to internal feed pipes, one wonders almost why they are tolerated at all. Indeed I often wonder why people tolerate the combination injector. I had a very close experience of them on the Midland Railway, and was con- cerned with the injector failures on something like 1,500 engines fitted with combination injectors, and no cure for it whatever was found until it was decided to withdraw the lot, and replace them by the under-type injector, which injector being placed behind the footstep is always flooded, preventing hot pipes. The internal injector delivery pipe is, I think, a very bad feature indeed, as has been pointed out by the examples put before us, especially with some waters. The fact is, the hot water passing through the feed pipe being heated up to such a high temperature as it passes through the boiler becomes more and more heated, the salts in the water are disintegrated, and sediment is deposited inside the pipe at the delivery end. This is got over to some extent by arranging that the pipe should be as straight as possible, and that the delivery end near the smokebox tubeplate should be opposite a plug which can be removed so as to clean the tube with wire rods or brushes. That is convenient if the men will only attend to it, but it is not foolproof. I think it would be very much better to dispense with the internal pipes altogether and have an dxternal feed pipe on to a clackbox. The Great Western arrangement is undoubtedly a capital one, and almost per- fect where you have water softening; but unless it is in mmbination with water softening you do not get the advan- tages which the Great Western reap from the arrangement.

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 44 JOURKAL OF THE INST. OF LOCO. ENGINEERE.

I have seen it tried without water softening and the trays get made up solid. I have in mind an engine we have been running for twelce months on the South Eastern and Chatham with the top feed arrangement. We have, un- fortun:rtcly, no water softming on that line, and the trays, over which this water runs bctorc it falls into the boiler, hale become made up solid two to three inches deep in two months. Still it is a good thing for all that, because the scale would have settled on all the heating surfaces and become caked and baked hard, whereas it is collected par- tially in the trays and the rest thrown to the bottom of the boiler, where it can be washed out. The top feed is bound lo come, I believe, and if it can only be used in conjunction with water softening then JOLI will get the full advantage from it. The Weir Feed Pump.-Here again it all depends upon the water. The “ Weir ” feed pump is ;I perfectly good appliance where the water is good, but on the South Eastern and Chatham Railway we could do nothing with it at all. It became choked solid at the condenser at the end of a month. If we had water softening, there again the “ Weir ” feed pump would have been a great success. Steel Stays.-The Great U’estern uses gin. diameter steel stays, II threads per inch, and it seems to answer with them admirably, but it should be borne in mind that it is in combination with the top feed and water softening. That is where they obtain the advantage. One railway tries steel stays with nothing of this kind of thing and reports “ no good,” but if only it had been tried in com- bination with other circumstances then you would reap the advantage, and it is no doubt the same with steel fireboxes. We shall have much better results if we only use them along with the other devices. Flexible Stay Bolts.-In connection with these, I may add that in this month’s “ Railway Engineer,” there is a little article on the use of flexible stay bolts in America which struck me particularly. I read that in America :it the present time there are nine and three-quarter millions af flexible stay bolts running on 1,700 and over locomo- tives, 1,234of which are fully fitted with flexible stay bolts, this being taken over a period of six years. The average number of stays fitted per engine is 544 and it is pointed out that the failures due to breaking have been only .343 per cent. If America has come to it, I believe we shall in time. It seems to be the only cure for the one thing the m;rtter with the modern locomotive, that is its boiler. In the Master Mechanics’ proceedings for last year there is

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 LOCOMOTIVE FIREBOXES-MANNERING. 45 a little interesting article by Mr. G. L. Young, of America, who made some very clever experiments on the question of the expansion of fireboxes and the use of flexible stays. He records that the flexible stayed boiler, as compared with the rigid stayed boiler, had a difference in the expansion of the fireboxes as 31 to 13; that is, the flexible stayed box could go up so much better (as 31 per cent. to 13 per cent.) than the rigid stayed box, and the result was the flexible stayed boiler, with its natural tendencies all provided for, did ever so much better in the length of its life. Mr. Sanderson: I would like to ask Mr. Mannering one question, if he will kindly answer it in his response. This raising of the tube sheet I am familiar with in the steel tube sheets, but to nothing like the extent he has mentioned in his experience. I should like to ask whether they use the roller tube expander or the sectional tube expander. We stopped the use of the roller tube expander at the engine house years ago for the reason that it stretched the tube holes too much and restricted the men to the sectional expander. Mr. Mannering : Copper tubeplates subjected to the continued use of any type of tube expander will go up or out, according to which direction the line of least resistance lies in the plate ; the more one uses the expander the worse they become. Mr. Sanderson: The sectional expander does not do this to the same extent as the roller expander. Mr. Mannering: It may not have the same effect on a steel tubeplate. My references entirely relate to copper tubeplates. Mr. W. Vaughan: In replying to the paper presented by Mr. Mannering one must heartily congratulate him upon the concise manner he has dealt with an absorbing subject, always extensive in applicatiod as it affects the upkeep of locomotive boilers and fireboxes while in charge of the Running Department staff, especially at this time when the margin of time for attention, owing to the reduction of available power and congestion, is reduced beyond the prac- tical minimum. Those connected with the running sheds will bear me out as to how difficult it is to attend to locomo- tives under the present circumstances to keep them anywhere near right. In this connection I would make a few remarks, also as to the practice with which I am acquainted.

