Journal Institution of Locomotive
Volume 35 (1945)
|Steamindex home page Updated 2015-05-14||Key file||The IMechE virtual library is accessible (full papers, all diagrams, photographs, extensive tables, etc).via SAGE|
Journal No. 183
Clarke, C.W. (Paper 450)
Technology of the heat treatment of steel. 3-29. Disc.: 30-8.
.Meeting of Western Branch of the Indian and Eastern Centre held at Bombay on 17 December 1943: Mr. H.P. Renwick occupied the Chair.
Indian paper: problem arose during WW2 that there were an inadequate number of plants capable of heat treating steel. The. object of heat treating steel is heat to improve its physical and mechanical propaerties. Treatments include
Sanford, D.W. (Paper 451).
The relationship between smokebox and boiler proportions. 40-53. Disc. : 53-76. 5 diagrs., 2 tables.
Third Ordinary General Meeting held at Institution of Mechanical Engineers, London, on Thursday, 30 November 1944, at 5.30 p.m.: Mr. W. S. Graff-Baker, President of the Institution, occupying the chair. Repeated at First General Meeting (Session 1944-45) of the Birmingham Centre held at the Midland Hotel, Derby, on Wednesday, 31 January 1945, at 7.30 p.m.: chair being taken by Mr. E.S. Cox.
Attempted to find a relationship between the proportions of the chimney and blast pipe on the one hand, and the boiler proportions on the other. The factors involved were many and variable, and it was impossible to arrive at suitable dimensions solely by calculation. The final adjustment still depended on trial and error: nevertheless, theory was of considerable help in enabling the designer to avoid major errors, and was also of considerable assistance towards a correct interpretation of eflects which are observed during actual trials.
Based on precis containd in Locomotive Mag., 1945, 51, 42-3. The blast pipe and chimney have two functions to perform: to eject into the atmposphere all the products of ccombustion produced in order to obtain a given power output and to obtain a vacuum in the smokebox to draw the reuired amount of air or gas through the grate and tubes. The problem confronting the designer is to fulfil both these requirements with the least possible exhaust pipe pressure. If the problem. to be faced were merely the ejecting of a given volume of gas per unit of time, it is clear that the larger the diameter of the chimney and the blast pipe nozzle the better, because the larger the chimney the less energy is. expended in ex- hausting the mixture of escaping steam and gases. However, to provide an effective draught a sufficient vacuum must be created in the smokebox to ,overcome the, resistance of the boiler and it is this consideration that determines the upper limit of the chimney diameter, and also that of the blast pipe orifice.
The resistance of the boiler is made up of the sum of the resistances offered by the ash pan, firebed, firebox, and the tubes to the passage of the combustion air. The greater these resistances the greater must also be the degree of rarification in the smokebox. The size of the chim- ney, that is, its diameter, and through that the diameter of the exhaust nozzle, determine the vacuum obtainable. The diameter of the chimney governs the velocity with which the smokebox gases are ejected, which must be such that the velocity of egress equals the velocity with which gases outside the smokebox would rush down the chimney under the influence of the vacuum created within. the smokebox, This is the sImple and approximate method of stating the case. While computations can be made to establish gas velocities for a given vacuum, they are unfortunately not applicable in practice, largely due to the fact that gas velocities are not constant and that the jet of exhaust steam has a greater velocity at its centre or core than at the sides.
This is of interest and importance, and explains why all recent development work undertaken with the idea of improving the efficiency of the jet of steam has been centred upon finding means for splitting the jet or usmg a multiplicity of jets in order to make use of the high velocity of the centre portion. The much larger engines now used which necessarily require boilers of high evaporative capabilities has forced attention to the exhaust steam passages and the design of the blast pipe and chimney. In the interests of cylinder efficiency back pressure must be low, while on the other hand large boilers offer relatively high resistances to the gas flow, for though a large grate may have a somewhat low resistance due to a thinner fire, the gas flow per tube may be, and in fact is high, this latter being brought about because in the case of large boilers the net gas area through the barrel is and must be low in proportion to, that of the firegrate, for the reason that it is usually easier to find room for a large grate than it is to provide a large barrel. diameter.
