Proceedings Institution of Mechanical Engineers:
1940s
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Stanier, W.A.
The position of the locomotive in mechanical engineering. 50-61 + 4 plates.
13 illus., diagr., 3 tables. (Presidential Address).
When commencing his training in January 1892, locomotive practice
on the Great Western, under the guidance of William Dean, was very much the
same as that of other railways of the time. The locomotives were comparatively
small, with steam pressures up to 140 psi., but very quickly another phase
began; steam pressures were raised to 160 psi and a bogie became necessary
in front to provide a lengthened wheelbase on which to carry the larger boilers.
About the year 1902, Churchward brought out the first big departure from
current practice, when he built six-wheel-coupled express passenger engines
with cylinders having 30 in. stroke and fitted with valve gear having an
unusually long travel and a greater lap. These characteristics made it possible
to work the engine so that greater advantage was obtained from the expansion
of the stcam. Churchward continued to adopt these features throughout the
whole of his career as chief mechanical engineer of the Great Western. This
practice has been adopted and developed gradually on all the other English
railways and it is the development that has taken place on the LMS over the
last ten years to which he principally refered.
A review of the efficiency of the steam locomotive, based on LMS testing
plus a forecast of future development: makes reference to Goss and thr Altoona
test plant
Halcrow, W.T.
A century of tunnelling (Twenty-eighth Thomas Hawksley Lecture). 100-16.
16 figs.
Advances associated with mechanical engineering progress:
Cox, E.S. Balancing of locomotive reciprocating
parts. 148-62.
Since the British Bridge Stress Committee’s reportt of 1928,
an increase had occurred in the speed capacity of locomotives. After showing
how the recommendations of that Committee have been met in modern British
locomotive design, the effects of higher rotational speeds are discussed,
and tests with the lifting of coupled wheels off the track at maximum speeds
and with various proportions of reciprocating balance are described. Since
the necessity may arise for reducing hammer blow values still further to
meet civil engineers’ requirements, the possibility of reducing or
eliminating the amount of reciprocating balance becomes important. The effect
of this factor on the locomotive itself is discussed theoretically, expressions
being given for the amplitude of the resulting horizontal and lateral
oscillations. Available practical evidence in support of the theoretical
considerations is described, and conclusions are reached regarding the conditions
under which it is still necessary for locomotive reciprocating parts to be
balanced.
The modern locomotive was capable of speeds up to 8 rps and the resulting hammer blows with the usual percentages of reciprocating balance could attain much higher values than envisaged in the Bridge Stress Committee report in 1928.
The phenomenon of wheel bouncing at high rotational speeds was first observed in America in 1937, and tests have shown that it could occur in British practice in certain circumstances.
Thus locomotive design in the direction of reducing hammer blow still further needed reconsideration
As regards the effect on the locomotive, longitudinal and nosing oscillations depend on the weight and length of engine, weight of reciprocating parts unbalanced, and characteristics of the drawbar springs. They are independent of speed.
Theory suggested that three- and four-cylinder engines which are already in a state of balance with regard to longitudinal forces, do not require any portion of their reciprocating parts to be individually balanced to deal with the nosing couple, because of the small magnitude of the displacement. Three-cylinder engines with zero reciprocating balance were already running in Britain.
In two-cylinder engines, theory–supported by a certain amount of practical evidence–indicated that some degree of reciprocating balance was still required if undue longitudinal oscillations are to be avoided. The percentage required will vary with the engine characteristics, and a method has been suggested for arriving at the amount. Not less than 40% balance appears to be required on the heavier type of British two-cylinder engine weighing from 65 to 75 tons.
For the highest speeds, therefore, multi-cylinder engines are the most desirable, if they are of the reciprocating type. If it is thought necessary to balance a percentage of the reciprocating parts, the four-cylinder is preferable to the three-cylinder type, from the point of view of hammer blow. If this balance is eliminated, there appears to be little to choose between the two types.
The final criterion as to what percentage of balancing is necessary is the magnitude of the oscillations which can be admitted on the engine, having regard to riding comfort for engine crew and passengers, wear and tear, maintenance costs, and safety.
Practical experience so far recorded tended to support the theoretical conclusions.
Colam, Sir Harold Nugent and Watson, John Douglas
Hammer-blow in locomotives: can it not be abolished altogether? 163-6. 2
diagrs., table
Abstract only: full paper
Min. Proc. Instn Civ. Engrs.,
1941 (Paper 5243)
Colbeck, E.W., S.H. Smith, and L. Powell, B.
Caustic embrittlement. 63-73. Disc.: 150, 88-98. 20 illus., 3 diagrs.,
7 tables.
Results of experimental work on caustic embrittlement. The apparatus
chosen was based on one used in recent American work pertformed by Straub
and Bradbury (1938). In this, the solution to be tested is contained in a
hollow sealed tubular specimen, heated to any desired temperature in the
steam boiler range, and subjected to a tensile load by means of a spring.
It had not been possible to reproduce the results claimed by Straub, but
a number of examples of intergranular cracking were produced. Some of these
have been obtained when using dilute solutions containing amounts of NaOH
and silicate such as would be found in boiler waters. There is evidence that
embrittlement occurs more readily in poor-quality steel and under conditions
of non-uniform stress distribution, but it has not been possible to reproduce
results with any degree of A few experiments with an entirely different type
of specimen have been carried out; and in The paper also contains a survey
of the more important literature on caustic embrittlement Certainty. these,
intergranular failures have also been produced. published between 1935 and
1941.