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 46 JOURNAL OF THE ISRT. OF LOCO. EXOISEERS.

Conkerning the provision of fusible plugs for locating responsibility in cases of damage to crown or tubeplates through shortness of water they appear essential, as the definite results of overheating are not always immediately apparent. To allow an elasticity of control to prevail until the crown plate is down and leaking transpires, before notice is taken of it, seems soarcely good practice and tends to risk. The few plugs fused in traffic to cause delay is scarcely worth considering as a reason for departure from an established custom, and drivers hardly admit shortness of water. The utility of using more than one plug placed towards the middle of crown plate is open to question, and I am in agreement with the author that temporary backwash of water has led to fusing. The reference to cases where discolouration had taken place and the back plug failed to fuse, is realisable under circumstances as mentioned in Mr. Sanderson’s experiences of the metal being affected. Renewals of plugs are three-monthly for boiler inspec- tor’s examination, failing a previous defect notified by the driver or leading boilermaker upon his weekly examination of the firebox, which of necessity affect the thread of plug holes. I consider a fine threaded taper plug preferable to a coarse threaded parallel plug, as in tapping up after wear B 1ongetJife is given and bushing up avoided. Concerning Nos. 21 and 22 Brighton Co.’s locomotives, B point which appealed to me was the advantage of the superheater engine in lessened water consumption, which would account for the difference in the life of the fireboxes ; but the extreme difference in the two engines points to causes not made clear, and a statement as to condition of plates, tube and stay holes, with a mileage comparison, would be advantageous. Concerning the life of tubeplates, I have in mind an engine recently returned from the shops with a new tube- plate after ten years’ service in a bad district for water; one of Mr. Drummond’s tanks fitted with pumps and feed water heater, in which system a deal of scale deposit is left in the water tanks, and has a definite effect in lessening tube renewals, etc. Boilers in the district referred to with the feed water heater will run six months longer than an injector fitted engine before the tubes are removed for dirt. Concerning water delivery systems, that of the Great Western appears satisfactory for elimination of scale de- posit, and water delivered direct at the front end of the boiler gives good accessibility. As regards internal delivery

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 LOCOMOTIVE FIREBOXES-MANNERING. 47 pipes, I am in agreement with others that they are not practical. Concerning the use of steel stays with protection nuts for stay ends in the fire-way, can the author give reasons for their unsuitability for the upper section of the side plates gt the bend? Referring to the use of stays with holes for locating broken stays, the method has not continued with the L. and S.W.R.; practice shows a lessened life of the stay owing to weakness. Experienced boiler inspectors can locate broken stays, and no advantage can be claimed for using the hole for expanding the stay in the plate. I may men- tion a case where it was tried by drilling a tin. by xin. hole in the centre of a series of rtin. leaky stays, and drifting them into the plates unsuccessfully. These stays have a tendency to break away, and I have known cases with side tank engines where 20 to 30 stays had to be removed in the running shed to locate a defective stay on the outside casing behind the water tank, which made it unendurable for the enginemen, as a result of one of these stays being fractured. In drilling holes there is a tendency to set up a fracture. As reference has been made to the use of hollow steel stays on the L. and S.W.R., we find it an excellent stay where slight cracks start from the stay hole after the I3in. copper stay becomes unsuitable. They are used up to nin., the threads being 14 to the inch. The stay is fitted into the plates by the use of a square drift, driven into the hollow part of the stay and pulled in the plate by the use of a ratchet. These stays rarely require renewing if the cracks are properly taken out, and save, in many cases, a patch in the plate; they last up to three years in service. One end is countersunk for beading over, about tin. of the stay being left outside the plate for this purpose, and when leaking takes place, the stay is drilled down with a counter- sunk drill-to remove the hardened section-and re-beaded. Another feature of this stay is that it can be drifted to expand from the iwe, and does not split in the operation ; neither does it requlre to be riveted over to such an extent as large copper stays. In cases of a flaw from a stay hole, when the plate is otherwise good, we use a copper bush up to 24in. diameter, with a stay put through the bush after it has been screwed into the plate, when a 2in. steel stay becomes unsuitable. In this case the steel stay is drilled back flush to the outside casing plate, land acts as a bush, instead of opening the outside casing plate to the larger dimension ; the existing

