Journal Institution Locomotive Engineers
Volume 42 (1952)
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Visit ro the Willans Works, the English Electric Company, Rugby, 8th April 1952. 28-30.
New electric rolling stock for the Indian Government Railways.
Fifth Ordinary General Meeting of the Session 1951-52 held at the
Institution of Mechanical Engineers, London, on Wednesday 16 January 1952
at 5.30 p.m., Mr. J. S. Tritton, President, occupying the Chair. The President
then introduced Mr. S. E. Lord (Member), Mr. J. F. Thring (Graduate) and
Mr. H. H. C. Barton (Member), who presented their papers on '' New Steel
Electric Railway Stock for the Indian Government Railways," which were afterwards
discussed, and for which, on the motion of the President, a vote of thanks
was accorded to them. Three Papers read :
Lord, S.E. (Paper No. 507)
A quarter of a century of progress in Indian electric stock. 32-43.
Thring, J.F. (Paper No. 508)
Structural design of lightweight steel coaches for Indian Government Railways.
44-58.
Of 112 coaches being supplied to the GIP and the HB&CI Railways,
56 were driving motor coaches being produced by Metropolitan- Cammell Carriage
& Wagon Co.
Barton, H.H.C. (Paper No. 509)
New multiple unit rolling stock for India, operational performance and the
electrical equipment. 58-68. Disc.: 69-79.
Outlines the character of Bombay's suburban rail traffic and some
of the operating features. It describes the electrical equipments of the
new multiple unit rolling stock manufactured in this country for the G.I.P.,
now the Indian Central Railway, and the B.B. & C.J.', now the Indian
Western Railway. During WW2 this stock occasionally worked from Bombay over
the 1 in 37 grades of the Western Ghats. Excluding the lines beyond Kalyan,
but including the Harbour
Sir William Stanier, (70) said that the building
of lightweight stock had been very much in his mind for d number of years.
On the LMS in 1938, the Liverpool and Southport stock had had to be renewed,
and he remembered the late Mr. Fairburn saying that for every ton that could
be saved in the weight of the stock, he could save 210 a year in current.
That had been an incentive to get some lightweight stock.
In the Derby drawing office there had been a very able young designer, Mr.
Moon, who unfortunately died during the war. Mr. Moon had developed a design
(taking advantage of the Vierendeel truss) for some lightweight stock which
had given some very interesting figures. The motor coach seated 88 and weighed
40 ton 5 cwt. The trailer coach seated 102 and weighed 23 ton 2 cwt. Sir
William had been able to give particulars of that construction and the means
used to develop it in a paper which he had prepared for presentation to the
American Society of Mechanical Engineers and the Institution of Mechanical
Engineers' Joint Meeting in September, 1939; he had gone over to America
to give the paper, but unfortunately the Conference had been cancelled and
he had come back by the next boat. However, the paper had been printed and
was in existence.
The intention had been that this principle should be developed for main'line
stock, but unfortunately the war had come, and this hampered development.
Sir William emphasised the importance of remembering that weight,was a very
important asset or liability when considering costs. The more lightweight
stock was developed, the better the services that could be given. Lightweight
stock would reduce wear and tear and it would reduce the power required;
and, provided it was possible to look after the corrosion, to which Mr. Cock
had referred, it would produce very much better stock than existed at
present.
Journal No. 226
Marsh, G.C. (Paper No. 510)
Recent developments in vacuum brake equipment. 95-134. Disc.: 134-70. 48
figs.
Second Ordinary General Meeting of the Manchester Centre was held
at Engineers’ Club, Manchester, on Wednesday 28 November 1951, the Chair
being taken by D. Patrick.
