Journal Institution of Locomotive Engineers
Volume 43 (1953)
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Den Hollander, F.Q. (Sir Seymour Biscoe Tritton Lecture).
Efficiency in the choice and application of locomotives. 12-28.
Special General Meeting held at the Institution of Mechanical Engineers, Westminster on 5 March 1953 at 17.30 at which The Sir Seymour Biscoe Tritton Lecture was delivered: President. C.M. Cock was in the Chair.
The Netherlands Railways. choice of motive power was based on the need for increased productivity and to reduce fuel costs. There was a high demand for passenger travel, and this was best met by electric multiple units which afforded high acceleration. On a few less intensive services diesel electric multiple units could provide the same degree of acceleration and afford comparable passenger comfort. On lines with very light traffic diesel railcars were used. Electrtic locomotives, which lacked the high rate of acceleration could be used on freight at night and on long distance pasenger services with few stops. It was considered that electric traction made the most effective use of fuel, most of which had to be imported into Holland.
Marsh, S.W. (Paper 518)
Recent developments in the use of rubber in railway engineering. 30-60. Disc.: 60-83.
General Meeting held at the Institution of Mechanical Engineers, London, on Wednesday 17 December 1952 at 5.30 p.m.: Mr. R.C. Bond, Vice-President, occupying the Chair who apologised on behalf of the President who was absent abroad,.
Author was Chief Engineer, Andre Rubber Company,
Showed the general made in the use of rubber in the Railway Industry in the last ten to fifteen years. It is confined solely to Locomotives, Carriages and Wagons and does not cover signalling and permanent way. It is not intended to include normal buffing and drawgear springs or auxiliary bearing springs, as such details have already been covered in past papers, and their use in the railway field is now well known.
1 . lntroduction.
2. The general advance which has been made in the compounding of rubbers, including use of the well-known synthetics, also bonding techniques.
3. General explanation regarding the design of rubber mechanical units, including some already in general use.
4. Units now under consideration and the trend in modern design work today.
Robertson, A.S. (Paper No. 519)
Limitations of acceleration and braking with electric traction: a study of the limitations imposed on performance by wheel to rail adhesion and electric traction equipment during acceleration and braking. 85-115. Disc.: 115-49.
General Meeting held at the Institution of Mechanical Engineers, London on Wednesday 14 January 1953 at 5.30 p.m., Mr. C.M. Cock, President, occupying the Chair.
Even on well maintained track, it is probable that small irregularities will initiate wheel slip, particularly when working at high speed and high tractive effort. Adhesion values up to and, above 20% can be obtained even at high speeds, but the probability of obtaining such a high figure at high speed is uncertain and depends to a large extent on the state of the track.
Journal No. 232
Bond, R.C. (Paper No. 520)
Organisation and control of locomotive repairs on British Railways. 175-216. Disc.: 217-65+5 folding plates. (incl. 2 col.). 6 iIlus., 4 diagrs., 11 tables.
Forty-second Annual General Meeting. held on 18 March 1953. President introduced Mr. R.C. Bond.
Main aim was to increase locomotive availability. Defined the classification of repairs into "heavy" and "light". Selection of locomotives for repair. Includes mileage/overhaul statistics for several classes as shown below.
AVERAGE MILEAGE BETWEEN PERIODICAL REPAIRS OF PRINCIPAL REGIONAL TYPES OF LOCOMOTIVES
|Region||Class of locomotive||Average mileage between periodical repairs|
|4-6-0 "Royal Scots" (taper boiler) and 5X conversions||
|4-6-0 Class 5||
|4-6-0 Class 5 with manganese steel liners||
|2-8-0 Class 8||
|2-6-4T Class 4||
|2-6-4T Class 4 with manganese steel liners||
|2-6-0 Class 4||
|2-6-0 Class 2||
|2-6-2T Class 2||
|Western||4-6-0 " King"||
|Southern||4-6-2 "Merchant Navy"||
|4-6-2 "West Country" and "Battle of Britain"||
|4-6-0 "Lord Nelson"||
|4-6-0 "King Arthur"||
A period in months since previous shop repairs was laid down for each class which, casualties excepted, had to elapse before locomotives were considered for shop repairs. This period was based on past experience, having regard to the nature of the service and the annual mileage the locomotives were running. Typical periods laid down for the then new BR standard locomotives were as follows:-
Class 7 4-6-2 15 months
Class 6 4-6-2 18 months
Class 5 4-6-0 24 months
Class 4 4-6-0 28 months
Class 4 2-6-0 30 months
Class 2 2-6-0 36 months
Class 4 2-6-4T 28 months
Class 3 2-6-2T 33 months
Class 2 2-6- 2T 36 months
Consideration was given to the different practices adopted by the
pre-nationalisation companies. Examination of locomotives coming in for overhaul
was considered to be very important. The limits of wear were considered.
The provision of spares was very important, especially boilers. Costing and
efficiency were significant.
Discussion: Opened by R.A. Riddles (pp. 217-18) who criticised the 85% availability target and considered that it should be much higher. Noted Bond's contribution to workshop efficiency in Scotland. Stanier (218-19) noted how efficiency at Crewe had been greatly enhanced through the new erecting shop instigated by Beames.
K.J. Cook (219-20) was strongly critical of Bond's statement: that "The wide variations in mileage at which individual locomotives of the same class require attention in the works, to which reference has already been made, clearly preclude the use of average mileage between repairs as a satisfactory basis for determining when the locomotive should be sent to the works." That, Mr. Cook, suggested, was an illogical statement. Provided there were the fundamentals of accuracy of repair and close tolerances, for which basis accuracy was necessary, then the mileage basis should become and was the only really logical basis on which to make the preliminary selection. He was rather perturbed to see that so many engines of certain main line classes required general or intermediate repair at considerably less than 40,000 miles. He suggested it was due to the fact that there was fundamental inaccuracy. If the basis particulars of the locomotive were dealt with with real precision, then if the engine fell down before it ran to within a very close distance of the specified mileage figure there was obviously some definite cause. From his own experience he could say that where engines were repaired with basis accuracy and close tolerances, it had been extraordinary how closely they ran time and time again and right throughout the classes to their average mileage. In his view there were at least four reasons, three of which were quoted in the Paper, that could be put forward to suggest that mIleage was really the correct guiding basis for repairs. Mr. Bond had referred to the measure of making good wear and tear, and that measure was the mileage run; unit cost was expressed as cost per mile, and it is also stated that the costs of maintenance and mileage between repairs were related to design features as a guide to future policy and practice. He suggested that that was the simplest method in which to make the selection and the very first question, without exception, which was asked by the Shopping Control was: - what was the mileage since the last repair? If engines were accurately repaired he suggested that the mileage was the best and simplest method which could be used. Under "Provision of Spares" the Author stated: "At one works" he was probably referring to Crewe "where the trouble was particularly acute, the problem was met by building one spare set of frames complete with cylinders, dragbox and stretchers for each of three numerically large classes of locomotive, with outstanding benefit to the progress of repairs at a time during the late war when every locomotive was needed for traffic." According to English parlance he did not think that that was" playing cricket," as it affected days under repair and it did not appear that the argument that it had, been sound financial policy to provide spares to that extent held good!
J.F. Harrison (220) mainly noted that the primary loss in time was through shortage of materials in the erecting shop.