Turner, T. Henry
Corrosion of boiler tubes. 74-88. Disc.: 150, 88-98. 6 diagrs., 5
tables.
A very extensive review which included locomotive boiler tubes. Turner's
response to the extensive discussion was given on pp. 97-8..
Meyer, Adolf.
The first gas turbine locomotive. 1-10.
Traces history of electrical transmission for locomotives in which
steam or Diesel engines have been the prime movers, and refers to the important
contributions made by Messrs. Brown Boveri and Company, Ltd., Baden, Switzerland
in this. Although there were over 1,000 exhaust and gas turbines in service,
the locomotive forming the principal subject of the paper was the first example
in which this form of power is applied. After dealing with the design of
the turbine in general, an imaginary trip is taken with the driver of the
gas turbine locomotive. Explains the principles of operation, and the method
by which the system of governing enables the machine to adapt itself to running
conditions. The safety devices are described in detail, and some attention
is given to the opportunity afforded by a locomotive of this type for the
adoption of power braking. Concludes with an analysis of the economic prospects
of gas turbine locomotives, which comprises some useful comparisons with
other types of motive power, including valuable information in graphical
and tabular form.
Volume 152 (January-December 1945)
Johansen, F.C.
High-speed cinematography. 224-5. + 4 plates (including 1 colour). 36
figures
George Stephenson Address: LMS Reserach Department: described the
techniique as such, rather than its applications.
Lomonossoff, G.V. and Lomonossoff, G.
Condensing locomotives. 275-88. Disc.: 289-303.8 illus., 25 diagrs., 4 tables.
Bibliog.
Covers both reciprocating and turbine type of locomotive.
Discussion: Bulleid (289) remarked
that the paper treated the subject on an academic level. The steam locomotive
to-day was in competition with other forms of traction. It had betn criticized
as being inferior to diesel-electric locomotive and electric locomotives,
chiefly because of its lack of availability. Lack of availability was
fundamentally due to the use of raw water in the boiler, which caused the
steam locomotive to be out of service for about 12% of its time; consequently
anything which could be done to reduce that loss of service, necessitated
by washing out the boiler or repairing damage due to dirt in the boiler,
would at once contribute to the greatly increased availability of "what was,
after all, the best traction machine in existence." The present paper, therefore,
by calling attention to the question of the recovery of the water, was very
valuable; for that recovery was much more important in locomotive practice
than any saving of, say, 2%, 3%, or 4% in the fuel burned. For a coal consumption
of the order of 50 lb. per mile (including lighting-up), the fuel thrown
away when the engine was taken out of service, the losses when the engine
was standing, and, above all, the fact that at one moment the locomotive
would be working at high rates of output, using the whole of the steam available,
and at another moment would be running under very low conditions of pressure
and very early cut-off, it was not to be hoped that any substantial reduction
in the fuel used would be effected by condensing. On the other hand if it
was possible to avoid filling the boiler with raw water, that would be a
means of very substantially improving the use which could be made of the
locomotive. For that reason, Mr. Knudsen's experiments in the Argentine were
very interesting, though there again the commercial factor was being ignored.
Mr. Knudsen's locomotive cost 1.45 times as much as an ordinary engine, and
had a tender which was even more complicated than the locomotive itself;
and that would finally prevent any such arrangement becoming normal practice.
After the war, when it was possible to devote attention to such matters,
it would be appropriate for the Institution, which had been founded by a
great locomotive engineer, to carry out a scientific investigation into the
means whereby the use of raw water could be avoided, and above all to find
what could be done towards recovering the latent heat which was at present
discharged into the atmosphere.
Stanier (289): In this country, circumstances did not permit
the efficient use of turbine power, because the conditions varied foot by
foot along the road. When an engine had a demand, as Mr. Bulleid had said,
for maximum output over a short section and then for minimum output over
the next it did not promote the efficient working of the turbine. The experiment
made on the LMS with a non-condensing turbine locomotive had indicated, so
far, that the coal consumption per drawbar h.p.-hr. was very much the same
as with the normal four-cylinder locomotives on work of the same nature.
The turbine locomotive was employed only on straightforward runs between
London and Liverpool, and not on trains stopping at many intermediate stations.
The coal consumption per drawbar h.p.-hr. was of the order of 2.8 lb. for
the reciprocating locomotives and 2.78 lb. for the turbine, while the water
consumptions were 24.7 lb. and 24.8 lb. respectively. The corresponding
evaporations per pound of coal were 8.3 lb. and 8.4 lb. In regard to condensing
apparatus, the difficulties experienced up to the present in this country
had, he thought, usually been mechanical; the condenser had given more trouble
than the engine and the turbine. In Russia they seemed to have overcome the
difficulty with the Henschel arrangement. The height of the condensing gear,
however, was about 14 ft. 6 in. above rail level. It might not be necessary
to have so great a height, but presumably if the height was reduced a much
longer condenser would be required, and there would be difficulty in
accommodating it within the normal limits. He was interested in the
authors’ statement that the reciprocating engine with condenser could
be useful if it was desired to conserve water, but that if a saving in coal
consumption was required it was necessary to sacrifice some of the saving
in water and have a turbine to supply the power. The turbine locomotive might
be very satisfactory on long stretches of line such as were found in Russia
or in Australia or in the Argentine, but he had already indicated that it
was difficult to find a satisfactory field for it in Britain. ,H. Holcroft
(292-4) Anderson system
Bulleid, O.V.S.
