THE BRITISH OVERSEAS RAILWAYS HISTORICAL TRUST
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Kevin Jones' Steam Index
Proceedings Institution of Mechanical Engineers:
1930-1939
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Pendred, Loughnan St. L.
Random reflections: Address by the President. 943-54.
"What I have been endeavouring to do is to stir up a spirit of courage
and adventure amongst our members. All around us we see new methods springing
up and the infallibility of old laws and old beliefs being challenged. Something
should come out of it all, and I hope our own young British engineers and
scientists will give rein to their thoughk, and the spur to their activities."
Quotations from Kipling and Robert Louis Stevenson! Account in
Locomotive
Mag., 1930, 36,
388.
Volume 120 (January to June 1931)
Unveiling of Replica of Tablet affixed to George
Stephenson's Cottage at Wylam-on-Tyne on 20 February 1931. 249-51.
Unveiled in the Institution's Headquarters by Richard W. Allen. The
original bronze tablet had been affixed to the exterior of Stephenson's cottage
in June 1929. The commission for the plaque had been given to Professor Maryon,
of Durham University, which Sir Archibald Ross undertook to cast in his own
foundry.
Gresley, H.N.
High-pressure locomotives. 101-35. Disc.:135-206 + 3 folding plates. 8 illus.,
14 diagrs., 2 tables, 2 plans.
In his paper on "High-Pressure Locomotives," read on Friday evening,
January 23, before the Institution of Mechanical Engineers, Mr. H. N. Gresley,
chief mechanical engineer of the L. & N.E. Ry., described some special
features of considerable interest relative to the water-tube boiler of the
high-pressure engine No. 10,000, which was completed to his designs at the
end of 1929 at the Darlington Works. To prevent the formation of scale in
the tubes of the boiler, so far as possible, arrangements were incorporated
to heat the feed water, so that its temperature when delivered into the water
chamber was over 400°F. or only about 50° less than that of the
saturated steam in the boiler. Much of the scale and mud was thus thrown
down in the forward portion of the top drum of the boiler, and after running
over 15,000 miles only a slight deposit of hard scale was found on the inner
rows of tubes in the firebox. Any economy in maintenance would become fully
apparent after the engine had been running for a few years.
It had been ascertained that the cost of a water-tube boiler, similar to
that fitted to No. 10,000, would not be appreciably greater than that of
the wide firebox pattern as fitted to L. &N.E. Ry. "Pacific" locomotives.
The most expensive details of the water-tube boilerthe solid forged steam
and water drums-were not subjected to the action of the fire, and consequently
might be expected to have a long life.
When stationed at Gateshead the locomotive worked express trains from York
to Edinburgh and back, involving a daily run of about 420 miles. Whilst other
engines of the "Pacific" type in the same link require washing out after
running 1,000 to 1,500 miles, this engine ran 5,000 miles without washing
out, and when opened up it was found that the boiler was exceptionally clean
and the tubes in good condition. The superheater elements of the boiler of
No. 10,000 are located in the forward portion of the central flue, and are
subject to radiant heat. In order to prevent the flame impinging directly
on the ends of the elements, a brick column is provided in the centre of
the main flue immediately in front of the brick arch. Notwithstanding this
precaution, and owing to the fact that there were no data available as to
the effect of radiant heat on superheater elements, the temperature to which
steam was superheated during the preliminary trials was excessive, temperatures
of 900°F. being obtained; consequently the lengths and area of the
superheater elements have been reduced, so that a temperature of approximately
700°F. can now be obtained, and this is regarded as sufficient. The
superheater elements are situated between the boiler and the regulator and
are, therefore, always subject to full boiler pressure. In order to prevent
overheating when the regulator is closed, the steam supplied for auxiliary
services is taken from the superheater and passes through a coil of ribbed
pipes laid in the feedwater chamber, thus raising further the temperature
of the boiler feed and at the same time de-superheating the steam. This
de-superheated steam is led to the reducing valve where its pressure is reduced
to 200 lb. per sq. in. Steam from this reducing valve supplies a manifold
pipe on the footplate across the front of the boiler above the firehole door.
From this manifold pipe steam at 200 lb. per 'sq. in. pressure is taken for
supplying all the auxiliary services, such as the injector, vacuum ejectors,
and steam brake, reversing gear, steam sanding, steam heating, whistle, and
turbo-generator. It has been possible to retain the standard steam fittings
for this purpose. Only the safety valves, regulators, and water gauges have
had to be made to suit the working pressure of 450 lb. per sq. In.
The heating surface figures are now as under:-
Firebox 919 ft2.
Combustion chamber 195 ft2.
Small tubes 872 ft2..
Total evaporative 1,986 ft2.
Superheater:
Number of elements 12
Diameter. inside 1.18 in.
Heating surface 140 ft2.. .
Total heating surface 2,126 ft2..
Having only two sets of valve gear, it was regarded as necessary to be able
to vary the cut-off of the high-pressure cylinder independently of that of
the low-pressure cylinder, and only by trial at varying cut-offs could the
best results be realised. Therefore the rocking link by which the high-pressure
valve is actuated, is so arranged that provision is made by means of a slot
and die-block to varv the travel of the valve, at the same time retaining"
the combination lever to keep the lead constant. The reversal of the low-pressure
valve-gear, and consequently of the whole engine, is actuated by the ordinary
form of steam reverser, and a similar equipment is provided to vary the
high-pressure cut-off. Both these equipments are attached to the shafts they
actuate, and being so remote from the footplate their delicate control was
not easy. This has been successfully effected by the use of telemotors; another
telemotor is also provided for operating cylinder cocks.
As built, the engine had two high-pressure cylinders 12 in. in diameter and
two low-pressure cylinders, each 20 in. in diameter, all cylinders having
26 in. stroke. It has been found that by reducing the diameter of the
high-pressure cylinders to 10 in. a more equal distribution of work between
the high-pressure and low-pressure cylinders results.
In his paper, Mr. Gresley described in some detail the notable high-pressure
locomotives which have been built by the American Locomotive Co. to the designs
of Mr. J. E. Muhlfeld for the Delaware & Hudson Railroad: the
Schmidt-Henschel three-cylinder compound locomotives, built by Henschel &
Sons for the German State Rys., as well as the Paris, Lyons & Mediterranean
Ry., and by the North British Locomotive Co. for the L.M. & S. Ry., the
Winterthur high-pressure tank locomotive built by the Swiss Locomotive &
Machine Co. to the designs of Mr. Buchli, and the Schwartzkopff-Loftier
three-cylinder locomotive, built by the Berlin . Machine Works to the order
of the German State Rys.
In opening the discussion on Mr. Gresley's paper, the President said they
had listened to an admirable paper from a chief mechanical engineer who had
produced an engine that might be considered with pride as an "all British"
production. As so many were desirous of discussing the paper, and the discussion
would probably have to be adjourned, he invited those who had come from a
long distance to speak first. Mr. Scarth, of Yarrow & Co. Ltd., said
that although the boiler of No. 10,000 departed somewhat from the usual Yarrow
form, an outstanding feature of the type had been retained in the small number
of riveted joints, and further, the water tubes could be readily inspected
internally, while ashes and coke could be easily removed. He thought higher
working pressures could be considered for future locomotives. Some interesting
remarks on the performances of the Schmidt-Henschel and Loftier locomotives
were made by Mr. Wempe of the Schmidt Superheating Co. of Cassel, and he
was followed by M. Hoffner of the French State Rys., and M. Rogers of the
P.L.M. Sir Henry Fowler then gave some of his experiences on the high-pressure
locomotive of the Delaware and Hudson RR As the President suggested that
a boiler-designer should give his views, he called on Sir John Thornycroft
to make a few comments. This gentleman gave Mr. Gresley great credit for
the way in which he had succeeded in depositing the hardness of the water
in the form of sludge, which could be blown out. Good water circulation was
of the utmost importance if the generating tubes were to be kept in order,
and he wondered, when the boiler was working very hard, if the proportions
of the heating surface were such as to give the circulation required. Mr.
R E. L. Maunsell in his remarks, said he hoped later on that Mr. Gresley
would give details of the cost of maintenance, running costs, etc. Referring
to the arrangements made at the front end for keeping the steam clear of
the cab windows, he mentioned the success of the "blinker" plates used on
the Southern Ry. Mr W. A. Stanier spoke of the Delaware & Hudson RR
locomotives which he had had an opportunity of seeing, and the troubles they
had had with too many tubes in the firebox. Lieut.-Col. E. Kitson-Clark confined
his remarks to questions as to the mechanical details of No. 10,000. He wished
for more particulars of the bogie arrangement under the firebox, and further
asked where the tail rods for the highpressure cylinders were. He also referred
to the ratio between the diameters of the high-pressure and the low-pressure
cylinders, and to the method adopted for varying the cut-off in the high-pressure
cylinders. At the resumed discussion on the 7th inst., when replying, Mr.
Gresley showed a very ingenious electrical device for ascertaining if any
scale is present in the water tubes, glowing lamps being extinguished whenever
the working end of the instrument, pushed down a tube, encountered scale.
The above is based directly on the brief summary which which appeared in
Loco. Rly Carr. Wagon Rev., 1931,
37, 38-9.
Locomotives described include the Delaware & Hudson two-cylinder compound
locomotive of 1924; the Schmidt-Henschel three-cylinder compound locomotive
of 1926; the Swiss Winterthur high-pressure locomotive (2-6-2T) of 1927;
and the Berlin Machine Works Schwartzkopff-Löffler three-cylinder locomotive
of 1930. He then described No. 10000, with its Yarrow boiler. Discussion:
N.H. Scarth (Yarrow) (Pp 135-6); F. Wempe (Schmidt)(136-7); G. Haffner (Chief
Engineer, French State Railways p. 137); A.C. Roger (French State Railways
p. 137-8); Sir Henry Fowler (138-9) who commented on
other high pressure locomotives, on the oil separator on the Löffler
boiler, and on the chimney and smoke deflectors fitted to No. 10000;
R.E.L. Maunsell (p. 140) commented on smoke deflection;
W.A. Stanier (pp 140-1) supposed that since
the days of the Brotan firebox, locomotive engineers had thought that they
would like to try water-tube fireboxes or water-tube boilers. It had been
left to the Author to show them that not only a watertube firebox but a complete
water-tube boiler was possible for a locomotive. He had had the opportunity
of seeing the Delaware and Hudson Railway engine with a water-tube firebox,
and he had gathered from Edmonds, the chief mechanical engineer of the railway,
that the trouble with the first engine which had been built had been due
to tubes of too small diameter in the firebox, and that he had subsequently
enlarged the diameter of the tubes with advantage. He asked if the Author
had found that the outer tubes in his boiler received any appreciable amount
of radiant heat from the fire.
There was little to criticize in the Paper under discussion unless one had
had experience with the type of boiler with which the Author was experimenting.
He hesitated, therefore, to express any opinion of the boiler other than
that it seemed to be a sound mechanical design. He would, however, like to
ask the Author whether he had considered, in proportioning his cylinders,
reducing the low-pressure cylinders to 18 inches diameter rather than the
high-pressure to 10 inches diameter. He also wished to ask whether the ordinary
means of lubrication with a pressure lubricator were satisfactory with
high-pressure steam.
E. Kitson Clark (141): commented on the ratio betwen the hp and lp cylinders
and cited E.W. Selby J. Instn Loco
Engrs Paper 257.
H.A. Stenning (p. 142-4) Stenning said that
regarded from the point of view of economy, it seemed that the chief object
of the designers of the high-pressure locomotives which had been described
had been to eliminate the expense of the ordinary type of firebox and its
maintenance. No high-pressure locomotives had been running for any length
of time. Apart from the American type, there was only the multi-pressure
boiler of the Schmidt type to judge of in service, and that only over a very
limited period. He was not satisfied that it was a long enough time to enable
one to draw conclusions, but it was known that at the end of three years
of more or less continuous service the water-tubes of the closed circuit
had been examined and found to be as good as when they had been installed.
He had pieces of the tubes which had been examined in his possession and
they showed no deterioration either inside or outside. If, however, circulation
in water-tube boilers or a water-tube circuit was at all inefficient, all
sorts of troubles would occur. He had encountered some of them in the
Schmidt-Henschel engine built at the North British Locomotive Company's works
in this country. Excessive temperature combined with excessive pressure had
set up stresses which were more serious in their effects than those due to
pressure alone. For modern high-pressure boilers new materials had to be
used and he was sure that the Author would admit that the choice of a suitable
material for the drum to keep it within permissible limits of weight had
been a problem. The use of special steel which was necessary tended to make
the construction costly, and it was more important to know whether the increased
capital cost was balanced by the reduction in the maintenance costs of the
firebox than to ascertain how many pounds of coal the engine burned per ton-mile.