R.A. Smeddle (220-1) commented on statement (page 181) that the frequency of repairs was governed as much by the mechanical condition of the locomotive as by the boiler. To some extent it depended, in his view, on which region of British Railways was being discussed. In some regions it was found that boilers lasted longer between repairs than in others. If one was fortunate to obtain a large mileage out of the boilers, it was almost invariably found that there was trouble with worn tyres, loose axle boxes, etc., although the latter had to a great extent been cured by the by the fitting of manganese-steel liners to the boxes. That was proved on reference to Table IV where a great improvement is shown on Class 4 and 5 engines as a result of the use of manganese-steel liners. If the boiler would hold out, as apparently it did on regions with water softening, then it was a great help to securing greater mileage between repairs. On the subject of mileage, he was interested in Table III where the average mileage from general repair was said to be 64,268 miles. Surely that was rather low. He extracted the Western Region's figures and found that the mileage was 80,000 and average time in months from general repair 41. It therefore appeared that the mileage was slightly lower on some of the other regions. The higher average on the Western Region might be accounted for by the attempt being made to put the best into the repair of the engines. He had worked on three regions, but was not so familiar with the LMS, or Crewe, and in his view the quality of the repairs at Swindon had a great influence on the mileage which it was possible to obtain there between general repairs and between general and intermediate repairs, the mileage between the two being approximately the same. The statement on page 188 that the smaller the number of days taken to repair each locomotive, the lower will be the number of engines at the works was interesting. The aim was, therefore, to complete the repairs in the shortest possible time. He suggested that it might be better to put it round the other way and reduce the number of engines in the erecting shops. That was done at a works with which he was previously associated. Weeks were being taken to repair the engines so a number were taken out of the shop and the reduction in the number of days as a result was surprising. With regard to the staging or belt at Crewe, at Swindon there was similar staging of repairs. The pits are arranged transversely with a traverser in the middle and engines were moved to the various positions by means of overhead cranes.
R. Arbuthnott (221-3) from the private locomotive manufacturing industry commented on the huge improvement wrought by the use of manganese steel axlebox liners, and asked why they had not become universal, and also asked what improved boiler boiler and was informed by Bond (230): better water quality, higher standard of shed maintaenance, and improvements in design: ample water spaces, larfe radii in the bends of firebox plates and steel or monel firebox stays.
E.S. Cox (223-5) added very little apart from noting that the use of manganese steel axlebox liners had increased tyre life and that some modern designs were excessively complex (he was presumably refering to multiple cylinders).
H.H. Swift (225) noted that a system of progressive repair had been introduced at Ashford and that this had led to a 10% improvement in productivity.
I.C. Forsyth (225-8 (3 illus.) described a welding repair method adopted at Crewe for fitting a pre-assembled front-end onto the Princess Royal main frames, which indicated that trouble was experienced through the cylinders working loose and fracturing..
Dymond, A.W.J. (Paper No. 521)
Operating experience with two gas turbine locomotives. 268-336.
Sixth Ordinary General Meeting of the Session 1952-53 held at the Institution of Mechanical Engineers on Wednesday 18 February 1953 at 17.30;. C.M. Cock, President, occupying the Chair.
Brown-Boveri gas turbine locomotive No. 18000 and Metropolitan Vickers locomotive No. 18100. Discussion: Sir William Stanier (pp. 292-3) made pertinent remarks on the gas turbine locomotives, and the difficulties encountered with operating the steam turbine locomotive on the LMS (reproduced in section on Stanier)
E.F. Spanner (305-6) wrote that a train heating boiler built into and forming part of a powerful modern locomotive can be a tremendous nuisance if it fails to function properly, and robs the train of its heating service. Writing as one personally responsible for a number of train heating boiler installations he observed that:train heating boilers require: adequate space, a reasonable allocation of weight, a compartment well ventilated when moving in either direction and an adequate and non-aerated feed water supply. Too often the space offered is unduly limited and a good job cramped for as little as an additional 6 in. on length and 6 in. on width of floor space. Two principal types of train heating boiler equipment are available: flash type and lightweight firetube type. There is a fundamental difference between the two in regard to character . and weight, type first being light in weight but heavy on maintenance and second being from 25% to 50% heavier, but of robust and long lived construction. When account is taken of the weight of fuel and feed water which has to be carried for a normal run, the difference in weight between type (1) and (2) is reduced to less than 10%. (c) An oil-fired train heating boiler requires a great deal of air at from 1 to 2 in. w.g. pressure for maintaining combustion under all conditions, i.e. with the locomotive at speed in either direction, in the open air and through tunnels, cuttings and so on. Cases have occurred where excellent results were secured running" ahead," as as it were, and poor results running" astern." There have also been cases in which the combination of a restricted compartment, a boiler of high output and little ventilation has resulted in the operation of automatic controls being affected. . (d) Feed supply to an oil-fired boiler is seriously affected by conditions at the suction end of the feed line. Special precautions should be taken to ensure;(1) that the suction is always well drowned at all times and under all conditions of acceleration and deceleration, running around right and left hand curves and so on; (2) that where possible, arrangements are made to ensure that the water tanks are filled with inert flue gas rather than air (this involves taking gas from the boiler flue to the air inlet and air escape to the feed tank); (3) that good water is used and~the boiler washed out periodically; ( 4) that the boiler, is filled right up to the crown from the non-aerated feed tank at each" shut down," in order to prevent air being "pulled back" into the boiler so causing corrosion above the water level. Attention to all these points, and to the selection and maintenance of adequate controls is essential to the establishment of satisfactory running service.
Journal No. 233
Reed, Brian (Paper No. 522)
Running tests of a 500 h.p. diesel-mechanical locomotive.. 366-97. Disc.: 397-411.
Ninth Ordinary General Meeting held at the Institution of Mechanical Engineers, London, on Wednesday 15 April 1953, at 5.30 p.m., Mr. C. M. Cock, President, occupying the Chair.
The losomotive tested was one of two eight-wheel 500 bhp machines built for Peruvian Corporation for service on the Paita-Piura Railway, a 62-mile line with short grades of 1 in 29-30 and longer grades of 1 in 35-50, laid almost entirely without ballast. The specified top speed was 33 m.p.h.; and most of the freight traffic and the few mixed and passenger trains on this route were handled by these two 55-ton locomotives, which had been in revenue service now for a year with satisfaction.
First time a diesel-mechanical locomotive had been dynamometered in line freight service in United Kingdom and, incidentally, the locomotive showed the highest sustained drawbar pull recorded in Great Britain up to that time (October 1951). Measurements with the dynamometer car showed: (a) that very high drawbar pulls of great steadiness could be maintained at all speeds; and that up to 3 or 4 m.p.h. factors of adhesion of 3.013.2 to 1 could be maintained with dry unsanded rails; (b) that even under unfavourable conditions, i.e. with loose-coupled stock, experience enabled gear-changes to be made with peak or surge pulls no greater than those of steam traction, and generally with considerably lower surges; (c) that gear-change times, and fall in tractive effort during those times, were of no practical importance in normal line work: and (d) that the governing system of the engine and the engine connection to the wheels prevented slip as normally understood. Finally, the trials as a whole substantiated claims as to the reliability of diesel-mechanical locomotives; and, more especially, the extreme consistency and steadiness of performance under all rail conditions.