Locomotives I have known. 341-52 + 6 plates. 18 illus., 12 diagrs.,
11 tables.
A select group of locomotives reviewed by the author.
Newberry, C.W.
A study of the riding and wearing qualities of railway carriage tyres having
various profiles. 25-35. Disc.: 35-40.
Results from preliminary experiments to devise a technique to record
the transverse motion of a railway coach wheel travelling at speed: this
used a cine-camera to produce slow-motion films of the contact region between
wheel and rail. The visual impression of the cine-screen image was transcribed,
by means of a specially developed apparatus, into graphical form from which
the wheel motion could be analysed. The wearing qualities of each tyre profile
tested have been assessed by a comparison of the tyres at various stages
of wear, the profiles being recorded by a specially accurate method developed
for the purpose. Tests have been made with tyres turned to the standard ARLE
(Association of Railway Locomotive Engineers of Great Britain and Ireland)
profile having a 1 in 20 coned tread, and with experimental profiles having
cylindrical treads or 1 in 100 coned treads. The records of wheel motion
are discussed, together with direct observations on the riding of the trains
concerned; and the various profiles are considered from the points of view
of riding, wear, manufacture, and maintenance.
Discussion: C.E. Fairburn (36-7) noted that in 1935 Sir Harold Hartley and
the writer, when travelling in the United States, visited the Chicago Rapid
Transit Company and were very kindly shown the film records and given a full
account of the tests with cylindrical tyres which had been made on vehicles
using that company’s lines. In the London, Midland and Scottish Railway
tests the question was considered largely in its relation to the riding qualities
of the stock, but the Chicago tests arose from considerations of track
maintenance. During the spring thaw, after the severe winter frosts experienced
in that region, very heavy expenditure was incurred in track maintenance
and re-alignment. Experience showed that that expenditure was substantially
reduced when cylindrical treads were substituted for the 1 in 20 taper profile
previously in use. As the lines ran through the city, there were many sharp
curves, and flange wear was rapid; but it was found that there was no appreciable
difference between the two profiles in that respect. In any case, the saving
in civil engineering expenditure was much more than sufficient to compensate
for any possible increase in the cost of tyre re-turning. The question was
discussed also with the Illinois Central R.R. and the Chicago, Burlington
and Quincy R.R. These companies were interested primarily in the riding of
the stock; the former had been using cylindrical treads on multiple-unit
electric vehicles with success for two years or more, and the latter had
adopted them for some axles on the Burlington Zephyr train, but neither company
could make a definite pronouncement about their wider adoption on ordinary
steam-hauled stock. With this information about American experience available,
it was decided that tests should be made in this country, and the electric
stock on the Liverpool-Southport line was very suitable for the
purpose.
Walter, A.J.R.
Modern methods of water treatment. 282-7. Disc.: 288-93. 6 ddiagrs.,
tables.
All natural water supplies contain impurities which often have a profound
and far-reaching effect on the products being made and on manufacturing costs.
The introduction of new processes for materials and more efficient power
generation has in turn made essential the removal of even extremely small
amounts of impurities from water that a few years ago would have been tolerated.
For example, the increase in boiler pressures alone over the last twenty-five
years has called for complete revision of the quality standard of boiler
feed water. Fortunately those responsible for research into, and practising
the art of, water purification have kept a step ahead of these new requirements
and most waters can now be treated in one way or another so as to render
them suitable for practically any purpose. Revolutionary discoveries have
been made and applied in the field of water treatment. This paper describes
the major advances, among them new crystallization and precipitation processes
developed for lime-soda softening and particularly the entirely new chemical
field discovered in hydrogen ion exchange materials and acid adsorption
materials. The combined use of these two new discoveries has resulted in
the development of equipment for the production of the equivalent of distilled
water without heat or evaporation.
Johansen, F.C.
Locomotive practice. 351-2. Disc.: 352-79.
The Author was employed in the Research Department, London, Midland,
and Scottish Railway, Derby. The discussion related to the whole Conference
on Surface Finish at the Institution on 9 March 1945.
The influence of the conditions of service maintenance and long life of a
locomotive has the consequence that the only surfaces to which exceptionally
fine finish was imparted were on parts which might give immediate trouble
and never be self-rectifying without such attention. Thus, journals of coupled
wheel axles have shown, over a number of years, that progressive improvement
of surface finish diminishes the occurrence of overheated bearings, especially
in the early stages of use. The tendency, therefore, was for all engine and
tender journals to be fine-tuned, fine-ground, and finally lapped. Shrouded
leather split collars, enclosing felt pads loaded with oil and emery powder,
were strapped around the journals, and were belt-driven by electric motors.
Simultaneously the motors were oscillated axially, and the wheel-axle assembly
was slowly revolved. Crankpins were usually hand polished after being ground,
but crank journals could be machine-lapped, the driving motors being adapted
to run up and down inclined rails. As an alternative to the lapping machine,
the cylindrical parts of journals and the radiused fillets at their ends
were polished (after the fine-turning operation) by felt pad and emery, applied
while the assembly was mounted in a lathe.
Volume 154 (January-December 1946)
Bulleid, O.V.S.
Some notes on the "Merchant Navy" class locomotives of the Southern
Railway. 316-33. Disc. 333-43 + 4 plates. 13 illus., 20
diagrs., 2 tables.