Coal was a comparatively small factor and what was required to be known was
the total cost of drawing a ton load for a given distance.
He had doubts as to which of the two-cylinder high-pressure, or the
three-cylinder or four-cylinder compound engines, was the best arrangement.
In England the three-cylinder engine was used. Again, the proper degree of
superheat to use was a question which had been raised for many years. In
the early stages of superheating 100° F. of superheat was considered
ample. To-day 250° to 300° F. of superheat was customary, and one
might well consider whether a pressure of 450 psi was necessary, or whether
still higher pressures would be advantageous. There was probably some happy
mean between the highest and lowest both of pressure and temperature, but
what it was he would not like to say. Nevertheless, the answer governed the
problem of balancing capital cost and maintenance upon which the ultimate
economy rested. The Author had mentioned that one of the tubes in his locomotive
became overheated at one point. Could he give some indication of the degree
of heat to which it was subjected, and the exact location of the tube Z He
assumed the Author had employed a fire-door of the automatic type. That was
most important in high-pressure locomotives, because if anythmg went wrong
the whole of the contents would be blown out through the fire-hole pretty
quickly at a pressure of 450 psi. In the closed circuit of the locomotive
Fury built for the London, Midland and Scottish Railway, there were
120 gallons of water, and, as he himself was unfortunately aware, on an explosion
taking place in this closed circuit, the whole of this was blown out in about
three seconds. He asked if the Author had considered what would have happened
to the fire-bars as a result of using preheated air. If they were found to
deteriorate more quickly than in the normal firebox, he suggested that they
should be treated with aluminium.
He noticed that the blower pipe had been carried along so as to clean the
tubes near the centre of the boiler, but he did not think it was carried
down to the bottom of the firebox near the corners where it was rather important
to place it so as to clear the ashes from the bottom of the water-tubes in
the firebox itself. In most of the engines described, the steam-drum was
protected by cross water-tubes underneath the bottom surface, or at any rate
the drums had been taken out of the line of the fire. In the Author’s
engine, the steam-drum was immediately above the brick arch, and he was not
at all sure that it would not get burnt. The designers of the Schmidt-Henschel
engine adopted protective means, for their steam-drum was in exactly the
same position. The effect of the flame or gases of combustion circling round
the end of the brick arch was very severe and it seemed to him that there
was a blow-pipe action directly on the surface above it. He asked whether
the large smokebox had any appreciable effect on the exhaust, pressure in
the cylinders. He assumed that the baffles for circulating the gases were
now placed in such a position that no excessiv; temperature occurred in the
superheater. The difficulty of excessive superheat had also been mitigated
by moving the superheater further to the front of the engine.
He thought these locomotive experiments were the most interesting events
occurring on British railways. The railway companies had broken away from
their traditional conservatism and were now actually carrying out more
experiments here than in any other country of the world. Three such experiments
were in progress-the Author’s, the Schmidt-Henschel locomotive for the
London, Midland and Scottish Railway, and the pulverized-fuel locomotive
on the Southern Railway-all aiming to draw tons more cheaply within the allowable
limits of weight and gauge. He felt sure that as a result, the locomotive
would still maintain its position as the cheapest tractor the world had ever
seen.
Ernst Gysel (144-5) referred to the soluble deposits
of scale in the portion of the boiler which was most intensely heated by
the fire. A thin layer of such hard scale was found in the tubes surrounding
the firebox in the Winterthur high-pressure locomotive after some 25,000
miles of service. It was pcssible to remove this scale completely and no
tubes had to be taken out of the boiler, but naturally the matter had been
intensively discussed between the responsible engineers of the firm with
a view to deciding whether there was any danger due to such deposits, and
whether the use of natural water in boilers of the type built, for instance,
by Mr. Gresley or that built by the Swiss Locomotive Works was subject to
certain limitations. He would like to have Mr. Gresley’s opinion on
that question. He would like to say that the figures of steam and coal
consumption which Mr. Gresley had mentioned in connexion with the Winterthur
locomotive had been carefully measured and checked by railway officials in
Switzerland, when the locomotive was subjected to tests on the Czeczott
principle, and when making use of the dynamometer car which was attached
to the locomotive. There was no doubt that with high pressures of steam,
a coal consumption of less than 24 lb. per d.h.p.-hr. could be obtained (the
best figures had been 1.9 to 2 lb.), and this enabled the designer to build
engines of a reasonable size with greater power than had hitherto been possible.
The locomotive built by the Author was of the type 4-6-4, and he was wondering
whether criticism he had heard from certain quarters, that that type of
locomotive might sometimes be deficient in adhesion weight, was justifiable.
Did it happen in service, say when running at high speed, that too much load
was supported on the leading and trailing axles and that, in consequence,
the driving axles became unloaded and the locomotive had a tendency to slip
? He was personally of the opinion that that criticism was not justified,
as means could always be provided to secure an even distribution of the load,
but it would be interesting to hear how the Author’s engine had behaved
in service with regard to that point.adhesion charcteristics of 4-6-4;
W.W. Marriner (Yarrow, pp 145-7) said he was sorry
he could not carry out the wish of the President and give an opinion as to
the value of higher pressures for locomotives, but he could say that in marine
work during the last five years pressures had increased by one-half. A pressure
of 400 Ib. per sq. in. was quite common to-day, and, if it was safe to prophesy,
600 lb. per sq. in. might in two years be quite usual. A recent list had
shown a number of enormous land boilers which had been made in the United
States, all of them having an evaporation of over 200,000 Ib. of water per
hour, and all having pressures of over 1,000 lb. per sq. in. Those high pressures
were being used in conjunction with turbines, and since one understood that
it was at the lower end of the pressure range that the steam-turbine had
the advantage in efficiency, and that a reciprocating engine had the advantage
at the higher end, in he thought that high pressures for locomotives were
very likely to be a thing of the future. When the Author had invited Mr.
Yarrow to co-operate with him in the design of his locomotive boiler, Mr.
Yarrow had been very pleased to accept, and he could assure them that all
Mr. Yarrow’s staff had a1so been delighted. It was surprising how much
they had learned by their association with the Author and his staff. The
members had no idea of the difficulties there were in getting such a powerful
machine into such a small space, and within the limits of the permissible
weight. They had even learned a great deal about boiler-making itself. It’
had been mentioned that the bottom of the steam-drum was directly exposed
to flame. For that reason the bottom of the drum was made thinner, a practice
which his firm had adopted for many years for very much higher rates of
evaporation than occurred even in the Author’s locomotive. It was done
in order that the transmission of heat might not be impeded by thick metal,
and not the least trouble was experienced in consequence. When his firm had
been called in some time ago by the American Locomotive Company to assist
them with the designs of a high-pressure locomotive boiler, they had not
gone as far as they had done in this case. The Americans, however, had enormous
advantages, which they had not realized then, in their very much larger
loading-gauge and less severe weight restrictions. From the experience gained
in connexion with the locomotive under discussion, he had no doubt that if
locomotive engineers were going to use high pressures extensively it would
be necessary to adopt an all-water-tube boiler, and not to have stayed surfaces,
He might add that Mr. Gresley’s boiler would have been a much simpler
problem if there had been another foot of headroom. Col. Kitson Clark had
pointed out the bold step which Mr. Gresley had taken in putting the trailing
driving axle in front of the firebox. That had helped them considepbly. It
would, in fact, have been extremely difficult for his firm had not Mr. Gresley
been able to propose that way of getting out of a serious difficulty. Sir
John Thornycroft, as one might expect, had put his finger right on the central
difficulty in designing a locomotive water-tube boiler. The first thing one
had to choose was whether to have considerable complexity of design, or
simplicity but with provision for cleaning the tubes. There was no doubt
at all that the Author had adopted the correct solution. With regard to the
temporary hardness, everything possible had been done in order that the water
entering the steaming part of the boiler was as pure as possible. It would
be seen that the feed-water was introduced into the front end of the drum
where there were no tubes. Inside the drum there was a Gresley injector.
In an ordinary injector the steam drew the water, but in this injector the
water drew the steam. Consequently the water was heated practically to the
temperature of the steam in the boiler. As a result the temporary hardness
of the water was deposited on the forward side of the weir in the drum. With
regard to the permanent hardness of the water, it was surprising that their
knowledge of chemistry had not enabled them to deal with it in any way except
by letting it deposit and subsequently scraping it off. When using hard water
a very good indication as to the circulation was given by the appearance
of the inside of the tubes, and when using coal a very good indication was
given by the deposit on the outside of the tubes as to whether they had been
hotter than usual. In the Author's boiler they had been more than satisfied
with regard to the circulation. Whether or not that was due to Mr. Gresley
insisting on his firm putting in tubes almost twice as big as they had wanted
to he would not like to say, but there was no doubt it was successful. What
they now knew about circulation made one wonder what on earth happened in
a locomotive boiler of the type they used to install in destroyers-very large
boilers with narrow water spaces, which burned best Welsh coal at the rate
of 90 lb. per sq. ft. of grate. As to the future, there was not the least
difficulty in making a boiler similar to that of locomotive No. 10,000 for
any pressure that might be required. The system of air-heating which had
been adopted in the Yarrow-Gresley boiler was so efficient that the loss
from radiation which might be feared with high pressure and temperature was
very small indeed, and it was quite independent of the temperature of the
boiler itself. It was possible that the next step would be to stoke the boiler
by mechanical means, especially for very large sizes, but at present in this
country one man was quite able to do the work.;
Charles King (147-9) queried the efficiency of 18% claimed for the
Löffler boiler; P.J. Cowan (149-52) mentioned improvements in
boiler feed; that Horatio Allen suffered from leaky seams and stated that
wheel arrangement of 10000 was really 4-6-2-2; W. Gregson
(153-5) discussed problems of hard water with the Brotan firebox and
queried "how did No. 10,000 compare with the 250 lb per sq in in four-cylinder
simple engines of the G.W.R. which had always been noted for their economical
running" (Gresley did not respond!);
E.L. Diamond (154-6) remarked that one admired the Author’s locomotive,
not only as an ingenious product of the engineers’ skill, but most of
all because the designer had brought to his problem a broad sense of proportion,
so that this engine might be regarded as the culmination of a series of designs
and developments which had had as their object not the production of a
spectacular test figure, but the conferring of a real commercial gain to
the railway operating department. In that connexion, it was surprising that
no reference was made in the Paper to the Baldwin compound locomotive with
a boiler pressure of 350 psi which was so fully discussed by Mr. Lawford
Fry in his paper before the Institution in 1927. That locomotive also was
a sound, practical development, and not merely a freak experiment having
little relation to the actual facts “of locomotive operation.
The Author had said early in his Paper that designers of locomotives were
only following the lead set by the designers of large stationary plants and
marine engines. One had sometimes thought that that had been true too literally
; high pressures had become a fashion, and the locomotive engineer had felt
he must have his highpressure engine too. And so they had had the somewhat
anomalous position of tentative and risky experiments with enormously high
pressures whilst more than half their standard locomotives offered a comparable
possibility of economy by the elimination of valve leakage and a reduction
of their low-pressure limit by 5 or 10 psi, an economy which merely required
the redesign of their valve-gear according to the best modern practice.
For what were the facts? The theoretical utmost gain in efficiency which
could be obtained in a locomotive by increasing its pressure from 250 psi
to 450 psi. was about 20%, corresponding to an increase in the Rankine cycle
efficiency from 18½ to 22½%. That assumed roughly the same superheat
temperature in both cases, about which he would have more to say in a moment,
and a back pressure of 17psi. absolute. But how many locomotives exhausted
against a back pressure of 17psi. at their normal running speed ? Still a
minority he feared. It was not always realized that whilst it was possible
to obtain an indicator diagram showing a low back-pressure line from almost
any locomotive, that line would show a far less favourable state of affairs
at high speed, and an exhaust pressure at 25 psi absolute was much nearer
the figure actually appropriate in most cases. The reduction of that pressure
by 8 psioffered a gain of over 10%, or fully half that attainable by an increase
of boiler pressure by 200 psi. Only those who had had extensive footplate
experience knew how seldom a locomotive ran with the regulator fully open.
Indeed, thousands of locomotives scarcely ever had their regulators fully
opened, and he had often wondered what was the good of maintaining a boiler
at a pressure of even 200 psi when the steam in the cylinder never exceeded
150 psi. or so. Much of the locomotive’s work was done at a mere fraction
of its total power output, and that would considerably reduce the saving
in coal that could be expected from the highpressure locomotive in service.