Discussion: O.V.S. Bulleid (53-5) was highly critical of he use of a mercury U-tube for measuring smokebox vacuum and advocated the Cambridge Instrument developed with Gresley. Described his WW2 experiment of fitting a locomotive with two separate chimneys in an attempt to break-up the exhaust trail. He advocated larger chimneys with a 7 to 1 ratio rather than the more usual 3 to 1 ratio. and cited work on Lord Nelson class chimneys H.I. Andrews (55-6) commented upon smokebox efficiency and its measurement; E.S. Cox (56-9) thought that chimneys might "certainly be made larger than at present" and noted that the Duchess Pacific with double chimneys were working at nearly the Author's suggested criteria. He also described the evolution of tube sizes in the Jubilee class boilers which attained 1 7/8 inch with a double chimney; W.F. McDermid (59) noted that Great Eastern locomotives working on Brentwood bank with a full regulator had a clear exhaust when notched up and Sanford noted that the thickness of the fire was essential for good steaming; E.C. Poultney (59-60);
T. Henry Turner (60) referred to statement that Theory may be likened to a candle and experience to the sunlight, said it would be desirable to know something more about what had been found by experiment, and therefore he would like to ask the Author, with the aid of the Research Department or the Institution staff, to add to the Paper a bibliography, and line sketches of typical blast systems. There were so many that it might be difficult to choose representative ones, but he felt that the Institution should be able to present some historical background to a Paper of this kind. He would like to ask what had been found with regard to the need for circularity, and to what extent it was possible to depart from circular chimney or nozzle without getting into trouble. If it were possible to depart from it, then it would be very simple experimentally-and possibly the testing plant at Rugby would undertake it later-to arrange a locomotive with manual control of the size of the nozzle and of the chimney. If it were possible to depart from complete circularity an arrangement of the type shown in the accompanying sketch (Fig. 5) might be tried. That would be simple with the chimney, but not so simple with the blast nozzle. He would like to ask what was known with regard to the need for circularity of locomotive chimneys and blast nozzles and whether tests had been carried out with manually-controlled variable ones; H. Holcroft (61-2) asked why quite small leaks into the smokebox had such a major influence on steaming and Sanford in reply could give no sound reason; W.F. McDermid (62) noted his own papers in Journals No. 108 and 112 (1932/3);
W.H. Hutchinson (62-3) said Holcroft had already referred to the point which he desired to make. When chimneys were mentioned he thought of the old Belgian 2-4-2 locomotives with the square chimney. It was a hideous object. He did not know whether it was actually square inside, but it looked rather like a brickworks outside.
The Great Western Railway always had the reputation of being in the first rank for front end design, but many of their engines designed by Mr. Churchward had rather small chimneys, and it was only in comparatively recent times that a chimney of relatively large dimensions had been fitted. Mr. Holcroft, he believed, had had some experience on the G.W.R. in the early days, and might be able to give some information about that. He was thinking in particular of the Mogul engines, which, in the early days at any rate, had a chimney of very small diameter, but apparently did not suffer from any lack of steam.
The calculations in the Paper were interesting, but it would take a long time to go through them and work out the figures for all the different classes of locomotive on a railway. He did not know whether anybody could be persuaded to do so; it might provide some shocks, and make people think a little more about front end design.
H. Holcroft, replying to Mr. Hutchinsons question, confirmed that he had been one of those concerned in setting out the standard chimneys on the G.W.R., the proportions of which were based in the first place on GOSSSf ormula. They were then tried out on the road and subsequently modified to suit the conditions on the Great Western line.
E. W. Selby, referring to the Belgian engines with the square chimney, said that the chimney was square inside as well as out, and they had a square blast pipe with two flaps at the side to provide a variable blast.
The President (Mr. W. S. Graff-Baker) said he had listened with great interest to a Paper and discussion on a subject of which he had to confess tcommented upon the very small chimneys fitted to some GWR locomotives, notably the 43XX class - Holcroft replied that these were designed using the Goss formula; Hutchinson also refered to the square Belgian chimneys which E.W. Selby noted were square inside and Sanford noted that such chimneys were sound as there was a great surface area for a given cross-section.