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 48 JOURXAL OF THE INST. OF LOCO. ESGINEERS. bole in the steel stay is tapped to make it the receptacle for the I&n. copper stay put through the bush. The use of this method is confined to one stay hole, two bushes not being allowed together. Concerning the flexible stay bolt, advocated by Mr. Sanderson, my information is that they have a tendency to turn the tubeplate back from the flange as much as an inch and to throw the tubes out of alignment. In the use of solid crown bars, we experienced the difficulty of scale deposit with our local tank engines, and at one time a portion of the crown was cut away for cleaning, as illustrated, but a recent method adopted is to remove all the roof stay bolts from the bar and lift it from the firebox, and with a bent steel tool the whole,of the top of the crown plate can be cleaned. We find this a reliable method of cleaning the roof bars when the deposit has got Tound the legs of bar. Concerning the cracks at the top bend of side plates, these seem applicable to all types, but, as mentioned by Mr. Mannering, the engines can remain in service for a considerable period under constant supervision after the crack has developed, if leaking does not take place. If leaking occurs it necessitates stopping the engine for patching. The plugging up of tube holes is a practice not confined to any particular type when cracks develop between bridges. But other than in the two top rows, reduced tubes are fitted. In all cases of putting in plugs, if they run con- secutively they are interlocked. With the direct-stay box, the expansion of the crown must be more uniform than in one with bars ; and this with greater accessibility for washing out is a distinct advantage. So far as its liability to work upwards from the top flange of the tubeplate is concerned, have steps been taken by those who use this type of box to strengthen the front end by a cross crown bar? In small patching, the new plate is fitted internally to give the pull of the collar stud upon the full plate, no thread being put into the side plate. The type of firehole door as mentioned is used con- siderably on our system, being a satisfactory one, easily manipulated, and safe in wse of a burst tube, with the late Mr. Drumrnond’s improved corrugated rack in place of a trigger catch and notch in the rack. In case of extreme pressure, with a burst tube it would close the door and meets the objection to a bad blow from a fusible plug. We have experienced cracking of these firehole rings, a failure which is dealt with best by means of a steel patch

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 LOCOMOTIYE FIHEl3OSES-MASNERIXG. 49 fitted across the crack and secured by two sin. steel studs, which last a considerable time. The cast iron protection plates are xery satisfactory in protecting the rivets and seams from the scorching action of the fire. Mr. Henbrey: I can only rise to thank you and your Council for the very entertaining privilege of being here and having heard such an interesting discussion. I am merely here as a visitor and whatever remark I make is quite impromptu. The chief thing that has arisen is the fusible plug and my experience has been with that on a par with Mr. Mannering’s. Where two plugs are used, could not you do away with one? Where the back plug has gi\en way, it is due, as Mr. Mannering has stated, to the back- wash. It has given the driver such a fright, and this fright becomes infectious, so that you cannot knock it out of the men and get them to run with a reasonable quantity of water. The consequence is continual priming. I think there is a great deal in this question that Mr. Mannering has brought forward with regard to this back plug. Mr. W. A. Lelean: I have one or two notes here, but I do not wish to end the discussion if anyone else has any further remarks to make. With reference to fusible plugs, Mr. Sanderson re- ferred to zinc as being used in America, but I think the general practice in this country is to use lead as the chief component of the fusible alloy. Perhaps the author could tell us what their practice is. The mixture in general use in India is g of lead to I of tin. With reference to the different designs of these plugs it is not always easy to account for the variations found. I have shown two examples on the wall, one with a hole for the core formed with distinct square-edged collars on it and the other with R simple tapped hole. Each has the top end of the core widely countersunk. One of the necessities for the safe- guarding of a boiler by its fusible plug seems to be a systematic and frequent withdrawal of the plug, removal of the scale which has formed over the top of the core, and if necessary renewal of the fusible core if the metal seems oxydized or otherwise altered in nature at the bottom end of the plug. Where plugs are allowed to become coated over with a thick scale this scale often fails to crack at once when the core melts, though the countersinking of the top of the core hole, by rendering the span great,-r, weakens the resistance of the deposit when the core melts from under it. In this connection it is difficult to under- stand the design in which the core is domed at the top

