[Footnote: Paper read before the Civil and Mechanical Engineers' Society,
April 2, 1884.]
By H. MICHELL WHITLEY, Assoc. M.I.C.E., F.G.S.
A little more than half a century ago, but yet at a period not so far
distant as to be beyond the remembrance of many still living, a
clear-headed North-countryman, on the banks of the Tyne, was working out,
in spite of all opposition, the great problem of adapting the steam engine
to railway locomotion. Buoyed up by an almost prophetic confidence in his
ultimate triumph over all obstacles, he continued to labor to complete an
invention which promised the grandest benefits to mankind. What was
thought of Stephenson and his schemes may be judged by the following
extracts from the _Quarterly Review_ of 1825, in which the introduction of
locomotive traction is condemned in the most pointed manner:
"As to those persons who speculate on making railways general throughout
the kingdom, and superseding every other mode of conveyance by land and
water, we deem them and their visionary schemes unworthy of notice.... The
gross exaggeration of the locomotive steam engine may delude for a time,
but must end in the mortification of all concerned.... It is certainly
some consolation to those who are to be whirled, at the rate of 18 or 20
miles per hour, by means of a high-pressure engine, to be told that they
are in no danger of being sea-sick while on shore, that they are not to be
scalded to death or drowned by the bursting of a boiler, and that they
need not mind being shot by the shattered fragments, or dashed in pieces
by the flying off or breaking of a wheel. But with all these assurances,
we would as soon expect the people of Woolwich to suffer themselves to be
fired off upon one of Congreve's ricochet rockets, as trust themselves to
the mercy of such a machine going at such a rate."
These words, strange and ludicrous as they seem to us, but tersely
expressed the general opinion of the day; but fortunately the clear head
and the undaunted will persevered, until success was at last attained, and
the magnificent railway system of the present, which has revolutionized
the world, is the issue. And the results are almost overwhelming in their
magnitude. Here, in Great Britain alone, 654,000,000 people travel
annually. There are 14,000 locomotives, and the rolling stock would form a
train nearly 2,000 miles long; while the number of miles traveled in a
year by trains is more than 10,000 times round the world; and the
passengers would form a procession 100 abreast, a yard apart, and 3,700
miles long.
These stupendous results have been attained gradually; if we go back to
1848, we find that on the London and Birmingham Railway the number of
trains in and out of Euston was forty-four per day. The average weight of
the engines was 18 tons, and the gross loads were, for passenger trains 76
tons, and for goods 160. Now, the weight of an express engine and tender
is about 65 tons, and gross loads of 250 to 300 tons for an express, and
500 tons for a coal train are not uncommon, while not only have the trains
materially increased in weight, owing to the carriage of third-class
passengers by all (except a few special) trains, and also to the lowering
of fares and consequent more frequent traveling, but the speed, and
therefore the duty of the engines, is greatly enhanced. A "Bradshaw's
Guide" of thirty-five years ago is now a rare book, but it is very
interesting to glance over its pages, and in doing so it will be found
that the fastest speed in all cases but one falls far short of that which
obtains at present. The following table will show what the alteration has
been:
_________________________________________________________________
| 1849. | 1884. |
|Speed miles|Speed miles|
| per hour. | per hour. |
-----------------------------------------+-----------+-----------+
Great Western--London to Didcot. | 56 | -- |
" " to Swindon. | -- | 53 |
North-Western--Euston to Wolverton. | 37 | -- |
" Northampton to Willesden. | -- | 51½ |
South-Western--Waterloo to Farnborough. | 39 | -- |
" Yeovil to Exeter. | -- | 46 |
Brighton--London Bridge to Reigate. | 36 | -- |
" Victoria to Eastbourne. | -- | 45 |
Midland--Derby to Masborough. | 43 | -- |
" London to Kettering. | -- | 47 |
North-Eastern--York to Darlington. | 38 | -- |
" " | -- | 50 |
Great Eastern--London to Broxbourne. | 29 | -- |
" Lincoln to Spalding. | -- | 49 |
Great Northern--King's Cross to Grantham.| -- | 51 |
Cheshire Lines--Manchester to Liverpool. | -- | 51 |
-----------------------------------------+-----------+-----------+
With this problem then before them, increased weight, increased speed, and
increased duty, the locomotive superintendents of our various railways
have designed numerous types of engines, of which the author proposes to
give a brief account, confining himself entirely to English practice, as
foreign practice in addition would open too wide a field for a single
paper.
Commencing then with passenger engines for fast traffic, and taking first
in order the Great Western Railway, we find that it holds a unique
position, as its fast broad gauge trains are worked by the same type of
engine as that designed by Sir Daniel Grooch in 1848, although, of course,
the bulk of the stock has been rebuilt, almost on the same lines, and
rendered substantially new engines. They are single engines of 7 ft. gauge
with inside cylinders 18 in. diameter, and 24 in. stroke; the
driving-wheels are 8 ft. in diameter, and there are two pairs of leading
wheels, and one of trailing, all of 4 ft. 6 in. diameter. The total wheel
base is 18 ft. 6 in.; the boiler is 4 ft. 6 in. diameter, and 11 ft. 3 in.
long. The grate area is 21 square feet, and the heating surface is, in the
fire-box, 153 square feet; tubes, 1,800 square feet; total, 1,953 square
feet. The weight in full working order is, on the four leading wheels, 15
ton 18 cwt.; driving wheels, 16 tons; trailing wheels, 9 tons 10 cwt.;
total, 41 tons 8 cwt. The tender, which is low-sided and very graceful in
appearance, weighs 15 tons 10 cwt., and will hold 2,700 gallons of water.
The boiler pressure is 140 lb. on the square inch, and the tractive power
per pound of steam pressure in the cylinders is 81 lb. These engines take
the fast trains to the West of England; the Flying Dutchman averages 170
tons gross load, and runs at a mean time-table speed of 53 miles per hour,
which allowing for starting, stopping, and slowing down to 25 miles per
hour through Didcot gives a speed of nearly 60 miles an hour.
