Journal of the Institution of Locomotive Engineers
Volume 8 (1918)
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Journal No. 25/26
Rea, J.W.H. (Paper No. 55)
Some notes on the working of superheater engines with special reference to lubrication. 3-10. Disc.: 11-60.
Fifth Ordinary General Meeting was held at Caxton Hall, on Saturday, 26 October 1917, when the Secretary, on behalf bf the Author, Mr. J. W. H. Rea Member, Western Railway of Buenos Aires, Argentine Republic, read the following paper,* Some Notes on the Working of Superheater Locomotives, with Special Kefermce to Lubrication. author was based in Argentina, but paper was presented in London. He believed that only English railway to adopt as standard the use of a displacement lubricator in conjunction with highly superheated steam was the Great Western, whose locomotives perform, on a very reasonable fuel consumption, what is probably, year in year out, some of the hardest work in the country. On his last trip to Europe he was favoured by Mr. Churchward with an engine pass for a round trip between Paddington and Exeter, going direct and returning via Bristol, and was much impressed by the free running of the three engines upon which he rode. In the light of experience he must admit himself an advocate of the displacement system.and criticised the drawbacks of the mechanical system. J. Clayton (11-13) noted that LSWR used sight feed lubricators with superheated steam, although there was a risk of carbonization. He also mentioned the W.M. Smith snifting valve: "The steam jet or anti-carboniser as it is called is not a new thing. Those who remember W.M. Smith, of the North Eastern Railway, and his snifting valve in which he arranged to have a little jet of steam when the snifting yalve was open, will see the same idea".
Journal No. 27/28
Jones, A.D. (Paper No. 58)
British railways and the War: Address by the President. 78-87.
A very general presentation of Britain's railways contribution to the War effort during WW1. The most significant item of mechanical engineering was the assembly of ambulance trains by several individual companies. Locomotives were loaned to the Government. The movement of troops and munitions to the departure points for the battle fronts required a major effort. Leave trains for troops also contributed to inferior services for former customers who were forced to meet fare increase. Cross Channel steamers were greatly affected and the murder of Captain Fryatt, master of the GER vessel Brussels is given emphasis. .
Sanderson, R.P.C. (Paper No. 59)
American practice in the draught appliances of locomotives. 90-108. Disc.: 108-30. 13 diagrs.
First Ordinary General Meeting of the 1918 Session held at Caxton Hall, Westminster, on 16 February 1918, at 14.30, the President (A.D. Jones, O.B.E., M.I.Mech.E.) in the chair.
Began with the design and testing by the Pennsylvania Railroad of ashpans, moved on to the universal use of rocking grates in the USA, and ended with the design of blast arrangements.
Master Mechanics Exhaust Pipe. The principles on which this exhaust pipe design were based were sound, but incomplete. They were
There must be no sudden or abrupt change of form of the passages.
There must be no sudden or abrupt change of direction of the passages.
The reduction of area to bring the jet down to the size of the required nozzle tip from that of the cylinder passage opening must be gradual and easy.
The combining point of the two jets must be as low as possible consistent with the first three mentioned conditions.
The angle at which the two jets came together must be as small as possible.
The centre line running from the centre of area of the cylinder opening through the corresponding centre of area of the exhaust pipe at the combining point must strike centrally in to the guide below the tip.
A short guide is required above the combining part to straighten the jet up true with the centre line of the chimney.
The. entry to the exhaust nozzle must be easy and free from shoulders or abrupt contractions.
Maxwell Dunn (108 et seq) commented upon thrashing locomotives. A.R. Bennett (111-12) had noted GWR 0-6-0STs at Didcot with spark arrestor chimneys and was informed that these were employed in the Company's provender stores.
Journal No. 29/30
Kelway-Bamber, H. (Paper No. 60)
Coal and mineral traffic on the railways of the United Kingdom. 135-53; Disc.: 154-67. 235-51.