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 50 JOURNAL OF TIIS INHT. OF .LOCO. ESGINEERS. thus giving the deposit the best possible form to resist the steam pressure when the core is melted from beneath it. With reference to the advantages of superheating, it seems probable that with a given maximum weight pzr axle it would be possible to design a rather more powerful engine by using a superheater, for although the superheater itself would add about I to 14 tons, yet a smaller boiler would probably be sufficient, and would thus allow the use of slightly larger cylinders with correspondingly heavi-r motion to suit without exceeding the weight limit. Hitherto, however, practical considerations of duplication, etc., have led to the retention of the existing boiler and engine, but the addition of the superheater has enabled the pressure to be reduced zolbs. per sq. inch, the cylinders being in- creased proportionately so as to keep the tractive effort the same as in the non-superheated engine and the same motion being used. As Mr. Vaughan pointed out it is this reduc- tion of pressure which accounts for most of the advantage which the author shows in his comparisons. With reference to the position of the feed inlet, if trays are to be used without the use in combination with them of water softening plant, to which Mr. Clayton so aptly referred, then there certainly seems need for the pro- vision of special facilities for cleaning out these trays easily and effectively, especially if there is going to be a rate of deposit anything like that represented by two inches in a few months, such as one speaker referred to as common in his experience. With reference to the delivery pipes becoming solid a plan was adopted which seemed to have some possibilities, viz., to make the delivery pipe with a flange which was interposed between the mounting or delivery pipe flange and the seating on the boiler. By making the hole in the seating larger than the outside diameter of the pipe the joint could be broken and the pipe, even when scaled, could be drawn out and put into the fire, thus quickly freeing the scale inside and outside. After this design had been adopted, however, a locomotive superintendent reported it was found to be unnecessary as by keeping their delivery pipe perfectly straight and periodically removing the mounting they could clear the delivery pipe by using a round rod about I inch dia. fitted with a rose cutter on its end. Here again the matter is a question of the local conditions, hardness of the scale which is formed, frequency with which this clearing out can be done, etc. If it could be cleared before the scale gets too hard no doubt such arrangement might prove very effective, and if so one would

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 LOCOMOTIVE FIREBOXES-MANNERING. 5' strongly advooate the simpler arrangement in preference to the additional flange and removable pipe. With reference to the stay nuts, I notice the author refers to nuts splitting in service. In this connection it may be of interest to narrate a similar experience which we have had, but which was traced to welded nuts having been used. It seems that in the neighbourhood in which the boilers concerned were made it was a very general practice ta use welded nuts throughout the locomotive, and apparently quite in good faith the firm seemed in doubt whether nuts could be readily obtained made solid. This led to an investi- gation, and on taking the matter up with one of the largest makers of nuts in the country we learned that about two- thirds of the nuts are made out of the solid. In Oase anyone else is thus troubled it may be of interest to them to know this, and if they find their nuts welded to learn that they can easily get them in future made out of the solid if demanded. Then with reference to stays being allowed to run with- -out any heads in the firebox, I am sorry that Mr. Clayton has had to leave early as I was going to ask him if he could confirm my recollection of an experiment which I think the Midland Railway Co. made some years ago to show the difference between stays in a copper plate with and without heads. My recollection is that the stays with- out heads pulled out with about 60 per cent. of the load which the headed stays sustained. If this is so it appears doubtful practice to allow boilers designed for stays with heads to run with no heads on the stays. This, of course, does not apply to an occasional stay with wasted head here and there, nor does it apply to stays without heads in the steel wrapper plate in which a steam-tight stay screwed in from the inside of the firebox seems to make quite a sound job. With reference to roof stays, I have shown on the walls an example of stays, for the front end of the box, which pass through mountings fitted on the outside shell. These stays have a nut on the outside end, which can thus be tightened from the outside as the top of the firebox rises at the front end with repeated re-expanding of the firebox tubeplate. The end of the stay with the nut is enclosed in a screwed cap fitted steam-tight to the mounting. This device seems to have some possibilities in it, though doubt- less there will be a tendency for scale to form in the caps, but this could be watched from time to time when the caps were removed. When the firebox tubeplate top flange rises, as the author has so clearly explained, even in cases as