British Railways had recently confirmed their adherence to the Vacuum Brake
for all main line services, and adopted many of the latest devices then available
on their new standard locomotives and carriages. Similarly many African and
Indian Railways were in the process of modernising their Vacuum Brake Equipment,
whilst the Republic of Indonesia had chosen the latest type of vacuum brake
as standard on all the new locomotives and rolling stock now being built
to rehabilitate the war devastated railways in that country. For many years
before WW1, the vacuum auto brake remained almost unaltered in its original
form except on the GWR where Churchward introduced many new features such
as engine driven vacuum pumps and direct admission valves, some of which
had spread to all Regions of British Railways. It was not until the 1930s
when large freight locomotives were introduced in India and South Africa
for hauling long vacuum fitted trains, that the question of adequate ejector
capacity was seriously tackled and the common sense rule established that
the size of the maintaining ejector must be related to haulage capacity,
the potential leakage factor being obviously higher on longer trains. For
long vacuum fitted freight trains the addition of automatic slack adjusters
has contributed greatly to efficient braking, whilst the adoption of the
lower working vacuum of 16 in. or 18 in. for freight working, coupled with
the provision of more powerful ejectors, had enabled brake release times
to be much reduced.
See Holcroft (140-2.) page
95 for long contribution by him on the development of vacuum pumps by
Churchward and by T.G. Clayton on the Midland Railway. W.A. Tuplin (142-3);
E.S. Beavor (144) wished for some form of automatic coupling to incorpoarte
the vacuum hose; K. Cantlie (146) noted that the only methods for creating
vacuum on steam locomotives were the ejector and crosshead pump whereas rotary
exhausters were successfully used on diesel and electdc locomotives: a turbine
might prove more economical in steam. Another experiment might be a vacuum
pump similar to the Westinghouse cross-compound pump which he knew to be
very economical in steam consumption.
Journal No. 227
Harrison, J.F. (Paper 511)
The application of welding to locomotive boiler copper fireboxes. 178-214.
Disc.: 214-22.
Forty-First Annual General Meeting of the Institution was held at
the Institution of Mechanical Engineers, on Wednesday 19 March 1952, at 5.30
pm., Mr. J. S. Tri!ton, President, occupying the Chair.
The repair and construction of locomotive copper fireboxes by welding is
not a recent development, since simple repair work of this kind was being
carried out in Germany in 1916, and by the early 1920s more elaborate work,
such as the insertion of patches, the repair of tubeplates, and the insertion
of half or three-quarter sides, had been successfully accomplished. By 1925
several all-welded copper fireboxes had also been built. In the UK it was
not until 1927 that the repair and manufacture of new copper fireboxes by
the oxy-acetylene welding process had become an established practice, the
Great Western Railway being the first in the field followed some time later
by the London Midland and Scottish Railway.
On the London and North Eastern Railway, Great Central Section, the cost
of firebox repairs was exceptionally heavy, frequent copper stay and plate
renewals being necessary owing to the very bad water conditions met with
in that region, possibly the most damaging to boilers in Britain. During
the war years great difficulty had been experienced in obtaining the necessary
copper plates for renewals, so the Author, then Mechanical Engineer, Gorton,
originated at those works serious investigation into the possibilities of
effecting repairs to copper fireboxes by the oxy-,acetylene welding process.
In 1943 a Technical Assistant, who was a specialist in welding, was engaged
to carry out the necessary deve!opmcnt work under the jurisdiction of the
Author.
The first objective was to ensuire that any welds produced would have a tensile
strength equal to that of the parent plate and successfully bend through
180 degrees when hot. To reach this standard approximately six months of
experimental work was found necessary.
Following this stage certain welding repairs were carried out on fireboxes,
such as building up wasted radii in tube and doorplate flanges, and in December
1944 a further experiment was carried out by fitting to a Diagram 15 boiler
(O4 class 2-8-0 Freight Locomotive) two new lower half wrapper sides by welding.
It is of interest to note in passing that this firebox gave a further 4½
years of life, which equals approximately 60 per cent increased life an average
firebox. From 1945 onwards a considerable number of half or three-quarter
copper sides were fitted and repaircd by welding. These experiments were
further extended by the insertion of new plate in and around firehole mouth
pieces, the insertion of pieces in tube and doorplate flanges (this latter
development being considered from experience a better repair than the building
up of worm plate edge laps), patches let into the wrapper sides (lower half)
were developed where it was considered to be more economical than the fitting
of a complete new half plate, the reinforcing of the radius of firehole flanges
of the solid ring type doorplate, the welding of fractures in the tubeplate
crowns from both sides simultaneously, and most recently the development
of sealing the copper stays in the lower portion of the firebox wrappers.