Presented at Derby on 31 January 1945 with E.S. Cox as Chairman (remarks 69-71); T. Baldwin (71); J.W. Caldwell (71-2) noted the power loss in exhaust due to back pressure; G.F. Horne (72) noted that the US 2-8-0s combined good smokebox vacuum with soft exhaust; E. Durnford noted Chapelon's use of large steam passages; E. Sharp (73) observed that smokebox vacuum varied with different rates of working; D.W. Peacock (74)
Meeting at Derby, on 31st January, 1945. 69
The convener and acting Secretary being Mr. E. Durnford, who said that the last occasion that that Centre of the Institution-met was on the 15th March, 1939, in that hotel, to hear a Paper on Progress in the Iron Foundry, and since then there had been no meeting of that or any other local Centre. In the time which had elapsed since then, their Chairman, 1,ieut.- Col. G. S. Bellamy, had moved permanently to Scotland, and their Hon. Secretary, Mr. F. J. Pepper, had gone with him. Their Vice- Chairman, Col. H. Rudgard, had gone south to London, and the Committee by the terms of its appointment no longer existed, because it was retired formally as from May 3Ist, 1941. A temporary committee, consisting of the following members of the old committee, Messrs. Bailey, Spital and Hall (representing Birmingham), and Larkin, Rankin and Sanford (representing Derby), with the addition of Messrs. Cox; Caldwell and Durnford; Mr. Cox acting as Chairman and Mr. Caldwell as Hon. Sec. The Chairman then introduced Mr. D. W. Sanford, who read his Paper, entitled The Relationship Between Smokehox and Boiler Proportions.
Journal No. 184
Meeting in London, 22nd February, 1945. 83-4
The President announced with the greatest regret the decease of Mr. A. C. Carr, V.D., which took place at his home in London on January 25th, 1945. Mr. Carr, who became a member of the Institution in 1917, was elected a Member of Council in 1925, and was President for the Session 1935-36. The members stood in silence for a few momepts as a token of respect. The minutes of the meeting held on 25th January, 1945, were read by the Secretary, and were confirmed and signed as correct. The following applicants for membership were duly elected :
The President said it was necessary for the Corporate Members present to choose two or three scrutineers for the purposes of the ballot to be held at the Annual General Meeting for the election of Members of Council to fill the vacancies and invited nominations. None being forthcoming, he suggested the appointment of Mr. Selby and Mr. Lynes, on the understanding that, if one of these gentlemen were unable to attend, the other might co-opt someone to take his place. This was agreed to.
Collins, A.F. (Paper 452)
Power-operated doors for railway rolling stock. 84-104. Disc. 104-9.
Fourth Ordinary General Meeting held at the Institution of Mechanical Engineers, London on Thursday, 22 February 1945, at 5.30 p.m., Mr. W.S. Graff-Baker, President of the Institution, occupying the chair.
The President, in introducing the reader said that Mr. Collins had been associated with the development of door mechanisms for the London Passenger Transport Boards rolling stock since the first practica1 doors were put into service, which meant going back to 1918, from a design point of view. He therefore knew a great deal about his subject, a fact which would be confirmed by his Paper. Anyone who wanted a practical demonstration of his knowledge had only to take a Tube train.
When the London 'Transport tube lines were first built it was considered sufficient to provide a gangway at each car end with a door in the car body giving on to this gangway which was enclosed by collapsible steel gates operated by a gateman. A crew for a six-car train consisted of a driver and five gateinen, one situated at each pair of gangways, the rear one acting as guard. This arrangement under crowded rush hour conditions interfered with passenger movement, whilst the number of staff was disproportionate to the number of passengers carried. The problem became most acute on the end cars which had one gangway only. When rolling stock was constructed in 1917 for the Central Line extension from Wood Lane to Ealing Broadway, the end cars were designed with an additional doorway with a hinged door, arranged to be closed by means of door checks and to be held locked in the closed position until released by the guard. The London Electric Railway was experimenting on similar lines with cars built to this pattern: the stock jointly owned by the London Electric Railway and LMS for operating the Watford service had cars fitted with centre doorways of controlled by the guard. Besides not being unsuccessful mechanically, it did not solve the excessive number of staff employed. Thc London Electric Railway put into service in 1920 forty new trailer cars fitted with pneumatically-operated doors at the middle and at each end, and converted, to run with these cars, twenty motor cars fitted with double centre doorways and an end vestibule doorway for the guard. Two guards were employed, each controlling half the train doors from the appropriate motor car. The success of this arrangement was apparent.
Mr. W. A. Agnew (Past President), who had been engaged in work on air-operated doors at an even earlier period than the Author, commented on the fact that the earlier types of door equipment were not mentioned in the Paper, and said that the first use of air-operated doors in this country was on the District Railway in 1905, when over 400 cars were fitted with air-operated sliding doors, and also had centre doors. It was true that those doors had a very brief existence; the public did not like them, and even the comic Press made fun of them. Although everything possible was done to try to make those doors operate satisfactorily, it was found that they were of such a design as to prevent any real improvement being effected.