Confirmation of the importance of those considerations would be found by
studying published results of locomotive tests. The coal consumption of standard
passenger locomotives had been reduced from over 4 lb. per d.h.p.-hr. to
3 lb. per d.h.p.-hr. simply by equipping them with modern long-travel piston-
or poppet-valves. The further reduction claimed for even the very high-pressure
locomotives was only to 2½ lb, and those claims were not yet fully
substantiated. Whilst they still had so many 4 Ib. per d.h.p.-hr. locomotives
running about, it was obvious which was the first method of reducing that
coal bill of £12,000,000. The question of the lower limit of pressure,
was, moreover, one that became increasingly acute as the upper limit was
raised. A locomotive which had a boiler pressure of 450 psi. required the
steam to be expanded to six times its original volume (making allowance for
the clearance steam) as compared with the three-anda- half times necessary
for a locomotive having a pressure of 250 psi, if the same back pressure
was to be maintained. In other words, if more careful attention was not given
to valve-gear and cylinder port design in the high-pressure locomotive, most
of the gain of efficiency accruing by adding 200 psi. at the upper end of
the scale would be lost by adding a few pounds per square inch
But this was not all. at the lower end ! The urgency of that consideration
was emphasized by the fact that some difficulty had been experienced in securing
adequate expansion of the steam in recent locomotives pressed to 250 lb.
per aq. in., and it had even happened in individual cases that an improvement
in coal consumption had been effected by reducing the steam pressure at the
regulator valve.
The Author was probably well enough aware of those considerations ; compounding
in itself was not sufficient to secure adequate expansion of the steam, and
one turned with the deepest interest to the table of dimensions on page 120
to find that the Author had given exceptional length of travel to his valves,
and to the cylinder drawing on page 132 to find that admirably short, straight,
and wide ports had been included in the design. Another factor which should
not be passed over was the influence of superheat temperature. Was it sufficient
that steam at 450 Ib. per sq. in. should be superheated to about the same
temperature as steam at 250 psi in locomotive practice, or were locomotive
engineers soon going to follow the stationary plant designers and hanker
after temperatures of 1,000° F. ? The Author said that a temperature
of approximately 700" 3'. was considered sufficient, and he hoped he would
allow no one to shake him in that belief, at any rate until he contemplated
adding a condenser to his equipment. It was of course true that with increase
of pressure increase of temperature was necessary to maintain the same dryness
fraction in the steam' at exhaust. But who was certain that the steam of
a modern superheater locomotive had any moisture in it at all at the end
of expansion in the cylinder when running at normal speed ? He had failed
to find any experimental evidence on this point, and an investigation that
he had made some time ago * suggested that at a high speed the degree of
superheat was so much increased by throttling at admission that the steam
was still above saturation point at the moment of release in the cylinder.
If that were so, it would be absolutely futile to enter the hazardous region
of high steam temperatures so long as the steam-locomotive remained, by the
necessity of its circumstances, so much more rough-and-ready an affair than
the power generating steam-plant.
R.J. Glinn (156-8) spoke about mobile power stations equipped with water
tube boilers used during WW1 (illus. page 159).
Gresley in response on page 162 noted that some
questions had been raised with regard to the construction of the back of
the engine. There had been no room to put in a bogie because it would be
seen that the ashpan was placed very low. The trailing axle was really a
Bissel truck with Cartazzi slides for centralizing. The axle in front of
it was interchangeable with that used on the Pacific engines. It was a peculiar
arrangement, and it had to be adopted because of the circumstance he had
mentioned. The result, however, was that the engine was very easy riding.
There was always the possibility with a 4-6-4 type engine of getting a
symmetrical arrangement, resulting in the setting up of a swaying movement.
A dissimilar side control at the leading end from that at the trailing end
tended to break the synchronization. Certainly the engine described had no
tendency to set up a periodic side sway. As to whether it was a 4-6-4 or
a 4-6-2-2, he should certainly describe it as a 4-6-4. He imagined that 4-6-2-2
would be the correct designation of an engine having a bogie in front, followed
by six wheels coupled, a booster on the next axle, and a pair of carrying
wheels behind.
Gresley in response on page 164 Major Gregson
had referred to the magnesium limestone content of the water in the district
through which the engine No. 10,000 would have to work, and reference had
also been made by another speaker as to the desirability of softening the
water. Probably the deposit in the inner tubes of the engine was due to magnesium
limestone; it had been very hard. On the question of watersoftening generally,
not only for the engine under discussion, but for all the existing engines,
he was firmly of opinion that if the water in England could be treated ao
as to be similar to that which was available in Scotland, the expenditure
on the water-softening plants would be repaid in a comparatively short time
by the lower cost of maintenance of locomotive fireboxes. In Scotland engines
were running their full time between general repairs with practically no
dirt in the boiler. One of the new Pacific engines of the L.N.E.R. was stationed
in the Edinburgh district, and ran between Edinburgh and Glasgow and Edinburgh
and Berwick, and also to Newcastle. After running 90,000 miles it had come
into the works for general repair. He was at the works at the time, and he
had himself examined the firebox. It looked perfect, and not a single stay
had to be renewed. If that engine had been running in England south of the
Tweed, 200 or 300 stays would probably have had to be renewed after running
that mileage. The total life of a firebox in Scotland was a great deal longer
than that of a firebox in England.
The paper was discussed in Manchester on 5 February and the following
contributed: H.L. Guy (165-7);
Captain H.P.M. Beames (166-7) said it afforded
him very great pleasure to pay tribute to his old friend, the Author, and
he was sure that every one who had watched the progress of locomotive No.
10,000 would have been impressed with the courage and resourcefulness shown
in its design. Moreover, to those who, like himself, had to maintain boilers
of the Stephenson type, the successful attempt which the Author had made
to eliminate large flat stayed surfaces promised future relief from a great
deal of trouble. Indeed, the presence of those surfaces had been one of the
reasons which had restricted the advance of pressure in locomotives hitherto.
He wondered, incidentally, what trade was supposed to deal with the building
and maintenance of a boiler of that type. He could foresee some lively
controversy between the fitter, the boiler-maker, and the tuber ! On looking
at the diagram of the locomotive, it would appear that the centre of gravity
was pitched rather high and that the engine might be unsteady, but he understood
that at high speeds it was a particularly steady-running machine. It might
also be supposed from the diagram that as a result of the free passage through
the boiler given to the flue-gases the smokebox temperature might be rather
high. He asked what this temperature was, and mentioned that in an engine
of the " Royal Scot " type a smokebox temperature of 650' F. was attained
under certain conditions. Could the Author also say how much water per pound
of fuel was evaporated ? He inquired, further, whether any trouble was
experienced in keeping up the refractory walls between the flues and the
surrounding air chamber, and whether any trouble was experienced due to
evaporation.
One of the difficulties with the ordinary type of superheater boiler was
that the superheater was confined in flue tubes which frequently became blocked
with cinders. In the type of locomotive they were now discussing, however,
that trouble could not occur, but he nevertheless supposed that a certain
amount of ash passed through the superheater, and he asked what means were
adopted to clean it. Another point which would appeal to engineers was that
the feed-water in the Author's locomotive was fed to the boiler by injectors,
and it was not necessary therefore to incorporate a complicated system of
pumps as in some of the other locomotives which had been described. In view,
however, of the very high velocity with which the feed-water had to pass
through the injectors he wondered if there might not be some trouble due
to erosion of the cones.
He had asked that question in America when he had seen the first of the
high-pressure What kind of piston packing was used? locomotives, and he had
been assured that the packing in the locomotive at that time, after about
six months’ running, was the original packing fitted in the engine.
The packing and lubrication, indeed, had been so satisfactory that no alteration
had been required.. He saw that a special form of regulator was used in the
Author’s engine. Was it a multiple-valve regulator, and did it give
any trouble due to the high pressure of the steam ? Finally, he asked how
the engine-drivers and the fwemen reacted to the higher pressure, for he
well remembered the time when an old driver had handed in his resignation
because the boiler pressure of his locomotive was increased from 6 to 12
Ib. per sq. in.
J.N. Gresham (167) referred to an article (Railway Engineer, 1931,
52, page 65). in which the thermodynamics and economy of high-pressure
locomotives were studied, and the interest on additional capital cost plus
probable increase in cost of maintenance were plotted against possible thermal
economy. Unfortunately, the figures were presented on the basis of the cost
of German coal, which needed to be rectified to meet English conditions,
but it was stated that an increase in maintenance costs of £2’76
per annum would be likely to absorb 14 per cent in coal economy, and an increase
in capital cost of £1,500 would require 7 per cent saving in coal to
pay for itself. Looking at some of the high-pressure locomotives described
in the Paper, they were bound to form the opinion that the capital cost of
such locomotives must be such as to necessitate an enormous saving of coal
to justify them. The Author, however, had stated definitely that in the case
of his own locomotive the capital cost would not be materially increased
and they could see for themselves that the number of auxiliaries was very
much less than in the case of the other designs, and the general arrangement
such as one would anticipate a small reduction in maintenance cost. A study
of the article to which he had referred would convince them of the wisdom
of the course Mr. Gresley had taken. He asked if the Author could give them
any idea of the air pressure under the ashpan after the air had passed through
the passages around the boiler shell
R.C. Bond (167) mentioned he had recently riden
on one of the German Schmidt-Henschel high-pressure locomotives and of seeing
the Schwartzkopff-Loffler engine, and he had been struck by the complication
of those machines. The Schmidt-Henschel locomotive, however, did its work
very satisfactorily, and appeared to require very little additional attention
on the part of the engine crew. The only added responsibility was the maintenance
of two water levels in place of one, which, under certain conditions, might
be difficult. He thought that what was so very satisfactory about Gresley’s
locomotive No. 10,000 was its essentially British simplicity, and whilst,
as the Author had said, a number of years would have to elapse before any
definite results could be obtained in regard to actual savings, he thought
there was not much doubt that the maintenance cost of the locomotive should
be very little, if any, more than in normal circumstances. He would have
liked to have seen some indicator diagrams and to have had particulars of
the performance of the engine measured in drawbar horse-power output. The
locomotive was interesting not only as a high-pressure locomotive fitted
with a water-tube boiler, but also as a high-pressure compound. With one
notable exception, the L.M.S. standard three-cylinder compound, compound
locomotives had not been a success in this country. In his opinion the L.M.S.
engines owed their outstanding success primarily to the simplicity of their
design and to the fact that there was very little possibility of their being
handled other than was intended by the designer. He felt, therefore, that
the time would come when the Author would find it desirable to combine the
control of the high and low-pressure cut-offs on one reversing lever. Although
a welltrained driver might be able to arrange the cut-offs to the best advantage
under varying working conditions, in many instances men had their own personal
ideas, which did not always lead to efficient results. He inquired whether
it had been necessary to fit non-return valves connecting the low-pressure
steam-chests with the ends of the high-pressure cylinders in order to place
them in equilibrium when starting away from rest on the low-pressure cylinders.
The reduction in diameter of the high-pressure cylinders from 12 inches to
10 inches altered the ratio of the high- and low-pressure cylinder volumes
from 1 to 2.77 to 1 to 4, and that in itself called for comment. The Author
had stated that he had found it necessary to redistribute the work between
the high- and low-pressure cylinders, but he wondered whether that could
not have been done merely by altering the cut-off in the high-pressure cylinders
relative to that in the low-pressure cylinders. With the reduction of
high-pressure cylinder volume it appeared to him that it would be possible
either to increase or decrease the proportion of work done in the highpressure
cylinders according to the relation of the cut-offs in the two cylinders.
He would like to know, therefore, whether it was desired to increase or decrease
the work done in the high-pressure cylinders and also what were the cylinder
clearances and the receiver volume, since both would have a considerable
effect on indicator diagrams. The high-pressure cylinder had a 34-inch piston-rod
but no tail-rod. With so small a cylinder that would give a difference of
roughly 12 per cent in the forces on each side of the piston, and he thought
it might have been desirable to provide a tail-rod. In examining the design
of the boiler, a point which struck him was that the brickwork round the
grate was somewhat shallow- If the engine were working with a fairly thick
fire at the back of the firebox there might be some risk of burning coal
coming into contact with the tubes, and be thought, therefore, that it might
be desirable to carry the brickwork slightly higher, Captain Beames had referred
to the accumulation of unburned fuel. Normally it deposited in the smokebox
and was removed at the end of a run. He wondered, in the case of locomotive
No. l0,000, not only how it was removed, but exactly where it accumulated.