Morgan, R.E. (Paper No.523)
The development of the Farnboro electric indicator and its application to the steam locomotive. 412-21. Disc.: 421-5. 6 diagrs.
Fourth Ordinary General Meeting of the Manchester Centre held at Reynolds Hall on Thursday 26 February 1953 at 6.30 p.m., the chair being taken by Mr. D. Patrick.
Also reviews locomotive indicator development in general including mechanical Indicators, e.g. Dobbie McInnes and Maihak. These indicators are simple in design and use and lend themselves to easy calibration under static conditions. They require some form of reducing mechanism, usually in the form of a linkage system driven from the crosshead, since in most cases the size of the diagram is only of the order of 3 in. x 1½ in. The pressure measuring element has appreciable inertia and this can easily lead to spurious effects, especially at the higher engine speeds. They are usually used for stroke base diagrams, but are adaptable.
Optical Indicators-Cathode Ray type, e.g. Cossor, Dodds. These indicators then required "complicated electronic systems" and produced small diagrams. The inertia effects are negligible and they can be used on either crank angle or stroke base. In most cases the pressure measuring element is sensible to changes in temperature and this must be compensated for. This type of indicator is very suitable for extremely high engine speeds and is chiefly used for comparative analysis of cylinder events. A high speed cine camera was often employed when these indicators were in use. Both mechanical and optical indicators give an indicator diagram for each cycle of events.
The Famboro Electric indicator was simple in design and easy to operate. It is designed to be driven from the axle or crank shaft of the engine and the diagrams, 14 in. x 7 in., are usually taken on a time base. The inertia of the pressure measuring system is negligible even at high engine speeds and the indicator is quite simple to calibrate.
These indicators give diagrams on either a stroke base or a time base or both. The stroke base diagram has the major advantage of permitting the easy computation of i.h.p., but this is really the only thing to be said in its favour. On the debit side are : the size of the drum, and therefore the diagram, must be small to reduce inertia effects due to rapid acceleration at high speeds. Secondly, the diagram is cramped at the ends where the principal valve events occur, that is, lead, cut-off, release, depending of course on speed, and a 3 in. diagram does not lend itself to accurate analysis from this point of view, if the effects of deliberate changes in valve events are to be analysed.
With the introduction of large scale testing of locomotives by British Railways after WW2, the problem of the most suitable type of indicator for use on a steam locomotive had to be decided. Spring and piston indicators of the Crosby type had been generally employed for indicating trials on the road, and experiments with cathode ray type indicators had been carried out prior to the war both by the LNER and LMS, but the results were inconclusive. The decision reached was that the Farnboro indicator appeared to be the most suitable and after consultation with Messrs. Dobbie McInnes, manufacturers of this type of indicator, two of these machines were ordered, one to be used at Rugby Locomotive Testing Station, the other by the MTUs for trials on the line.
It must be stated here that the Farnboro indicator was not originally designed for use on a steam engine, but was principally intended for the indicating of piston type aero engines, both on the test bed and in flight, but it was hoped that the special type of pressure element supplied for use on a locomotive would overcome possible difficulties caused by condensation occurring on the insulating material used in the element.
The Farnboro system consists essentially of a pressure measuring device and a machine on which to record that pressure at its appropriate piston position The pressure measuring device, known as the element is located in the cylinder cover of the engine being indicated. The element has a shuttle piston which is subject on one side to cylinder steam pressure and on the other to a reference air pressure which can be varied as required by means of a control cock on the indicator. This piston, whose movement is restricted by electrical contacts, is free to move under the influence of either air or steam pressure depending on which is the greater of the two.
Discussion: J. Fore (p. 422) asked how the system was adapted for four-cylinder locomotives and was informed that in the case of a four-cylinder engine (8 beats per revolution) the dead centres and therefore the diagrams would be spaced at approximately 45 of crank angle. When the locomotive had only 4 beats per revolution then there would be no alternative but to take two separate cards, and accept the time interval between them, care being taken to ensure that the boiler pressure and speed remained the same for each card.
D. Patrick (p. 421) had opened the discussion and received the following response: the matter of all cylinders being indicated simultaneously was a most important point in favour of the Farnboro indicator. The diagram for each cylinder end was formed as had been described earlier, but four or more elements could be used, each element recording by means of the spark which punctured the paper the exact point at which the reference air pressure was balanced by the cylinder steam pressure and its appropriate phase position. Considering one revolution, each element gave two sparks, then for a two-cylinder locomotive eight sparks per revolution would be recorded, all on the same pressure ordinate, but correctly spaced in accordance with the angle between cranks, and the cut-off of the locomotive concerned.
Journal No. 234
Bond, Roland C. (Presidential Address)
Years of transition. 439-63 + 4 folding plates. 15 illus., 7 diagrs.
This address surveys the post 1923 period in broad economic/technological terms. It reflects the policies of Bond's former chief (Stanier). Bond examined six experimental locomotives:
1. Armstrong-Ramsay Condensing Turbine Locomotive.
2. Beyer-Ljungstrom Condensing Turbine Locomotive.
3. Schmidt-Henschel High Pressure. LMSR 4-6-0 6399.
4. High pressure compound with water tube boiler. LNER 4-6-4..
5. Non-condensing Turbine Locomotive. LMSR 4-6-2. 6202.
6. Simple expansion 0-6-6-0 "Leader" Class. Southern Rly:
Of these locomotives the most successful was, I think, the LMSR condensing turbine locomotive No. 6202. It ran 439,931 miles in earning service; and although fuel economy was limited to that which could result from a reduction in heat losses compared with a reciprocating engine working between the same temperature and limits, dynamometer car tests showed a saving in coal consumption of approximately 7 per cent. Certain mechanical troubles were experienced and the availability record of the locomotive was not As a result of the experience gained over a period of 15 years, decided to convert this locomotive to 4-cylinder simple propulsion...
|Eastern Region A1 (then almost new)||93,363|
|Western Region Castle||87,424|
|Eastern Region A4||86,614|
|Southern Region Lord Nelson||81,611|
|Western Region King||78,987|
|Southern Region Merchant Navy||75,687|
|Southern Region West Country||74,650|
|London Midland Region Duchess||73,188|
|London Midland Region Rebuilt Royal Scot||70,495|
|London Midland Region Class 5 4-6-0||56,969|
Micklethwaite, N. (Paper No. 524)
Distribution of fuel on British Railways with regard to coal and coke. 464-73. Disc.: 474-5.
Fifth Ordinary General Meeting of the North Eastern Centre held at the Danum Hotel, Doncaster, on 29 January 1953 at 7 p.m., the Chair being taken by Mr. D.C. Stuart.
Next to wages fuel was by far the greatest expense in the motive power department. In 1951 coal and all fuels, the vast majority being coal, cost £38 million as against an overall wage bill in the motive power department of £45 million. The coal consumed was 13,549,000 tons in all regions, the Eastern and North Eastern Regions using 2,600,000 and 1,097,000 tons respectively. These figures were not decreasing and it was therefore our main aim to keep these costs as low as possible
Compton, J.N. (Paper No. 525)
The design and construction of steel fireboxes. 475-96.