The construction was very simple-not nearly so elaborate as those since devised by the Author-and consisted merely of a little engine fitted on the top of each door, something like a bicycle inflator. Air was usedYrom the compressed air system for the brakes, and was admitted into those little cylinders by means of valves. Between each carriage there had to be a gateman who was perched precariously on the buffers to operate the valves. In that position he could not see very well when to close the doors, which led to some little difficulty with the passengers.
He believed that those doors lasted for only about eighteen months, but they were a gallant effort to introduce power operation. After that the doors were operated by hand, and continued to be so until recently. The operating manager was glad to reduce the number of gatemen, and that had been one ot the most powerful reasons for fitting air-operated doors on the Tube railways; it had been possible to make great economies after the last war by fitting air-operated doors and so reducing the staff, but the system adopted, of course, was very different from that tried out in 1905.
He would like to ask what reducing valve the Author found to be the best in order to reduce the main line pressure to that used on the doors. The Author mentioned that the rubber sensitive edge of the doors, which used to be fitted with a japanned leather surface, now had a plain rubber surface. The original intention of the japanned leather was not merely to allow skirts to be withdrawn if they were caught in the door but to prevent water getting in from the curved top of the door; it was found that the polished surface readily shed the water. Reference was made in the Paper to trains equipped with purely pneumatic control for the doors. That apparatus in fact worked very well, and he would suggest to those requiring power-operated doors on short trains that that was an attractive way of dealing with the problem.
Mr. H. Holcroft congratulated the Author on compressing a great deal of valuable information into a comparatively short Paper, a model of its kind. Speaking as an onlooker, he remarked that what struck him about the apparatus was the absence of any anti-friction arrangements. There was a slide at the top of the door which would, one would imagine, create a certain amount of friction. He did not know whether ball- or roller-bearings were provided on the rollers carrying the door, but any reduction in friction would of course economise in air by requiring very much less pressure to work the doors.
Apparently there had not been much experience so far with the individually-operated doors where the passenger had to press a pushI button. He did not know whether there was a push-button outside the car as well as inside, but it seemed to him there might be some difficulty in passengers who were strange to the method obtaining entrance to the train if they did not quickly grasp how to open the doors, more so at night on open sections of the line.
The psychological effect on the travelling public of power-operated doors of the type installed could not be overlooked; there was bound to be a certain feeling of resentment and dismay when, owing to the arbitrary closing of the doors, some members of a party were left behind on the platform while others had boarded the train, especially where children were involved.
Mr. Blackshaw (Visitor) said the impression whieh would undoubtedly be gained from the Paper was that the door gear was the acme of simplicity, but he could give the assurance that there was far more in it than would appear from the Authors very brief Paper and from the very simple diagrams that accompanied it. There had been at times what seemed insurmountable difficulties, and it was extraordinary to find what could really happen with such a simple thing as a piece of door-operating mechanism. When he first came in contact with it. he thought that there could not be much in a gear to open a door, and that it must be a perfectly simple job: but he was very soon disillusioned.
Mr. L. Lynes said one could not fail, when travelling on the rolling stock of the London Passenger Transport Board, to appreciate the excellence of the door performance, and since he had had occasion recently to live in the London district he had come to admire it more than ever. It occurred to him while he was on his way to the meenng that he had yet to see a door fail, and after seeing the staggering figures given at the end of the Paper he wondered whether he ever would; the odds seemed to be many millions to one that he would not. He was not sure whether that excellent performance was to be attributed to the design or to the maintenance; probably both were entitled to the credit, but it was an outstanding testimonial that the doors gave such an excellent performance.
The tunnels presented a situation to which the sliding door was the obvious answer, and therefore the problem had been an easy one in that respect.
He was struck by the noiselessness of the operation compared with the hinged doors on ordinary suburban stock, which made such a shattering noise when they were swung to. Another feature was the rapidity of their operation. He had been noting the time taken to detrain and take on passengers, and very often the whole movement was carried out in something of the order of ten seconds. That was partly due to the orderliness with which passengers were able to alight, thanks to the conveniently-placed and wide doors.