T. Henry Turner. (202-3.) said that as welding was
a borderline subject between metallurgy and engineering, it might be as well
to have the metallurgical point of view. Twenty-five years ago all the British
railways were using tough pitch arsenical copper for fireboxes, and then
the Great Western introduced de-oxidised copper. When Mr. Turner heard that
he passed on the information to Sir Nigel Gresley who was not then interested
in firebox copper welding. However, Sir Nigel had the foresight to change
the specification and introduce the use of de-oxidised arsenical copper so
that welding could be done in the future if desired. Thus, when the Author
was moved to do something about copper firebox welding, there was a fair
quantity of de-oxidised arsenical copper upon which to start. The subject
of the paper deserved more consideration by locomotive engineers in this
country than elsewhere, because of the many thousands of copper fireboxes
in use as compared with the preponderance of steel fireboxes in a number
of countries, and the use of steel in stationary and marine boilers.
The Author dealt mainly with his practical development work at Gorton. There
was no doubt that had it not been for the Author's initiative, very little
copper welding would have been done on the LNER. Mr. Turner had looked into
the literature, and submitted a short bibliography on the subject which was
not without interest, because it started off forty years ago. At that time,
when the Institute of Metals was very young, an Italian, Dr. Carnevali, read
a paper in which he spoke of his experiments in the oxy-acetylene welding
of copper. In those days the difficulties of welding copper were very great
because the great thermal conductivity of copper made it nearly impossible
to get the intensity of heat needed in the locality of the weld; the copper
absorbed gases readily at high temperatures, and copper oxidised and dissolved
its own oxides at high temperatures. With the gassed and overheated copper
welds then produced, hammering was sometimes of no use at all, and the resultant
welds were full of cracks and blowholes.
What factors of the welding of copper had changed to make the Author’s
paper of practical value whereas Dr. Carnevali only warned of difficulties?
Firstly as regards the nature of the oxy-acetylene flame; this was now
controllable, and if a reducing flame were played on to copper which contained
oxide, serious cracking occurred inside the copper, quite unrelated to external
stresses. Cracking did not occur, however, with a neutral flame and de-oxidised
copper, i.e. one to which phosphorus had been added and of which a residue
remained. That lesson was driven home to the speaker by the cracking of almost
all the copper cable bonds welded to rails in the Manchester-Sheffield
electrification when they were first applied. The cracks burst inside the
copper, due to the effect of the hydrogen in the flame and the oxygen in
the copper, producing steam under explosive conditions.
Secondly as regards the different types of copper; Dr. Cook read a paper
to the Institution in 1938 recording tests on four different types of copper,
and if we extract from them the tensile properties at elevated temperatures
we may produce a curve of the type shown in _. Fig. 19. It is important to
note that all four varieties suffered a similar loss of tensile strength
from nearly 15 tons at room temperatures down to below 2 tons/sq. in. at
800°C.
Thirdly as regards the welding rod there had been a development in the
introduction of the silver content and a trace of phosphorus from the
metallurgical point of view; but there was also an engineering development
in the direction of better welding tools. The welding tools were not available
in the early days, and the system of training welders had been much improved.
It would be interesting to know whether the Author had carried out any practical
trials with annular flames for welding rivets.
The inspection ot welds had been helped by the introduction of X-rays which
permitted examination below the surface of welds, without destructive testing.
However, he agreed with a previous speaker who said that it was not possible
to see many little cracks inside the copper by means of X-rays. When he examined
one of Mr. Lockley’s prototype welds made at Gorton three or more years
ago, it was necessary to cut sections from it to find that the welding process
had not affected the firebox copper. That method of examination ruined the
weld even if it did teach the nature of the metal, so X-rays were of help
and the K.E. Research Department’s (Metallurgy Division) mobile X-ray
coach had been used recently to examine non-destructively welds in copper
fireboxes. The carbon arc welding system had been applied to copper using
high amperage, say 400 amps and a high voltage of say 50 volts, and Mr. Chaffee
in his paper wrote “ No metal can be fabricated more rapidly or at a
lower cost than can copper by this method. . . . So far he understood that
method had not been applied to locomotive fireboxes; it might be worth
investigating in the workshops.