Third Ordinary General Meeting of the North Eastern Centre held at Great Northern Hotel, Leeds on 10 December 1953 at 6.45 p.m., the Chair being taken by Mr. J.G. Dickson.
The author probably worked for the Yorkshire Engine Company. Advantages of copper fireboxes:
(i) Superior conductivity with the result that the rate of heat transfer is higher than with steel, in spite of the necessity for using a thicker section.
(ii) Long life: even with water of low alkalinity corrosion is negligible.
(iii) Easy material to work under manufacture and comparatively easy when repairs by patching are required provided particular skilled labour is available.
The disadvantages, and therefore the advantages of steel fireboxes more than outweigh the advantages:
1 . High cost even after setting off higher scrap value.
2. Necessity for riveted construction. Although copper fireboxes have been constructed by welding, both in Britain and on the continent, it cannot be said that it is accepted practice, and copper fireboxes continue to be built by the riveting method. The disadvantages of riveted lap joints are cost of manufactures, the skill required involving what must be looked upon as a declining trade and the localised overheating and concentrated stress resulting in the development of cracks particularly in the region of the caulked seams.
3. The adoption of steel for fireboxes presents a comparatively simple fabrication which can be built up by arc welding of butt jointing seams with comparatively thin plate. Evcn the tube plate need be no thicker than ½ in. for normal steam pressures instead of the specially thickened up copper tube plates which are nccessary to ensure against tube leakages. It wais an obvious scqucl to weld the tube to the tube plate. The other plates are usually only 3/8in. instead of ½ in. necessary for copper, and therefore the loss due to non-conductivity is reduced considerably, and there is no discernible disadvantage due to the slight slowing up in the rate of heat transfcr.
4. The whole steel firebox can be stress relieved after welding and before insertion in the firebox shell for staying and tubing, and therefore there should be no inherent high stress.
5. Advantage can be taken with a steel firebox to eliminate the fire hole ring and even the foundation ring at the junction with which plates frequently waste, due to local overheating combined with localised stress. For large fireboxes thermic syphons can be welded in, thereby increasing the heating surface considerably and providing support to the crown sheet to supplement the crown staying provided.
6. Where weight is important, a steel firebox and its staying is lighter than a copper firebox.
7. Maintenance is eased as welding makes repairs by inserting new plates, a comparatively simple job.
8. One of the main troubles, however, with copper fireboxes is the tendency for the tube plate to be stretched and pushed upwards by the greater linear expansion, and particularly by the rolling of tubes. The maintenance staff are very apt to be the cause of this, when working in a hot firebox, with the result that the tube plate flange becomes distorted at the top and all sorts of serious troubles result. Even in the case of large main line boilers, this trouble has caused cracks in the top flange, particularly with fireboxes with combustion chambers, and although various methods are adopted to protect the copper tube plate, the steel tube plate does not suffer from these troubles and the crown staying is far simpler. Steel boxes are more suitable for direct crown staying.
9. The life of a steel firebox, provided water conditions are not corrosive or low in alkalinity, is often nine or ten years, which is half the life of the boiler. The copper firebox is unlikely to last the life of the boiler in spite of its longer life. 10. The reduced size of stay consequent upon the adoption of steel increases flexibility and reduces the obstruction of the water space, but it is the design of the comparatively short water space stays in steel which requires a very careful study, and this was considered at length.
Discussion: C.F. Ryan (494) said that the Author, in listing the advantages of the steel as opposed to the copper box, had said there was a marked saving in weight, and also an advantage in delivery. If one could use a higher tensile steel in this job, one could get a saving by reducing the thickness of the plate. One of the disadvantages with a screwed stay would be the loss of strength at the screwed portion, hence it might be possible to use a welded stay. Another disadvantage would be the corrosion danger, and the speaker was not actually aware whether there is a steel which would give better corrosion properties. There is a rustless 40-ton steel which has a higher tensile strength than the ordinary firebox plate, and equally good welding properties with the ordinary plate. Provided that the steel had better corrosion resisting properties than the existing firebox plate stecl, it occurred to the speaker that it may possibly be a good thing to experiment. He snggested that stainless steel might he used and hc asked if the Author would comment on the possibilities of stainless steel fireboxes.
H. M. MacIntyre (494) said that almost 30 years ago he had to take out copper boxes and change over to steel at the rate of about 4 to 5 per month. With regard to maintenance, steel boxes were very easily patched, so much so that when it came to modify numbers of boilers whicn were non-superheated, one simply cut out a portion of the tube area and welded a new piecc in. With regard to the thickness of the tubeplate, he agreed that 3/8in. should not be exceeded. Copper ferrules could be used on the tubes, expanded in the barrel followed by beading over and welding. He had nevcr thought of turning the boiler up on its end to weld, and had nevcr filled it with water, and he had had no complaints. He expressed surprise that no allowances were given for the tubes in the way of staying the tube plate. He was also surprised that the illustration did not show the hollow stays.
Journal No. 235
Vandy, W. (Paper No. 526)
The production of steel wagons. 502-31. Disc.: 531-9. plan, 5 diagrs., 26 illus.
Author was Works Manger, Shildon Wagon Works. Mass production techniques and widespread use of welding, including development of jigs and automatic welding machines.Illustrations include an iron ore tippler, coke wagon, hopper coal wagon, an experimental bulk cement wagon and a bogie iron ore wagon of the type used to Consett. Discussion: C.A. Gammon (532-3) noted that the LMS had employed mass production techniques to manufacture timber wagons from 1923.
T. Henry Turner (534) said that the Paper showed that the Author had inherited a very fine tradition in Shildon. He recalled the time when Mr. A. C. Stamer took the speaker round that works in 1930, and also the later guidance of Mr. Thompson, Mr. Peppercorn and Mr. Smeddle; but the man who stood out in Mr. Turners memory was Mr. Cruddas. He was a real works engineer and the pioneer of many things which Shildon Works did before other works considered them. His flash-butt welding was an adjunct to the smithy, bringing the smithy technique up to date. His multiple-head oxygen cutting was another modern way of helping the smithy. He introduced flash-butt welding for three-link couplings and fabricated steel axlcboxes, of which he was the pioneer, in these works which are located in the country, and which might therefore have been backward. Instead of that Shildon enjoyed a tradition of progress, and their workpeoplc stayed there and developed their own methods and tools in a keenly progressive manner.
Axleboxes-On the question of Shildon axleboxes, he had one criticism to offer, that he saw on the track too many of their doors open and coal slack in the bearing; something needed to be done to kccp the axlebox doors shut.
Corrosion-With regard to corrosion, it so happened that in the Shildon works a hundred 20-ton side door opening coal hopper wagons were built about 1939, in the sloping bottoms of which were incorporated symmetrically plates of four different steels; namely mild steel, copper-bearing steel and two low-alloy steels. This was done in conjunction with the Iron and Steel Institute Corrosion Committee, and a R.I.S.R.A. report on ten years of examination of those wagons was published by the Iron and Steel Institute some two years ago. It seemed to show that it would pay to use some lowalloy steels.
However, the percentage corrosion reduction offered by any lowalloy steels in thiy country or in other countries was still relatively small as compared with stainless steels and one was therefore led to consider improved methods of protection against corrosion.