[Illustration: FIG. 1.--GREAT WESTERN RAILWAY.]
The average consumption of coal per mile, of thirteen of these engines,
with the express trains between London and Bristol, during the half-year
averaged 24.67 lb. per mile, the lowest being 23.22 lb., and the highest
26.17 lb., the average load being about eight coaches, or 243 tons. We
have already seen that in 1849 the Great Western express ran at a higher
rate than at present, being an exception to the general rule; and the
fastest journey on record was performed at this time by one of these
engines, when on May 14, 1848, the Great Britain took this Bristol
express, consisting of four coaches and a van, to Didcot, fifty-three
miles, in forty-seven minutes, or at the average speed of sixty-eight
miles an hour. The maximum running speed was seventy-five miles an hour,
and the indicated horse-power 1,000. A class of engines corresponding to
this type in their general dimensions, but with 7 ft. coupled wheels, was
introduced on the line, but it was not found successful. Through the
courtesy of Mr. Dean, I am enabled to give a table showing the running
speeds and loads of the principal express trains, broad and narrow gauge,
to the West and North of England, run on the Great Western Railway.
_Great Western Railway.--Average Speed and Weight of Express
Trains._
------------------+---------------------------+----------------------
| Speed to first stopping |
| station. | Weight of train.
+-------+--------+---------+-------+---------+-----
| | | Average | | |
Train. | | | speed-- |Engine |Carriages|
| | |miles per| and |and vans,|
|Station|Distance| hour. |tender.| empty. |Total
------------------+-------+--------+---------+-------+---------+-----
| | miles | | tons. | tons. |
BROAD GAUGE TO WEST OF ENGLAND: | | | |
9.0 Paddington to |Reading| 36 | 47 | 67 | 149 | 216
Plymouth | | | | | |
11.45 do. |Swindon| 77¼ | 53 | 67 | 104 | 171
| | | | | |
NARROW GAUGE TO THE NORTH| | | | |
10.0 Paddington to|Reading| 36 | 39.2 | 60 | 190 | 250
Birkenhead | | | | | |
4.45 do. |Oxford | 63½ | 48.8 | 60 | 129 | 189
------------------+-------+--------+---------+-------+---------+-----
[Illustration: FIG 2.--GREAT WESTERN RAILWAY.]
The narrow gauge trains are worked by two classes of engines. The first is
a single engine with inside cylinders 18 in. diameter, 24 in. stroke. The
driving wheels are 7 ft. diameter, and the leading and trailing wheels 4
ft. The frames are double, giving outside bearings to the leading and
trailing axles, and outside and inside bearings to the driving axle; this
arrangement gives a very steady running engine, and insures, as far as can
possibly be done, safety in case of the fracture of a crank axle. The
frames are 15 inches deep, of BB Staffordshire iron. The wheel base is,
leading to driving wheels, 8 ft. 6 in; driving to trailing wheels, 9 ft.;
total, 17 ft. 6 in. The boiler is of Lowmoor iron, 10 ft. 6 in. long and 4
ft. 2 in. outside diameter. The grate area is 17 square feet, and the
heating surface is, tubes, 1,145½ square feet; fire-box 133 square feet;
total, 1,278½ square feet. The boiler pressure is 140 lb. on the square
inch, and the tractive power per lb. of mean pressure in cylinders, 92 lb.
The weight in full working order is, engine, leading wheel, 10 tons; ditto
driving wheels, 14 tons; ditto trailing wheels, 9 tons 10 cwt.; tender,
with 40 cwt. coal and 2,600 gals. water, 26 tons 10 cwt.; total, 60 tons.
These engines are extremely simple, but well proportioned, and are a very
handsome type, and their average consumption of coal, working trains
averaging ten coaches, is about 24.87 lb. per mile. The standard coupled
passenger express engine on the narrow gauge has inside cylinders 17 in.
diameter and 24 in. stroke; the coupled wheels are 6 ft. 6 in. diameter,
and the leading wheels 4 ft.; the wheel base is 16 ft. 9 in. The frames
are double, giving outside bearings to the leading axle, and inside
bearings to the coupled wheels. The boiler is 11 ft. long by 4 ft. 2 in.
diameter; the grate area is 16.25 square feet; and the heating surface is,
tubes, 1,216.5 square feet; fire-box, 97.0 square feet; total, 1,313.5
square feet. The boiler pressure is 140 lb., and the tractive power per
lb. of steam pressure in the cylinders, 88 lb. The weight in full working
order is on the leading wheels, 10 tons 5 cwt.; driving wheels, 11 tons;
trailing wheels, 9 tons 15 cwt.; total, 31 tons.
[Illustration: FIG. 3.--LONDON & NORTH-WESTERN RAILWAY.]
[Illustration: FIG. 4.--JOY'S VALVE GEAR.]
Turning now to the London and North-Western Railway, we find that between
1862 and 1865 the express trains were worked with a handsome type of
engines, known as the "Lady of the Lake" class. They have outside
cylinders 16 in. diameter and 24 in. stroke, with single driving wheels of
7 ft. 6 in. diameter, and leading and trailing wheels 3 ft. 6 in.
diameter, with a total wheel base of 15 ft. 5 in. The frames are single,
with inside bearings to all the wheels. The boiler is 11 ft. long and 4
ft. diameter, and the heating surface is in the tubes, 1,013 feet;
fire-box, 85 ft.; total, 1,098 feet. The tractive power per lb. of steam
pressure in the cylinders is 68 lb. The weight in full working order is on
the leading wheels, 9 tons 8 cwt.; driving wheels, 11 tons 10 cwt.;
trailing wheels, 6 tons 2 cwt.; total, 27 tons. The tender weighs 17½ tons
in working order. These engines burn about 27 lb. of coal per mile with
trains of the gross weight of 117 tons, which is not at all an economical
duty. About 1872, the weight of the heavier express trains on the
North-Western had so increased, that a new standard type for this service
was designed, and is now the standard passenger engine; it has inside
cylinders 17 in. diameter and 24 in. stroke; the driving and trailing
wheels are coupled, and are 6 ft. 6 in. diameter, and the leading wheels 3
ft. 6 in. The frames of steel are single, with inside bearings to all the
wheels, and the boiler, of steel, is 9 ft. 10 in. long and 4 ft. 2 in.