Very extensive account of the justification for the design and
observations on its performance in service.
Volume 155 (War Emergency Issues, 13-24, 1946)
Plummer, G.A.
The Development of the La Mont Boiler in Great Britain. 333-45. 9 illus.,
20 diagrs.
The La Mont forced-circulation boiler was introduced into this country
in 1936, and although considerable experience was already available on the
Continent (where some 150 installations then existed) the need for further
development was immediately apparent, not only to bring this type of steam
generator into line with British practice, but also because the installations
then existing were comparatively small units operated for the most part at
moderate steam pressures and temperatures. Author was Director in charge
of development and research, Messrs. John Thompson Water Tube Boilers, Ltd.,
Wolverhampton.
Begg, G.A.J., Hebblethwaite, W.M., and Cooke, G.
Operating experience with La Mont boilers, with special reference to feed
water problems. 346-57. Disc. 357-75.
Experience at the power plant of I.C.I., Dyestuffs Division and I.C.I.,
Alkali Division. The discussion (all in the form of written communications)
do not appear to show any direct railway interest, although it would seem
that Stanier was well aware of this work going on "not a thousand miles from
Crewe".
Bulleid, O.V.S.
Presidential Address. 1-5 + 10 plates. 42 illus., diagr., 3 tables.
Included the reason for introducing the Leader design as
follows:
1 To be able to run over the majority of the Company's lines.
2 To be capable of working all classes of trains up to a speed of 90 miles
per hour.
3 To have its whole weight available for braking and the highest possible
percentage thereof for adhesion.
4 To be equally suitable for running in both directions without turning,
with unobstructed look-out.
5 To be ready for service at short notice.
6 To be almost continuously available.
7 To be suitable for 'common use.'
8 To run not less than 100,000 miles between general overhauls with little
or no attention at the running sheds.
9 To cause minimum wear and tear to the track.
10 To use substantially less fuel and water per drawbar horse-power
developed.
Diamond, E.L.
Development of locomotive power at speed. 404-16. Disc.: 417-43.
The power developed per unit of cylinder volume of locomotives in
the speed range 250 to 400 rpm had doubled. In the 1900s mean effective pressure
tended to diminish with increase of speed, rather than with boiler evaporative
capacity to limit engine power. The most advanced designs maintain the mean
pressure at a high percentage of the calculated value to the highest speeds,
and the effect of valve events and clearance volume on the calculated mean
pressure thus becomes of practical importance, especially as designers were
endeavouring to use considerably higher steam pressures in single-expansion
cylinders.
The effect of these factors over a wide range of steam pressures in the form
of basic data graphs of mean pressure, relative efficiency, and steam
consumption. It is shown that without the decrease of clearance volume and
increase of expansion ratio which compound expansion affords, the improved
thermal efficiency which higher steam pressure offers cannot be fully realized
above about 250 psi boiler pressure, though greater power can be obtained.
Then an examination was made of the actual deviation of mean pressure with
speed for a wide range of locomotives, including some of the most recent
designs, and the reasons for the radical improvement are indicated. In 1905
Dalby suggested a simple proportional relationship between mean pressure
and speed. Such a relationship did not hold for modern locomotives, and a
simple exponential law is proposed with a single coefficient characteristic
of the locomotive. This law may be used to estimate the power of a future
design at any speed, or as a criterion for assessing the performance of an
existing locomotive in respect of power developed, which is generally of
more importance to railway companies than thermal efficiency.
Steam locomotive design may appear to have remained static for the previous
fifty years as compared with the technical developments of stationary steam
plants and other forms of prime mover. It is true that there have been no
fundamental changes in the construction or the working principle of the steam
locomotive apart from the use of higher steam temperatures. Yet the power
capacity of the average locomotive of 1900 was a mere fraction of that of
the then best contemporary designs, for the same unit cylinder volume at
the speed of running prevailing in 1939. If the performance of locomotives
over the range of speed 250-400 r.p.m. was examined, it may justly be claimed
that progress has been commensurate with that of other established types
of engine. If it had not been so, it is almost certain that the non-condensing
reciprocating engine would not have maintained its pre-eminence for railway
service.
It has to be admitted that the spectacular developments of locomotive performance
in recent years are not entirely the result of devices or principles unknown
at the beginning of the century. The performance of a locomotive in practice
is, however, so dependent on the steam-producing capacity of the boiler that
there grew up a habit of basing any study of its power on the evaporative
capacity of the boiler. Some years ago the author made a survey of the various
methods that have been used for calculating and measuring locomotive horse-power,
and it will be found that almost all the early formulae were based on the
boiler, notably those of Frank (1887) and Goss (1901) which expressed the
power of a locomotive as a function of the heating surface. It has generally
been a fundamental assumption that the power of a locomotive is limited by
its evaporative capacity, but whilst this is obviously true in a broad
theoretical sense, it has not always been true in practice of large-wheeled
locomotives.
D.K. Clark, whose paper on “Expansive Working
of Steam in Locomotives” read before this Institution in 1852 can
still be read with interest. Clark laid down that the volume of the high-pressure
steam chests should be equal to that of one cylinder. This rule had long
been forgotten till the Nord Company proved once more its value in some tests
in 1897.
Mean Effective Pressure Curves for Various Locomotives on Truly Comparative
Basis (The values of K in the characteristic power equation for each locomotive
are given alongside the corresponding curve):.