A short bibliography on copper welding for fireboxes (13 entries)
Meeting of North Eastern Centre at Danum Hotel, Doncaster on 27 March
1952: T. Matthewson-Dick in the Chair.
T. Matthewson-Dick (209) asked about the method
of testing the welded seam adding that he knew that to prove the weld equal
to the strength of the plate the 180° bend test was usually made, but
it was not clear why this vicious test was necessary to prove equality of
strength. He asked if there was a definite syllabus for the training of staff
in the use of oxy-acetylene torches for copper welding. To indicate the degree
of training success he asked what was the expectation of failures in, say,
every five men given trajning.
Meeting at Midlands Hotel, Derby on 2 April 1952: M.S. Hatchell
in Chair.
C.S. Cocks (210-11) said it was very encouraging
to find an engineer who had the courage of his convictions, and having been
faced with an unsatisfactory condition, did something about it to improve
it, thereby progressing in engineering.
He felt that whilst they were wedded to copper fireboxes, it was imperative
to prevent copper stays from leaking. It was perhaps unfortunate that steel
fireboxes were not generally adopted, as it would then not be so difficult
to perform the welding operation. In connection with the fitting of the copper
stays, he asked if they were riveted over on the outside of the steel wrapper
before being welded on the inner firebox, or afterwards, since if they were
riveted before welding, it would be necessary to leave the stay projecting
on the inside of the firebox; it would also be interesting to know how much
was the projection.
In view of the Author saying that the copper weld had the equivalent strength
of the parent metal, he asked if the ultimate aim was to have a completely
welded stay placing complete reliance on the 100 per cent weld.
The Author had said that heat had a lot to do with the question of welding.
In view of this Mr. Cocks asked why such a wide angle was used for the weld
deposit. The aim surely should be to make the angle of weld as small, as
was reasonably possible, less heat would then be needed and less metal
deposited.
He asked if 3/16 in. gap per foot run of weld was required,
since if the weld was 10 ft. long there would be a gap of 17/8
in. at one end. He thought it was quite clear from the Paper that welds followed
each other and there was no question of step back welding being used. Regarding
marking off, he suggested it might be better to make a simple template of
the staying of the portion of the box in which the stays were to be welded.
While the method used by the Author of placing centre pops in convenient
places to enable the re-marking of the plate to be done without much difficulty,
this method could only be followed where the stays followed a regular pattern,
but was of no use for the stays at the forward end of a firebox with a sloping
throat plate. In such cases the stays at the forward end followed no regular
pattern, but were pitched at regular intervals to stays in the plate between
the lap joint and the part of the firebox where regular pattern stays commenced.
It seemed to him in either case the job would be more simply and cheaply
done by using a suitable template, as such templates could be made to drawing
and checked as necessary against each individual firebox.
Fell, L.F.R. (Paper 512)
The Fell diesel mechanical locomotive. 223-71.
Eighth Ordinary General Meeting of the Session 1951-52 was held at
the Institution of Mechanical Engineers, Storey’s Gate, London, on
Wednesday, 16 April 1952, at 5.30 p.m., Mr. Julian S. Tritton occupying the
Chair.
This precis is based upon material recorded
by Rutherford in Backtrack, 2008, 22, 238 et seq. wherein
he noted that "Surprisingly extensive drawing office and technical support
manpower was expended on the 2,000hp Fell 4-8-4 diesel-mechanical. In this
paper Fell revealed that not only was the wheel arrangement and layout of
the locomotive decided by British Railways engineers but that Derby drawing
office and works was responsible for the complete design and manufacture
of the machine". Fell stated, "The wheel arrangement of 10100 was selected
by British Railways as being the most suitable for their purpose, involving
the simplest possible arrangement of this transmission, but it was by no
means the only possible arrangment." Further, "Dealing with the suggestion
that the transmission was a bought out part, Fell pointed out that the whole
of the gearbox was made by British Railways. They designed it, made the original
drawings, made all the patterns, cast it, machined it themselves. All they
did not do was to cut and grind the gears. This was one of the claims in
favour of the system - that the steam locomotive men could make the main
item of the transmission instead of having to buy the whole thing out. The
whole of the control gear was also made by British Railways - drawn by them
and made by them, which was very different from the case where electricity
was employed." Finally, "... this was British Railways' very own diesel
mechanical express locomotive. They had designed it from a clean sheet of
paper and had built it.