diameter. The steel used has a tensile strength of 32 to 34 tons per
square inch, all the rivets are put in by hydraulic pressure, and the
magnetic oxide on the surface of the plates where they overlap is washed
off by a little weak sal-ammoniac and water. In testing, steam is first
got up to 30 lb. on the square inch, the boiler is then allowed to cool,
it is then proved to 200 lb. with hydraulic pressure, and afterward to 160
lb. with steam. The fire-box is of copper, fitted with a fire brick arch
for coal burning, and the grate area is 15 square feet. The heating
surface is, in the tubes, 1,013 square feet; fire-box, 89 square feet;
total, 1,102 square feet. The wheel base is 15 ft. 8 in., and the tractive
power 88 lb. for each lb. of steam pressure in the cylinders. These
engines, working the fast passenger trains at a speed of about 45 miles
per hour, burn about 35 lb. of coal per mile, when taking trains weighing
about 230 tons gross. A variation from this type has been adopted on the
Northern and Welsh sections, known as the "Precursor" class. These engines
have 5 ft. 6 in. coupled wheels, and weigh 31 tons 8 cwt. in working
order, but in other respects are very similar to the standard engines just
described; with the Scotch express, averaging in total weight 187 tons,
between Crewe and Carlisle, over heavy gradients, they burn 33 lb. of coal
per mile. These engines, although much more powerful than the standard
type, are not nearly of so handsome an appearance, the drivers seeming
much too small for the boiler under which they are placed. But by far the
boldest innovation on existing practice is the new class of compound
locomotives now being introduced by Mr. Webb. It is a six wheel engine,
with leading wheels 4 ft. diameter, and two pairs of drivers, 6 ft. 6 in.
diameter. The trailing drivers are driven by a pair of outside cylinders,
18 in. diameter and 24 in. stroke; and the leading drivers by a single
low-pressure cylinder--which takes the exhaust steam from the
high-pressure cylinders--of 26 in. diameter and 24 in. stroke, placed
under the center of the smoke-box. The boiler is the same as that in the
standard type of engine, but the wheel base is 17 ft. 7 in., and in order
to allow it to traverse curves easily, the front axle is fitted with a
radial axle-box, which is in one casting from journal to journal, and
fitted at each end with brass steps for the bearings; the box is radial,
struck from the center of the rigid wheel base, and the horn plates are
curved to suit the box, the lateral motion being controlled by strong
springs. Another peculiarity of this engine is that, instead of the
ordinary link motion, it is fitted with Joy's valve gear, which is now
being more and more adopted. This gear--which is of a most ingenious
decription--dispenses altogether with eccentrics, and so allows the inside
bearings to be much increased, those on these engines being 13½ in. long;
and it is also claimed for it that it is simpler and less costly, weighs
less, and is more correct in its action than the ordinary link motion; the
friction is less, the working parts are simplified, it takes less oil,
and is well under the driver's eye. It also allows larger cylinders to be
got in between the frames of inside cylinder engines, as, the slide valves
may be placed on the top or bottom of the cylinders. This latter advantage
is a great one, as, with the ordinary link motion, large cylinders are
exceedingly difficult to design so as to get the requisite clear exhaust.
The action of the gear is as follows: A rod, a, is fixed by a pin at b, on
which it is free to turn, and is attached to a rod, c, at d, the other end
of which link is fastened to the connecting rod at e. At the point, f, in
this rod another lever, g, is connected to it, the upper end of which is
coupled to the valve rod, h, at i, and just below this point a second
connection is made to a block at j, sliding in a short curved piece, k.
The inclination of the block, k, governs the travel of the valve. The
total weight of the engine in working order is: On the leading wheels, 10
tons 8 cwt.; front drivers, 14 tons 4 cwt.; rear drivers, 13 tons 10 cwt.;
total, 37.75 tons. The tender weighs 25 tons in full working order. The
boiler pressure is 150 lb., and the usual point of cut-off in the high
pressure cylinders, when running at speed, is half-stroke, while the
pressure of steam admitted to the large cylinder is never to exceed 75 lb.
per square inch. The average consumption of coal between London and Crewe
is 26.6 lb. per train mile, or about 8 lb. per mile less than the standard
coupled engine. In an experiment made in October, 1883, one of these
engines took the Scotch express from Euston to Carlisle at an average
speed, between stations, of 44 miles an hour, the engine, tender, and
train weighing 230 tons, with a consumption of 29½ lb. of coal per mile,
and an evaporation of 8.5 lb. of water per pound of fuel.
Mr. Webb's object, in designing this engine was to secure in the first
place a greater economy of fuel, and secondly, to do away with coupling
rods, while at the same time obtaining greater adhesion, with the freedom
of a single engine. The cost is much more than an ordinary locomotive, but
the saving in fuel is said to be 20 per cent. over the other engines of
the North Western Rail way. These engines run very sweetly, and are said
to steam freely, although with only half the usual number of blasts; but
from the small size of the high pressure cylinders, they are liable to
slip when starting heavy trains, as the low pressure cylinders are not
then effective, while the consumption of coal does not seem to show the
saving that would have been expected, when compared with ordinary engines
doing similar duty on other lines; for instance, the Great Northern single
engine takes trains of the same weight with the same consumption of coal
and at a somewhat higher speed. But it must, of course, be borne in mind
in making such a comparison, that the fuel used may not be of the same
quality.