The Author had pointed out that in the operation of any water-tube boiler,
prevention of scale formation was of the first importance ; if scale was
kept out of the boiler it must obviously be deposited somewhere else, perhaps
in the feed-water heater, and he would be interested to know how frequently
the latter had to receive attention. He did not know whether it was generally
appreciated that the washing-out of boilers cost a very large sum. On one
of the British railways over 3,000 boilers were washed out each week, which
resulted in each locomotive being out of service for any time up to sixteen
hours. If all locomotives could be fitted with boilers which would run 5,000
miles instead of 1,500 miles between washing out, the saving would be very
considerable. The Author had mentioned an evaporation figure of 20,000 lb.
per hour on a four-hour basis. He asked if that was the maximum rate of
evaporation of which the boiler was capable when working a heavy train.
Considering the Author's standard 4-6-2 express passenger locomotives, working
at 180 lb. per sq. in. boiler pressure, which would probably he capable of
developing 1,500 indicated horsepower for long periods, and assuming a steam;
S. Jackson (170-2); D.W. Sanford (LMS p. 172); C.H. Browne (on scale p. 172);
E.F. Lang (on the relatively low boiler pressure p. 173) and Gresley responded
(pp. 173-6).
The paper was discussed in Leeds on 12 February: speakers included
F.C. Lea (177-8); E. Kitson Clark (178); W.T. Athey
(178-9) stated that he had entered Gateshead as an apprentice in
1887, commented on compounding and boiler scale; R. Alan Thwaites (179) observed
that the engine was in no sense a freak and he imagined that it was likely
to be the forerunner of many similar ones, though some of the Continental
engines described in the Paper might not survive. There was something very
British about engine No. 10,000 both from the point of view of mechanical
design and appearance. He thought that the only serious problem in operation
was likely to be the water supply. The Author had adopted ingenious steps
which largely but not entirely prevented the deposition of scale in the tubes,
but it was interesting to note his view that if high-pressure locomotives
came into general use it would probably be found economical to treat the
feed-water. With this he entirely agreed, but he would go even further and
suggest that it might be necessary to de-aerate it. In power-station practice
where high-pressure boilers were employed it was necessary to eliminate from
the feed-water both scale-forming solids in solution and oxygen. If oxygen
were present severe pitting was liable to take place in the top drums at
abont water-level. Boiler feed-water for an express locomotive was handled
in such a way as to aerate it almost to the point of saturation. If, however,
the water in the tender was kept under a partial vacuum, much of the oxygen
might be removed. A thin deposit of scale would of course greatly reduce
corrosion, but if in the future the water was so treated that no scale resulted,
then serious consideration would have to be given to this question of the
oxygen conten; A.W. Chapman (179 on scale); J.J. Sheridan (179-80); John
Blundell (180-1); G.A. Musgrave (181) noted his own involvement in the design
of the boiler between 1924 and 1930 when the locomotive entered service.
Gresley replied on pages 181-3.
The paper was discussed at a meeting in Glasgow on 18 March: speakers
included: Harold E. Yarrow (183-4); A.L. Mellanby (184-5);
David C. Urie (185) suggested that the boiler
was the main point of interest at the moment to locomotive engineers. He
took it that the Author’s object had been to design a high-pressure
locomotive boiler which should not greatly exceed in initial and maintenance
costs a modern locomotive boiler of standard type. Realizing that, he had
faced the fact that he must use raw water for boiler feed, and it was interesting
to note the measures which were being adopted to precipitate as much of the
solid matter as possible before the water entered the boiler tubes. Subsequent
experience in this direction would be watched with interest by all locomotive
engineers. He saw no future for a high-pressure locomotive unless its costs
were not in excess of normal locomotives built for similar duties, because
additional capital charges would quickly absorb the coal saving under normal
working conditions as distinct from selected trials. He did not expect that
the saving under such conditions could be much more than 10%. It had been
mentioned by the Author that roughly 1 ton of coal had been saved in 8 on
the round trip from London to Edinburgh. This was roughly 12½% and if
60,000 miles was the average annual mileage 150 tons of coal might be saved
per annum. This did not leave much room for additional capital cost. He very
much welcomed the remarks of Professor Mellanby in connexion with the high
pressures which were the fashion or had been the fashion until lately. Indeed,
he would say of some of the locomotives which had been described that they
were not before their time but after it. He thought, personally, that the
direction in which the Author was going was the one which was most likely
to be fruitful in its results. He had no doubt that if additional locomotives
of the type were built the cost of subsequent boilers would be considerably
less than that of the pioneer boiler, and he noticed that the Author mentioned
that the cost of this boiler should be very little in excess of that of the
standard locomotive boiler used in his Pacific locomotives. He fully agreed
that to increase the pressure from 450 to 900 or 1,200 lb. per sq. in. would
add very little to the gain in thermal efficiency, but might add considerably
to the maintenance costs.
Lindsay Foster (186-7) said that he was by no means clear as to the
mechanism of the heat transmission between the closed circuit in the
Schmidt-Henschel system and the steam evaporating drum. He presumed that
the closed circuit was merely a means of carrying the heat from the fire
to the high-pressure boiler in order to keep away from the hottest surface
of the locomotive the crude water that was used in service. It appeared from
the diagram that there was a good deal of space in the air-preheating passage
in the Author’s locomotive. Unless that space was necessary for reducing
the resistance to the passage of the air he thought the air would be considerably
more heated if it were restricted to a minimum so as to increase the velocity
and ensure turbulence.; Robert Fox (187); J.M. Harper (188); Leonard Hyde
(188-9);
George Ness (189) who chaired the meeting wondered
whether water-tube boilers might not prove advantageous for locomotives other
than main-line engines: experience with shunting locomotives for colliery
sidings had shown that as the boiler pressures had been increased, the life
of the fiebox was reduced. Whereas, some years ago, for colliery and
contractors’ purposes one could reckon on a life of from ten to twelve
years for a firebox, they were now not at all surprised to find it more or
less worn out in four years. This generally depended on the curves and the
gradient of the bank on which the locomotives were operated. He asked what
was the life of the average locomotive firebox for railway purposes, and
whether it had appreciably shortened in recent years. One thing quite evident
from the high-pressure boiler described in Mr. Gresley’s Paper was the
magnificent engineering skill displayed by its design and construction. It
was entirely different from the old type of boiler, and he thought especially
that they could not praise too highly those who had forged the drums, and
in such short time effected so great a reduction in their price.
T.E.H. Heywood (190) replying on behalf of Gresley
said that he was very much surprised to hear that fireboxes of shunting
locomotives in collieries were only lasting four years. The fireboxes of
similar locomotives on the L.N.E.R. would last ten or twelve years, though,
of course, he did not mean that they would not require any repairs during
that time. In the event of any abuse with regard to leaky tubes, it might
even be necessary to put in a new tube-plate or portion of a tube-plate.
Undoubtedly it was of primary importance in connexion with the firebox of
a locomotive that the stays and tubes should be kept tight. Experienced
boiler-makers had said that if leaks in the firebox were attended to without
delay and washing out was done properly, the firebox would last for the life
of the locomotive. Shunting up gradients produced uneven expansion in the
firebox and intensified stay and tube trouble, but he could not understand
any colliery company in that district, with its good water, having undue
trouble.
The adoption of the water-tube boiler for existing engines was a matter which
had still to be considered, and it could not be decided until further trials
had been made. Trials of the use of pulverized fuel for locomotives had been
carried out in this country, but he did not think that even Messrs. Yarrow
would go the length of saying that the use of pulverized fuel was an established
practice in marine work. It was much easier to use pulverized fuel for marine
or stationary work than in a locomotive. The cost of the Author’s locomotive
and its maintenance, and in fact the economic side of the whole experiment,
could not be stated yet. The engine was experimental, and one could not base
the capital cost of a highpressure locomotive on what this engine had cost.
He hoped a representative of Messrs. Yarrow would answer the questions about
the boiler. The work in regard to the rivets, drums, etc., was altogether
different from ordinary locomotive boiler practice ; and he and his colleagues
had learned a great deal from the work which had been executed by Messrs.
Yarrow.
T.S. Finlayson (192) asked what variation was
permissible in the high-pressure cut-off when the low-pressure cut-off was
set at 60%. The centre of gravity of the locomotive was behind the centre
of the coupled wheel-base which was inherent in the design, and he thought
that might cause a tendency to produce lateral movement at the front end
when running at high speed. The laminated springs on the bogie and coupled
wheels were comparatively short, hence the deflexions were small and might
produce harshness in running. One of the trailing trucks had a long laminated
spring while the other had coil springs, giving deflexions greater than those
of the coupled and bogie springs. It might be that in time the rear springs
would settle down and the weight on the coupled wheels increase.
Lomonossoff, G.V.
Problems of railway mechanics. 648-59. 2 diagrams.
Theoretical paper: from the point of view of analytical mechanics
a railway train is a system of rigid bodies connected partly by rigid and
partly by elastic bonds. As a rule, motion of this system is not uniform:
the forces of inertia of all the parts of a train need to be take into
consideration. These can be divided into two sections: those having progressive
motion only along the track and those having rotary motion as well. For the
latter, namely the wheels, the permanent way is a non-preventative obstacle.
If this obstacle and all bonds between the separate parts of a train were
rigid the solution of the problems of railway mechanics would be rather
easy.
Woolltscroft, G.W. The training of an engineer.705-12.
The London, Midland and Scottish Railway in Derby had three grades
of apprenticeship:
(1) Trade apprentices usually destined to become craftsmen.
(2) Priivileged apprentices, usually with secondary or public school training,
who have to pass an entrance examination. These apprentices generally commence
in the works at a later age than the former, and are allowed two mornings
per w-eek, with pay, to attend a part-time engineering course at the Derby
Technical College.
(3) The highest form of apprenticeship, namely pupils who had usually obtained
an engineering degree, and who have a still more varied workshop training
than the former.
Gresley, H.N.
Locomotive experimental stations. 23-39 Disc.: 40-53. illus., 6 diagrs.
Described and illustrated earlier or existing plants: The Chicago
& North Western Railway opened one in 1895, Columbus University initiated
one in 1899, the Pennsylvania Railway installed one at the St. Louis exhibition
in 1904 (this employed Alden brakes), the Swindon test plant opened in 1905,
the German State Railways opened a plant with Froude water brakes at Grunewald
in 1931 and a plant was under construction at Vitry-sur-Seine. Gresley noted
that a locomotive testing plant arranged on the lines outlined by the Author
embodies many features of an essentially novel character, and there is much
detail work still to be done before the scheme can be regarded as complete.
On the other hand, it is claimed that such a plant offers considerable
advantages:
(1) The provision of a wind tunnel in which a locomotive can be tested.
(2) The arrangement of coupling the supporting wheels by means of bevelled
gears directly to the longitudinal shafts produces conditions which approximate
more closely to normal running conditions. Under normal running conditions
a locomotive progresses along a fixed rail. Therefore a fixed locomotive
should drive something resembling x caterpillar track, and the nearest workable
mechanical arrangement to this is a set of supporting wheels rigidly coupled
together. This eliminates the possibility of slipping on one of the supporting
wheels, and the proportion of the power transmitted through the coupling
rods is approximately the same as that which is obtained under running
conditions.
(3) With the braking equipment concentrated in one place, fixed on rigid
foundations, and away from the supporting wheels, the brakes are more accessible
and can be more readily adjusted, and the use of flexible pipes, which is
necessary if the brakes are directly coupled to the supporting wheels, is
obviated.
In conclusion the Author submits that the provision of a British Locomotive
Experimental Station is more essential now than at any other time. On the
Continent and in America large sums of money are being expended upon the
scientific development of locomotives, and these countries are obtaining
orders in markets which were formerly wholly British. To meet this competition,
and to provide for this country locomotives of the highest efficiency, it
is necessary that we should have equipment second to none for the investigation
of locomotive economy.
Very extensive abstract in Locomotive
Mag., 1931, 37, 258-61 which includes some of the diagrams,
notes presented in Cambridge and fails to record discussion.