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 52 JOURSAL OF THE IYST. OF LOCO. ESGISlXRR. much as sin., it is manifest that something must yield, and our experience also shows fracturing at the precise poirtt which the author indicates. As preventing this bending of the copper wrapper plate where it joins the tubeplate, there seems much to recommend the short roof bars arranged at the front end of the firebox with their heels resting in the ordinary way on the tubeplate and their other ends slung from the outside wrapper plate, and having the ordinary roof stay bolts to support the front end passed up through the crown plate and screwed into these short roof bars, so that as the tubeplate top rises with the re-expandings of the tubes it carries with it these roof bars and with them the bolts holding up the firebox crown plate, thus pre- venting any bending of that plate at the junction with the tubeplate. Mr. Sanderson referred to the great advantage from the use of circulator plates between the two shell plates of the firebox. I am rather surprised that more has not been done in this direction and there are one or two such devices now being put forward. Most locomotive officers will, however, I am afraid, look askance at anything that tends to fill up the waterlegs, though I feel satisfied if they would only have the courage to instal them they would find certain advantages from these circulating plates in the boiler. The natural fear is to introduce any obstruction to the washing out or inspection of these waterways, but these circulator devices are said by inducing strong currents to practically clear the whole of the deposits out of the water- legs and throw them forward into the boiler barrel where they are more easily removed. Mr. Sanderson has since confirmed that this was his experience and that the water- ways were undoubtedly cleared of deposit by using these circulating plates. Mr. Clayton referred to broken bridges, and there is something to be said for the avoidance of continuous straight lines in the rows of bridges. We have in certain cases thrown the side tubes out of line and even omitted an occasional tube to avoid breakages through bridges at the sides of the tubeplate, for it has been felt that the loss of heating surface has been more than compensated for by the longer life of the tubeplate. mrith reference to the position of injectors there seems to be a general agreement in later practice to revert to the former position advocated by Mr. Clayton, viz., under the footplate where the injector can be always flooded, SO giving that initial condensation to the incoming steam SO necessary to start the injector working, and which is lacking

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 IAOCOMOTIVIZ FIREROSES-MANNERI~~. 53 when the steam enters a hot injector body as it often is when the injector is situated on the back of the firebox. One more point. Mr. Vaughan referred to the fire- hole door of Mr. Drummond’s design provided with a sector with corrugations instead of notches and having a spring plunger. I do not know what others’ experience of these spring plungers is, but we found if‘ well oiled the door would often jar shut in running just as the fireman was shovelling in the coal. On the other hand, when not thus kept well oiled they required a considerable effort to pull the door open and the native firemen found it hard work to open them constantly on the long runs. To get over this a handle has been devised in which a weighted catch does away with the use of a spring and the handle for opening the door is formed on the back of this weighted catch, so that on coming to open the door the fireman lifts the catch out of engagement with the sector as the first movement, and he can then swing the door open without any resistance. On letting go the handle the weighted catch holds the door firmly fixed where placed by the fireman. At the same time, should a tube burst, the pressure on the inside of the door would be sufficient to cause the weighted oatch to slide over the corrugations in the sector, so shutting the door and preventing the enginemen from being scalded, in accordance with Mr. Drummond’s idea in the original design with spring plungers. Mr. Smith Mannering: Mr. Chairman,-I wish to thank you and those gentlemen who have so ably, and also in such a friendly manner, taken part in the discussion on my paper. The subject is a very difficult one to write about, even to those like myself whose whole time is occupied with the wear and upkeep of locomotive boiler fireboxes during their useful career on the road. It opens up a wide field for careful observation and investigation. As might have been expected, the discussion has chiefly borne upon the principal points of the paper, viz. :- (i.) The fusible plug, its function and value. (ii.) The comparative wear of locomotive fireboxes of superheat and non-superheat class. (iii.) The top feed delivery arrangement for boiler feed, and the disadvantages of the use of the com- bination injector. (iv.) The adoption of steel stays with protection nuts in copper fireboxes.

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 54 JOURNAL OF THE INST. OF LOCO. ENGINEERS.

No further special comment is needed on that portion of the paper allotted to firebox repairs, as the illustrations and photographic reproductions are taken from actual every- day shed repair practice. Mr. R. P. C. Sanderson’s remarks and experiences on the use of steel fireboxes on American railways are most interesting and instructive. As I understand we shall very shortly be hearing further from him in the form of a paper on this subject, I will refrain from passing any lengthy comments on his remarks. His allusion to the “ letting go” of firebox crown sheets is rather startling. For my own part, I am bound to say that I have never heard of a copper firebox crown collapsing on the Brighton Railway Company’s system owing to overheating of the plates caused by shortness of water. A great many express locomotives designed by the late Mr. Robert Billinton for this Company, with boiler pres- sures of 18olbs. per square inch, were constructed with copper fireboxes and flat level crown sheets, and fitted with one fusible plug at the front end only. These engines never gave any trouble owing to the omission of a back plug, and certainly no case is on record of any failure due to a collapsed crown sheet. If, as is stated, steel fireboxes have so many advan- tilges over those made of copper, it is a wonder that they have not found favour in this country-they may be cheaper in the first cost and efficient when new, but will they stand the same test and strain after a prolonged life of working on the road? Would cracks in the crown sheets, for instance (as pointed out and illustrated in my paper), be permissible in a thin steel plate, and be considered safe? I should say not! Copper fireboxes have an immense advantage, in my opinion, over those made ,of steel, owing to the fact that there is a greater margin of safety in them under all conditions of wear. It is not sufficient to form a criterion of the value of any firebox (be it made of copper or steel), by the results as seen on the test,pits. In order to get the true value of either, one must be conversant with the condition of them after a prolonged period of useful service, be in a position to determine that value by the general condition then, say what defects constitute a weakness and still warrant a con- tinued safe working, and also what constitutes a real struc- tural weakness sufficient to throw the firebox out of action altogether. Looking at the question from this point of view, I fel confident that the copper firebox will continue to find