Mr. Stirling, of the Great Northern, has adopted an entirely different
type of engine to those last described. Holding strongly that single
engines are more economical not only in running, but in repairs, and that
cylinder power is generally inadequate to the adhesion, he has designed
his magnificent well-known class of express engines. They have single
driving wheels 8 ft. in diameter, with a four-wheel bogie in front and a
pair of trailing wheels, 4 ft. diameter, behind. The frames are single,
and inside of one solid piece; the cylinders are outside 18 in. diameter
and 28 in. stroke; and the valve gear is of the usual shifting link
description. The boiler is of Yorkshire plates, 11 ft. 5 in. long and 4
ft. diameter, and the steam pressure is 140 lb.; while the tractive power
per lb. of steam in the cylinders is 94 lb. The fire-box is of copper, and
the roof is stayed to the outer shell by wrought iron radiating stays
screwed into both; a sloping mid-feather is placed in the fire-box.
[Illustration: FIG. 5.--GREAT NORTHERN RAILWAY.]
The tubes, 217 in number, are of brass, 1-9/16 in. diameter; and the
heating surface is in the tubes, 1,043 square feet; fire-box, 122 square
feet; total, 1,165 square feet. The fire-grate area is 17.6 square feet.
The wheel base from the center of the bogie pin to the trailing axle is 19
ft. 5 in., and the weight in working order is, on the bogie wheels, 15
tons; driving wheels, 15 tons; trailing wheels, 8 tons; total, 38 tons.
The tender weighs 27 tons. These engines are remarkable for their
efficiency; the traffic of the Great Northern Railway is exceedingly
heavy, and the trains run at a high rate, the average speed of the Flying
Scotchman being fifty miles an hour, and no train in the kingdom keeps
better time. "Those who remember this express at York in the icy winter of
1879-80, when the few travelers who did not remain thawing themselves at
the waiting-room fires used to stamp up and down a sawdusted platform,
under a darkened roof, while day after day the train came gliding in from
Grantham with couplings like wool, icicles pendent from the carriage
eaves, and an air of punctual unconcern; or those who have known some of
our other equally sterling trains--these will hardly mind if friendship
does let them drift into exaggeration when speaking of expresses." The
author well remembers how, when living some years ago at
Newcastle-on-Tyne, it was often his custom to stroll on the platform of
the Central Station to watch the arrival of the Flying Scotchman, and as
the hands of the station clock marked seven minutes past four he would
turn around, and in nine cases out of ten the express was gliding into the
station, punctual to the minute after its run of 272 miles. Such results
speak for themselves, and for the power of the engines employed, and one
of the best runs on record was that of the special train, drawn by one of
these locomotives, which in 1880 took the Lord Mayor of London, to
Scarborough. The train consisted of six Great Northern coaches, and ran
the 188 miles to York in 217 minutes, including a stop of ten minutes at
Grantham, or at the average rate of 54½ miles an hour. The speed from
Grantham to York, 82½ miles, with three slowing downs at Retford,
Doncaster, and Selby, averaged 57 miles an hour, and the 59 miles from
Claypole, near Newark, to Selby, were run in 60½ minutes, and for 22½
consecutive miles the speed was 64 miles an hour. In ordinary working
these engines convey trains of sixteen to twenty-six coaches from
King's-Cross with ease, and often twenty-eight are taken and time kept.
Considering that the Great Northern main line rises almost continuously to
Potter's Bar, 13 miles, with gradients varying from 1 in 105 to 1 in 200,
this is a very high duty, while, with regard to speed, they have run with
sixteen coaches for 15 miles at the rate of 75 miles an hour. Their
consumption of coal with trains averaging sixteen ten ton carriages is 27
lb. per mile, or 8 lb. per mile less than the standard coupled engine of
the North-Western with similar loads. Mr. Stirling's view, that the larger
the wheel the better the adhesion, seems borne out of these facts; thus to
take twenty-eight coaches, or a gross load of 345 tons, up 1 in 200 at a
speed of 35 miles an hour, would require an adhesive force of 8,970 lb.,
or 600 lb. per ton--more than a quarter the weight on the driving wheels.
These engines are magnificent samples of the most powerful express engines
of the present day.
The London, Brighton, and South Coast Railway Company has in the last few
years had its locomotive stock almost entirely replaced, and instead of
seventy-two different varieties of engines out of a total of 233, which
was the state of locomotive stock in 1871. a small number of
well-considered types, suited to the different class of work required, are
now in use. Mr. Stroudley considers--contrary to the opinion once almost
universally held--that engines with a high center of gravity are the
safest to traverse curves at high speed, as the centrifugal force throws
the greatest weight on the outer wheels, and prevents their mounting; also
that the greatest weight should be on the leading wheels, and that there
is no objection to these wheels being of a much larger diameter than that
usually adopted; in fact, by coupling the leading and driving wheels where
the main weight is placed a lighter load is thrown on the trailing wheels,
thus enabling them to traverse curves at a high speed with safety, while
it permits of a larger fire-box being used; and these principles have been
carried out in the newest class of engines, especially designed for
working the heavy fast passenger traffic of the line.
The modern express engines are of two types. The first is a single engine
with 6 ft. 6 in. driving wheels, and leading and trailing wheels 4 ft. 6
in. in diameter and a wheel base of 15 ft. 9 in. The frames are single,
with inside bearings to all the wheels; the cylinders are inside, 17 in.
diameter and 24 in. stroke. The boiler is 10 ft. 2 in. long and 4 ft. 3
in. diameter; the fire-box is of copper with a fire-grate area of 17.8
square feet, and the heating surface is in the tubes 1,080 square feet,
fire-box 102 square feet; total, 1182 square feet. The weight in working
order is about 35 tons. These engines have a tractive power of 89 lb. per
pound of mean steam pressure in the cylinders, and their consumption of
coal with trains averaging nine coaches is about 20 lb. per mile. The next
type of engine designed has coupled wheels under the barrel of the boiler
6 ft. 6 in. diameter, with cylinders 17¼ in. diameter and 26 in. stroke,
and were found so successful that Mr. Stroudley designed a more powerful
engine of the same class, especially to take the heaviest fast trains in
all weathers.