Contributors to the discussion included G.V. Lomonossoff (40-2);
Stanier (42-3) commented on the Churchward plant and
improvements made to reproduce actual running conditions on the plant and
to power absorption: "perhaps the only one present who had had experience
of a locomotive testing plant installed in this country, he could confirm
all that Professor Lomonossoff had said about the difficulty of securing
uniform results at constant speed. The locomotive testing plant at Swindon
had certainly served a useful purpose, but it had to be remembered that
locomotives were required to work on railway lines and it was impossible
to reproduce in a testing plant service conditions. One of the principal
requirements of Mr. Churchward, who had installed the plant at Swindon, was
that a locomotive should be capable of maintaining a drawbar pull of over
2 tons at a speed of 70 miles per hour. Mr. Churchward had been quite unable
to fulfil that requirement on the testing plant, but locomotives of the type
tested had amply fulfilled that requirement on a level stretch of line between
Bristol and Taunton when tested by means of a, dynamometer car. It had very
soon been found that the testing plant at Swindon had inadequate capacity
to absorb the power obtainable from a modern locomotive. There were also
other difficulties in connexion with the plant. Most locomotive plants had
at some time or other given trouble in the shaft bearings. It was indeed
quite difficult enough to absorb the power of an individual axle, so far
as his experience went, but in the plant suggested by the Author the power
was carried first from the wheels to the shaft and thence to the brakes and
dynamos at right-angles by means of bevel-gearing, and it did seem to him
that this was to seek unnecessary trouble.
In view of the possibility of increase in the use of electric traction which
was now looming ahead, he thought that it should be further considered whether
a testing plant was still justified.
C.H. Bulleid (University of Nottingham p. 43) noted that the effect
of the variable conditions on the road had been brought home to him very
vividly many years ago when he had tried to compare two loconiotives by plotting
curves for each showing the connexion between horse-power and speed. He had
secured a large number of diagrams from two totally different engines, but
when he had plotted the average curves he had found they were almost identical.
He then realized that he had not been studying the locomotives at all ; he
had been studying the train and the schedule to which it was being run !
He felt that a testing plant such as the Author had foreshadowed would be
as important to engineers as the Froude tank was to naval architects.
C.H. Kuhne (pp 43-5) spoke about the Froude water dynamometer used to test
road vehicles; T.R. Cave-Browne-Cave (page 45) spoke about wind tunnels;
F.C. Lea (46).
Kitson Clark, E.
Humanity under the hammer [Presidential Address]. 107-41.
History of the hammer and hammering.
Carpmael, Raymond.
The manufacture and use of steel railway sleepers, 315-77.
Included Round-hole loose-jaw type (Indian State Railways); Webb's
Pattern: Rafarel's Patent Sleeper (1887)
Dymond, A.W.J.
Some factors affecting the riding of coaching stock. 465-504. Disc.: 505-21.
25 illus & diagrs.
D. Raymond Carpmeal (505-6) spoke about the GWR use of the Hallade
recorder; R.F. McKay on latex foam seating; A.N. Moon (508-14) spoke about
the riding qualities of six-wheel bogies, tyre wear, overhang and portable
accelerometers supplied by the Cambridge Instrument Co.; S.R.M. Porter (514)
on the transverse velocity of the bogie frame relative to the bolster; A.S.
Quartermaine (GWR, 514-15) on newly laid rail. G.H. Sheffield (515-18): the
Pullman bogie was introduced to England by Sir James Allport of the MR.
Twinberrow, J.D.
The mechanism of electric locomotives. 51-106. Disc.: 106-54. 36 figs.
Nose-and-axle suspended motors. the expected improvement in the rate
of wear of track and of tyres was not realized by the substitution of locomotives
of this description for normal steam-locomotives. It was found that the wear
of flanges and of the rails on curves was reduced when the bogie trucks were
connected by a hinged joint, capable of transmitting shearing forces, the
wheel-base then being conveniently described as Bo +
Bo. The tendency of each truck to nose outwardly produces a reaction
on the hinge pin and slews the wheel treads across the rails, without heavy
pressure on the flanges. Axle-mounted armatures: the gearless motor, having
the armature mounted directly on the axle, was adopted by the New York Central
Railroad for working main-line trains over the electrified lines connected
with the Grand Central Terminus in New York. The first group of engines had
the 1.Do.1 wheel arrangement, but the single-axle pony trucks
as originally fitted were replaced by four-wheel bogie trucks, after the
occurrence of a disastrous derailment. Later and more powerful locomotives
had eight driving axles, assembled in two identical trucks, each main truck
being prolonged and supported at its outer end on a pivoted motor guiding
truck. This type of wheel-base may be defined as
Bo.Bo+Bo,Bo Auxiliary control
of the angular deviations of the guiding trucks was necessitated in order
to suppress hunting motion at high speed.
Bulleid, C.H.
The importance of metallurgy to the engineer. 767-72.
Very general paper which advocated a greater understanding by engineers
of iron, steel and other metals as materials. "The principles underlying
the heat-treatment of steel are not really difficult to understand, and a
knowledge of this subject is essential to-day... Engineers are generally
mystified by the phenomenon known as fatigue. There has recently been a revival
in the use of wrought iron in places where it had been replaced by steel.
It is said to be less subject to fatigue, to resist shock better, and to
corrode less rapidly than steel. If these claims are true, its use may well
be justified in spite of the fact that its tensile strength is less. Steel
castings are widely used, and when properly made they are very reliable...
Engineers are meeting great difficulty from the phenomenon known as creep".
Ends with corrosion and pitting.
Fell, L.F.R.
The compression-ignition engine and its applicability to British railway
traction. 3-33. Disc.: 34-61.
Advantages of the oil-electric system
Fuel cost approximately halved.
In most cases one engineman only required
no standby losses.
Fuel transportation charges greatly reduced.
large saving of water is effected.
Man-hours are saved in the running shed by the elimination of fire lighting,
boiler washing, and locomotive requirements (i.e. fire cleaning, turning,
and taking water).
Continuous 24-hour day service can be obtained when necessary, and the engine
is at all times available for immediate use. Refuelling points can be placed
as conveniently as are water cranes.
Smoke and waste steam are eliminated, together with their deteriorating effects
on buildings, rolling stock and passengers’ clothing. Dead fires, smokebox
ash and boiler scale in shed pits and on the rail side are absent, thus saving
labour in their removal.
General cleanliness of the railway is improved.
Watson, F.R.B.
The production of a vacuum in an air tank by means of a steam jet. 231-65.
Disc: 266-300.
Academic research perfgormed at Bristol University. Author mentions
vacuum ejectors for railways, but neither representatives from the railways
nor from euquipment suppliers appear to have attended the meeting. The main
results of these experiments given with reference to continuous air flow
conditions through the ejector were:
(1) Over-expansion of the steam in the nozzle took place during all the tests
described, as this gave satisfactory results over a wide pressure range,
but a high vacuum could also be produced by an under-expanded jet.
(2) The series of stationary waves in the steam jet, upon which the successful
action of the ejector appeared very Iargely to depend, extended for a certain
length outwards from the nozzle.
(3) With a steady admission steam pressure and over-expansion in the nozzle
the photographs showed that the stationary waves varied thus : (a) wavelengths
increased (and therefore the overall length of wave series) with increased
vacuum; (b) waves swelled transversely with increased vacuum, and vice versa
in both cases. These results were deduced from separate experiments using
an air Pump.
(4) A direct deduction from (3) above was that the wave series was more "
tapered " in form when discharging against a gradually rising pressure along
its length (working conditions in air ejector) than when the jet discharged
into a region of nearly uniform pressure (air pump conditions).
(5) When a sliding diffuser was moved inwards over the jet the vacuum increased
and a position was reached when the core of the jet, with its layer of entrained
air, probably just filled the throat entrance. A sudden rise of about 5 inches
to the higher range of vacua then took place, and the globular part of a
wave was always observed to be inside the throat after this sudden rise.
If the movement of the diffuser was continued, and if the diffuser had a
long parallel throat, another smaller rise would take place at the next
wave.
(6) It is evident from (5) that the correct setting of the throat entrance
relative to the nozzle outlet is a very important length, and its determination
is entirely omitted in the theory of the ejector. The maximum value of this
length was found to increase with increased steam pressure, and it was evidently
some function of the wavelength in the jet outside the nozzle. At a steam
pressure of 140 psi. by gauge for the particular nozzle used, the
maximum value of this distance was practically two wavelengths.
(7) In a diffuser with a long parallel throat (a length equal to two diameters
was used) at the higher vacua, vigorous waves extended right through the
throat into the entrance of the tail piece. This type of diffuser admitted
a longer and more powerful jet than the one with a very short throat, and
it gave a higher and more nearly constant vacuum over a wider range of diffuser
setting.
(8) Of the two forms of diffuser entrance used, namely (a) short rounded
and (b) tapered, the latter gave, on the whole, better results than the
former.
(9) The performance of a steam-operated air ejector should be based on the
calculated nozzle discharge and not on the condensed steam collected. The
percentage of the true steam weight carried off by the entrained air leaving
the condenser varied very considerably on different days, but values as high
as 25%t were obtained.
(10) Low steam pressures were found to be unsuitable. The lower limit in
these experiments to give a high vacuum with a fairly good steam-air ratio
was about 120 psi by gauge. At this steam pressure the vacuum produced was
nearly 25 inches and the steam-air ratio was 10.4, the steam quantity used
being the calculated nozzle discharge when the initial superheat was
10°F.
Schuster, L.W.
The investigation of the mechanical breakdown of prime movers and boiler
plant. 337-479.
Volume 125 (July to December 1933)
Russell, Robert
Factors affecting the grip in force, shrink, and expansion fits. 493-535.
Lomonossoff, G.V.
Diesel traction. 537-613. Bibliography (95 citations). 36 diagrs.
Read before the North Western branch in Manchester on 5 October 1933,
and before the North Eastern branch in Newcastle upon Tyne on 28 March 1934.
Intriguingly this Russian-authored paper began with a brief historical sketch
of locomotive development in England. .
Locomotives with a reciprocating non-condensing steam engine have three serious disadvantages:
- Unsteadiness of torque at the driving wheels, which decreases adhesion.
-
The presence of harmful horizontal and vertical forces which produce recoiling and “hammer blow.” In the latter respect a considerable inclination of the cylinders is especially harmful.
-
Excessive fuel consumption. The overall efficiency of the Planet was less than 2%, and for the very latest steam locomotives of the reciprocating type did not exceed 11%. On the other hand, even a second-rate motor car has an efficiency of more than 20%. The two-stroke double-acting diesel engines of the German battleship Deutschland showed an efficiency of about 40%
On suburban lines electric traction has had a more definite success, nevertheless only 1.6 per cent of the worlds railway system has so far been electrified. The reasons being:
-
Losses between power plants and trains are very considerable. Electric locomotives do not consume more than 14% of the energy in the fuel burnt at the central power plants. On the other hand, the efficiency of the engines in omnibuses and lorries is over 20%.
-
Electrification approximately trebles the capital irretrievably sunk in a given transport scheme. According to the most recent data the cost of electric locomotives is only 18% of the total cost of electrification, the cost of the wiring and substations being 40%, and that of central power plants 42%
-
No possibility of moving electric power stations in accordance with fluctuation of traffic. Self-propelling locomotives are, however, transportable. Therefore, when there is a sudden and temporary increase in the traffic of any given district, supplementary motive power can be quickly sent to that district, and equally quickly removed again when it is no longer required.
Fuel:.Precise experiments made in Germany, Italy, and the Soviet Union,
both on "testing blocks" (test rigs) and on the track, have established that
the average efficiency of diesel locomotives is over three times as high
as that of the best reciprocating steam locomotives. On the other hand, the
same experiments show that the efficiency of any diesel locomotive depends
not only on that of the Diesel engine itself, but also on the transmission
and method of control.
In the U.S.A., 600 h.p. Diesel-electric shunting locomotives showed over
a period of two years a maintenance cost of £93 per thousand hours,
whereas this cost for corresponding steam locomotives 22 was £556. The
former figure is, however, doubtful because for certain 300 h.p. Diesel
locomotives the cost of maintenance 22 reaches £194.
Porter, S.R.M.
The mechanics of a locomotive on curved track. 457-61.
LMS Research Department.
Outlined some methods of calculating the flange forces acting at the wheels
of a locomotive or of any other rail vehicle running on curved track. For
this purpose, a locomotive is considered as an assemblage of trucks variously
linked together, a truck being defined as "any number of wheel pairs held
parallel to each other in a frame". Thus a 2-6-4 tank engine consists of
three trucks, the leading pony truck constituting the first, the coupled
wheelbase the second, and the trailing bogie the third. When a truck runs
on curved track, continuous slight slipping takes place at some or all of
the wheels, whether the latter are coupled together or not. It is possible,
however, to imagine a point, within or adjacent to the truck wheelbase, such
that if a wheel were placed there, of the same diameter and coupled to the
other wheels of the truck, it would undergo pure rolling without slip, either
longitudinally or laterally. This point is termed the centre of friction
of the truck. Cited
Uebelacker..