Galvanising-Some years prior to nationalisation consideration was given as to whether the open goods steel wagons which Mr. Cruddas pioneered could not be taken piece by piece -and zinc coated in a hot galvanising tank, to show the mechanical engineer as a demonstration some completely galvanised wagons.
The civil engineer used galvanising of steel with good results as did the marine engineer, and even the automobile engineer when he built the Land Rover galvanised many of the exposed bits and pieces; but oddly cnough there did not seem to be a single British Railway mechanical engineering works which used galvanising, so it did seem that such a demonstration should be made.
Unfortunately the disturbances caused by nationalisation killed the idea at first, and then when it was taken up again by the late Mr. Pugson the price of zinc soared and it became almost unobtainable. Fortunately, however, zinc was now cheaper and obtainable once again so that tests with galvanising of steel wagon components were again a practical possibility. Figs. 2 and 3 showed components which could almost certainly benefit by being galvanised.
Thinning-If a component went out of service due to thinning, the thinning was not only due to abrasion on the side which wore by friction, but also on the other sides due to corrosion. To take, for example, an Instanter coupling, if it were galvanised friction would soon rub away the zinc at two places, but zinc had the property of preventing corrosion of the steel in its neighbourhood. Normally such a coupling would go out of service through thinning but if it were galvanised to prevent corrosion at the back, the coupling would remain serviceable for a longer time. Metal spraying could be used as an alternative in some cases either with zinc or with aluminium. For real protection against the corrosion difficulty mentioned by the Author at the beginning of the Paper, galvanising or metal spraying were better than painting.
Bearing Metal-It would be interesting to hear from the Author whether other Regions of British Railways were still using the former LNER carriage and wagon bearing metal with 56 per cent tin. That particular bearing metal was popular because of its excellent casting properties, and although mechanical tests had shown merits in other bearing metals, the former 56-60 per cent tin alloy was probably the easiest bearing metal to cast and so resulted in the minimum of defective bearings in manufacture.
Ell, Samuel O. (Paper No. 527)
Developments in locomotive testing. 561-91. Disc.: 591-633; 729-34 + 4 folding plates. 2 illus., 19 diagrs. Bibliog. .
The thermodynamics of the locomotive is inseparably linked with the mechanics of the train. It was shown how this can be accomplished in locomotive testing in a manner both analytical and demonstrative. In describing its development it was shown (1) how the performance and efficiency of a steam locomotive can be expressed by a three-fold relation and by a two-fold relation in thermo electric units, and (2) why the mass, system of locomotive and train and its normal mode of progression must be preserved in demonstrative analytical testing. Since the normal mode of progression is one of variable speed, an outstanding problem has been the control of the thermodynamic factors at variable speeds. Finding a solution in apparatus and methods which are simple and easily applied, a full description and analysis was given of a test on the Controlled Road Testing System. How the results of a number of tests are coordinated was described and the paper concluded with a discussion of the implication of the results in respect to the efficiency of the locomotive as a mobile power plant and as a motive power unit with its associated operating problems.
Illustrated by tests conducted with King class 6001 using controlled road testing. On page 565: "Then, with respect to the steam rate-power relation, it was demonstrated that this is the Willans' relation. Every student of steam should, but usually does not, know Of the fundamental connection between the indicated steam rate and hypothetical mean effective pressure for the two conditions of governing by throttle and by cutoff. P.W. Willans, 60 years ago, showed that similar relations held for the practical engine and the distinctive curves for the two conditions are known by this name. And of course, it applies to the steam locomotive, though one may search its literature in vain for a mention of it": see also an Appendix and Paper by Willans..
Discussion: Stanier (pp 591-2): said he could not help thinking that if he could have had the advantage of some of the information now in the possession of designers and obtained by the careful analysis of the testing of the various thermodynamics and mechanical parts in the construction of locomotives, he would have been much happier in the work which he undertook. It was very interesting to see that the old dynamometer car, the underframe of which he designed when in the drawing office, was still running. He recalled that when he started in one of the drawing offices he had the privilege of working in the old dynamometer car. It was a four-wheeled vehicle with a fifth wheel for operating the mileometers, and it originally had a laminated spring something like a buffer spring. Mr. Pearson, who was doing experimental work, designed a spring built up of separate plates with rollers between the plates, and that spring was in the present dynamometer car. Therefore the work done by Mr. Pearson was still helping in the work being carried out at Swindon. He wondered whether the very interesting and ingenious method of obtaining the steam flow from the tip of the blast pipe which operated a gauge on the footplate might not be of some guidance to the footplate staff if they had to work the engine to the degree of accuracy and speed which he Author forecasted on his test. A thing which had puzzled him for a long time, having ridden on many engines, was whether the right practice was to notch up as close as possible and have a full regulator, or whether to let the gear out a bit and ease it on the regulator. He had never been able to solve that problem himself, and it seemed possible to find an answer. The impression he gained was that it was all very well to have a gear which could be notched up to 10 per cent and work at full regulator, but it put a good deal of stress on the gear, and drivers found that it was better to work at 18 to 20 per cent and ease the regulator. He desired personally to thank Mr. Ell for having presented the Institution with such an excellent Paper which would be a source of interest and reference for a number of years to come. In fact, a5 long as steam locomotiyes ran. Mr. Cock did not think that they would run much longer, but there was still life in them and the work done by the Author had put another period on their life because more efficient locomotives were bound to result from it.
J. Fore (730-1) recorded that an LMS 4F 0-6-0 had been modified at Swindon with an improved blastpipe and chimney and that on tests on the North Wales main line the maximum continuous steaming rate had improved from 12,000 to almost 21,000 lb/hr. D. Patrick (731) asked whether Goodfellow Tips had been evaluated..
Journal No. 236
Tuplin, W.A. (Paper No. 528).
Some questions about the steam locomotive. 637-65. Disc.: 665-714: 1954, 44, 167-73. illus., 10 diagrs. 3 tables.
Most of this paper, including the monumental, but mainly destructive commentaries by Carling, Ell and Holcroft are considered on the Tuplin page and are not repeated here. An outsider's (but a professional engineering outsider) view of locomotive development. The paper is interesting in that all of Tuplin's views more widely aired in several books and many magazine articles were subjected to scrutiny by professional locomotive engineers (thus the response is especially interesting).
Tuplin argued that the extra weight demanded for stronger boiler plates invalidated the "advantage" of adopting higher boiler pressures. The following Tuplin criteria were subjected to Tuplinesque scrutiny by Carling:.
(a) The higher temperature of the water means higher temperatures
in all the main components and this can affect the copper firebox and copper
stays appreciably as that material begins to lose strength as the temperature
rises above about 300°F.
(b) The higher temperature and pressure of the water accelerates any chemical action of its impurities on the boiler.
(c) The thermal stresses in critical parts of the firebox wall may be increased by the effect of the greater thickness.
A key feature of Tuplin's paper, and one debunked by Ell was Table III best speed ranges on page 647 wherein the best speed range in terms of boiler/cylinder capacity and the best speed for valve performance were listed together with their overlap if any: there was alleged to be none for the GCR Director class, and only the range 50-59 for the King class: the latter was clearly perceived as a red flag by a bull by Ell!