The 8:45 A.M. train from Brighton has grown to be one of the heaviest fast
trains in the kingdom, although the distance it runs is but very short,
while it is also exceptional in consisting entirely of first class
coaches, and the passengers mainly season ticket holders; it often weighs
in the gross 350 tons, and to take this weight at a mean speed of
forty-five to fifty miles an hour over gradients of 1 in 264 is no light
work.
[Illustration: FIG. 6.--LONDON, BRIGHTON, AND SOUTH COAST RAILWAY.]
The engines known as the "Gladstone" type have inside cylinders 18¼ in.
diameter and 26 in. stroke, with coupled wheels 6 ft. 6 in. diameter under
the barrel of the boiler; the trailing wheels are 4 ft. 6 in. diameter,
and the total wheel base is 15 ft. 7 in. The frames are inside, of steel 1
in. thick, with inside bearings to all the axles. The cylinders are cast
in one piece 2 ft. 1 in. apart, but in order to get them so close together
the valves are placed below the cylinders, the leading axle coming between
the piston and slide valve. The boiler is of iron, 10 ft. 2 in. long, and
4 ft. 6 in. diameter; and the heating surface is, in the tubes, 1,373
square feet; fire-box, 112 square feet; total, 1,485 square feet. The
grate area is 20.65 square feet, and the tractive power per pound of mean
cylinder pressure is 111 lb. The weight in full working order is--leading
wheels, 13 tons 16 cwt.; driving wheels, 14 tons 10 cwt.; trailing wheels,
10 tons 8 cwt.; total, 38 tons 14 cwt. The tender weighs 27 tons.
To enable these engines to traverse curves easily a special arrangement of
draw-bar is used, consisting of a T-piece with a wheel at each end working
in a curved path in the back of the frame under the foot plate; on the
back buffer beam a curved plate abuts against a rubbing piece on the
tender, through which the draw-bar is passed and screwed up against an
India-rubber washer, thus allowing the engine to move free of the tender
as the curvature of the road road requires; the flanges on the driving
wheel are also cut away, so as not to touch the rail. In order to reduce
the wear of the leading flanges, a jet of steam from the exhaust is
directed against the outer side of each wheel. The center line of the
boiler is 7 ft. 5 in. above the rails, and the tubes, of which there are
as many as 331, are bent upward 1½ in., which permits expansion and
contraction to take place without starting the tubes, and they are stated
never to leak or give trouble. The feed-water is heated by a portion of
the exhaust steam and the exhaust from the Westinghouse brake, and the
boiler is consequently fed by pumps, is kept cleaner, and makes steam
better. The reversing gear is automatic and exceedingly ingenious, the
compressed air from the Westinghouse brake reservoir being employed to do
the heavy work. A cylinder 4½ in. diameter is fitted with a piston and
rod attached to the nut of the reversing screw, and a three-way cock
supplies the compressed air behind the piston; this forces the engine into
back gear, and by allowing the air to escape, the weight of the valve
motion puts the engine in forward gear. There are no balance weights, and
the screw regulates the movement. There is also a very ingenious speed
indicator, which consists of a small brass case filled with water, in
which is a small fan driven by a cord from the driving wheel; a copper
pipe leads from the fan case to a glass gauge tube; the faster the fan
runs the higher the water will stand in the tube, thus indicating the
speed.
The author has been led to describe this engine fully on account of the
numerous ingenious appliances which have been adopted in its design. In a
trial trip on October 3, 1883, from Brighton to London Bridge and back,
with an average load of 19½ coaches, or 285 tons gross, and with a speed
of 45 miles per hour, the consumption of coal was 31 lb. per train mile,
evaporating 8.45 lb. of water per pound of coal, and with as much as 1,100
indicated horse-power at one portion of the run. The finish and painting
of these engines is well considered, but the large coupled wheels give a
very high shouldered appearance, and as a type they are not nearly as
handsome as the single engines previously described.
From the Brighton to the South-Western Railway is but a step; but here a
totally different practice obtains to that adopted on most lines, all the
passenger engines having outside cylinders, where they are more exposed to
damage in case of accident, and, from being less protected, there is more
condensation of steam, while the width between the cylinders tends to make
an unsteady running engine at high speeds, unless the balancing is
perfect; but the costly crank axle, with its risk of fracture, is avoided,
and the center of gravity of the boiler may be consequently lowered, while
larger cylinders may be employed. On the other hand, inside cylinders are
well secured, protected, and kept hot in the smoke-box, thus minimizing
the condensation of steam. The steam ports are short, and the engine runs
steadier at high speeds, while with Joy's valve gear much larger cylinders
can be got in than with the link motion. Thus modern improvements have
minimized the advantages of the outside class.
The passenger engines for the fast traffic are of two types, the six-wheel
engines with 7 ft. coupled wheels, and the new bogie engines which are
being built to replace them. The former have 17 in. cylinders with 22 in.
stroke, and a pair of coupled wheels 7 ft. in diameter, the leading wheels
being 4 ft. diameter, and the wheel base 14 ft. 3 in. The grate area is
16.1 square feet, and the heating surface 1,141 square feet. The total
weight in working order is 33 tons. The chief peculiarity of this type of
engine consists in the boiler, which is fitted with a combustion chamber
stocked with perforated bricks, the tubes being only 5 ft. 4 in. long.
These engines are very expensive to build and maintain, owing to the
complicated character of the boiler and fire-box, but as a coal burning
engine there is no doubt the class was very efficient, but no more are
being built, and a new type has been substituted. This is an outside
cylinder bogie engine, with cylinders 18½ in. diameter and 26 in. stroke;
the driving and trailing coupled wheels are 6 ft. 6 in. diameter, and the
bogie wheels 3 ft. 3 in. The wheel base to the center of the bogie pin is
18 ft. 6 in.; the heating surface is, in the tubes, 1,112; fire box, 104;
total, 1,216 sq. ft. The weight of the engine in working order is 42 tons.