He had been interested in the Authors remark about soldiers opening doors which were closed. He noticed recently a number of hefty house-repairers come along and hold the doors back while they all got in, and he wondered what took place so far as the guard was concerned during that operation. It would be interesting to know how the guard was made aware that a disturbance of the ordinary working was taking place. In another case a lady who had travelled past her station pressed the push-buttbn. Nothing happened, but he would like to know what took place as far as the guard was concerned when those operations were carried out.
Discussion: g public. W.A. Agnew (104-5) stated that the first use of air-operated doors in Britain was on the District Railway in 1905, when over 400 cars were fitted with air-operated sliding doors, and also had centre doors. It was true that those doors had a very brief existence; the public did not like them, and even the comic Press made fun of them.
Hopking (107) mentioned that on the Tyneside electric lines they had suffered not from too much friction on the doors but from too little. They did not use air-operated doors, but in the early days the doors ran too well, and this led to complaints. They had therefore to fit a small brake in connection with the passengers handle which put pressure on the rail except when the door was being deliberately opened or closed, and that overcame the difficulty. He would like to ask the Author why it had not been possible even in war-time to operate the passenger push-button. He could understand that passengers must not be allowed to open the door in the blackout if the train was not at a station, but he assumed that the guard had some means of preventing that being done. On the other hand, the incoming passenger might even in the blackout be allowed to open the door, provided the guard closed it.
White, J. (Paper 453)
Notes on braking of railway vehicles [with special refernce to compressed air equipment]. 110-130. Disc.: 130-8.
Joint Meeting of the Institution of Locomotive Engineers, and the Institution of Engineers, Australia (Sydney Division) held at Science House, Sydney, on 7 December 1943: The Chairman of the Mechanical Engineering Branch of the Institution of Engineers, Australia, was in the Chair.
It has been well established that higher rates of acceleration and deceleration are not only necessary for the improvement of the service, but the cost of providing these improvements is economically warranted by the more intensive use of rolling stock, permanent way, and facilities that result. In recent years considerable capital expenditure has taken place in New York and London directed to securing improved acceleration and braking.
In order that the efficiency of suburban transport systems may be maintained at a high level, it seems important that the ultimate objectives of the service should be determined, particularly in regard to rates of acceleration and deceleration. Once such a determination is made, Selection of accelerating and braking equipment should be made in accordance therewith. It would probably not be necessary to immediately apply all of the equipment ultimately required, but all equipment applied should be regarded as an instalment of the final scheme. Otherwise, premature obsolescence, and expensive replacements may be necessary in order to meet future transport requirements. DISCUSSION. Mn Young (Member
Journal No. 185
Turner, T. Henry (Paper 452)
Prevention of corrosion and corrosion fatigue. 159-204. Disc. 204-20. Bibliography
Sixth Ordinary General Meeting of the Session 1944-45 held at the Institution of Mechanical Engineers, London, on Thursday, 17 May 1945, at 5.30 p.m., Mr. W. S Graff-Baker, President of the Institution, occupying the chair.
1. Corrosion and corrosion fatigue are natural phenomena to be expected by designers in metal constructions.
2. Corrosion will turn the cleverest mechanisms into dust and scrap metals unless they are constantly protected.
3. Corrosion prevention is better than repair.
4. Designers have not yet learnt to eliminate moisture traps and ledges where moisture stays in contact with metal.
5. Corrosion must be fought and can be fought economically.
6. Corrosion Research must be more generously staffed and financed -preservation is as necessary in peace as supply in war.
7. There is no discharge in the war against corrosion
The following presis appeared in Locomotive Mag., 1945, 51, 104 et seq. In many forms of mechanical engineering where metals and alloys are used in the form of constantly oiled moving parts corrosion plays a rela- tively small part in the life of the component. On the other hand railway vehicles spend their life exposed to the weather, and in such cases where metal parts are not constantly cleaned and oiled corrosion occurs at once if the metal is bare. Even if protective coatings are used corrosion will still occur when in service the coating is worn through or damaged. The rate of corrosion will then depend mainly on the moisture content and acidity of the atmosphere in contact with the metal. Neutral and mildly alkaline solutions are seldom corrosive, but slightly acid liquids corrode metals rapidly. .
Axles. Fig. 1 shows the appearance of an axle which gave long service before it failed by fatigue. Some of the old wrought iron and steel axles have lasted 40 or 50 years, but this one would not have failed at all but for the excessive corrosion caused by the slightly acid drip from the wet coal of the tender of which this was the leading axle. The first axle of tenders is apt to be corroded more than the others, because when the fireman slakes his dusty coal water is apt to drop on the leading' axle, and the corrosion so accentuated joins with the normal tension stresses m the axle skin as it rotates in service, to produce dangerous grooving and accelerated corrosion fatigue.