1 Midland 4-4-0 superheater locomotive (1917).
2 Original P.O. compound superheater Pacific locomotive (1909).
3 Pennsylvania K4S locomotive in original form.
4 Pennsylvania K2S locomotive.
5 Pennsylvania E6S locomotive.
6 L.M.S. rebuilt Royal Scor locomotive.
7 Pennsylvania K4S locomotive rebuilt with Franklin poppet valve
8 Rebuilt P.O. compound locomotive No. 3705 (Chapelon).
9 Pennsylvania TI locomotive with Franklin poppet valve gear
Alternative abstract see Loco. Rly
Carr. Wagon Rev., 1947, 53, 66-7.
Discussion: See also Tuplin's
comments on low pressure locomotive boilers.
Bulleid, O.V.S., Peppercorn, A.H., Hawksworth, F.W.
and Ivatt, H.G.
Railway power plant in Great Britain. 235-9 + 4 plates. 12 illus., diagr.
(s. & f. els.) 2 tables. (Centenary Lectures).
The Institution celebrated its Centenary by presenting surveys of
the state of the art in many activities. Thus, the surveys were very concise,
but in the case of two of the contributors
(Ivatt and
Bulleid) very concentrated.
Peppercorn's and
Hawksworth's contributions
(especially the latter) were lesser in impact, but still give an excellent
survey of locomotive development at that key time. With the exception of
Bulleid who was a prolific contributor, the other contributions were virtually
their sole public utterances. Greater detail is presented under each of the
authors. Loco. Rly Carr. Wagon Rev.,
1947, 53, 106-7 carried a long precis, but this is not reproduced
(see references to each contributor).
Armand, L. Motive power trends on European
railways. 239-45.
Following WW2 devastation the prime task for the railways was the
rehabilitation of existing machines, but the magnitude of the railways’
requirements permits consideration to be given also to new equipment and
the launching of new building programmes, and consideration was given to
directions in which the railways might develop. The survey covered steam,
diesel, and electric locomotives from the mechanical engineering aspect.
Special versus Conventional Locomotives. Between the two world wars
a great effort was made on the continent to carry out experiments with new
types, in which a departure was made from the conventional Stephenson locomotive.
It was considered that the overall thermal efficiency at the wheel rim was
poor, and an early series of researches, carried out particularly in Germany
between 1925 and 1935 was aimed at the realization of a higher efficiency
by the use of higher pressure (as in the Schmidt, Loffler, and other similar
locomotives), or by the use of turbines and condensers (as in the Krupp,
Maffei, and such types). These attempts came to an end, as is well known,
owing to the conclusion that the savings which they gave were not justified
in view of the additional complication and increased maintenance costs.
In France, there was a notable increase in efficiency — a rise from
8% to 11% — had been obtained with conventional locomotives of the Pacific
(4-6-2) type on the Paris-Orleans Railway in 1930, trials which as yet are
scarcely completed, have been undertaken with special types of locomotives
with a view to obtaining : (1) a higher efficiency by the use of high-pressure
water-tube boilers; (2) the employment of novel driving mechanism to take
advantage of high-pressures and to eliminate coupling rods.
These trials are outlined in the following three subsections, in which the
main conclusions arrived at on the French Railwavs are also given.
(a) Velox Boiler.
A Velox boiler was fitted in 1939 to an ordinary recimocating 4-6-0 locomotive;
the pressure is 16 kg/cm2, but this boiler was equally capable
of producing steam at pressures of 50-80 kg/cm2. This type of
boiler was costly and too complicated for railways, and in present circumstances
a diesel locomotive might be preferable, as it would appear to offer the
same advantage in high-speed service whilst showing also a better
efficiency.
(b) Winterthur High-pressure Locomotive with Individual Axle Drive.
The Winterthur 4-6-4 locomotive placed in service in 1939 provided experience
with two new departures from conventional practice: a high-pressure boiler
working at 60 kg/cm2 and the use of small steam engines —
two per axle — each having three cylinders. The crankshaft was driven
at 1,000 r.p.m., and each unit developed 500 h.p., giving a total of 3,000
h.p. for the locomotive. Trials of this machine were suspended during practically
the whole of WW2, but had resumed. The driving units gave satisfaction, but
the boiler was shown by its behaviour to be somewhat delicate owing to its
construction in two portions, one boiler carrying water at 20
kg/cm2 and feeding the high-pressure boiler working at 60
kg/cm2. The saving in fuel, which probably did not exceed 20 %
did not justify the difficulties of maintaining the boiler, which had the
further drawback that its components are inaccessible. Nevertheless this
experiment should eventually make some extremely interesting information
available for consideration when it is desired to build locomotives with
driving bogies, e.g. a machine mounted on two six-wheeled bogies to eliminate
entirely the “hammer blow” of conventional locomotives. However,
the scope for such applications is limited.
(c) Schneider Locomotive with Individual turbine drive.