Second Ordinary General Meeting of the Institution was held at Caxton Hall, Westminster, on Saturday, 23 March 1918, at 2.30 p.m., the President (Mr. A. D. Jones, O.B.E.) in the chair. The paper was also read and discussed on Tuesday, 24 September in the Philosophical Hall, Park Lane, Leeds.
Had 45-ton bogie wagons been used to haul the Admiralty coal traffic during WW1, about 25% less coal would have been consumed by the locomotives hauling the trains, and the reduction in dead weight hauled would have been 33%.
Webster, H.C. (Paper No. 61)
The arrangement of enginemen's duties. 171-7. Disc.: 177-92.
Third Ordinary General Meeting held at Caston Hall, Westminster on Thursday, 18 April 1918, at 7 p.m.; the President, Mr. A.D. Jones in the chair. Author: Chief Mechanical Engineer's Department, G.E.R., Stratford
Journal No. 31/32 (July/August 1918)
Gresley, H.N. [Paper No. 62]
Inaugural address [of the Leeds Centre]. 199-214.
Inaugural Meeting Leeds Centre held in the Philosophical Hall, Park Lane, Leeds, on Saturday 11 May 1918, at 4.0 p.m..
From a historical standpoint this is highly interesting as Gresley made observations about Webb's compounds. He noted that the Greater Britain 2-2-2-2 Queen Empress was known by the footplate staff as the Scarlet Runner and that the white Queen Empress aged like a meerschaum pipe. He noted that Webb's experiments with friction wheels led to showers of sparks and wheel flats.
"There was no lack of enterprise in those days at Crewe; a triple expansion engine was tried, a figure 8 firebox, and several boilers with a water space underneath and at the sides of the ashpan were built. Although it would not appear that the evaporative capacity of the ashpan was likely to lead to much increased efficiency, it at any rate provided a suitable receptacle for the accumulation of sludge and scale."
Tractive effort, per se, is useless as a comparative measure of the power of engines. On the Great Northern Railway there are two very instructile examples of this fallacy.
"Mr. Ivatt's first " Atlantic " engines had comparatively small boilers according to present day practice. The heating surface was 1,442 square feet and a grate of 26.75 square feet. The large boiler "Atlantics" have 2,500 square feet of heating surface and 31 square feet of grate. Except for the boilers, the engines are identical so far as boiler pressures, cylinders and wheel diameters are concerned. Therefore the tractive powers are equal, but the large boilered Atlantics have proved to be much more powerful as express engines than the Atlantics with small boilers, and are able to haul much heavier trains and keep time; in fact, there is as much, or more, difference between the large Atlantics and the small ones as there is between the small Atlantics and the old 4-4-0 engines.
Then later on when the 2-6-0 type was introduced the first ten had small boilers-4ft. 8in. diameter. The later ones had boilers gft. 6in. diameter, but the grate area was the same in each case, and the engines in other ways were identical.
During the last year's work the ten engines with the smaller boilers consumed about 5lbs. more of coal per mile for the whole year than the engines with the larger boilers, although they were otherwise similar in every respect."
He emphasised the need for large boilers noting the size of that to be introduced with the K3 class. He also observed that some of Ivatt's boilers on the large Atlantics had been in service for sixteen years and had still to be scrapped. He could not see any advantage in Belpaire fireboxes as it was possible to direct stay round-top fireboxes. He favoured the use of outside cylinders with Walschaerts valve gear as these were simpler to oil. He also favoured mechanical lubricators and was an advocate of standardisation in principle, and without question the standardisation of wagons. He complained that three quarters of the heat generated in the firebox was wasted up the chimney. He noted the need for feed water heaters: live steam heaters were used in marine applications, and there was a need to develop exhaust steam heaters. There was a need for better grates. He also commented on articulated rolling stock.
Visit to ihe North-Eastern Railway Works at Darlington, Tuesday, June 25th,
1918. 215-23. 3 illus.
Thirty members (group photograph) of the Leeds Centre visited the Locomotive Shops of the North-Eastern Railway at Darlington. They were received at the Works Managers Office by Mr. A.C. Stamer, Acting Chief Mechanical Engineer, and Mr. Norman Lockyer, Works Manager.