Journal No. 228
Cock, C.M. [Presidential Address]
Motive power for railways. 281-305.
"Even today the steam locomotive suffers chronically, as it has done
for a century and a quarter, from an unfortunate inability to digest the
full substance of its calorific food. Aggravated by a large appetite, this
incurable indigestion leads to other ancillary ills in processes of repairing,
fuelling, watering and general servicing, and realising all this, railwaymen
are seeking for other forms of traction having better qualities in thermal
efficiency and availability, always however, with a wary eye on the cost."
Practical alternatives to the steam locomotive, not necessarily in order
of precedence:
(1) Self propelled rail cars.
(2) Electrification.
(3) The diesel-electric locomotive.
(4) The gas turbine locomotive
Electrification at 50 cycles: Mercury arc rectifiers: Morecambe/Heysham-Lancaster
trial about to start. Mentions Aix-les-Bains to La Roche-sur-Foron in France
and even earlier system in Germany (1936) between Freiberg and Seebrugg.
"For various reasons, including economic consideration, the British Transport
Commission had accepted the 1,500 volt d.c. system as standard for British
Railways but the 50 cycles system has not been ruled out for electrification
of secondary lines with light traffic" Includes the operating costs of diesel
locomotives in the USA.
"Unless the Coal Board magically can produce more coal of satisfactory quality
from yet unknown fields, the position will degenerate from one of gravity
to utmost gravity. Electrification at least will assist in easing the position;
complete electrification in this country would save at least 8½ million
tons of coal per annum, and because low grade fuel would be consumed in central
power stations, the saving of best quality coal would be 14 million tons.
The use of oil with diesel locomotives would also assist; in the USA for
traction purposes, one ton of diesel fuel will do the work of at least 94
tons of coal. If strategic hazards are to be taken into account, it must
be remembered that without oil all our defence services would be immobilised;
and even in the event of a complete changeover to oil by the railways, the,
maximum additional load imposed on the supply organisation would be, if American
results are repeated here, of the order of only 5.5%. If and when nuclear
energy becomes available, electric traction would appear to be the most
convenient way to use it."
Graff-Baker, W.S. (Paper 513)
Considerations on bogie design with particular reference to electric railways.
306-39. Disc.: 339-61.
General Meeting of the Institution of Mechanical Engineers held on
4 January 1952 at Storey's Gate, London S. W.1, to which members of the
Institution of Locomotive Engineers had been invited. Mr. A. C. Hartley,
C.B.E., BSc. (Eng.), President of the Institution of Mechanical Engineets,
took the Chair. Mr. A. W. Manser, B.Sc.(Eng.) (M.) read the paper entitled
" Considerations on Bogie Design, with Particular Reference to Electric Railways
" in the absence, through illness, of the Author Mr. W. S. Graff-Baker,
B.Sc.(Eng) (M.).
Ends paper by suggesting that only one motor should be fitted per bogie and
that there should be more motor bogies per unit. Sir William
Stanier (339-40) opened the discussion and sung the praises
of the Dean bogie. R.A. Riddles (349-50) made one of his
rare contributions in which he praised the standard bogie, sought means for
assessing ride quality and commented on the high cost of flexible wheels
(presumably resilient wheels). .T. Henry Turner (350-1) noted the problem
of electric current flow through the bogie on three and four rail systems.
He also commented on welded rails..
Loosli, H. (Paper No. 514)
Railway electrification in Switzerland, with special reference to the Swiss
Federal Railways and their rolling stock. 362-82. Disc.: 382-7.
Eighth Ordinary General Meeting of the North Eastern Centre held at
the Great Northern Hotel, Leeds, on 22 May 1952, the Chair being taken by
Mr. D. C. Stuart.
Journal No. 229
Jarvis, R.G. (Paper No. 515).
The railways and coal. 390-404. Disc.: 404-24: 1953, 43,724-9.
Bibliog.
Joint Meeting was held-with The Institute of Fuel at the Institution
of Mechanical Engineers, Storey’s Gate, London, S.W.l on 1st May 1952,
the Chair being taken by Dr. G. E. Foxwell, President, The Institute of
Fuel.