Concluded with three actual examples:
0-6-0 engine, weight 51 tons, passing slowly round a 40-chain curve without
superelevation ; flange force, 7.1 tons at leading coupled wheel.
2-6-4 tank engine, weight 86½ tons, travelling at 60 mile/h round a
40-chain curve superelevated 3 inches ; flange forces, 1.0 ton at pony truck
wheel, 4.3 tons at leading coupled wheel, and 4.6 tons at leading bogie wheel.
4-6-0 express engine, weight 85 tons, travelling at 70 mile/h round a 308-chain
curve superelevated 31/8 inches; flange forces, 4.6 tons at leading bogie
wheel, and 13.2 tons at leading coupled wheel. The latter figure is sufficient
to cause derailment, and in fact the conditions corresponded with a recent
accident (Weaver Junction, London Midland and Scottish Railway, 1930), where
the leading coupled wheels of an express locomotive became derailed on a
curve at high spced.
Coker, E.G. and Levi, R.
Force fits and shrinkage fits in crank webs and locomotive driving wheels.
249-275
This experimental investigation relates to a general method of measuring
stress distribution when force fits and shrinkage fits of the plane stress
type are employed in engineering practice. Important cases occur in the webs
of built-up crankshafts for locomotives and diesel engines. When the latter
are of high power and short stroke, so that crankshaft and crankpins are
large and relatively close together, the initial constructional stresses
are shown to attain high values.
More complicated cases, from an experimental point o! view, occur in the
driving wheels of locomotives with a tyre shrunk over a wheel centre having
a crank and balance weight integral therewith, while the main axle and crankpin
are forced or shrunk in. Such a case is examined with reference to a driving
wheel of the London Midland and Scottish Railway locomotive Royal Scot,
and the stress distributions measured in various parts of a model of it are
described in detail.
Haslegrave. H.L.
Relation between theory, experiment, and practice in journal bearing design.
435-75
Volume 130 (April to October 1935)
Sinclair, Harold
Recent developments in hydraulic couplings. 75-157. Disc.: 158-90.
The first hydraulic coupling to be applied to a diesel locomotive
was on a 300 h.p. locomotive, (illustrated Fig 39) constructed by Hudswell
Clarke and Company, Ltd., early in 1930 for the Junin Railway in Chile.
Discussion: T. Horbuckle (LMS, 166-7); J.F. Alcock (Hunslet, 167-9) spoke
about the locomotives supplied to the LMS;
Haworth, H.F. and A. Lysholm
Progress in design and application of the Lysholm-Smith torque converter,
with special reference to the development in England. 193-230. 9 illus.,
26 diagrs.
Hahn, Wilhelm
Voith turbo transmission. 231-47. Discussion (with two above Papers):
248-70.
T. Hornbuckle (261-2) noted the co-operation
with Haworth in the design of railcars for the LMS.
Coker, E.G. and Salvadori, M.
Stress waves in the tyres of locomotives. 493-512.
When a locomotive wheel rolls on the track, the tyre is squeezed between
the wheel centre and the rail. The former acts as a roller of variable
springiness at each point of its periphery owing to its necessarily intricate
shape, while the rail also offers a springy resistance which changes at every
point between a pair of chairs. The result of the mutual pressures exerted
by the wheel centre above and the rail below is to produce a stress wave
of variable intensity in the tyre as it advances along the rail, with a peak
value immediately over the contact area when no tractive effort is being
exerted. A photo-elastic investigation of one case of a stress wave travelling
in a tyre is described in the paper as an illustration of a number of others
of practical interest.
Volume 133 (1936)
Gresley, H.N.
[Presidential address]. 251-65. 3 tables.
The presidential address of Sir H. Nigel Gresley, C.B.E., D.Sc., delivered
on Friday, 23 October, from which the following extracts have been made,
[taken frrom Locomitive Mag.,
1936, 42, 346-] took for Its main subject, as may have been expected,
the steam railway locomotive, especially in view of the progress made during
the last forty years. In 1898 S.W. Johnson, locomotive superintendent of
the Midland Railway, and President of the Institution for that year, gave
a comprehensive address on the details of the mechanical equipment of British
railways, including locomotives, carriages, wagons, brakes, signals and permanent
way, and also gave an epitome of the passenger, goods and mineral traffic,
and of the financial position-in fact, a valuable summary of the conditions
then existing on our railways. That address was amplified by tables, diagrams,
etc., showing the progress durmg the preceding thirty or forty years. In
1907 T. Hurry Riches, locomotive superintendent of the Taff Vale Railway,
again reviewed the position in a paper read before the Institution, giving
a detailed description of the most recent types of locomotives then in service
of the many British railway companies.
Reverting to railways forty years ago, in Johnson's time, Sir Nigel pointed
out there were no British locomotives which weighed with their tenders 100
tons, no engines with a higher steam pressure than 175 lb. per sq. inch,
no grates with an area of more than 27 sq. ft., and no express engines with
a higher tractive effort than 19,400 lb. In fact, most of them were much
smaller in each of these respects. To-day we have engines weighing 165 tons,
steam pressures of 250 lb. per sq. inch, grate areas up to 50 sq. ft., and
tractive forces of over 40,000 lb. The power of British locomotives has increased
by 100 per cent. since Mr. Johnson's year of presidency. In those days the
weight of the heaviest Scotch expresses from Euston and King's Cross averaged
260 tons, WIth a maximum of 300 tons. To-day it is an ordinary occurrence
for trains to exceed 500 tons in weight and sometimes they attain 600 tons.
The speeds have also been steadily increasing during the last few years.
Table 1 gives the comparative main dimensions of locomotives described by
Johnson and those in service to-day.
In 1898 Mr. Johnson deplored the limitations of the 4 ft. 8½ in. gauge,
and enlarged on the difficulty which was even at that time encountered in
crowding the machinery into the confined space between the frames. The
limitations of the track gauge of 4 ft. 8½in. have not, however, imposed
on British engineers difficulties comparable with those set by the loading
gauge, that is width and height. Locomotives on American and Continental
railways have the same track gauge, but can be built so much higher and wider
that engines of more than double the weight and power of the most modern
British engines are common abroad.
In 1932 a new stage in the development of railway operation was initiated
by the introduction of extra high-speed railcar services. Railways on the
Continent, particularly in Germany, and in the United States of America,
were being badly hit by competition from road and air services. The Diesel
engine had reached a high state of development and railway engineers in
conjunction with the manufacturers produced Diesel-electric railcars capable
of maintaining much higher aver- age speeds than those of the steam train.
The fast railcar afforded many obvious advantages over the road competitor.
It could run at higher average speeds over the well-laid tracks, effectively
controlled by an efficient system of signalling, and consequently with much
greater safety. It also afforded many advantages over air transport, because
of its safety and reli- ability and independence of weather conditions.
Incidentally the costs of transportation were cheaper. Furthermore, what
it lost in speed as compared with air services it gained in being able to
pick up and set down its passengers at railway stations situated in the heart
of the great cities instead of at an aerodrome located some miles away.
After prolonged trials in Germany the Flying Hamburger was put into
regular service in May 1933; its average speed is 77.4 m.p.h. It consists
of two coaches only, articulated, and carried on three bogies. The motive
power is two Maybach 410 H.P: Diesel engines mounted on the outer bogies
and directly coupled to electric generators. Traction motors of the ordinary
type are mounted on the axles of the carrying wheels. In 1933 similar extra
high-speed railcar services were started in France. The cars are fitted with
four 200 h.p. Bugatti petrol engines, making a total of 800 h.p. per car.
Speeds comparable with those on the German railways are run, and it is claimed
that the fastest speed of any rail vehicle has been attained by Bugatti railcars.
In the United States, the Union Pacific Railroad put into service the first
super-speed internal combustion engine unit in 1933. This was a three-coach
train fitted with a 600 h.p. Winton engine. By the use of aluminium alloy
for constructional purposes the weight of the complete train was brought
down to 120 tons, advantage having been taken of the experience obtained
in the construction of aeroplane bodies. The carriages, however, are 8 inches
less in width and 3 ft. less in height than the standard coaching stock on
American railways. The height of the centre of gravity of the stock is lowered
by about 25 inches and the wind resistance is, of course, also considerably
reduced, Consequent upon the success of this innovation further trains of
increased power and seating capacity were built for the Union Pacific. Other
railways followed, probably one of the most successful trains being the
Zephyr of the Chicago, Burlington and Quincy Railroad. The coaches
forming this train are also very light, stainless steel framing being used
throughout. The success and popularity which has followed the introduction
of the various extra high-speed trains, both on the Continent and in America,
is such that their running has now become firmly -established and is bound
to be extended. Both France and Germany are particularly active in this
direction.
The demand for trains of greater carrying capacity has led to the development
of steam locomotives capable of maintaining similar speeds and of hauling
much heavier trains; such locomotives 'have been built in Germany and America.
In Germany new streamlined high-speed locomotives were built, and in May
1936 a steam-operated service was started between Berlin and Hamburg making
an average speed of over 74 m.p.h., which is now probably the fastest
steam-operated train in the world.
In America notable examples of stream-lined high-speed steam locomotives
are provided by the 4-4-2 type for the Chicago, Milwaukee Railway, known
with its stream-lined train as the Hiawatha, and the more recent engine of
the 4-6-2 type for the New York Central, known, with its luxurious 440-ton
train, as the Mercury. This challenge by the steam locomotive has been taken
up by Diesel engine makers of America, and the Winton Company have produced
a double locomotive for the Atcheson, Topeka and Santa Fe Railway, having
two 900 h.p. engines in each unit, making a total of 3,600 h.p. The engine
weighs 240-tons, but the first cost must be very greatly in excess of that
for a steam locomotive of similar power.
The fast services provided by these various trains have re-established the
railways in public estimation and have not only recovered large numbers of
passengers from alternative forms of travel but have also created new and
additional traffic.
In England conditions are not quite the same. Competition with railways by
air services is never likely to be as intensive as abroad. The distances
between the great industrial centres are shorter, the aerodromes are generally
some long distance from the cities, and owing to fogs and the general visibility
conditions of our climate, the reliability of maintaining daily air services
can never com- pare with those of other great countries. The first example
of the streamlined extra high-speed train on British railways is the Silver
Jubilee train running between London and Newcastle, a distance of 268
miles, in four hours, with one intermediate stop at Darlington, the average
speed between Darlington and London, a distance of 232 miles, being 71 m.p.h.
At first glance this does not appear to be such a difficult task as that
of the 74 m.p.h. run of t he steam-operated Hamburg-Berlin train of the German
State Railways. But when consideration is given to the many long and steep
gradients and certain compulsory speed reductions, the performance is really
more meritorious. On the Berlin-Hamburg line, after leaving the environs
of the termini, the road is practically flat and free from speed restrictions
and curves, and the whole line is exceptionally suitable for the maintenance
of continuous high speeds.
It may be of interest to hear what led to the construction of the Silver
Jubilee train which started on 30 September 1935, and also to hear the
results of the first year's working. Sir Nigel visited Germany in 1934 and
travelled on the Flying Hamburger from Berlin to Hamburg and back;
he was so much impressed with the smooth running of the train at a speed
of 100 m.p.h., which was maintained for long distances, that he thought it
advisable to explore the possibilities of extra high-speed travel by having
such a train for experimental purposes on the London & North Eastern
Railway. He approached the makers of that train and furnished them with full
particu- lars as to gradients, curves, and speed restrictions on the line
between King's Cross and Newcastle. With the thoroughness characteristic
of the German engineers they made exhaustive investiga- tion and prepared
a complete schedule showing the shortest possible running times under favour-
able conditions and then added 10 per cent. to meet varying weather conditions
and to have sufficient time in reserve to make up for such decelerations
or delays as might normally be expected.
The train weighing 115 tons was to consist of three articulated coaches and
generally similar to the German train. The limes for the complete journey
were given as 4 hours 17 minutes in the up direction and 4 hours 15¼
minutes in the down. The train provided seating capacity for 140 passengers.
The accommodation was much more cramped than that provided in this country
for ordinary third class passengers, and it did not appear likely to prove
attractive for a journey occupying four hours. The general manager suggested
that with an ordinary " Pacific" engine faster overall speeds could be maintained
with a train of much greater weight, capacity, etc. A trial with a train
of seven bogie coaches demonstrated that the run could be accomplished with
reliability in less than four hours under normal conditions.