N.E.R. electric freight locomotives. 223-5 + plates. 2 illus.
Newport to Shildon electrification>
Cylinders for Atlantic type engine N.E.R. 225-6 + plates. 7 illus.
The three cylinders of Z1 Atlantic, with the steam chest, formed one complete casting, which when ready for machining weighed 3¼ tons. The cylinders were 16½ins. diameter by 26ins. stroke, the centres of the outside cylinders being 6ft. 2½ins
Journal No. 33/34
Carlier, S. (Paper No. 63)
Heating of trains and the problem of coal saving. 255-67. Disc.: 267-92.
Thursday, 26 September at 7.0 p.m., in Caxton Hall, Westminster.
Bouhon system used exhaust steam for steam heating to reduce fuel costs.
In his response to the discussion (pp. 291-2) the Author reacted to the Chairman's remarks on the use of pulverised coal on locomotives, noting that some two years before, when visiting America, he had travelled on the footplate of a 2-8-0 engine, No. 1200 of the Delaware and Hudson Railroad, working on this principle. The arrangsment of the firebox was peculiar, being furnished with two systems of brick arches, the seondary arch being about the usual shape of firebox arch, but the primary-arch covering the so-called combustion furnace which was completely furnished with firebricks. Through the primarj-arch were inlets, by means of which the flame and heated gases were conveyed to the firebox itself. The pulverised coal was blown into the combustion furnace under the primary-arch by a current of air, and by this meains a very high temperature was obtained: thus perfect combustion was assured. The furnace was very wide, and was supplied with three fuel and air pressure nozzles, but Carlier wondered whether it would be possible to employ one large nozzle and adopt a smaller or narrower combustion furnace . By so doing the temperature might be higher still. The distance between the primary-arch covering the combustion furnace and the secondarj-arch protecting the tubes seemed to be of no great importance in the matter. The system was working quite satisfactorily in every respect, but the maintenance of the combustion chamber seemed to be a serious item of expenditure as firebricks deteriorate very quickly. On the other hand, the utilisation of waste coal affords an attractive proposition. The principal feature of the system was that there is an increase in haulage capacity of the engine amounting to 30 to 50%. To use pulverised fuel to the best advantage in locomotive boilers a complete alteration of the present shape of the latter is needed, especially th,e design of firebox.
Journal No. 35 (November 1918)
Paterson, W. (Paper No. 64)
District supervision of the locomotive department of a British railway. 296-352.
Third Ordinary General Meeting of Leeds Centre held at the Philosophical Hall, Leeds, on Tuesday, 29 October 1918, at 7 p.m.: H.N. Greslcy, Chairman of the Centre, in the chair. Illus.: LYR Low Moor motive power depot: breakdown train (interior and exterior), women cleaners posed on LYR Atlantic, wheel drop (with cover on and open)
Holcroft, H. (Paper No. 65)
Three-cylinder locomotives. 355-68. Disc.: 368-95; 476-91.