Other cases of the corrosion of axles have been noted near carriage lavatories, and under fish vans, where there is sometimes appreciable drip of salty water.. Further cases investigated have been those of dining car carriage axles where the large dynamo pulley was clamped so as to permit the retention of moisture, with the production of a multitude of small corrosion fatigue cracks: for- tunately they were found by the routine inspection before failure occurred.
Springs. Locomotive, carriage and wagon springs are relatively roughly finished as com pared with the best automobile practice, and they are often not well painted. They generally appear rusty and there can be no doubt that corrosion plays an appreciable part in their fracture in ser vice in such failures as occur. Their design obvi ously requires them to be subject to repeated bend- ing. In a dry atmosphere s~ch bendmg. would be well within their fatigue limit ; that limit for any given shape is lower where they are in contact with moisture. The suggested improvement m finish, removal of sharp edges, shot-blasting'to produce compression stresses in the surface are all no doubt worth study, but coating or interleaving with zinc would seem to be equally desirable from the cor- rosion-fatigue failure point of view.
Tyres. The wear on main line railway tyres :is undoubtedly accelerated by the heat crazing of the tread by cast iron brake shoes and corrosion of the surface so roughened. Sudden failure in service seldom occurs from this cause. On the other hand, where corrosion occurs at the back of the tyre it is much more dangerous, for here the tyre is in tension above the point of rail con- tact, and if water enters between the tyre and wheel centre corrosion-fatigue is a natural conse- quence. The smoothest surface of the tyre back and wheel centre rim, coupled with good priming, painting and varnishing, seem sufficient in most cases, but where special difficulty is encountered with corrosion, as in the very moist atmosphere of Malaya, experiment might be made with the zinc coating of the wheel rim and tyre back, followed by the most thorough painting and varnishing of the finished assembly.
Wagon underframes . Corrosion is to be seen on old steel wagon underframes, but serious loss of section only takes place over many years where moisture is held trapped between riveted plates, or lodges on horizontal ledges or in corners. It is probable that the corrosion of steel railway wagons is not the determining factor of their life in this country. They probably become obsolescent before they are dangerously weakened by corrosion. That would not be true if the section of the plates and members was made appreciably thinner. It may be possible, however, to decrease the weight of steel used in any given wagon, without mcreasmg the corrosion risk, if use is made of the low-alloy steels to which reference is made later in the paper. With this in mind the author suggested to the Chairman of the Corrosion Committee and to Sir Nigel Gresley in February, 1938, the testing of four grades of steel in the four symmetncal bot tom plates of 100 new L.N.E.R. hopper wagons. This test has now been under observation for over five years, and up to the present there is. no out standing difference in the rates of corrosion measured, although two of the steels are low-alloys. These have appreciably higher tensile strength than the mild steel or copper-bearing normally used. The u.t.s. of the four steels under test is 29, 31, 36 and 38 tons per sq. 'in. respectively. Three-link coupling. The typical British wagon coupling is made from wrought iron or mild steel and exposed to atmosphenc corrosion during its whole life. There can be no doubt that Its wear is accelerated by corrosion; and a. case can be made out for the use of a suitable, tough low-alloy steel which would corrode at a slightly lower rate. The same may be said of almost all chains, and the Admiralty, which can scarcely avoid taking corrosion into account, permit lighter chains in steel than were traditionally made from wrought iron.
Carriages. Corrosion is easily observed in carriages of main-line railways where the sides are made from steel panels. The paint is roughened all too quickly at the bottom edge of the windows, and the convenience of acid cleaners lS sometimes over-ruled by this fact. A more insidious form of corrosion occurs at the back of the panels of car- riages, and tests with steel and with light-alloy panels have shown that they are liable to suffer excessive corrosion, in our suburban tunnel atrnospheres, unless completely and continuously protected by paint, varnish or other such means. An unusual case of corrosion noted in carriages was that of the hot-water tanks of the war-time casualty evacuation trains. We have also noted corrosion in compressed air pipes, and in the studs of locomotive brick arches, and in many boiler components.