[Illustration: FIG. 7.--MIDLAND RAILWAY.]
The Midland Railway route to the North is distinguished by the heavy
nature of its gradients; between Settle and Carlisle, running through the
Cumberland hills, attaining a height of 1,170 ft. above sea level, the
highest point of any express route in the kingdom; and to work heavy fast
traffic over such a line necessitates the employment of coupled engines.
The standard express locomotive of this company has inside cylinders 18
in. in diameter and 26 in. stroke. The coupled wheels are 6 ft. 9 in.
diameter, and the leading wheels 4 ft. 3 in., the total wheel base being
16 ft. 6 in., and the tractive force 104 lb. for each lb. of mean cylinder
pressure. The boiler is of best Yorkshire iron, 10 ft. 4 in. long and 4
ft. 1 in. diameter. The grate area is 17.5 square feet, and the heating
surface is, in the tubes, 1,096; fire-box, 110; total, 1,206. There are
double frames to give outside bearings to the leading axle, as in the
Great Western engine, and the engine is fitted with a steam brake. The
weight in full working order is--leading wheels, 12 tons 2 cwt.; driving
wheels, 15 tons; trailing wheels, 11 tons 6 cwt.; total, 38 tons 8 cwt.
The tender weighs 26 tons 2 cwt., and holds 3,300 gallons of water and 5
tons of coal. Latterly a fine type of bogie express engine has been
introduced, with inside cylinders 18 in. diameter and 26 in. stroke, and
four coupled driving wheels 7 ft. diameter. The total wheel base to the
center of the bogie pin is 18 ft. 6 in. The grate area is 17.5 square
feet, and the heating surface is, in tubes, 1,203 square feet, and
fire-box, 110; total, 1,313; and the engine weighs 42 tons in working
order. These engines take fourteen coaches, or a gross load of 222 tons,
at 50 miles an hour over gradients of 1 in 120 to 1 in 130, with a
consumption of 28 lb. of coal per mile. The London, Chatham, and Dover
Company has also some fine engines of a similar type. They have inside
cylinders 17½ in. diameter and 26 in. stroke; the coupled wheels are 6 ft.
6 in. diameter, and the bogie wheels 3 ft. 6 in., the wheel base to the
center of the bogie pin being 18 ft. 2 in. The boiler is 10 ft. 2 in. long
and 4 ft. 2 in. diameter, the grate area is 16.3 square feet, and the
heating surface is, in the tubes, 962 square feet; fire-box, 107 square
feet; total, 1,069. The boiler pressure is 140 lb., and the tractive force
per lb. of steam in the cylinder 102 lb. The weight in full working order
is, on the bogie wheels, 15 tons 10 cwt.; driving wheels, 13 tons 10 cwt.;
trailing wheels, 13 tons; total, 42 tons.
Mr. Worsdell has lately designed for the Great Eastern Railway a fine type
of coupled express engine, which deserves mention. It has inside
cylinders 18 in. diameter and 24 in. stroke, with coupled wheels 7 ft.
diameter and leading wheels 4 ft. diameter, the latter being fitted with a
radial axle on a somewhat similar plan to that previously described as
adopted by Mr. Webb for the new North-Western engines; the frames are
single, with inside bearings to all the wheels, and Joy's valve gear is
used. The boiler pressure is 140 lb., and the tractive power per lb. of
mean cylinder pressure 92 lb. The total wheel base is 17 ft. 6 in. The
boiler, which is fed by two injectors, is of steel, 11 ft. 5 in. long and
4 ft. 2 in. diameter. The grate area is 17.3 square feet, and the heating
surface is, in the tubes, 1,083; fire-box, 117; total, 1,200 sq. ft. The
weight in working order is, on the leading wheels, 12 tons 19 cwt.;
driving wheels, 15 tons; trailing wheels, 13 tons 4 cwt.; total, 41 tons 3
cwt. These engines burn 27 lb. of coal per train mile with trains
averaging thirteen coaches. It has been seen that the Cheshire lines
express between Liverpool and Manchester is one of the fastest in England,
and the Manchester, Sheffield, and Lincolnshire Railway Company, who works
the trains, has just introduced a new class of engine specially for this
and other express trains on the line. The cylinders are outside, 17½ in.
diameter and 26 in. stroke, with single driving wheels 7 ft. 5 in.
diameter, the leading and trailing wheels being 3 ft. 8 in. diameter. The
total wheel base is 15 ft. 9 in., and the frames are double, giving
outside bearings to the leading and trailing axles, and inside bearings to
the driving axle. The boiler is 11 ft. 6 in. long and 3 ft. 11 in.
diameter, and the grate area is 17 square feet. The heating surface is in
the tubes 1,057 square feet; fire-box, 87 square feet; total, 1,144 square
feet. The tractive force per pound of mean cylinder pressure is 88.4 lb.
The weight in full working order is, on the leading wheels, 11 tons 3
cwt.; driving wheels, 17 tons 11 cwt.; trailing wheels, 11 tons 18 cwt.;
total, 40 tons 12 cwt. This engine is remarkable for the great weight
thrown on the driving wheels, and its cylinder power is great in
proportion to its adhesion, thus allowing the steam to be worked at a high
rate of expansion, which is most favorable to the economical consumption
of fuel. There are numerous fine engines running on other lines, such as
the new bogie locomotives on the North-Eastern and Lancashire and
Yorkshire railways, and the coupled express engines on the Caledonian; but
those already described represent fairly the lending features of modern
practice, and the author will now notice briefly the two other classes of
engines--tank passenger engines for suburban and local traffic and goods
engines. The Brighton tank passenger engine is a good example of the
former class; it has inside cylinders 17 in. diameter and 24 in. stroke.