To secure a sufficient margin of power it was considered essential to streamline
the engine and train as efficiently as possible and at the same lime to make
alterations to the design of the cyl- inders and boiler which would conduce
to freer running and to secure an ample reserve of power for fast uphill
running.
The train was completed early in September of last year and after a few runs
on which excep- tionally high speeds were reached went into ser- vice on
30 September. It completed twelve months' service of five days weekly on
30 Sept. last, and had run 133,464 miles during that period and carried 68,000
passengers. There has only once been an engine failure when the train had
to be stopped and another engine substituted. The financial results are very
encouraging. The seven coaches forming the train and the streamlined locomotive
cost £34,500. The gross receipts from the running of this train amount
to 13s. l t d. per mile. Operating expenses, which include locomotive running,
carriage expenses, wages of traffic staff, carriage cleaning, advertising,
etc., amount to 2s. 6d. per mile. These figures exclude profits on the dining-car
service and interest on capital cost of the train and locomotive. A supplement
is charged to all passengers, whether paying fares or holding contract tickets
or free passes; it is 5s. first class, and 3s. for each third class passenger,
and the annual receipts from this item alone has amounted to, £12,000,
or roughly 33 per cent. on the first cost of the train.
It will be appreciated that the result of the experiment has been very
encouraging. It may seem almost paradoxical that in order to secure the high
average speed of the train extra high- speed is not necessary. The fact remains
that in ordinary running the train does not exceed a speed of 90 m.p.h. Other
express trains with much lower average speeds often attain maximum speeds
as great as those run by the Silver Jubilee. Where the time is gained
is by running uphill at similar speeds to those normally run downhill. To
illustrate this point in the most elementary manner it is only necessary
to state that to run a distance of 15 miles at 30 m.p.h. occupies 30 minutes,
a similar distance at 60 m.p.h. takes 15· minutes, and at 90 miles p.h.
takes 10 minutes. To increase the downhill running speed from 60 to 90 m.p.h.
therefore only saves 5 minutes, but to increase uphill running speeds from
30 to 60, m.p.h. saves 15 minutes. This obvious fact was mentioned because
it is not yet fully appreciated how much overall train times are reduced
by running fast uphill.
Dynamometer car records of the running of this train of 220 tons and the
dynamometer car of 32 tons behind the tender show that only about 400 draw-bar
horse-power is required to maintain a speed of 80 m.p.h. on the level, but
when on a rising gradient of 1 in 200, 1,000 to 1,200 drawbar horse-power
is necessary. The locomotive, however, is having to exert an additional 300
h.p. to lift itself up the gradient of 1 in 200, and thereore m effect, correctmg
tor gravity, is havmg to exert what is equivalent to 1,400 h.p. to pull the
train up this gradient at 80 m.p.h. To this must be added 350 h.p. to overcome
the resistance of the locomotive, making a total of 1,750 h.p.
A very important factor in connection with the working of trains at high
average speeds is the air resistance and the advantage of streamlining. The
trains referred to in Germany, France, and America, and the Silver
Jubilee are all streamlined. Experiments have been made at the National
Physical Laboratory with scale models of the streamlined Pacific engine of
the Silver Jubilee type and an ordinary type Pacific engine to determine
the comparative head-on wind resistance and to calculate the horse-power
required at various speeds to overcome the air- resistance. The results are
shown in Table 2. To maintain a schedule of 71 m.p.h. between London and
Darlington with this train entails an average running speed up hill and down
dale of 80 to 90 m.p.h., after making allowance for start- ing, stopping,
and the various speed restrictions. It will be seen from Table 2 that
streamlining results in a saving of over 100 h.p. continuously at these speeds
on a still day. There is, however, generally a wind of greater or lesser
intensity, and consequently, as the power required to overcome air resistance
varies approximately as the cube of the speed, such reduction as may result
when running with a favourable wind is not to be compared with the extra
power required on the opposite working against a contrary wind. Hence it
follows that in the same case of this train the probable average saving of
power due to streamlining is considerably in excess of 100 h. p.
Dynamometer car experiments with this train show that although, as stated,
only about 400 drawbar horse-power is required on the level, the average
drawbar horse-power on the run from London to Newcastle is 620. To this must
be added the horse-power required to overcome the internal resistance and
the head-on air resistance of the locomotive which with an ordinary Pacific
engine at 80 m.p.h. is about 450 h.p., but with a streamlined engine is reduced
to 330 h.p. The saving in power output due to streamlining the locomotive
is therefore in the region of 10 per cent.
The coal consumption of the engines working this train average 39 lb. per
mile; if the consumption of coal is proportionate to the power, the savmg
due to streamlining is about 4 lb. per mile, an average of about 200 tons
per annum. When running downhill during experimental runs at very high speeds,
up to 110 m.p.h., the effect of wind resistance was much more marked. The
drawbar horse-power required amounted to 1,200. The head-on air resistance
and frictional resistance of an ordinary Pacific engine is equivalent to
800 h.p., making a total of 2,000 n.p. Thhe effect of streamlining at tnat
speed IS to reduce the head-on resistance by 250 h.p., the net saving therefore
being equal to 12½ per cent.
An experimental run with the Silver Jubilee train was made recently
between Newcastle and Edinburgh and back. On this occasion the weight of
the train behind the.tender, including the dynamometer car, was 252 tons,
and in working the train up the long grsadient of Cockburnspath of 1 in 96
the minimum speed was 68 m.p.h. The actual drawbar horse-power was 1,460;
a further 660 h.p. was required to overcome the effect of gravity on the
166-ton engine, in addition to which some 400 to 500 h.p. was required to
overcome the air and frictional resistance of the engine at that speed. Therefore
the actual power output of the locomotive was between 2,500 and 2,600 h.
p., a figure which has never previously been attained by a locomotive in
Great Britain. If the demand for longer and heavier trains becomes insistent,
there is no insuperable difficulty in providing engines of greater power
capable of working longer trains at these speeds. There is, however, one
great obstacle. Owing to the density of traffic in England it is a difficult
matter for the operating departments to arrange train workings so that a
clear path can be secured for such extra high-speed services. The whole object
of the introduction of trains of these overall speeds would be defeated if
there were a liability of the trains being held up and delayed by other traffic.
The more the general traffic is accelerated the easier becomes the task of
finding a path for such trains.
One of the main difficulties is in connecton with the slow running of goods
trains, particularly over sections of the railway where only two running
lines are provided. The mineral trains scheduled at less than 20 m.p.h. are
the worst offenders. During recent years the running of fast brake-fitted
goods trains has been considerably in- creased, with a view to meeting the
competition of the road, but only a very small percentage of the railway
companies' wagons are fitted with continuous brakes. It would not be safe
to run wagons connected with three-link couplings, and no form of continuous
brakes, at high speeds, because of the great distance such trains would run
before they could be brought to a stand by the application of brakes on the
engine and guard's van only.
In America all railway goods vehicles were fitted with the Westinghouse brake
many years ago and during more recent years the whole of the goods and mineral
wagons running on the principal Continental railways have also been fitted
with continuous brakes. It must be admitted that in this matter the British
railways have failed to make progress when compared with the railways of
other countries. The failure is not due to lack of enterprise, but to the
inherent difficulties and cost of fitting the whole of the wagons running
in this country with continuous brakes. There are approximately 1½ million
wagons running on British railways, of which about 700,000 are privately
owned. To fit the whole of the British wagons with continuous brakes would
probably cost in the region of £30,000,000. It is difficult to make
out a case to justify this enormous expenditure. The acceleration of goods
trains would produce many beneficial results, the transportation and delivery
of goods could be expedited, the cost of working goods trains would be lessened
because the overall transportation capacity of the locomotives and wagons
would be increased, consequently less rolling stock would be required; and
the congestion of lines would be reduced. The idea to be aimed at is to run
all trains at the same speeds. Credit must be given to the late Mr. G. J.
Churchward of the Great Western Railway who designed the first locomotives
of the 2-6-0 type in 1911 for express goods services. Table 3 shows the progress
which has been made in more recent years in the design of engines built primarily
for working mixed traffic or express goods trains.
Thomson, A.S.T.
Investigations in film lubrication. 413-72.
...fluid friction conditions. The second short section deals with
experiments on a Deeley friction machine and shows the effect on the boundary
friction of the...
Johansen, F.C.
The air resistance of passenger trains. 91-160. Disc.: 160-208.
Engineering Research Officer, London, Midland and Scottish Railway,
Derby. The folloowing abstract was published
in Locomotive Mag., 1936, 42, 371..
Experiments with model trains in a wind tunnel at the National Physical
Laboratory, Teddington, were described in a paper given on November 27 at
the Institu- tion of Mechanical Engineers by Mr. F.C. Johansen, engineering
research officer of the L.M.S. Railway, Derby. These tests should enable
engineers to determine the exact advantages to be expected from various forms
of streamlining. With ideal streamlining, the possible reduction in air
resistance is one of 75 per cent. The corresponding fuel economy, Mr. J ohansen
mentioned, is in the neighbourhood of £1 an hour at 100 m.p.h.
Alternatively, the maximum attainable speed could be increased by 12-25 per
cent. according to the degree of streamlining adopted. Air resistance could
be reduced by 50 per cent. without drastic departure from conventional design.
The ideal streamlined train was a continuous cylindrical body with well-rounded
ends, having a polished surface free from external fittings and irregularities.
The worst direction of natural winds is not one directly ahead, but from
30 to 60 degrees on either side of the head direction according to the type
of train. Streamlining is, on the whole, more effective in dealing with the
influence of side winds than against head winds or in still air. Whereas
the Silver Jubilee train of the L.N.E.R. is streamlined, the record-breaking
train of the L.M.S.R. on the London and Glasgow run was one of conventional
appearance. Another point mentioned by Johansen was the "surprisingly large
proportion" of the air resistance of a railway coach, especially in cross
winds, contributed by the bogies and under carriage structure. It is consequently
advantageous to use articulated stock, to include the under carriages in
streamlining measures, and to extend the fairings to the ends of the coaches,
leaving no exposed gaps between them. The air resistance is less if the under
carriage is totally enclosed than if only side valances are fitted. A
£aired shape at the tail end of a train reduces air resistance to an
extent which is more marked the more complete the streamlining, but greater
advantage can be gained by fairing the front than by fairing the rear end.
The general object of the research was to obtain data from which to estimate
the economic value of reducing the air resistance of passenger trains and
to indicate the directions in which feasible departures from conventional
forms of design might most profitably be pursued. Manifestly the costs of
modifying design and construction of operating and maintaining high-speed
trains must be considered along with the potential savings in power, and
increased earning capacity, before the overall effect on net revenue can
be appraised, and before the degree of air resistance reduction can be decided.
At the outset of the project it appeared probable-and was subsequently confirmed
experimentally that the air resistance of all the coaches in a train of normal
length would exceed that of the locomotive; perhaps offering, in consequence,
wider opportunity for monetary saving in return for a given expenditure on
modification of design. Throughout the experiments, accord- ingly, the effects
of changes of external shape were studied mainly in relation to coaches.
The influence of certain modifications on the air resist- ance of the locomotive
was, of course, included, but the comprehensive aerodynamic study of the
steam locomotive was postponed for subsequent investigation. The wind tunnel
has been found of undisputed utility in aeronautical research, and offers
means of investigating the air resistance of trains which has preponderating
advantages over full-scale experiments. For while the results of wind tunnel
experiments on model trains may be subject to some uncertainty from differences
in scale and mode of operation between the full-size train and its model,
they are at least consistent among themselves, being obtained under controlled
conditions by precise measurements of air resistance alone. The effects of
modifications of shape, moreover, are likely to be less open to error from
scale and similar differences than the absolute values of air resistance,
and they can be deter- mined by a wind tunnel far more quickly and cheaply
than is possible on the full scale. In the present state of aerodynamical
knowledge, a wind tunnel experiment is the only avail- able means of
predetermining the air resistance of a new form of train before it is actually
construc- ted. In full-scale trials on the other hand, apart from the
impossibility of controlling the natural wind, air resistance cannot practically
be segrega- ted from other components of resistance nor be controlled throughout
a succession of tests. The investigation was carried out with models in a
7 ft. wind tunnel at the National Physical Laboratory, on behalf of the L.M.
& S. and L. & N.E. Railways. These two companies, together with the
Southern Railway to whom the results were communicated, defrayed the cost
of the work. One model represented a "Royal Scot" engine and tender and six
60 ft. L.M.S. corridor coaches, complete in almost every detail of external
shape and measured 133.6 inches over buffers, the cor- responding full-scale
train being 445 ft. 3 in. Another model, which may be termed the Ideal train,
was made of polished wood to represent the fully streamlined equivalent of
the standard train. It consisted of seven vehicles of identical cross section
which could be connected by dowel pins at the ends to form a continuous parallel
body, faired at each end and having an overall length of 133.2 inches.