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 LOCOMOTIVE FIREBOXES-MAKSERIKG. 55 favour in this country. We may have to resort to steel fireboxes in the near future by sheer force of necessity, but certainly not from choice. Mr. Sanderson has called our attention to the almost universal use in America of flexible stays for staying the flat surfaces of steel fireboxes. While this practice cannot be doubted as the best one for giving perfect freedom for purposes of expansion and contraction of the plates with the abnormal dimensions of some of the locomotive boilers and fireboxes in use over there, the same thing does not apply here, and no advantage would be gained by introducing flexible stays, in the place of the well-tried solid copper ones, for use in copper fireboxes. If the renewals of broken copper stays were the only trouble that we have to contend with in the running sheds, then on this account the sheds might as well be closed altogether. In some districts we find the boilers extraordinarily free from broken copper $ays, while in others they will occasionally break in the positions shown in my paper and will, of course, be renewed as soon as they are detected by the shed boilermakers. Mr. Sanderson’s allusion to the repair by the oxy- acetylene welding process of local cracking of the plates of steel fireboxes is very interesting. We have had same little experience of this kind of repair in a few local service tank engines that were fitted with steel fireboxes and we have adopted this process of welding local cracks in plates with a measure of success. We have likewise welded the ends of the steel tubes in the steel firebox tubeplate of one of these engines, as so much difficulty was experienced in keeping the tubes tight for any lengthy periods by the usual methods of expanding them. I am sure we all thank Mr. Sanderson for his very interesting remarks. Mr. Clayton spoke of the advantages gained by the systematic use of fusible plugs and the warning note that is struck when they fuse in the firebox. With this recog- nised fact most of us agree, but whether more than one plug in a firebox crown is necessary is a matter of opinion and is still open to discussion. What of the locomotive engineers in this country who doubt the utility of the fusible plug and do not adopt it at all in their boilers? I note no comment has been made on this side of the question. Mr. Sanderson, speaking of the American practice, has told us that they have been discarded altogether in America, partly because of the danger connected with their use. I think it can be generally granted, however, that the majority

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 56 JOUKSAL OF THE ISST. OF LOCO. ESGISEERS. of English locomotive engineers do favour their use, and the result of the discussion is decidedly in favour of this prac- tice, viz., that one fusible plug at least is most desirable and necessary in the crown sheets of locomotive copper fireboxes. Mr. Clayton refers to the desirability of screwing the plugs in the crowns so that they project a standard distance into the water space and into the firebox. This is as it should be, and the practice on the Brighton Railway is quite in accordance with the idea. In referring to the portion of my paper on the pecu- lhrities of the comparative firebox wear and repair to engines Nos. 21 and 22, Mr. Clayton desires to know the respective mileage of each engine in order to form a better idea of the value of the data given. This information I can give him and I regret that I did not put it in the paper. Both engines ran approximately 250,000 miles each up to the end of June, 1916, were stationed at the same depot and were used on the same class of work. The fact of the superheat engine being able to accomplish, with a pressure of 16olbs., all that was done by the non-superheat one with 18olbs., proves, I think, the great advantage of the former over the latter, inasmuch 0s the superheating alone made it possible to work the engine with a reduced boiler pressure in competition with the other one. Furthermore, the pull on the fire due to the blast pipe top area is not the same in each engine, No. 21 having a top sin. diameter and No. 22 5th. I am of opinion that the blast action on the fire has more to do with the striking wear comparison of each engine's firebox than the actual reduction of the boiler pressure in No. 22, as set forth and discussed. This pressure question is a very difficult and perplexing one to answer. Running on the Brighton Railway there are a few non-superheat " Atlantic " type engines which were designed by Mr. D. Earle Marsh and constructed by Messrs. Kitson and Co., of Leeds, nearly eleven years ago, with boiler pressures of 2001bs. per square inch, and no trouble has ev'er been experienced with the fireboxes beyond the usual results arising from the ordinary reasonable wear and tear extending over a prolonged period of working. I can only conjecture that the heavy firebox repairs of engine No. 21, as stated in my paper, were occasioned by the heavy class of work that the engine had daily and con- tinuously to perform in working the " Southern Belle " from Victoria to Brighton, and vice versa, a sharp run of so& miles in the hour. On the other hand, the exceedingly good results obtained with engine No. 22, under similar