Fifth Ordinary General Meeting held at Caxton Hall, Westminster, on Saturday, 2 November 1918, at 2.30 p.m.; the President (Mr. A.D. Jones.) in the chair and Tuesday, 17 December 1918, at 7.0 p.m., at the Philosophical Hall, Park Lane, Leeds
"Probably no better example of successful design can be taken than the 8 ft. single wheelers formerly running on the Great Northern Railway. The first of these appeared early in the history of that railway, and for nearly forty years, defied all competition in thc running of express trains, the type being perpetuated with scarcely any alterations in detail until recent times. They gave excellent results, ran at the highest speeds, and no locomotives could have been simpler, although the single wheelers on the Midland Railway and other railways ran them closely" (opening page). "They [the Stars] exerted considerable influence, and their lead is due to the fact that they appeared at the proper moment in the development of the locomotive, and also because definite mechanical advantages were cheaply bought with the minimum of added parts." Holcroft then surveyed British three-cylinder designs with three sets of valve gear: the GCR and NER designs where "the mechanical advantanges gained are fully recognised, but the presence of three complete valve gears neutralises them in the eyes of many." He then mentioned the Gresley three-cylinder 2-8-0 and followed this by a detailed description of Holcroft's own conjugated valve gear and the advantages to be gained by three-cylinder propulsion: better starting acceleration, better balancing and elimination of hammer blow, better steaming and less spark throwing, lighter valve gear which is easier to handle.. Argued that a three-cylinder 4-4-4T could take the place of a two-cylinder 4-6-2T or 2-6-4T. This idea was pursued still further in the paper, and in the discussion, where it was considered that three-cylinder 4-4-0s would be able to perform the work normally allocated to 2-cylinder 4-6-0s: these reamarks may be regarded as the genesis for the Schools class. Discussion: Sanderson (Baldwin Locomotive Works pp. 369-71) argued that only very short locomotives with outside cylinders were liable to roll and sway: longer locomotives did not as the momentum of the mass of the engine will not permit these disturbing effects to produce a waving or sinuous motion., especially if leading and trailing trucks are fitted. He made reference to four-cylinder compound locomotives where "the two-cylinder engines are out on the road earning money when the four-cylinder engines are more frequently in the shop losing money".
J. Clayton (p. 371-3) took exception to Holcroft's statement: "The locomotive is therefore always somewhat of a compromise between conflicting interests." While [he thought] there is a measure of truth in this remark, [he suggested] that all engineering is compromise and that the successful engineer is he who can so design his locomotive or other machine that the best all-round results are obtained, rather than conflicting interests satisfied. That is a distinction with a difference, for in endeavouring to secure the best compromise all round, so far as ohtaining good mechanical and efficient results, all other interests arc satisfied; so, rather than call them conflicting, we had better say they aid and assist in obtaining the best. He then cited Holcroft's mention of the 4-4-2 engine, the North Star, on the Great Western Railway and that this engine was fitted with the "Deeley" valve-gear. It was a good gear of the "Walschaert" type, but, unfortunately, differing from it hy having the right-hand valve-gear different to the left-hand, and so added considerahlv to the cost without making the gear any better as such, though it does avoid the use of eccentrics. It also makes a hreakdown on one side of the engine a total disablement, as the motion on either side is dependent on the other.
It is rather singular that the three-cylinder locomotive has not been adopted more by British locomotive engineers, and it may be as Mr. Holcroft suggests, that it. has always been considered necessary to employ a third valve-gear for the third cylinder. This did not, however, deter the Midland Railway from adopting a three-cylinder compound, so eminently satisfactory on that road. Then Sir Vincent L. Raven, of the North-Eastern Railway, is not afraid of thc so-called extra complication of one extra valve-gear, as used on his successful three-cylinder locomotives.
Clayton was not convinced thut any arrangemcnt of levers and cranks such as suggested so ingeuiously by [Holcroft] in substitution for a third valve-gear would be quite so good or necessarily simpler. In any case, there would appear little to choose between the two methods of controlling the valve of the third cylinder. Further the three-cylinder engine has one great weakness, especially over the two-cylinder engine, and that is the crank-axle. This axle, having the crank in the centre, is undoubtedly weak, und necessitates a stronger axle and better-designed crank-sweeps than is usually assigned to the ordinary crank-axle. He did agree entirely with the Author in his advocacy of the three-cylinder locomotive as an improvemcnt over the usual but useful and faithful old two-cylinder type, especially where high powers are required. The turning moment is more uniform and regular than with the two~cylindcr or the four-cylinder types, as with three cranks no crank being opposite to the other the variation between maximum and minimum turning efforts is less marked. The balancing, however, is somewhat better in the four-cylinder engine, and this, taken in conjunction wilh the greater case with which only two valve-gears may be adaptcd or used, the stronger design of crank consequent upon the two instead of one inside-cylinder and the still more equable division of stt'esses, the first place should probably be given to the four-cylindcr locomotive.