In the Schneider 4-6-4 turbine locomotive, the boiler, of the conventional
type, works at 25 kg/cm2, but on each axle was mounted a turbine
running at 10,000 r.p.m., and developing about 1,000 h.p., i.e. a total of
3,000 h.p. Placed in service in 1938, this engine underwent trials at the
Vitry testing station where it developed an actual horse-power of 2,600 at
the wheel rim. When running at 100 km/h (62 m.p.h.) the fuel and water
consumption was that of a good locomotive of normal type. The experiment,
however, was not directed towards the attainment of a high efficiency, but
was rather a research into a new type of drive. The engine was kept in service
for some time, but unfortunately was severely damaged by the Germans in 1944
and could no longer be run. Nevertheless the experiment enabled the conclusion
to be drawn that it is possible to apply individual turbine drive to the
axles of a steam locomotive. Thus it should now be possible, as mentioned
in connexion with the Wimterthur locomotive, to produce a steam locomotive
with driving bogies, or an extra high-speed machine perfectly balanced in
regard to hammer blow; but these may well be expensive types of construction,
limited to special cases where they are justifiable. The diesel-electric
locomotive has established itself since the idea of a locomotive with individual
turbine drive has been put forward, and may afford a more practical
solution.
Conclusions regarding Special Types of Locomotives.
The conclusion to be drawn was that European experience, first in Germany
and more recently in France, had demonstrated that complexities of special
locomotive types nullify the advantages to be gained from them, and that
simplicity is a great virtue in locomotives. It is this simplicity of
construction and of operation which is the chief defence of the normal locomotive
against competition from other forms of motive power. It can therefore be
concluded that the steam locomotive will probably continue to follow, and
indeed to complete, its development on the lines of the conventional type.
It may be stated in general terms that, after having undergone a development
in thermodynamic details between 1930 and 1940, steam locomotive design was
dominated by an effort to achieve a robust construction in order to reduce
maintenance cost and to increase the annual mileage. The increased high level
of wages in maintenance work, and the need for amortizing the prime cost
whilst materials were continually rising in price, make it of paramount
importance to reduce the time during which engines are stopped: the principal
means to attain this object, both from the constructional and the operating
viewpoints were reviewed.
Increased Axle Loading. The robustness of the locomotive, in regard
to its various components, is bound up with the permissible axle load. The
drawbar horse-power of the French “Pacific” locomotives, weighing
105 tonnes had by 1930 risen from 1,600 to 2,300 as a result of thermodynamic
improvements, without any increase in engine weight. A higher adhesive weight
was, however, shown to be desirable, whilst further improvements which suggested
themselves were the fitting of a more powerful boiler, the use of roller
bearings, and further strengthening of the frames, which were by no means
sufficiently rigid. On most French lines the maximum axle load was 18.5 tonnes.
Certain sections, however, notably the Nord, could take 21 tonnes. It was
decided to raise the axle loading on French main lines to 23 tonnes, and
to 20 tonnes on most of the other French lines. In Belgium, an axle loading
of 24 tonnes has long been permitted. Spain has railways with a 22-tonne
maximum axle loading. This increase is a general tendency in Europe. An axle
load of 22.8 tonnes already exists on many British railways, notably the
London, Midland, and Scottish Railway and the Great Western Railway.
Concurrently with the use of a higher axle load there has also been a tendency,
in order to allow of a general increase in dimensions, to introduce an additional
carrying axle at the trailing end; this led to the 4-6-4 or 4-8-4 types for
passenger work, and undoubtedly we shall see 2-8-4 or 2-10-4 types for
freight.
Boiler Construction. The boiler, as is well known, is the most expensive
part of a locomotive from the viewpoint of maintenance. To ensure that the
boiler is worked to a reasonable degree, there is a tendency to use the largest
possible grates. The 2-8-2 French locomotives recently built for mixed traffic
have a grate area of 5 m2 and a grate area of 6 m2
can be envisaged for more powerful locomotives.
The thermic syphon, which is intended to increase heating surface and to
improve circulation, has been adopted on all recent French locomotives of
the 2-8-2P 2-10-0P, and 2-8-2R types. As regards construction, both American
and Belpaire types of firebox are in use. French preferences finally favoured
the Belpaire type.
A great saving in maintenance is obtained by using a welded steel firebox
in conjunction with complete system of feed-water treatment. The welded steel
firebox has the advantages of (1) a lower first cost than a copper firebox;
(2) a higher resistance to deformation of the firebox plates, since copper
plates are liable to deformation in engines carrying pressures in excess
of 16 kg/cm2. and (3) complete freedom from leakages both in the
tubeplates and also in the seams. Whilst steel fireboxes have been widely
adopted in France, their use is not yet general in Europe. The Belgian railways
did not use steel fireboxes until 1945, when they ordered some 280 locomotives,
so equipped, from Canada and the U.S.A. Steel fireboxes are, however, in
use in Spain; and it is possible that Germany may extend the use of the steel
fireboxes which were introduced there during the war.
Water Treatment. Treatment of feed water is one of the essential means
for reducing both maintenance costs and the time during which normal locomotives
are stopped. The procedure employed in France since 1939 consists of the
introduction of a compound which will prevent sludge from adhering to the
boiler, whilst at the same time protecting the steel plates against corrosion.
The improvement thus obtained has been considerable. Instead of having to
replace about 400 firebox stays at each overhaul, in bad-water districts
it has been only necessary to replace a few dozen; and the maintenance costs
have been reduced in the ratio of 10/1. In one extreme case at Joncherolles
depot (Nord), the mileage between consecutive general repairs doubled, rising
from 210,000 km to 420,000 km. The treatment is carried out in the tender
itself, but can equally be effected at fixed stations. Good results can only
be obtained by obedience to strict rules which oblige the water-treatment
staff to carry out the blowdown routine in a regular and methodical manner.