Copper:bearing Mild Steels. For many years it has been known that the resistance of mild steel to atmospheric corrosion is considerably increased by the addition of a small percentage of copper. Investigators have found that the superiority of copper-bearing steels over ordinary steels of the same variety is about 10 per cent. in pure air and 25 per cent. in industrial atmospheres. In tunnel conditions, however, no advantage is gained. Copper-bearing steels are suitable for bridgework and structural steelwork, railway rolling stock and locomotives, shipbuilding, gasholders and fencing wire. The smokebox, smokebox door and ashpan of certain locomotives have been made of this type of steel, a typical analysis of which is: Carbon. 0.15% Manganese 0.66%,. Silicon 0.05% Suphur. Phosphorous 0.04%. Copper.0.042%
High Nickel Alloys. These form a useful series of alloys which combine toughness with high resist- ance to corrosion. Monel metal is a silvery-white natural nickel-copper alloy. Official specifications give the following percentage limits for its com- position: nickel 63-70; iron 2.5 max.; manganese 2.0 max. ; aluminium 0.5 max.; silicon 0.5 max.; carbon 0.3 max.; sulphur 0.02 max.; copper-: balance. For castings 3 or 4 per cent. silicon may be added. Monel metal is available in the form of bar, rod, stampings, forgings, tubes, wire, plate, sheet, strip and castings. As it is highly resistant to the corrosive action of both pure and impure waters it has been used for important loco- motive firebox staybolts. It has been found that water which has been softened by lime/soda process sometimes attacks and corrodes the valve faces of such copper-tin-(lead)-zinc bronze boiler fittings as injectors, blow-off cocks and whistle valves. If such valves and the inserted seating were made of Monel metal, corrosion, cutting and steam leakage would be reduced.
Boiler Plates, Tubes and Stays. In the case of' locomotive boilers, remarkable reduction in locomotive boiler tube corrosion was soon noted in sheds where pitting of tubes had been excessive before the feed water was Jime/soda softened. The corrosion of boiler stays (see Fig. 2) and other components depends almost entirely upon the 'nature of the feed .water used and the attention given to feed-water treatment.
Water Treatment. The British main-line railway water-treatment chemists met two years ago and submitted to their chief mechanical engineers a statement of their agreed recommendations as regards locomotive boiler water treatment. This measure of agreement as to policy was a valuable step forward, but the writer is disappomted that, in practice, a primitive standard of feed water has been forced during the war penod on many modern locomotives. The L.N.E.R. water treat- ment section has had its attention drawn to cases of corrosion which have caused premature failure or curtailed the useful life of metals in a variety of circumstances. In this respect locomotive boilers using untreated waters are a chief source of trouble and corrosion, especially of boiler tubes, has be~n reported from many localities. The type of corrosion found in one area is not necessanly the same as in another, for this depends upon the nature of the feed waters evaporated. Acid waters, dissolved gases and waters containing corrosive magnesium salts are the worst offenders, causmg boiler tubes, barrel or roof stays to be corroded away.
111 iscellaneous. Blowdown valves and water- gauge safety balls may be mentioned as excep- tions to the rule that the metal or alloy matters little in comparison to the water. Stainless steel balls proved satisfactory in blowdown valves, and bronze balls have given good service in gauge glasses, whereas aluminium -bronze balls failed rapidly by de-aluminification when similarly used in certain wartime locomotive gauge glasses. In some cases where alkaline salt concentrations in the boiler have been high, lime/soda softened feed waters have given rise to corrosion of copper stays and tubeplates. The attack usually takes the form of wasting of stays, accompanied sometimes by honeycomb pitting of the tubeplate. Satisfactory cures have been obtained by maintaining lower boiler water concentrations in conjunction with an addition of tannin to the feed water. Lime/soda softened waters with high residual sodium car- bonate alkalinities have given trouble with cutting Fig. 3 of bronze valve seatings, and have also attacked other bronze boiler fittings. Decreasing the alkalinity of the treated boiler water usually reduces the trouble. .
On the L.N.E.R. there has been expene~ce of corrosion of lead in fusible plugs (see FIg. 3) exposed to alkaline soft water. The L.M.S.R. practice was to cover the top of the lead plugs with electro-deposited copper and so hinder neatly such corrosion but this precaution has not yet been thought necessary on the other main line railways.
Journal No. 186
Spencer, D.W. (Paper 453)
Notes on axle design and performance. 263-90. Disc.: 290-308.