Two cylinder designs were advocated as against the use of multiple cylinders: if multiple cylinders were adopted then he favoured the layout employed on the B16/2. Favoured narrow fireboxes and the absence of trailing axles. Cited Goss (this got him into a lot of trouble) to advocate the use of simple front ends as aginst multiple blastpipes and chimneys. He made a number of comments on the ergonomics of cabs and the operation of firehole doors.
Discussion: H. Holcroft (665-8) opened the
discussion and on page 666 (when well into his response) Holcroft noted that:
"In the Paper much prominence was given to thermal efficiency per se.
To the locomotive engineer, however, thermal efficiency was only one factor
of many and it had to be considered with due regard to all the others which
went towards the making of optimum power. It might well be
that in the end some sacrifice of thermal efficiency could be beneficial
in producing the most suitable motive power unit. Holcroft was highly critical
of Tuplin's assertions concerning low boiler pressures: "such engines were
amiable and reliable machines but most lethargic" Holcroft was also highly
critical of Tuplin's observations on firing methods, on superheaters, and
on lost motion in valve gear due to excesssive clearances (and cited his
own measurements to show that was not the case).
C.C.H. Wade (668) commented on firing techniques and the limits of endurance for firemen.
R.G. da Costa (668-71) was highly critical of Tuplin's observations on superheating, and in particular Tuplin's attempt to relate grate area to superheater surface and temperature; Tuplin's interpretation of Goss's observations on unconventional valve gear which da Costa considered had been made prior to what da Costa stated were "substantial improvements" in the design of valve gear, especially in poppet valves.
S.O. Ell (671-4) see Tuplin page.
Pelham Maitland (674) recorded that in a large number of instances where the boiler pressure had been raised there had been an immediate and, in aggregate, appreciable saving in coal consumption. On firing engines with wide fireboxes, the technique of firing to the four corners of the firebox and little elsewhere produced one outstanding feature. It tended to the more thorough combustion of the coal than otherwise would be possible, because the draught did not tear the fire to anything like the same extent as with a narrow firebox. That was a feature on which he would like the Author's comments-the tearing of the fire in a narrow firebox as compared with a wide firebox.
A. Hood (674-6) noted that Tuplin queried whether boiler designers set themselves targets regarding weight per unit of heating surface. So far as the private builder is concerned the answer was an unqualified affirmative inasmuch as the weight limitations imposed by the clients' specification set the target. Only those closely acquainted with the subject appreciate fully what these limitations mean, particularly when restrictions are placed on the. weight per foot run of wheel base as well as on axle loading. In the remarks on fireboxes Tuplin made no comment on firebox volume: it has been argued that much of the merit of the narrow box is derived from the ratio of volume to grate area being good, and the more general adoption of the combustion chamber seems to substantiate this. In fact it has been claimed that the narrow box is practically the ideal shape when dealing with oil-fired locomotives.
With regard to the comparisons of boiler weights, as given in Table 1, it may be suggested that a much more equitable basis of comparison might be to make this in terms of evaporation per hour from the various boilers. This would bring into play the division of the heating surface between the firebox and tubes. Such a comparison might be made either on the basis of any agreed rate of evaporation from the firebox and tubes or preferably on the basis of the recently published data on locomotive testing issued by British Railways.
The comparisons. made in the Paper are only fair if the locomotives are designed to the same ratios of fireboxes and tube surface. In a recent locomotive built in this country for overseas the total evaporative heating surface is in fact less than in a previous design, and the tube heating surface is some 4% less, yet the new design has permitted an increase of 40% in the firebox heating surface.
The concepts of "nominal speed," "specific speed" and " specific. effort" are highly interesting, but whether there will be general agreement with the conclusions which Tuplin derives from his analysis is open to question. Nevertheless, the argument put forward is worthy of close study.
There is probably no more debatable point in locomotive design than front end proportions, and also nothing which can so influence the performance of the locomotive in service, yet it would still seem that the only guide is experience based on previous designs, for despite the fact that the American Master Mechanics' proportions have been known for many years, it would seem that even in the USA there was nothing really standardised, at least tliat is the conclusion arrived at after studying the results of the front end experiments made in the University of Illinois, and Johnson seems to confirm this in his book on the Steam Locomotive.
While the Author's criticism of the 4-6-2 type on the basis of weight transfer may, perhaps, bear analysis for locomotives on British Railways, it cannot be applied to locomotives for railways where the permissible axle load is a limiting factor. Would the Author. faced with the problem of providing for a large boiler on a passenger locomotive, prefer to use a 4-8-0 with all it involves in the way of extra rods and resistance in preference to a 4-6-2 if the 6-coupled engine gives all the ,adhesion necessary? , As regards mechanisms one can readily agree with Dr. Tuplin when he says" the less of it the better," so why not go all the way and adopt servo motors which would put the steam locomotive driver on a par with his opposite number on other forms of power? .
The Author had referred to ash chutes for smokeboxes. Two past applications of this idea sprang to mind. Paget's 2-6-2 engine of 1907 had used such a chute, sealed at the top by a simple flat-seated plug held by its own weight in the top of the chute and with a long-lifting handle. Even simpler was the device used by F. W. Webb on his" Precedent" and 3-cylinder compound passenger engines, consisting of a chute tapering down to a rectangular hole about 6 in.x 2 in. quite open to the atmosphere! No attempt at sealing was made, but the front plate of the hopper was extended some inches below the back plate and turned over to give a crude ejector action due to the air stream when running forwards. He was not aware of any complaints of the steaming of the" Precedents," but would be reluctant to see such a device applied to modern locomotives!
He felt he must join issue with the Author on the subject of regulator operating mechanism. Whatever -the torque might be on the shaft to operate the regulator, the pull at the cab to overcome it would, of course, be the same if the mechanical advantage of tire existing and proposed linkages were the same. However, the weight of the operating rods alone on the" Britannia" boiler was of the order of 70 lb., and in view of the damage caused to them by cleaners standing on them, etc., he did not see that they could be lightened satisfactorily. Did the Author seriously suggest that the direct pull necessary to a~celerate this mass in opening the regulator would permit anything approaching the present sensitivity? He thought the Author should be copdemned to an eight-hour shift shunting with an .engine so fitted! In conclusion, he felt that drivers would rebel at the Author's suggestion to bring the cab window back close to where they sat. One thing that was very necessary in case of emergency was complete freedom of movement in the cab, and criticisms of the BR standard cab layout which had been voiced dealt with the driver's sense of being" boxed in " by the grouping of controls round him. With the proposed arrangement, the driver would be risking his skull even to tie his bootlaces!
Mr. P. R. Saunders (678-9) wrote that the Author pointed out that a 4-6-0 locomotive, particularly one with a high drawbar, would be better in some circumstances, such as starting on an up gradient or on an irregular track, than a 4-6-2 of similar nominal adhesion. The implication of this part of his Paper was, he assumed, that it was sometimes preferable on this account, to build a 4-6-0 rather than a 4-6-2, both engines having the same weight for adhesion. He would suggest, however, that 4-6-2's were only built when it was absolutely necessary from a consideration of the work required of the locomotive in other circumstances. The 4-6-2, with a larger firebox and boiler, would have a superior performance at speed, when maximum adhesion was not required, and may yet have a greater availability. In any case, Professor Tuplin's calculation of the weight transfer that took place would appear to be in some error. Since the coupled wheels were separately sprung, and the trailing axle had greater loading than the leading axle, this weight distribution among the coupled wheels exerted a levelling moment on the frame which was neglected when only the overall transfer of weight from the bogie wheels was considered. A calculation, taking that into account, showed that the transfer from idle to coupled wheels for a BR Class 5, 4-6-0 when the drawbar pull was 12 tons at 3½ ft. above" rail level was less than 1¾ tons, rather than 2½ tons.