The amount of water blown down may be about 200 litres every 50 km.
Mechanical Stokers. A mechanical stoker assists in solving the problem
of operating long runs because it obviates fatigue on the part of firemen
and allows the fire to be built up again, if need be, en route. It also solves
the problem of firing powerful engines which may burn more than 2,000 kg.
of coal an hour. Finally, it fulfils a need that is very evident from the
humanistic viewpoint. In France it has the added advantage of allowing the
use of non-coking coals, since that country is not well supplied with coal
of the coking variety. Mechanical stokers were first applied in France in
1932. The total number of French locomotives with mechanical stokers, including
machines now under construction, will shortly number about 1,700. It is also
noteworthy that experiments in their use were begun in Spain in 1935.
Frames. The benefit of a rigid framework has already been mentioned.
Until recent years the framework consisted of longitudinal steel plates from
28 to 35 mm. in thickness, which were but feebly supported by cross-stays.
A first step towards improvement was made when bar frames were adopted, in
which the longitudinal members were 100 mm. thick and which possessed sufficient
rigidity by themselves in the transverse direction. This type of bar frame
has been employed to some extent in Belgium, France, and Spain. A better
solution can, however, be obtained with cast steel frames of the
“monobloc” type used in America.
Cylinders. An important step was taken in France, in the direction
of achieving a more robust design, by abandoning the four-cylinder machine
and adopting a disposition with three cylinders. The axle with two cranks,
necessary for four-cylinder locomotives, is too fragile for modern
machines.
The use of three cylinders provides a compromise between the quest for a
strong crank axle (in which web thicknesses have increased from 110 to 250
mm., and a good stress distribution. The tendency to use three cylinders
is general in continental Europe. The Reichsbahn in Germany has been led
to adopt this arrangement for its locomotives, e.g. the 2-10-0’s, type
44; the 2-10-2’s, type 52; and so on, as well as for its Pacific (4-6-2)
type 03, in preference to the two- cylinder arrangement. This was done for
considerations relating to the maintenance of the mechanism and to the
distribution of the drive. Locomotives of the 4-8-2 and 2-10-2 types, which
have been built in Spain since 1942 — powerful machines with grate areas
of 5 m2 also utilize three cylinders. Naturally the preference
accorded to three cylinders only applies to powerful machines. For medium-powered
locomotives in France and elsewhere, two-cylinder simple-expansion locomotives
are now favoured.
Kiefer, P.W. Railway power plant from the United
States point of view. 245-51.
Summary of motive-power evaluations. The relative evaluations given
below are predicated upon:
(a) Locomotives of equivalent power and representing the latest state of
the design art.
(b) Equivalent through-line passenger schedules and freight operations and
efficient use of potential availability.
(c) Equivalent maintenance and servicing attention at all times.
(d) Accumulated knowledge and experience.
(e) The exclusion of fixed charges and maintenance expense, for motive-power
operating, servicing, and repair facilities. Where the use of steam may gradually
decrease, some reduction in the facilities required should take place, but
as a partial offset to the resulting savings, moderately increasing investment
is required in suitable facilities for other forms of motive power as their
number becomes greater.
It is emphasized that the following ratings for the gas- and steam-turbine
locomotives are speculative and at the present stage are based on design
characteristics, and possibilities only.
For the straight electric, Diesel, and steam, the order of placing are founded
on substantial experience, but for the gas- turbine and steam-turbine the
placings are estimated:
(1) Availability: straight electric, gas-turbine, Diesel-electric, steam-turbine,
reciprocating steam.
(2) Over-all Costs of Ownership and Usage: Diesel-electric or reciprocating
steam, straight electric (gas-turbine and steam-turbine not placed as there
are insufficient data for estimation).
(3) Capacity for Work: straight electric, gas-turbine, Diesel-electric or
steam-turbine or reciprocating steam.
(4) Performance Efficiency: Over-all performance: straight electric, gas-turbine,
Diesel-electric, steam-turbine, reciprocating steam.
Thermal Efficiency at drawbar: Diesel-electric, straight electric, gas-turbine,
steam-turbine, reciprocating steam.
Finally, to maintain the supremacy of rail transportation-so far as this
may be accomplished through the selection and introduction of modern locomotives
and cars-properly balanced quantities and kinds of rolling stock, both passenger
and freight, must be currently acquired. As conditions permit, this is being
done on the railroads of the United States.
For passenger service alone, the New York Central System is now taking deliveries
of a total of 720 new day-service and sleeping cars of most modern construction
and of thirty-one different types, fitted with the latest auxiliary equipment
and furnishings, which are to be made up into fifty-two additional streamlined
passenger trains for operation on improved schedules throughout the
system.
Parker, R.C. and P.R. Marshall.
The Measurement of the temperature of sliding surfaces, with particular reference
to railway brake blocks. 209-20. Disc.: 220-9 + 4 plates. 30 illus., 8
diagrs..
Authors employed by Ferodo Ltd. A pyrometer, which covered the temperature
range 200 to 900°C. (390 to 1,650°F.) with a response time of 10-3
seconds, had been developed for studying the temperature of stationary and
moving surfaces. The pyrometer had been used to determine the temperature
of the surface of a railway tyre, during brake applications under various
conditions, just as it emerged from beneath the brake block. Evidence is
adduced to prove that the temperatures measured were not very different from
those actually under the block. It is shown that the possible change in
emissivity of the tyre steel is insufficient to invalidate the results. The
variation and extent of the area of contact between brake block and tyre
were investigated simultaneously with the temperature measurement. It was
shown that high tyre surface temperatures (over 800°C) are an inevitable
result of “strip braking”. The preferred formation of heat spots
between the spokes of the wheel, and the unequal growth of heat spots across
and along the tread due to tyre distortion, were examined. An attempt to
eliminate strip braking by reducing the length of the standard brake block
to three-quarters, one-half, and one-quarter of its original length was made.