With regard to the point raised as to thc improvemcnt of the 4-4-0 engine by the use of three cylinders, I should say that, whilst some improvement would undoubtedly be effected, the chief limit to the type is the lack of adhesion, and recourse must be had to the three axles counted for heavy powers. Persoually, I favour the three or four-cylinder compound of either the 4-4-0 or 4-6-0 type, on the "Smith" system as used by the Midland Railway. This point of view, however, should be reserved until our next paper on the compound .locomotive, to be read shortly by Mr. Rieckie.
I was interested in Mr. Sanderson's remarks, and should like to support what he says about" rolling" and " swaying," and that you must take into account the design of the engine, and in the particular engine to which attention was called it is probably due very largely to the way the mass of the engine is steadied at its extremities.. As Mr.Sanderson very dearly pointed out to us, if the mass is great enough, the inequalities referrcd to are imperceptible.
Mr. H. Kelway.namber (The Leeds Forge Co.): I too would like to congratulate Mr. Holcroft on his excellent Paper, and to ask him how the starting effort of Mr. Gresley's three-cylinder 2-8-0 type Great Northern Ruilway goods and mineral engine compares with that of the two-cylinder engines of similar wheel arrangement and adhcsive weight, which have now been for some years in service on that Railway. Could he also tell us what amount of reduction in coal, oil and watcr consumption has resulted from the use of threc-cylinder engines?
Mr. Lelean: Always keeping in mind the point to which Mr. Sanderson referred-viz., the mass of the engine and its effect in smothering small disturbances and vibrations and so steadying the locomotive-the question arises whether it is really desirable to place the outside cranks opposite the inside cranks in the case of the four-cylinder locomotive. Mr. Clayton's diagrams showed the effects of two series of four impulses per revolution superimposed on one another in the case of the four-cylinder engine, and six impulses in the case of the three-cylinder c:ngine, but by setting the insidc cranks at 135 degrees to the outside cranks eight impulses per revolution would be obtained, and it has to be considered whcther the balancing troubles and the upkeep of thc extra motions would not be more than compensated for. I would like to ask the Author if he could give us any information as to whether there are any four-cylinder engines in which the cranks are thus arranged so as to give eight independent impulses in the rcvolution.
Mr. Clayton: I ought to just remark that, as I explained with the diagram just now, it is not so much that the four-cylinder engine gives eight impulses in the revolution; the point was that, occurring as they do, the difference between the maximum and minimum efforts was so very marked.
Mr. Lelean: But I understand that it is due to the inside and outside cranks being opposite each other. Why could they not be set at 135 degrees? "
Gairns: (p. 374): took it that when referring to three cylinders, and the equable turning moment realised thereby, his point is more particularly that the three cylinders are using high-pressure steam. When it comes to compounding there are two low-pressure and two high-pressure cylinders, and two of them would he comparable with ordinary two-cylinder praetice, the cranks heing generally at 90 degrees; hence there are two cylinders of the same character and one to a degree variable. Presumably, in running, as Sanderson and others have suggested, there would be compensation for this, and a certain steadiness is obtained from what may be somewhat unsteady units at starting, but at any rate there is not the equality that three-cylinder simple working gives, and it seems to me that most of our three-cylinder compoundsthe Midland and the Great Central particularly, for they are the most successful are really two-cylinder engines adapted and brought into the system.
I should think that the relatively variahle working value of the third cylinder must in some degree affect the balancing and equalising of turning moment as compared with the use of three simple cylinders.
I.E. Mercer (LNWR p. 374): The Paper deals more with means of working the centre valve by means of rocking-levers from outside valve-gears than with the three-cylinder locomotive as compared with other arrangements of cylinders. The Author scouts the idea of using more than two sets of valve-gear, but fails to advance arguments in support of such a basis for his Paper. He states that recent practice has been very largely in favour of such designs, but does not follow it up with the comparative results obtained. The first and maintenance costs of a locomotive are very important things, but are certainly secondary to successful operation with economy. Recently a leading article appeared in an important journal which strongly favoured rocking-levers and pin-joints, with small movement to a complete valve-gear. The point of view advanced was, that it is not the number of joints that count, but the type as well. This is all perfectly sound theory, but is it as perfectly sound practice? To commence with, very great care and size are needed in connection with all rocking-shaft hrackets.