W.O. Skeat (679-81 written communication) see Tuplin page
M.A. Henstock (693) argued that the reserve available with higher pressures was appreciated by the footplate crews; he noted that the LMS used nickel steel for some its boiler plates to reduce weight; he commented on eddy currents above the brick arch; and noted the problem associated with short connecting rods: heated bearings and crosshead wear. He did not understand the criticism about the" Patriots" and the" Royal Scots," they certainly have the same wheel diameter and cylinder sizes, but the tractive efforts were far from comparable, the first being 26,520 lb. and the latter 33,150 lb. This seemed a very big difference by which to compare a locomotive. The L.M. Region 2-6-0 Class 5, parallel boiler engine with a pressure of 180 lb./sq. in. and tractive effort of 26,580 lb. could be compared with the 2-6-0 Taper Bqiler Class 5 which bad a tractive effort of 26,288 lb., these two locomotives were, in his opinion, far more comparable to bring out the points that the Author was trying to make. Regarding the diagram showing the fire hole door, as he did not understand how it worked he asked if the Author would be good enough to give an explanation.The inward opening door was not a new idea. All the former L & Y Rly. engines had inward opening" flap" doors and one of the main disadvantages was the frequent renewal of this type of flap which burnt away very rapidly.
The diagrams of the regulator operating rod reminded him of what all designers should avoid, a "one view" scheme. The arrangement shQwnin the elevation looked no doubt feasible, but if the plan view of the boiler and rod had been shown a different picture would present itself, due to the rod having to pass the widest part of the firebox and 'be straight in the plan, t~e shaft at the multiple valve header would have to be extended considerably to line up the lever with the operating rod; this overhang was very undesirable on account of wear taking place and causing the gland packing to leak even more than at present.
The load required to open the pilot valve was 250 pounds and by the existing arrangement there was 'no chance of the rods being moved by anyone or anything from outside the cab.
If the Author's scheme could even be adopted, the chances were that this could result in the regulator being opened other than by using the handle in the cab, which would be very undesirable, especially when the engine was being serviced at the sheds, due to the possibility of the regulator being opened by some unauthorised person, cleaner, etc.
The Author unfortunately had not given anything concrete on which the designer could base a design for the smokebox; the diagram of smokebox proportions was like most, it fell short of giving the blast pipe cap diameter, or anything on which to base it for a given locomotive, the distance from the tubeplate and also the height below the centre line of the smokebox; these were the figures the designer had to search for, and how elusive they were.
D.R. Carling (694-8) see Tuplin page.
W.G.F. Thorley (698-9) noted that Tuplin stated that the object of superheating was to ensure that, despite the drop in temperature of the steam as it expanded in the cylinder, it did not become saturated. Could it not be said also that the superheater provided also a valuable addition to boiler steaming capacity inasmuch as the volume of steam was increased by its use? It would be recalled that the first two "Princess" class Pacific locomotives of the former LMS Railway had 32-element superheaters fitted in place of the original 16-element apparatus after only a short period of service, and the steaming was improved thereby. The Author had said in the discussion that the firebox volume was increased at the same time as the additional superheating surface was provided and therefore the value of the latter could not be assessed accurately, but in this connection it was pointed out that the number of elements had been increased without increase of firebox volume in both the Classes 5MT and 5XP locomotives of the same railway, as 'compared with the original arrangement and the steaming had been improved. The superheater had the advantage that, provided the flue tubes were kept reasonably clean, its efficiency remained unimpaired as the boiler scaled up internally; also it was sometimes able to evaporate water during periods of priming, which would be carried over into the cylinders of a saturated engine.
The Author recommended a 3-cylinder engine having the inside mechanism as readily accessible as that of the two outside cylinders and the B16/2 4-6-0 Class of the former LNER was instanced as an engine which nearly gave the desired feature of being able to be prepared without the use of a pit. It appeared, however, that in these circumstances the driver would have to pass between the trailing bogie wheels and the leading coupled wheels to gain access to some of the inside oiling points and this was a practice which could not be officially countenanced.
Mr. Thorley considered that the Western Region practice of lifting the flap plate between the application of each shovelful of coal, as mentioned under "Firebox" in the Paper, was brought about more by force of circumstances rather than by any conviction of the enginemen that it was the correct thing to do. Whilst such an attitude of mind on the part of the latter was a very good thing to encourage, the fact remained that if an engine would steam freely with the flap remaining down between consecutive shovelsful, then the flap remained down.
Meeting in Glasgow, 26 January 1954: A. Hood:
(704-5): noted that the first Merchant Navy class boiler was designed
and built in Glasgow, and at the request of the customer a second edition
of the boiler was designed and constructed which proved to be approximately
2 tons lighter than its predecessor. This was a typical example of the designer's
art which reduced the weight of the boiler yet maintained its original output.
J. Campbell (705) emphasised that higher boiler pressures provided "ample
reserve capacity. Considered that the inertia effect in valve gears noted
by Tuplin could be used as an argument against conjugated valve gears. E.F.
Clark (706-7) mentioned that comparison was seldom made between
steam locomotives and stationary reciprocating steam engines.
In this connection it was interesting to recall that on the
question of high superheat there were very few cases of steam temperatures
over 600°F. being used in stationary engines, especially those with
cast iron cylinders. The locomotive engineer tended to look at the performance
of the locomotive from the point of view of tractive effort, while on the
other hand, although for stationary engines conditions were different, engineers
considering them looked at their performance much more from the point of
view of steam flow and power output. On the question of eliminating unnecessary
mechanism, he suggested that exhaust valves could be cut out quite easily
by the adoption of the Uniflow system. He said that he thought all locomotives
would benefit enormously when rolling stock was fitted with roller bearings
and rail joints were eliminated by track welding. During a recent visit to
Germany when riding on a train which was admittedly hauled by an electric
locomotive, but on which the whole of the stock was fitted with roller bearings,
he had been most surprised to find that when the speed of the train had been
reduced to a walking pace, the whole train rolled on for a surprising distance.