It was found that reducing the brake block to one-quarter of its original
length completely inhibited heat spot formation, reduced by a factor of 2
the standard deviation of the stopping times under standard conditions, and
reduced the maximum temperature attained during brake application from over
800°C. to under 400°C.. The deleterious formation of martensite
was thus eliminated. It was found that the wear of the half-length brake
blocks, expressed on a thickness basis, was not twice but maybe equd to that
of a full-length block. Since the cost of a brake block is somewhat proportional
to its size it follows that a shorter block may be more economical than a
full-length block. It is concluded that the optimum size of a railway brake
block must be determined separately for each material and set of operating
conditions
Davies, R.D. and Cook, A.F. The motion of a railway axle. 426-34.
Disc.: 434-6. 2 illus., 14 diagrs.
Investigation of the motion of a single axle and pair of wheels by
means of a model, paying particular attention to the action of the flanges
and to their influence on the development of “hunting”. In
justification of the use of a single axle, evidence was produced that, owing
to the various clearances, the axles of a bogie are in fact largely free
to follow their individual paths. The effects of unsprung mass, wear of tyres
and rails, flange clearance, lateral stiffness of the track, and other variables
were studied. It is shown from considerations of dynamical similarity that
the speed at which oscillation of a given violence occurs varies approximately
inversely as the square root of the unsprung mass, and that a reduction of
this mass would therefore be beneficial. Possible changes in tyre profile
were discussed
Andrews, H.I.
The mobile testing plant of the London, Midland and Scottish Railway. 450-63.
Disc. 463-76 + 6 plates. 22 illus., 14 diagrs., 2 plans, table. Bibliog.
A dynamometer car plus a set of coaches which were equipped with electric
generators. These generators acted as a variable 'load" for the locomotive
being tested. Discussion: D.R. Carling (466) considered that the
importance of properly conducted tests, carried out under controlled conditions,
could not be over-emphasized, if full and accurate data were to be obtained,
on which to base changes in the design and utilization of locomotives. Tests
carried out under normal running conditions revealed what a locomotive could
do and how locomotives compared with respect to a particular piece of work,
but it was a laborious and often fruitless task to interpret the results
thus obtained in a manner of real use to the designer, as it was usually
impossible to isolate the many factors involved. The maximum of information
would be obtained by a combination of tests at a testing station and on the
line. Commented on counter pressure testing conducted on LNER. Stanier
(466-7) noted that he had been privileged to help test locomotives with
Gooch’s dynamometer car, and that had interested him in the testing
of engines. Mr. Diamond had referred to the leader in The Engineer
in 1898. At that time one felt that the results were rather unsatisfactory.
One never knew quite what one was measuring and one never knew that the answers
were quite what one wanted. However, those results had given an indication
as to what improvement, if any, had been made, and certainly they had helped
the Great Western Railway to realize that to get the steam into the cylinder
was quite as important as to get it out ! In that coxmexion, Churchward,
before designing the long-stroke valve gear, had made a single-cylinder unit
and had it carefully indicated as a stationary engine. That was why the Great
Western had adopted, in 1900, the long-stroke valve gear, and led the country
at that time.
Bulleid, H.A.V.
Cinematography in engineering. 185-90. Disc.: 191-5.
Although this paper is related to the production of nylon textile
fibres it is of interest (1) because the author was the son of the Bulleid
and a significant author of railway books, and (2) it cites two key papers
which link high speed cinematography with studies of the ride performance
of rolling stock.
Ljungström, Fredrik
The development of the Ljungström steam turbine and air preheater.
211-23.
Inheritance and family surroundings favoured the growth of inventive ability
in my late brother Birger, the next to the youngest of the eight children
in the family. My father was a land surveyor, whose professional activities
included the design and improvement of the various geodetic instruments he
used. Amongst his innovations was a field-tube for measuring distances, which
by this instrument were automatically projected down to the horizontal surface,
when hilly country was surveyed. For these and other instruments, he was
awarded a gold medal at the World‘s Fair in Philadelphia in 1876. The
instruments were manufactured by the family in a small home workshop, so
that his sons, from early childhood, had the advantage of a thorough practical
training in the art of instrument Thus, when my brother, who was serving
as an engineer in Aktiebolaget Separator, Stockholm, began in 1906 the work
which later resulted in the design of the Ljungstrom steam turbine, he had
the advantage of being an instrument-making artisan. Some of the details
in the Ljungstrom turbine bear wimess to this early training. But the most
important impulse was given to him by the inspiring example of the Parsons
turbine, which he was able to study at the Durham College of Science. When
the Ljungstrom turbine 1910 appeared in a unit, combined with two brakes
for testing purposes, and gave evidence of high efficiency, various experts
explained that this type of turbine was unsuitable for practical purposes:
it had a frail structure, and was more like a piece of clock-work than a
turbine. The inventor explained, however, that he would be very glad if the
turbine ran continuously like a clock. Significant for this phase in the
development