O.V.S. Bulleid (172) "was quite unable to understand
how a theory as to what would happen with a full-size train under working
conditions could be built up from results from small models, obtained under
such different conditions. He thought Commander Cave- Browne-Cave’s
suggestion, that a relationship should be established between the results
for models and for actual trains, was an essential requirement. There was
a tendency to encourage engineers to think that streamlining would effect
savings in train working which, in practical experience, would not appear
possible. He felt, moreover, in view of the London Midland and Scottish Railway
Company’s magnificent run from Euston to Glasgow in 6 hours with an
ordinary train worked by a Pacific engine not streamlined, that the air
resistances could not be anything like as high as the figures suggested in
the paper. The subject of streamlining was, he thought, still very much in
the initial stages and required considerably more investigation."
Still, E.M.
Some factors affecting the design of heat transfer apparatus. 363-411. Disc.:
411-35.
Lawford H. Fry (414-15) regretted that though the paper gave evidence
of a great deal of work and collected a large amount of information useful
in connexion with heat transfer, the information was presented in such an
unsystematic fashion that it was very difficult to disentangle the thread
of the argument and to apply the formulae to specific cases other than those
dealt with by the author. He had spent several hours trying to apply the
processes described in the paper to the problem of computing the heat transfer
in the flue of a locomotive boiler. The results obtained were not consistent
with observed values, and he was not sure whether this was due to difficulty
in understanding and applying the methods recommended or whether the methods
could not be extended to cover the case of the flue. From an analysis of
locomotive boiler tests it was found that the following figures were typical.
A flue of 2 inches inside and 2¼ inches outside diameter, 250 inches
long, surrounded by water at 388° F., carried 288 lb. of gases of combustion
per hour. The gases entered at 2,080°F, containing 549 B.Th.U. per lb.
and came out at 614°F., containing 149 B.Th.U. per Ib. The heat given
up by the gas was 400 B.Th.U. per Ib., representing a total of 115,200 B.Th.U.
per hour for the flue. As the flue had 10.9 sq. ft. of inside hcating surface
the rate of heat transfer was 10,580 B.Th.U. per sq. ft. of surface per
hour.
Volume 135 (January to May 1937)
Kitson Clark, E.
Engineering through the nations. 533-7 + 4 plates. 8 illus.
Ancient engineering
Proceedings, General Discussion on Lubrication and Lubricants, 13th-15th
October. 119 et seq
Other reports covered intrnal combustion engines by Ricardo, turbines
(Auld and Evans) and properties and testing (Gough).
Stanier, W.A.
General discussion on lubrication. Group II. Engine lubrication (reciprocating
steam engines). 139-43.
French and German State Railways consider that various grades of
superheater cylinder oil are desirable according to the degree of superheat
obtaining in the cylinder, whereas the Canadian National and English railways
employed only one grade. Of the opinions expressed about superheater cylinder
oils, the majority favoured compounded oils, since it was considered that
at the temperature of superheated steam the oil becomes much less viscous
and the fatty oil is partly decomposed, the decomposition products helping
in the formation of stable and resistant boundary films. Of special interest
was the use of emulsified oil, prepared by the German State Railways from
superheated steam cylinder oil and lime water, for use in locomotives working
under medium loads.
German State Railways used winter and summer grades oils for journals, motion,
etc, as did some English railways, whilst Canadian National and many English
railways prefered the same grade throughout the year; one English railways
considered that the inconvenience of changing the grade of oil twice a year
outweighed any possible advantage and in its experience no advantage was
obtained when the thicker summer oil was used. It was the practice of the
English railways to use a mineral oil containing a percentage of refined
raw rape oil, the percentage depending on the different classes of work and
the experience of the companies concerned, whereas the German State and Canadian
National Railways used mineral oil only. German State Railways used a higher
viscosity oil for lubricating the journals and gear of streamline locomotives,
this also being the practice of some English railways.
German State Railways used wick trimmings to supply oil to the valve gear,
and to connecting and coupling rod bushes: English railways used worsted
trimmings for the valve gear and either worsted trimmings, needle trimmings,
or felt pads for the rods.
Fairless, Thompson
The application of the locomotive to traffic working. 333-52. 8 diagrs.
Methods for analysing of steam locomotive power during traffic working
on railways lacking special testing facilities. The determination of cylinder
and boiler output, the treatment of locomotive and train resistances, and
the application of these factors to train loading, speed, and running time.
The calculation of fuel and water consumptions on a horse-power-hour basis
is given, also the method of application to train working. Then describes
the procedure for the practical application of locomotive power to trafiic
working, and the measurement of train capacity in terms of ton-kilometres
per train hour. The engine evaluated was one of a batch of 2-8-0 goods engines
on the Central Uruguay Railway.
Parsonage, W.R.
Short biography of George Stephenson. 373-91.
Selected for publication in connexion with the centenary in 1938 of
Holy Trinity Church, Chesterfield, in which George Stephenson is buried,
and the proposed building of a George Stephenson Chancel in the church.
Pp. 386-91 are extracted from the J. Scott
Russell presentation made in 1848. Records the meeting of Stephenson
with the great American writer, Emerson, in Chesterfield early in 1848 at
Whittington House, the home of Frederick Swanwick. Emerson remarked later
that “it was worth while crossing the Atlantic were it only to have
seen Stephenson-he had such force of character and vigour of intellect.”
“He seems to have the life of many men in him.” But he was a stricken
man and the end came only a few months later. Includes photographs of
Stephenson's tomb and memorial tablet, his birthplace and a portrait of
him.
Ambady, G.K.
Diesel traction on railways. 135-43. Disc.: 143-64. 6 diagrams
An analysis of various locomotive operating costs and the degree to
which each is influenced by the type of tractive unit selected, namely, steam
or diesel. The effect of possible higher availability or serviceability factors
with diesel locomotives was not likely to be as high as may be supposed.
Specification and design details of the various components of a diesel tractive
unit are discussed and in the particular case of a locomotive designed to
haul a load of 600 trailing tons at a maximum speed of 60 mile/h., the main
design data and performance curves are worked out with and without supercharging.
The general conclusion was that diesel operating costs compared with steam
became increasingly favourable as the power output required from the tractive
unit decreases, when the advantage of a self-propelled vehicle, such as three
unit railcar, over a train hauled by a locomotive became more pronounced.
The adoption of large diesel locomotives was likely to be restricted to fast
heavy goods traffic, and long-distance through passenger services. In India
opportunities for their application would be particularly limited. The climatic
and operating conditions will tend to accentuate the disadvantage of great
weight and high first cost, and the reduction in fuel and lubricating oil
expenditure as compared with steam traction is not likely to be such as to
compensate for this fully, at the then prices of coal and fuel oil.
Locomotive operating expenses comprise mainly : (a) capital charges, i.e.
interest on capital and amortization ; (b) fuel ; (c) repairs and aintenance
; (d) crews’ wages ; (e) lubrication ; (fi)water, and (g) auxiliary
services, namely, engine shed, watering and coaling faciiities, turntables,
etc. The economic application of Diesel traction will depend on the extent
to which its characteristics can be utilized, under the particular operating
conditions obtaining, to reduce the various items of locomotive expense.
Discussion: Oliver Field Allen
(ALCO 144-5) wrote to state that the capital
cost in the USA for diesel traction had fallen to less than twice that for
steam. L.F.R. Fell (151-4) cited his own paper presented
in 1933 noting that as indicated by the author's general conclusion,
the operating costs of Diesel locomotives, as compared with steam, became
favourable only when the weight of the unit to be propelled was comparatively
low. G.V. Lomonossoff (156-9) claimed that in the USSR steam locomotive mileages
had reached 9000 miles per month and that this had increased the competition
against employing diesel traction.
Mowat, Magnus
British engineering societies and their aims. 333-44.
The activities and objects of the Institution of Civil Engineers and
the Institution of Mechanical Engineers are described, with notes on other
national and local associations in Great Britain. Forms an excellent survey
of the general history and state of British institutions and learned societies
in the late 1930s. Paper presented at the Semicentennial Meeting of the
Engineering Institute of Canada, in Montreal, June 1937 ; reprinted by
arrangement with the Institute.
Volume 139
de Soyres, Bernard . The birth and growth of engineering in the West
Country. 539-45.
Includes Richard Trevithick and engines and pumps built in Cornwall
by Fox, Williams and Company, of Perran Foundry, and by Harvey and Company,
of Hayle Foundry. Brunel is mentioned, but mainly for his marine
activities.
Volume 142 (July-December 1939)
Stanier, W.A.
Lightweight passenger rolling stock. 13-32 + 16 plates.
This paper makes no attempt to compare British and American practice
because of the wide difference in operating conditions prevailing in the
two countries. Developments which have taken place in the last seven years
on the LMS are described, showing the improvements in the conventional British
passenger coach. This originally consisted of a separate riveted steel underframe
and timber-framed body, but to reduce weight without sacrifice of strength,
welding and high-tensile steel have been employed and timber gradually
eliminated. This has resulted in an increasing identification of the underframe
and body which has produced an all-steel coach giving a weight of about 500
lb. per passenger seat. Means adopted include the body side and underframe
combined into the form of a Vierendeel truss, the design of which is briefly
described, together with the method of calculating the stresses in the different
members. On the constructional side, the layout of the shops and the special
presses and tools are dealt with. A method of unit assembly has been adopted
and both spot and arc welding are largely used. Details are given of the
erection into a complete coach, and of the overload tests made on the finished
structure. Particulars are given of the savings in weight attained, and the
paper concludes with suggestions as to the direction in which further progress
may be sought in the future.
Introduction. In this paper no attempt is made to compare British with American
practice. The requirements are so different. Variations in climatic conditions
alone necessitate an entirely different practice and the restrictions imposed
by the smaller loading gauge in Great Britain call for an entirely different
treatment.
In Great Britain, largely owing to high platforms at the stations, the maximum
width over the cylinders of a locomotive is 9 feet and the maximum height
13 ft. 6 in., but generally only 13 ft. 1 in. The maximum weight on an axle
is 22 tons 10 cwt. (50,000 lb.), and this limits the tractive effort of a
six-coupled engine to about 40,000 lb. The maximum weight of a train is therefore
not more than 600 tons,-/- so that to enable a reasonable number of people
to be carried with the comfort necessary for comparatively short runs, it
has been the practice to build coaches 60 feet in length and weighing 30
tons.
In the past this was achieved by having a steel underframe and a body frame
of wood with wooden panelling and roof, but for many years now the general
practice has been to have a heavy steel underframe on which is mounted a
wooden-frame coach body sheathed in steel and with a steel roof. An attempt
will be made to show the trend of British design and the various stages through
which it has passed in the effort still to build 60-foot coaches not heavier
than 30 tons each.
Ripley, C.T.
High-speed lightweight trains. 97-111.
Author was Chairman ASME Railroad Division. The purpose of this paper
is to outline the changes which have occurred during the last five years
in high-speed passenger train cars and in motive power for hauling them and
the economic factors which have brought about these changes. The new designs
for passenger cars and the materials used in their construction are discussed.
A detailed comparison of steam locomotive and Diesel-electric locomotive
characteristics as they affect the operation of these new high-speed trains
is presented, Test data are included to indicate the importance of comparative
stress in track produced by the two types of power. Reference is made to
the steady improvement which has been made in steam locomotive design, but
it is shown that there is a need for some rather extensive experimentation
to make this type of power more suitable for this particular class of service.
In conclusion, the author presents his views on the general results which
have been secured from the operation of these new trains and the probable
trend in their future development.
Newberry, C.W.
An investigation into the occurrence and causes of locomotive tyre failures.
289-303 + 4 plates.
A detailed investigation was made by the LMS Research Department into
the causes of locomotive tyre faihres from two standpoints: first to determine
the cause of any particular failure, and second to find general relationships
between effect and cause in the matter of tyre defects. Examples are given
of the examination of individual failures, and of experimental work directed
to the improvement of wheel and tyre. In a statistical review, it is shown
that fatigue is the major cause of tyre failure, and many of the factors
which might influence the development of fatigue failure have been critically
examined and their responsibility assessed. In conclusion it is noted how,
by a change in tyre boring methods to increase the effective fatigue strength
of the tyre, and by modifications in design to ensure more uniform stress
distribution in the tyre, the occurrence of fatigue failures has steadily
declined.
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