He was quite sure that power was no being applied and this rolling on could
not be obtained with stock fitted with plain bearings. It was said that there
was no lessening of tractional resistance when roller bearings were used
over about 25 m.p.h., yet all trains had to be accelerated from standstill
to this speed. He thought there was a strong case for remembering that all
locomotives would benefit greatly when all stock was fitted with roller bearing
N. McKillop (707-8) With regard to the statement made by the Author that there were no means of comparing lower pressure boilers with higher pressure ones, McKillop said he was of the opinion there was a very good means of comparison. He believed he was right in saying that the first Gresley Pacific had a low pressure boiler and that eventually high pressure boilers were adopted, and the difference in performance was fantastic; very much less coal was burned and the mileage between shop overhauls increased from something like 60,000 miles to 102,000 miles in certain cases, which was due, in his opinion, to the high pressure boiler With regard to wide and narrow fireboxes and fallen brick arches McKillop asked if the Author did not agree that wide fireboxes were an advantage in the event of the brick arch falling. He also said there was no difficulty in maintaining steam with the wide firebox.He said the Author had not mentioned anything about the combustion chamber Gresley introduced to the Pacific engine. With regard to piston valves, McKillop said that on the indicator diagram the sharp corners were produced by large poppet valves opening instantaneously by cam gears and he asked if the Author thought there would be an improvement by the operation of piston valves by cam gears. He said he was rather surprised to find that Professor Tuplin thought the efficiency of operation of a locomotive fell when the engine was taken above 15 per cent cut-off. In practice it was a fact that very high efficiency of the Gresley valve gear could be obtained with much higher cut-off. With regard to window design, which was very important, McKillop suggested placing the glass at the rear of the tunnel instead of at the front. He said it was surprising that Professor Tuplin had criticised the throttle operation on the engine, because he must know that the throttle operation of a locomotive was a very vital thing to a driver. The driver, going at high speed, must get a fine adjustment of the throttle, and if he had the assistance of a steam-chest pressure gauge it was necessary that he ran a distance with the throttle so adjusted, as he could make it fluctuate between, not 25 lb. or 50 lb. of pressure, but 1 lb. of pressure. He said the device introduced into the throttle rod was done to give rigidity and putting the brake handle where the Author suggested reminded him that on one occasion the little window, where he suggested putting the brake handle, was smashed by a passing train. It was a highly dangerous practice to put any apparatus outside a fast moving engine for a driver to put his hand on. He thought the operation of the firedoor by the driver was fantastic. He asked if it was not the case that Gresley introduced the combustion chamber on the Pacific to prevent the tubes warping, as it was found that the tubes were liable to warp and leak very badly, and a short rigid type of boiler tube would reduce such leakage.
A.C.D. Malcolm 708) said he thought the Author would agree that the trailing truck helped to keep the engine on the rails, which had been proved on at least two classes of engine.He said he thought it was better to have a steady back end and that Mr. Hood had a very strong point there, and he asked if the Author thought the fitting of a Cartazzi truck justifiable, as a trailing truck improved the riding of an engine.
D. MacAulay (708) mentioned Cartazzi slides and firedcors. In his experience in India the Cartazzi slide slid so much that the engine used to leave the track. With regard to firedoors, the standard design of firedoor was a scoop turning inwards and connected to a handle by a trigger. This was also in use on the same Indian Railway. The fireman had to shovel each shovelful of coal with one hand and work the scoop with the other, and he kept a very constant steam pressure in the boiler.
Meeting in Newcastle-on-Tyne, 24 February
F. Johnson (712) asked the Author to comment on the fact that it was not so many years since all boilers had narrow fireboxes tending to keep the cylinders small, making it easier to increase power by raising the boiler pressure. He pointed out that it must not be forgotten in connection with weig:hts that with an increase of 15 per cent in the boiler capacity, to a boiler of the same weight, the lower pressure would call for an increase in the weight of water. If the boiler pressure were increased with the same size cylinder there should be an increase in the heating surface and grate area if the same power were expected from the locomotive. If the plates were merely thickened the same amount of coal would be burnt in the firebox and the same horse power created. He said that he thought that a greater superheater area was necessary for a locomotive which ran on a very short cut-off and he asked the Author to comment on this point. On the question of the transfer of weight with advantage to trailing bogies Mr. Johnson said that in his opinion the whole of the weight would not be taken by the trailing bogie. It would only be a portion of the weight. In commenting upon the regulator mechanism Mr. Johnson stated that so far as he was aware the regulator handle was often fitted with a trigger and locking ratchet and there should not be any necessity for an allowance for expansion as the regulator was only used when the boiler was in steam. In reply to Mr. Johnson the Author stated that he did not see how the firebox need control cylinder sizes. If big cylinders were wanted, the frame could be set in at the front end, and then the outside cylinders could be 25 inches in diameter if the connecting rods were placed against the wheel-bosses. When the size of the boiler and the speed-range for maximum power have been decided, the nominal tractive effort for highest cylinder efficiency in that range can be determined. The next step was to select the largest convenient cylinder volume and then to use the conventional nominal tractive effort formula backwards to find what pressure had to be provided to produce the desired nominal tractive effort in those cylinders. If only two cylinders were used to get the nominal tractive effort, the pressure might work out at 250 lb. per sq. in. as in the Class 7 Pacifies, whereas three cylinders would give the same result with about 185 lb. per sq. in. The Author said that boiler power is not determined by steam pressure but by grate-area and heating surfaces. It is true that a larger boiler holds more water and so the estimate of the boiler power possible within a given weight is not correctly based on empty weights of boilers As Mr. Johnson said, this fact reduces the possible gain in power/weight ratio from reduction of boiler pressure. The Author agreed that the higher the expansion ratio the higher the minimum desirable superheat, but added that shortening the cut-off below about 18 per cent does not raise the expansion ratio. He added that even the small superheaters used on the GW were evidently adequate for short cut-off working, at least with good maintenance.On the question of weight transfer the Author said that even if the springs of the rear truck and the preceding axle are equalised, the drawbar pull still transfers some weight on to the rear truck and therefore off the other wheels some of which may be driving wheels. If there is no rear truck, weight cannot be taken off the driving wheels by the drawbar pull, ,and so a 4-6-0 has some advantage in this respect over a 4-6-2. Regarding Mr. Johnson' s observations on the regulator rod mechanism the Author said that this was a good point. As expansion was small, the difficulty could in any case be got over by putting a locking trigger at the back end .
C.H. Swan (712) said that he had listened with interest to Professor Tuplin's remarks on the B.16 Class short connecting rod and from personal experience he knew that the great disadvantage was the short life of the little-end bushes; he suggested that the little ends should be fitted with roller bearings. In regard to the transfer of weight there was another factor to be taken into consideration. From the enginemen's point of view a Pacific is a much better riding engine than a 4-6-0 and from the maintenance angle the lateral wear on the trailing boxes is not normally so great on Pacifies. Mr. Swan said that a number of the uggestions made by Professor Tuplin were obviously very good as they seemed to adhere to former NE practice such as the Blades firehole door which hinged inwards from the top and closed with its own· weight, and there were the former NE type windows which opened inwards. The Automatic Train Control device mentioned by Professor Tuplin resembled the handle of the Ravens Fog Signalling apparatus which did away with the necessity for fog signalmen between Shaftholme and Berwick. The former NE vacuum handles could be reached from the window
Mr. Meicher (713.) asked if it were not possible for the therma efficiency of the locomotive to be increased by devoting further study to the volume of the smokebox.
Mr. Sadler (713) asked if Professor Tuplin could offer any explanation for the apparent reluctance to accept GW practice pointing out that. Gresley had to change a design after twenty years to fit with Churchward's design. Had it anything to do with boiler pressure?
De Sousa, C.H. (Paper No. 529)
The design of Indian Railways passenger coaching stock for greater comfort. 715-24.
The principal conditions which militated against comfortable travel in India were: climate, dust, noise, inadequate accommodation and lack of amenities,, and by implication the misuse of such amenities, notably wash basins and lavatories. The author considered that insufficient attention had been paid to the Indian's wish to sit with their feet tucked up.