British Railways consumed 15 million tons at a cost of £40m. Noted testing
to make savings, plus some anodyne comments on poppet valves and high pressure
boilers. On page 414 made some observations on experiments with pulverized
fuel. R.A. Riddles (404) noted that a fireman had only
to use 11 shovelfuls (1 cwt) more than necessary between Euston and Birmingham
to increase coal consumptiion by one pound per mile. Noted that spent much
on training enginemen.
Ikeson, W.C. (Paper 516)
Development of the oil-fired locomotive. 425-75. Disc.: 475-515.
Second Ordinary General Mecting of the Session 1952-53 was held at
the Institution of Mcchanica! Engineers, Storey’s Gate, London, on 22
October 1952, at 5.30 p.m., Mr. C. M. Cock, President, in the Chair.
Author was Chief Mechanical Engineer of the Iraqi State Railways in Baghdad.
Reviewed the Urquhart system (citing Urquhart's IMechE paper), Holden's system
used on the Great Eastern Railway (and cites Holden's paper to the International
Railway Congress in 1900), W.N. Best's system which was widely adopted in
the USA, H.G. Garratt’s ‘drooling’ steam jet burner used on
the Lima Railways in Peru.
The principal advantagcs in order of importance.
The principal disadvantagcs in order of importance:
The principal methods of oil firing in use were:
The Stanier 8F 2-8-0 type was amongst locomotive types in service and oil-burning. See also this author's discussion on paper by Roosen (Paper 607) in V. 50: pp. 266-70.
Andrews, H.I. (Paper 517)
Stresses in locomotive coupling and connecting rods. 533-79. Disc. 579-603.
Third Ordinary General Meeting of the Session 1952-53 held at the
Institution of Mechanical Engineers, London, on Wednesday 19 November 1952
at 5.30 p.m.: Mr. C. M. Cock, President, occupying the Chair
The design of both coupling and connecting rods was complicated by the
considerable inertia forces to which they may be subjected while working,
and as speeds and loads continually increased, designs were tending toward
the critical, and it became increasingly important, both that the working
of such rods was fully understood, and that the loads to which they were
subjected in service be ascertained. A theoretical paper with 21 citations
to other research on stress, notably that at the University of Illinois.
Discussion: E.S. Cox (579-81) said that thanks were
due to the Author for gathering together the available information on rod
design and adding something new. He confined his remarks to coupling rods,
which represented a more serious problem in British locomotive design than
did connecting rods. He divided the subject rather differently from the Author,
into two parts, one of which was concerned with making the most intelligent
and practical use of the largc amount of information, some of it a little
conflicting, which was available, and the other with the problem of filling
the gaps in the information available, which were still considerable. The
Author would no doubt be the first to agree that the last word on this subject
has not yet been said.
On the formation of British Railways there had been an opportunity of seeing
how the drawing offices of the different railways had dealt with the subject
of rod design. The methods had been extremely diverse. All designers had
made use of such basic ideas as the strength of a beam and the well known
strut formula, but in trying to apply these to actual design and to connect
them with actual practical conditions there had been wide variations in the
use of adaptations of the strut formula, such as those of Merriman, Rankine
and Fidler.
There had been different treatments of loads and stresses in relation to
factors of safety. In some designs the smallest rod section had been taken,
and in others the largest, and the final stresses had been related to the
yield or to the ultimate strength of the material, so that it had been possible
for a classic case to occur where a rod which failed was shown to have a
factor of safety of 13 by the method of calculation adopted by the company
responsible for its design, whilc the same rod calculated according to the
method of another company had a factor of safety of 2½. It was clear
that the methods originally adopted, therefore, left something to be desired
by leading to a false sense of security. What it meant was that each office
had proceeded by a process of trial and error to arrive at a design of rod
which in comparison with others would give reasonable and satisfactory service.
Whilst it could not be denied that 19,000 locomotives were running about
in this country with, on the whole, satisfactory results so far as their
rods were concerned, the present unsatisfactory basis did mean that occasionally
one received an unpleasant surprise.