The two coupled wheels under the barrel of the boiler are 5 ft. 6 in.
diameter, and the trailing wheels 4 ft. 6 in.; there are single frames
with inside bearings to all the axles. The boiler pressure is 140 lb., and
the tractive force per pound of mean cylinder pressure 106 lb.; the total
wheel base is 14 ft. 6 in. The boiler is 10 ft. 2 in. long and 4 ft. 4 in.
diameter, and the heating surface is in the tubes, 858 square feet;
fire-box, 90 square feet; total, 948 square feet. The engine is furnished
with wing tanks holding 860 gallons of water, and carries 30 cwt. of coal.
The weight in working order is 38 tons. These engines have taken a maximum
load of twenty-five coaches between London and Brighton, but are mainly
employed in working the suburban and branch line traffic; their average
consumption of coal is 23.5 lb. per mile, with trains averaging about ten
coaches.
Another example is Mr. Webb's tank engine on the North-Western Railway,
which presents a contrast to the foregoing. It has inside cylinders 17 in.
diameter and 20 in. stroke, coupled wheels 4 ft. 6 in. diameter, and a
tractive power per lb. of mean cylinder pressure of 107 lb.; the wheel
base is 14 ft. 6 in. with a radial box to the leading axle; the heating
surface is in the tubes, 887; fire-box, 84; total, 971 square feet; the
weight in working order is 35 tons 15 cwt. The engine is fitted with
Webb's hydraulic brake, and steel, manufactured at Crewe, is largely used
in its construction. The consumption of coal-working fast passenger trains
has been 28½ lb. per mile. There are many other types, such as the ten
wheel bogie tank engines of the London, Tilbury, and Southend and
South-Western railways; the saddle tank bogie engines, working the broad
gauge trains on the Great Western Railway, west of Newton; and the
familiar class working the Metropolitan and North London traffic. But the
same principle is adopted in nearly all--a flexible wheel base to enable
them to traverse sharp curves, small driving wheels coupled for adhesion,
and wing or saddle tanks to take the water. One notable exception is,
however, the little six wheel all-coupled engines weighing only 24 tons,
which work the South London traffic, burning 24¼ lb. of coal per mile,
with an average load of eleven coaches.
Goods engines on all lines do not vary much. As a rule they are six wheel
all-coupled engines, with generally 5 ft. wheels, and cylinders varying
between 17 in. and 18 in. diameter and 24 in. to 26 in. stroke; the grate
area is about 17 square feet, and the total heating surface from 1,000 to
1,200 sq. ft.; the average weight in full working order varies from 30 to
38 tons. One noteworthy exception occurs, however, on the Great Eastern
Railway, where a type of goods engine with a pony truck in front has been
introduced. The cylinders are outside 19 in. diameter and 26 in. stroke,
there are six coupled wheels 4 ft. 10 in. diameter, and the pony truck
wheels are 2 ft. 10 in. diameter; the total wheel wheel base is 23 ft. 2
in., but there are no flanges on the driving wheels. The boiler is 11 ft.
5 in. long and 4 ft. 5 in. diameter, the boiler pressure is 140 lb., and
the tractive force per lb. of mean cylinder pressure 162 lb.; the grate
area is 18.3 square feet, and the heating surface is in the tubes, 1,334
square feet; fire-box, 122 square feet; total, 1,456 square feet.
The weight in working order is on the pony truck, 8 tons 10 cwt.; leading
coupled, 12 tons 8 cwt.; driving coupled, 13 tons 5 cwt.; trailing
coupled, 12 tons 15 cwt.; total, 47 tons.
The tender weighs 28 tons in full working order. These engines take 40
loaded coal trucks or sixty empty ones, and burn 52 lb. of coal per train
mile, the worst gradient being 1 in 176. A notice of goods engines would
not be complete without alluding to a steep gradient locomotive, and a
good example is the engine which works the Redheugh Bank on the
North-Eastern Railway. This incline is 1,040 yards long, and rises for 570
yards 1 in 33, then for 260 yards 1 in 21.7, for 200 yards 1 in 25, and
finally for 110 yards 1 in 27. The engine, which is an all-coupled six
wheel tank engine, weighs 48½ tons in working order, it has cylinders 18
in. diameter and 24 in. stroke, and 4 ft. wheels, the boiler pressure is
160 lb., and the tractive force per lb. of mean steam pressure in the
cylinders is 162 lb. This engine will take up the incline twenty-six coal
wagons, or a gross load of 218 tons, which is a very good duty indeed.
Having now passed in review the general types of engines adopted in modern
English practice, the author would briefly draw attention to some points
of design and some improvements effected in late years. And first, as to
the question of single or coupled engines, there is a great diversity of
opinion. Mr. Stirling conducts his traffic at a higher rate of speed, and
certainly with equal punctuality, with his magnificent single 8 ft.
engines, as Mr. Webb on the North-Western with coupled engines, and the
economy of fuel of the former class over the latter is very remarkable;
this is, no doubt, owing, as has been previously pointed out, to their
ample cylinder power, which permits of the steam being worked at a high
rate of expansion. There is no doubt that if single engines can take the
load they will do so more freely and at a less cost than coupled engines,
burning on the average 2 lb. of coal per mile less with similar trains.