His experience of several designs on more than one railway is that such brackets are generally the first parts to give trouble in the valve-gear; therefore such experience would, suggest that a double set of valve-gear is less likely to cause anxiety than the use of, rocking-shafts and brackets. Massive construction, however, overcomes this weakness. Another point is that when any valve-motion has become worn, the locomotive suffers at a much more rapidly increasing rate than the wear of the motion. With a valve indirectly driven there is the loss of travel and poor operation due to the worn valve-gear, plus the loss by wear at each, pin-joint transferring the motion to the indirectly-driven valve. This serious defect can be largely overcome by again adopting massive joints, with every provision for lubrication, but all this addition in weight of parts means further increase in the dimensions of the valve-gear parts proper, and greater chance of enhanced wear and possibility of running hot as compared with a motion that only drives one valve.
With inside cylinders the bracing of the main frames is a more difficult matter, and the use of inside valve-gear as well will not greatly affect this problem.
If possible, the rocking-shaft drive should be taken direct from the valve-gear, and not from the front end of the valve-spindle, as although an approximately correct valve-setting for the second valve can be ohtained by experiment, it is quite surprising what the effect of the steam-chest temperature will be on the setting of the indirectly-driven valve, owing to the varying expansion of both valve-spindles. In some instances it is found necessary to set one valve without lead at one end, as the expansion of the spindles will alter the setting of the valve when running to this extent. The steam-chest temperature varies, so the setting of the second valve must also vary under different running conditions. In any case the valves nre necessarily badly set when such engines are getting under way.
It is not suggested on these accounts that the vogue of indirectly-drivcn valves is bad practice, but rather that the Author is mistaken in suggesting that the alternative practice is not worth consideration. The method the Author advocates can, without doubt, be made very successful if proper precautions are taken and the design of the engine in general, is suitable, but, even then, it is a question whether the result would be any better than that obtainable by Sir Vincent Raven's plan of, using three complete gears. So, far as he knew the NER. Class " Z" give no trouble, speaking particularly of the valve-gears, and most certainly ware giving excellent results in the haulage of traffic. The use of three inside link-motions instead of one and two outside gears, as adopted by Mr. Robinson on the GCR is, of course, nothing to do with the subject.
Also, to argue that it was Mr. Churchward's adoption of only two valve-gears that brought about the one or two other designs now extant is perhaps saying too much for one point of design. Had Mr. Churchward used four gears and obtained the very fine results he has done, it is quite likely that four-cylinder locomotives would have bcen very nearly as popular. Mr. Churchward, and Mr. Dugald Drummond too, first adopted four cylinders with four valve-gears for their other merits, although there were several hundred four-cylinder engines running on the LNWR with only two gears many years prior to the GWR and LSWR experiments. I am inclined to think the use of more than two cylinders had its fillip from another factor, which arose shortly after Mr. Churchward's Star class was introduced, namely, superheating; this led to increased cylinder diameters, with increased maximum pressure on all bearings, which in so many cases caused bearing troubles; these have by no means been overcome to this day. Yet to-day, in spite of the success of previous designs of three and four-cylinder locomotives, there is a certain amount of return to two-cylinder design, though no doubt two cylinders will in time have to be abandoned for heavy work.