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 LOCOMOTIVE FIREBOSES-MAXNERING. 57 service conditions, from a comparative firebox wear point of view, fully justify, I imagine, the conclusion drawn as to the value of. superheating the engine. I note Mr. Clayton does not appear to favour the prac- tice of screwing the superheat flue tubes into the firebox tubeplate, and he furthermore quotes that one of our large trunk lines has tried it and given it up. I am not in a position to dispute this statement, but perhaps the difficulty experienced by this method has resulted in some cases in pushing the tubes through the smokebox tubeplate and causing them to leak ; certainly one would expect this effect from holding them fast in the firebox. We have experi- enced this difficulty to an extent in some of our own engines, but as a set-off to this, I may be allowed to vouch that the powerful 4-6-4 “ Baltic ” superheat tank engines recently designed by Mr. L. Billinton, and constructed at the Brighton Company’s Works, had these tubes screwed id the firebox tubeplate and no leakage at all has occurred at the smokebox end. Seeing that two of these engines have now been running on express main line turns for upwards of two years, the system seems to commend itself as quite satisfactory. It would be superfluous to add that no leakage has taken place at the firebox end of these flue tubes.

CRACKEDTUBEPLATE BRIDGES. Mr. Clayton advocates reduced end tubes throughout in locomotive boilers in order to thicken up the bridges in the copper tubeplates. While this idea may commend itself to some engineers for the reasons advocated by Mr. Clay- ton, there remains the constant nuisance by its general adoption of the small tube ends becoming clinkered up with fine ash from the fire, thus necessitating the continual services of the shed “bar boy ” in rymering them out on shed and other days. I am pleased with the endorsement by Mr. Clayton of my remarks concerning the nuisance of internal delivery pipes from combination injectors. His experience with them is very extensive, and his comments are therefore worthy of the full consideration of all. His explanation, too, of the causes that lead to the choking up of the delivery ends of these pipes is very clear and explicit. Mr. Clayton makes a great point of enumerating the many advantages to be obtained by a combination of all the best known appli- ances and shed arrangements, which together, conduce to the useful service career of a locomotive boiler and its firebox ; this fact cannot be denied, but unfortunately these

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 58 JOURNAL OF TIIE ISST OF LOCO. ENGINEERS. ideal conditions do not exist on a great many railways, My paper was chiefly written in order to point out the various defects that are to be found and sought for in copper fireboxes of various designs during their useful ser- vice on the road when working under quite ordinary condi- tions, minus all the latest approved appliances and sur- roundings which have been mentioned. The number of locomotives coming under this cat.egory in this country must be many thousands. Mr. Clayton finally closes his remarks with a eulogy on the merits of the flexible stay bolt and the great number of them used at the present day for staying th.e flat surfaces of steel fireboxes of locomotives in America. I can only repeat what I said in reply to Mr. Sanderson, viz., that so far as the question applies to copper fireboxes and the proved reliability of copper stays in them, with ordinary care and under proper supervision, the flexible stay bolt in the light of our present experience does not commend itself. Mr. Vaughan has stated in a very concise manner the reasons generally accepted for the protective measures. gained by the practice of using fusible plugs in the firebox crowns of locomotive boilers. I do not for a moment wish it to be understood that when raising this discussion on fusible plugs, I was advocating the non-use of them alto- gether. The mere fact of at least one important railway company in this country not using them, alone suggested to me the reason and desirability for opening up a discus- sion-on the matter, and in the course of my remarks I have endeavoured to put that particular case in as favourable a light as possible, at the same time showing what would most likely happen to a firebox crown without a fusible plug in the case of shortness of water and the consequent overheating of the plates. Probably, if one sought the real' reasons from any of these locomotive engineers for abstain- ing from the general recognised practice of using fusible plugs, the reply would surely be forthcoming in the words of Mr. Vaughan that they consider there is insufficient reason " for departure from an established custom." Replying to Mr. Vaughan's comments on engines Nos. 21 and 22, I can only refer him to the additional data that T have given in reply to Mr. Clayton, and my reasons for endeavouring to explain the extraordinary difference in the wear and upkeep of the fireboxes of these engines. Concerning the use of steel stays with protection nuts and th,eir fracture and breakage in the side sets at the bend of the box, Mr. Vaughan asks for an explanation as to