Since the present paper became available, they had applied the Perry formula
to one or two rods, and, speaking generally, they found that if the rods
were short or medium in length it gave what they considered to be a reasonable
rod section in relation to other methods of calculation, but it was somewhat
weighted against the longer rod, in that it gave an uneconomically deep section
when the rod became long, if the same factors of safety were worked to in
each case.
The Author and other designers based their calculations on piston thrust
and crank effort and the force required to slip the wheels, but rods still
buckled from time to time, in spite of the application of high factors of
safety, and this tended to indicate that the strength of the rod had been
based not on the forces which actually crippled it, but on the forces which
had not crippled it. It was clear that there was another and more random
factor which was causing the intermittent failures to which they were still
subject to-day.
The Author had indicated that the effect of clearances was not decisive.
This could be supported by actual experience, because such rod failures as
took place often occurred on locomotives in good condition and with relatively
tight clearances; they were not confined to “sloppy” locomotives.
The view was coming to be held that the really destructive force was the
one associated with the stopping of slipping rather than that associated
with the commencement of slipping. That was a force which was not mentioned
in the paper and not much considered in the literature on the subject. He
would be glad to have the Author’s view on that. In other words, the
problem was really to know what force it was necessary to design against
rather than how to design rods to meet a certain force. He noticed that 20
pages of the paper were devoted to a consideration of stresses in what might
be termed the vertical direction – the centrifugal, with the strut bending
vertically – and only half a page to the horizontal strut effect. In
such experience as he had bad of railway work, however, he knew of very few
cases where rods had failed in the vertical direction, whereas bending of
rods outwards or inwards had from time to time caused some preoccupation.
The Author stated that to meet the stresses, both known and unknown, the
rod should be designed for the maximum stiffness in all directions. It was
perfectly possible to design rods in that way, methods originaly adopted,
therefore, left something to be desired because there were many successful
rods running trouble free with an I-section which was reasonably stiff, but
some designers deliberately introduced an element of flexibility by the use
of a very flat rod section, and, indeed, a recent experience of a very flexible
rod had drawn attention to the fact that there might be another possible
method of design in which this very flexibility was exploited to advantage
by making some use of the elastic strain energy of the material of the rod.
Mr. Cox hoped that a later speaker that evening would enlarge on that interesting
alternative.
On the experimental side, one had to agree with the Author that it was surprising
how few attempts had been made to obtain actual stresses and loads in service.
With reference to the tests which were described, the low speeds at which
those tests had been run was striking, not more than 175 r.p.m., and he wondered
whether there was any particular reason for that, having regard to the fact
that speeds up to 400 r.p.m. were run every day in this country. It was obviously
difficult to set up the conditions in which tests of this kind should be
carried out. He could mention the case of a rod which failed in service in
connection with high speed slipping, and yet when the same locomotive was
tested most rigorously, both on the plant and on the road, through the whole
range of its power and speed capacity during which slipping had freely occurred
it had been quite impossible to make the rods of that locomotive behave similarly
under observed conditions. It would be interesting tp have the Author’s
views on how, if they were to undertake strain gauge tests similar to those
illustrated in the paper, they should set about reproducing their limiting
conditions.
Failures could be cured, of course, by putting sufficient metal into the
rod. The particular instance which he had in mind was that of a class of
engine which had a few failures, and those failures completely disappeared
by the addition of some 60 lb. of metal in each leading rod, so that the
total addition of weight to the rods as a whole was 216 lb. That was less
than one per cent of all the revolving weights on the engine, which made
one wonder whether there was not too much preoccupation with reduction in
weight in the rods, at any rate if it was at the expense of introducing some
unreliability .
In conclusion, rods were still the simplest and cheapest means of coupling
to stabilise adhesion, and from Webb in the early days to the designers of
the Pennsylvania duplex locomotives in recent days, designers had ignored
at their peril the correct application of these rods. To illustrate what
the Author had referred to with regard to electric locomotives, onIy the
previous week Mr. Cox had been present at some tests on the Manchester and
Sheffield electrified road, where locomotives were beinq run up to the very
limits of their adhesion under different rail conditions. An electrical engineer
who was present said in his hearing what an advantage it would be if there
could have been coupling rods on those locomotives. It was clear that there
was still a great deal in this subject, and it was worth while persevering
with better use of what was known, and continuing to add to the knowledge
available.