He preferred the three-cylinder engine to any other for several reasons. With three cylinders there is only one inside crank to give trouble, and, as it is only driven by one-third of the power of the engine, it should give a far better account of itself than the inside-cylinder engine, while reducing the objections to outside-cylinders. Also, owing to only one crank in the axle, the driving-bearings can he of almost indefinite size, which is a great benefit. Cylinders are liable, with their fittings, to be more troublesome than valve-gear, so that I would rather have one more valve-gear than one more cylinder; this was before it was even suggested the third gear might be dispensed with if thought necessary. Although there is a somewhat wider variation in full gear between maximum and minimum torque with three cylinders than four, the actual maximum is not so high for a given mean, so that, even taking into account reduction of wheel-pressure on rail caused by the movement of the counter-balance for reciprocating parts, the three-cylinder engine is approximately equal to the four-cylinderto be precise, it is about two tons to the goodas regards necessary adhesive weight for a given horse-power.
In spite of these advantages, the three-cylinder simple locomotive seems ruled out as the possible future standard high-speed or even heavy mineral type, because he had always strongly advocated compounding. The MR three-cylinder compounds are probably amongst the best running in England, along with their GCR confreres. But as an ultimate type they have certain defects. To obtain the excellent torque of the three-cylinder quoted previously, each cylindcr must be of equal power. In the compound engines mentioned this feature is lacking, as the HP horse-power should equal the LP, which means the inside HP crank transmits as much power as the sum of the other two. Using two HP cylinders and one LP, there is no benefit in this respect. If one designs the horsepower of the HP cylinder to be only half that of the total LP, then one gets defective valve-operation and loss of the best economy possible. At the same time, as designed :at present the load on the inside crank is higher than with a simple engine owing to the above.
F.W. Brewer: (377-9) There is one sentence in the Author's Paper which goes straight to - the point, and if it were invariably kept in view would, I believe, prevent a great deal of misunderstanding. That sentence is: "The locomotive is always somewhat of a compromise between -conflicting interests." That is true. In locomotive practice it is virtually an axiom that you cannot very weIl combine every good feature at one and the same time in the one unit. Something has to be sacrificed. Consequently the locomotive engine represents a compromise between what is theoretically desirable and what is necessary on practical grounds. Between the two extremes there is plenty of scope for investigation and trial. In this connection I am glad to find that the fuller development of the 4-4-0 engine is advocated in the Paper. Twelve years ago I wrote an article recommending the enlargement of that type. The Author's suggestion that three cylinders should be used struck me as being un excellent one, as the cranks could then be placed 120 degrees apart, thus giving an even turning moment and doing away with the dead centre. In addition, the effect is to increase the adhesiona very important point in the case of a four-coupled engine, in which the weight on the two coupled axles could not much exceed 40 tons. Probably the Author is right in putting the highest I. H. P. of most 4-4-0
Journal Number 36
Riekie, John (Paper No. 66)
Compound locomotives. 405-29. Disc.: 430-75.
Meeting at at Caxton Hall, Westminster, on Saturday, 30 November 1918, at 14.30
Based on work in India. Discussion: J. Clayton (433-5) noted that the Smith/Deeley system was "highly successful" and achieved 1200-1300 hp over 15 miles. Fuel consumption was very low: 0.0916 lbs coal/ton mile and water consumption was also low: .797 lbs water/ton mile. Also cited the excellent PLM compounds and noted their flexibility.