First Ordinary General Meeting of the Centre held at the Midland Hotel, Derby, on Wednesday, 3 October 1945, at 7.30 p.m.: Chair taken by Mr. J. Rankin (Member cf Council).
The failure in service of a railway carriage axle is rare, but should it occur the results might be disastrous and in any case give rise to prolonged delay. The majority of service failures occur in the region of the wheel geat a short distance inside the wheel hub and investigations into axle design generally have for their object the elimination or reduction of the tendency for fatigue cracks to develop at this point.
The problem, which is by no means a nev one, has engaged the attention of investigators both in the United States of America and in this country and a good deal of valuable data has been published. Broadly speaking, approaches to the problem have been from two aspects: (a) Photoelastic study; ( b ) Series of physical tests. Several methods of reducing the sources of weakness and increasing the strength of axles at the press-fitted portions have been suggested, including the provision of annular stress relieving grooves on the inside hub of the wheel, raised seats at the pressfitted portions, and surface rolling of the wheel seats.
Ahat tempt has been made in this paper to summarise this and other information available, and to record the experience of London Transport railways.
D.F.C. Johansen (290-8); T. Henry Turner (298-301) on metal fatigue; E.S. Cox (301-2); T. Robson (302-3)
Graff-Baker, W.S. (Presidential Address)
The tools for the job. 310-22.
Opening General Meeting of the Session 1945-46 was held at the Institution of Mechanical Engineers, London, on Wednesday, 26 September 1945, at 6 p.m., Mr. W.S. Graff-Baker, President of the Institution, occupying the chair.
Important rubber in engineering paper: mentions resilient wheels used on PCC tramcars and the shear deformation bolster springs used on same vehicles. Also mentioned adaption of fluorescent lighting for railway rolling stock.
Journal No. 187
McClean, H.G. (Paper 454)
The mechanical design of the latest class F high-speed electric locomotives of the Swedish State Railways. 336-65. Disc. 365-77.
Third Ordinary General Meeting held at Institution of Mechanical Engineers, London, on Thursday, 25 January 1945, at 5.30 p.m.: Mr. W.S. Graff-Baker, President of the Institution, occupying the chair.
The Quill and Cup drive; Buchli or Brown Boveri drive and Wintherthur or S.L.M. drive were considered. H. Holcroft spoke on behalf of O.V.S. Bulleid (365-8) on the Southern Railway electric locomotives. E.S. Cox (369-72) spoke about Bissel trucks and Cartazzi axleboxes. J.E. Spears (372). W.O. Skeat argued that symetrical tank engines (2-6-2 and 4-6-4) did not ride as well as unsymetrical types, such as 2-6-4T.
McIntyre, H.M. (Paper 455)
Diesel electric locomotive: running and maintenance on the Buenos Aires Great Southern Railway. 396-487. Disc.: 487-528.
Paper presented before the Institution 2 June 1944, at Remedios de Escalada.
Conclusion. Having seen how the whole of the motive power requirements of the B.A.G.S. Rly. could be served by but four sizes of Diesel-electric power plants, it might be of interest to examine some of the advantages which would follow as a consequence.
The locomotive repair shops would show the most drastic alterations due to the disappearance of the boiler shop, reduction in size of the smithy, foundries, machine shop, brass shop, copper and erecting shops. This would involve some structural
modifications of the existing buildings, so a new lay-out is suggested. The main stripping, repair and assembly shops for the vehicles, bogies, wheels, traction motors, and power plants would be laid out in parallel on progress lines, under one roof with ample light and ventilation and no dividing walls. Petty stores, pump room and engine test beds would also be accommodated under the same roof. A schematic lay-out of such a project is shown (Fig. 52).
Only one quarter to one third of the oil fuel storage would be required at the running sheds and the same proportion of the present travelling tank wagons (or coal wagons) usqd in Departmental service. The water supply problem in bad or waterless zones would be solved and water softening plants would no longer be necessary. Coal piles would disappear.
The running sheds would not look so grimy as they do at present with ashpits and piles of cinders, whilst the disposal and transport of these need no longer occupy men and wagons.
Track maintenance would decrease in cost by the disappearance of hammer blows from steam locomotives driving wheels.
In conclusion the author would like to thank the General Manager and the Chief Mechanical Engineer of the B.A.G.S. Rly. for their permission to publish these notes, and also thanks the local manager of Sulzer Bros. for information supplied, and his colleagues of the Mechanical Department for invaluable assistance given in preparing the foregoing notes, drawings and photographs