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 LOCOXOTIVE BIKl

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 60 JOURNAL OF THE INST. OF LOCO. ENGINEERS. cannot see what else he can mean or refer to in his ques- tion. I am afraid that the introduction at this junction of anything more rigid would only have the effect of keeping the crown plate down and at the same time would intensify the difficulties experienced with the roots of the tubeplate flange going up, by causing fractures to take place in the seam-a not infrequent occurrence under existing conditions. I thank hlr. HenLreq for the support given to my paper in his few well-chosen remarks. Coming as they do from one with so long a practical experience in the manage- ment of an important main line running shed, his views on the fusible plug question are particularly valuable. Mr. Lelean raises the question of the alloy used for fusible plugs. It is the practice on our railway to fill the plugs with lead alone, the inside of the plug being, of course, properly tinned before recei\ing the lead. He refers to the different designs of plugs used, but all, more or less, have the same failing, inasmuch that the alloy in them will melt away from the underside of the plug and upwards until there is only left a depth of alloy equal to the thickness of the crown plate, and this will happen at the first trip that an engine makes after a fresh plug has been put’in. One of the best designs of fusible plug to meet this difficulty and to help in retaining the top portion of the alloy until it is actually fused by overheating from shortage of water in the boiler is the one employed on the Midland Railway. In this plug there is a bridge or circular collar of alloy formed in the core of the plug situated in about the middle of its depth. This bridge acts as a retainer and stops to an extent the pssibility of a plug wholly fusing prema- turely. Much has been said on the desirability of changing lead plugs systematically, but I clearly stated these desirable conditions in my pp”r xnd showed, I think, what steps were usually taken in the running sheds to meet these neces- sary requirements. I cannot add anything further in reply to Mr. Lelean on this subject. Mr. Lelean, in referring to the superheating of locomo- tives and the advantages to be gained thereby, particularly in relation to the wear and repair of the fireboxes, touches on the important question of engine design, but as this is going somewhat beyond the scope of my paper, I do not feel called upon to enter into a discussion concerning the subject. I may be permitted, however, to express the opinion that a smaller boiler introduced under the conditions pointed out by Mr. Lelean might not have the same desired

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 1,OCOMOTIVE FIREBoSER-MhNNEHIKG. 61 results in practice that would possibly be expected under these conditions from a theoretical point of view, although retaining the same maximum weight per axle. I note hlr. Lelean supports the general impression that the 20lbs. reduction in boiler pressure of engine No. 22 is chiefly responsible for the good results obtained in the wear and repair to this engine’s firebox. It may be interesting to state that several of our newest superheat tank engines are now running with boiler pressures of 17olbs. per square inch, the fireboxes giving every satisfaction and behaving well with this pressure. So far, they are quite on a par with the results obtained with No. 22. Mr. Lelean, in referring to the crown stay nuts splitting and dropping off the stay ends at the back end of the fire- box, advocates the use’of solid forged nuts in the place of lap welded ones. I explained during the discussion on this question that lap welded crown stay nuts were not an unmixed evil, as by dropping off occasionally (through being badly burnt, wasted and split) they would be renewed, which is far preferable, in my opinion, to allowing them to burn, waste, and remain in position, which would be the case in solid forged nuts. Not only this, the fact of a nut or two being split or missing will often be the means of drqwing the shed boilermaker’s special attention to the general condition of them and may cause him to change several more at the back end of the firebox at the same time. This is a question that can only be realised, like many others relating to the behaviour of locomotive fireboxes and their component parts during their service career on the road, by careful observation and experienced discrimination. The same line of reasoning equally applies to the stay head wastage to which Mr. Lelean refers. It would serve no useful purpose to further debate this important matter; it will always and must essentially be one that must be left to the discretion and acquired judgment of those who are held directly responsible for the safe working upkeep of locomotive fireboxes to decide from the time they leave the shops until they return for heavj repairs or renewals. Replying finally to Mr. Lelean’s remarks on the advan- tages gained by the use of the late Mr. William Stroudley’s fire hole door with deflector plate, to which I alluded in my paper, I would like to say that my sole object in men- tioning it was for purposes of comparison with other forms of fire hole doors in relation to the special protective value for arresting the rapid wear of the upper portion of the fire hole. In order to further show this recognised merit of

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 b2 JOURSAL OF THE INST. OF LOCO. ESGISEERS. its worth in these respects, a sketch is added to these pages showing the door in cross section open and shut, which I think should be sufficiently explanatory. I thank Mr. Lelean for his courteous and interesting criticisms and remarks on my paper. There is nothing else, gentlemen, that I wish to say. I therefore again thank you all very much.

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016 LOCOMOTIVE FIREBOXES, BY 8. MANFERING, MEMBER. ISST. LOCO. ENG. JOURNAL, VOL. VII.

Downloaded from jil.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016