F.W. Brewer (435-7): 'The principal subject of the Author's Paper is a very important one. It is not too much to say that, in marine work, compounding had become a sine qua non where reciprocating engines were concerned. Even allowing for the vastly different conditions under which locomotives perform their duties as compared with marine engines, still, a very natural question is :-To what extent could the compound principle be successfully applied to locomotives? What undoubtedly handicaps the solution of this matter is the fact that (in this country at any rate) power had been made subsidiary to economy. That is wrong. Power comes before everything. Having obtained the required power, as represented by boiler and cylinder capacity, the next step is obviously to ascertain the cheapest way in which that power could be developed. Theoretically, compounding offers one method of reducing the coal bill. Practically, and actually, it often does not effect any saving, either directly or indirectly. This result seems to show that the engines are in some respect or other incorrectly designed, and the explanation given by the Author is probably the right one, viz., that the majority of English compound locomotives have been so arranged. to develop the same power as, or a smaller power than that of corresponding simples with a similar boiler capacity. The descriptions of most compounds include a statenlent to the effect that increased power can be obtained by admitting boiler steam to the low-pressure cylinders, and, at first sight, this seems to give the lie to compounding, since the power being there, it might be argued that it would be more practical and sensible to utilise that power in a general way in preference to conserving it. By the very nature of its work, however, a locomotive is seldom required to exert its full tractive effort except at starting and on rising gradients; consequently that argument does not hold good. On the other hand, there appears to be some scope for a better utilisation of the exhaust from two or more cylinders, non-compounded. That is to say, there is room for using up the steam in a more complete manner than is possible with simple locomotives. I am not in favour of very early cut-offs as they strangle the power at its very source; moreover, by increasing the temperature range in the cylinders, they accentuate the chief evil which compounding is intended to remove or alleviate. Comparatively late cut-offs, on the contrary, give high mean effective pressures, but they 'mean, of course, relatively high terminal pressures ; hence it is here that compounding ought to come in, if at all. I am much struck with the Author's three-cylinder plan, which has evidently given excellent resuIts in India, and which would provide a sufficiently powerful engine of the 4-4-0 type. For larger types, the Author's four-cylinder and six-cylinder arrangements are of special interest. They represent a new and further development of the compound locomotive. It would be a great advantage if the practical utility of these developments could be tested by actual examples. The engines are somewhat complicated, however, and have an abnormally large cylinder capacity. These features might perhaps be justified by the requirements of the future; but, in any event, they should qot hastily be thrust aside, and the designs as whole would hrive to be reconsidered with a view to their being simplified as much as possible. At the same time, it the case of the locomotive, no greater mistake could be made than to aim at excessive economy. All such attempts in this country in the past have failed, from a strictly practical point of view, for the reason that economy has been put first and haulage efficiency Last. A reversal of that policy docs not necessarily mean wastefulness, even with superheated steam. Reverting to short cut-offs, experiments on stationary plants show that the ultraeconomic policy is also wrong in this connection, as the highest superheats, and the highest (relative) economics, are obtained when the engine is heavily loaded and worked with a comparatively late cut-off. The explanation is quite simple. With an early cut-off, the increased temperature range in the cylinder quickly absorbs the superheat and so neutralises the benefits expected to accrue from a high initial temperature of the steam. A high initial superheat is not synonymous with a high mean effective pressure, and the latter, after all, is the chief point, seeing that it represented the business side of the question. It simply means that, beyond a reasonctble margin for additional power, no enginc should be larger than is necessary for its daily alerage duties. An engine that is far too big has necessarily to be worked with an early cut-off, and this, in a commercial sense, signifies a loss, because of its reduced earning capacity. I think, therefore, that the Author is possibly justified in modifying his views respecting the impossibility of realising the full benefits of superheated steam with cut-offs later than 30%.
I entirely agree with the Authors objection to the usual practice of placing the inside and outside cranks of coupled-wheel engines on opposite centres, and the surprise is, perhaps, that this practice has endured so long. The arrangement gives an alternate pull and thrust, the bad effect of which must be reflected on the journals and axlebox brasses. The Authors valve-gear has several good features, not the least of which is the quick port opening for admission and exhaust. The slowing down of the lalye to a momcntary stop at half-stroke is also good. The thanks of the members are due to the Author for the great trouble taken by him in the preparation of his Paper. The different questions dealt with by him have been the means of throwing additional light on what are undoubtedly highly interesting problems affecting the improvement and future development of the locomotive.
Mercer (LNWR 438-40) spoke in favour of compounding. H.G. King (441-4) refered to the L&YR 4-cylinder compound 0-8-0s. H.W. Dearberg (445-52) commented on the Webb 4-cylinder compounds noting that the proportions of the cylinder volumes were incorrect and that the receivers induced drag in the low pressure engine. He also noted that the French compounds had good cylinder proportions. H. Holcroft (458-60) was critical of the compound concept as there was less friction in simple types. Smith Mannering (460-2) refered to the excellence of the copper tubeplates on the K class 2-6-0s.