With, regard to loads, it is a question whether any express train should
be made up with more than twenty-five coaches. The Great Northern engine
will take twenty-six and keep time, and the Brighton single engine has
taken the five P.M. express from London Bridge to Brighton, consisting of
twenty-two coaches, at a speed of forty-five miles per hour. Of course
where heavy gradients have to be surmounted, such as those on the Midland
route to Scotland, coupled engines are a necessity. Single engines are
said to slip more than coupled; thus an 8 ft. single Great Northern engine
running down the incline from Potter's Bar to Wood Green with twelve
coaches at the rate of sixty miles an hour was found to be making 242
revolutions per mile instead of 210; and in an experiment tried on the
Midland Railway it was found that a coupled engine with ten coaches at
fifty miles an hour made seventeen extra revolutions a mile, but when the
side rods were removed it made forty-three. The Great Western, Great
Northern, and Brighton mainly employ single engines for their fast
traffic; and the Manchester, Sheffield, and Lincolnshire have now adopted
the single type in preference to the coupled for their express trains;
while the North-Western, Midland, South-Western, and Chatham adopted the
coupled type. One noticeable feature in modern practice is the increased
height of the center line of boiler; formerly it was the great aim to keep
this low, and numerous schemes to this effect were propounded, but now it
has become generally recognized that a high pitched engine will travel as
steadily and more safely round a curve--given a good road--than a low
pitched one; and thus while in 1850 the average height of the center line
of boilers varied between 5 ft. 3 in. and 6 ft. 3 in., now in the latest
designs it lies between 7 ft. and 7 ft. 6 in. Single frames are very
generally adopted, but double frames and outside bearings to the leading
and trailing wheels, as in the Great Western engines, give great
steadiness in running, and this class has also double bearings to the
driving wheels, thus entailing greater security in case of the facture of
a crank axle. The general adoption of cabs on the foot-plate for the men
is another improvement of late introduction, although at first not
universally appreciated by those for whose comfort it was designed--"I
felt as if I was in my coffin," said an old driver when asked how he liked
the new shelter. Mild steel fire-boxes, which have been employed in
America, are not in favor here, copper being universally used; they have
been tried on the Caledonian, Great Southern and Western, North London,
and North-Western, and were found not to succeed. Brake blocks of cast
iron have now generally superseded wood; steel is being more and more
used, especially on the North Western. There is less use of brasswork for
domes and fittings, although it is claimed for brass that it looks
brighter and can easily be kept clean. There is greater simplicity of
design generally, and the universal substitution of coal as coke for fuel,
with its consequent economy; and last, but not least, the adoption of
standard types of engines, are among the changes which have taken place in
locomotive practice during the past quarter of a century.
[Illustration: FIG. 8.--LONDON, CHATHAM, & DOVER RAILWAY.]
[Illustration: FIG. 9.--GREAT EASTERN RAILWAY.]
[Illustration: FIG. 10.--MANCHESTER, SHEFFIELD, AND LINCOLNSHIRE RAILWAY.]
Having now reviewed, as far as the limits of this paper will allow, the
locomotive practice of the present day, the author would in conclusion
draw attention to what may possibly be one course of locomotive
development in the future. Time is money, and it may be in the coming
years that a demand will arise for faster means of transit than that which
we possess at present. How can we meet it? With our railways laid out with
the curves and gradients existing, and with our national gauge, and our
present type of locomotive, no great advance in speed is very probable;
the mean speed of express trains is about fifty miles an hour, and to take
an average train of 200 tons weight at this speed over a level line
requires between 650 and 700 effective horse-power, within the compass of
the best engines of the present day. But if instead of fifty miles an hour
seventy is required, an entirely different state of things obtains. Taking
a train of 100 tons, with engine and tender weighing 75 tons, or 175 tons
gross, the first question to determine will be the train resistance, and
with reference to this we much want careful experiments on the subject,
like those which Sir Daniel Gooch made in 1848, on the Bristol and Exeter
Railway, which are even now the standard authority; the general use of oil
axle-boxes and long bogie coaches, irrespective of other improvements,
would render this course desirable. With regard to the former, they appear
to run with less friction, but are heavier to start, oil boxes in some
experiments made on the South-Western Railway giving a resistance of 2.5
lb. per ton, while grease boxes ranged from 6 lb. to 9 lb. per ton. Again,
the long and heavy bogie Pullman and other coaches have the reputation
among drivers, rightly or wrongly, of being hard to pull. The resistance
of an express train on the Great Western Railway at seventy-five miles an
hour was 42 lb. per ton, and taking 40 lb. per ton for seventy miles an
hour would give a total resistance on the level of 7,000 lb.,
corresponding to 1,400 horse-power--about double the average duty of an
express engine of the present day. The weight on the driving wheels
required would be 18¾ tons, allowing one-sixth for adhesion, about the
same as that on the driving axle of the Bristol and Exeter old bogie
engines. Allowing 2½ lb. of coal per horse-power per hour would give a
total combustion of 3,500 lb. per hour and to burn this even at the
maximum economic rate of 85 lb. per square foot of grate per hour would
require a grate area of 41 square feet, and about 2,800 square feet of
heating surface. Unless a most exceptional construction combined with
small wheels is adopted, it appears almost impossible to get this amount
on the ordinary gauge. It is true the Wootten locomotives on the
Philadelphia and Reading Railway have fire-boxes with a grate area of as
much as 76 square feet, but these boxes extend clean over the wheels, and
the heating surface in the tubes is only 982 square feet; but although
these engines run at a speed of forty-two miles an hour, they are hardly
the type to be adopted for such a service as is being considered. On the
broad gauge, however, such an engine could easily be designed on the lines
now recognized as being essential for express engines without introducing
any exceptional construction, and there appears but little doubt that were
Brunei's magnificent gauge the national one, competition would have
introduced a higher rate of speed between London and our great towns than
that which obtains at present.
The whole question of the future introduction of trunk lines, exclusively
for fast passenger traffic, is fraught with the highest interest, but it
would be foreign to the subject matter of this paper to enter more fully
on it, the author merely desiring to state his opinion that if the future
trade and wealth of our country require their construction, and if a very
high rate of speed much above our present is to be attained, their gauge
will have to be seriously considered and settled, not by the reasons which
caused the adoption of the present gauge, but by the power required to
carry on the traffic--in fact, to adapt the rail to the engine, and not,
as at present, the engine to the rail. High speed requires great power,
and great power can only be obtained by ample fire-grate area, which for a
steady running engine means a broad gauge. The Gauge Commissioners of 1846
in their report esteemed the importance of the highest speed on express
trains for the accommodation of a comparatively small number of persons,
however desirable that may be to them, as of far less moment than
affording increased convenience to the general commercial traffic of the
country. The commercial traffic of England has grown and prospered under
our present system, and if its ever increasing importance demands high
speed passenger lines, we may rest assured that the ingenuity of man, to
which it is impossible to assign limits, will satisfactorily solve the
problem.
* * * * *