CERTAIN IMPROVEMENTS IN STEAM ENGINES
Year: 1848

page_text: GEORGE ARMSTRONG, of Newcastle-upon-Tyne, Esquire, F.R.S., send greeting.
WHEREAS, Her present most Gracious Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Second day of December, in the twelfth year of Her reign, did,
for Herself, Her heirs, and successors, give and grant unto me, the said
William George Armstrong, my exors, admors, and assigns, Her special
license, full power, sole privilege and authority, that I, the said William
George Armstrong, my exors, adñiors, and assigns, or such others as I, the
said William George Armstrong, my exors, adñiors, or assigns, should at any
time agree with, and no others, from time to time, and at all times thereafter,
during the term of years therein expressed, should and lawfully might make,
use, exercise, and vend, within England and Wales, and the Town of Berwick-
upon-Tweed, my Invention of "CERTAIN IMPROVEMENTS IN STEAM ENGINES;" in
which said Letters Patent is contained a proviso obliging me, the said William
George Armstrong, by an instrument in writing under my hand and seal,
particularly to describe and ascertain the nature of my said Invention and in
what manner the same is to be performed, and to cause the same to be
enrolled in Her Majesty's High Court of Chancery within six calendar months
next and immediately after the date of the said in part recited Letters Patent
as in and by the same, reference being thereunto had, will more fully and at
large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
William George Armstrong, do hereby declare that the nature of my said
Invention consists partly of improvements applicable to steam engines in
general, and partly of improvements applicable in particular to locomotive
steam engines adapted to run upon railways. And, I further declare that such
of my said improvements as are applicable to steam engines in general, consist
of,-
Firstly, a means of maintaining an equality of pressure between the steam
acting in the cylinder of a steam engine and the steam lodged in the cavities
of the piston so as to prevent the packing rings from being acted upon by
a force alternately tending to thrust them inwards and press them unduly
outwards; and, secondly, a means of preventing injurious shocks upon the
pistons, cranks, and cylinder covers of steam engines in consequence of water
lodging in the cylinders.
And, further, I declare that such of the said improvements as apply in
particular to locomotive steam engines adapted for railways, consist of, firstly,
the application to such engines of certain varieties of that description of boiler
in which the flues consist of small tubes placed in an upright position, and
which description of boiler I designate an upright tubular boiler; secondly, an
improved mode of collecting the steam in upright tubular boil, as applied to
such engines; and, thirdly, improvements in the arrangement and construction
of various parts of such engines, and in the mode of producing draught through
the fire used therein; but I only claim the improvements comprised under this
third head when the same are applied in combination with upright tubular
boilers. And in further compliance with the said proviso, I, the said William
George Armstrong, do hereby describe the manner in which my said Invention
is to be performed, by the following statement thereof, reference being had to
the Drawings annexed, and to the figures and letters marked thereon; and,
first, I will give a general description of the Drawings..
Figure 1 represents a side view of a locomotive steam engine embracing
the several improvements above referred to, as well such as are applicable to
steam engines in general, as those which apply to locomotive engines in par-
ticular; Figure 2 is a plan of the same, having a portion of the platform or
footboard removed, so as to shew the machinery beneath; Figure 3 is a front
view of the engine; and Figure 4 is a back view of the same. It will be
observed from a general inspection of these Drawings that the boiler, which is
of the upright tubular description, is placed behind the driving wheels, and
that the cylinders are placed at the forward extremity of the engine, the inter-

page_text: mediate space being covered by al platform, which protects the machinery
beneath and serves as a convenient standing place for the engine driver. In
this platform are contained doors or hatches, by lifting which complete access
can be had to all the machinery beneath, whether the engine be standing or
running. The platform projects beyond the sides of the engine, so as to
afford a free passage round the boiler to the tender and the back of the engine.
The cylinders are placed horizontally, and are cast in one piece, so as to bring
them and the centres of the driving cranks as near as possible to the centre
line of the engine. The slide valves are of that description known as piston
valves, by which very spacious steam ports are attainable with a small amount
of friction. The waste steam from the cylinders, instead of being applied, as is
usual, to produce a draught of air in the chimney, at the expense of a con-
siderable back pressure upou the pistons, is discharged through a free vent
and is applied to heating the feed water in its course to the boiler. The boiler
has two chimneys in order to afford an air passage commensurate with the
sectional area of the tubes, which is much larger than can be obtained in the
ordinary construction of engine. A jet of steam supplied direct from the
boiler is projected into each chimney for the purpose of exciting the draught,
and a cock is provided to regulate the force thereof, and to shut off the same
when the action of the jets is not required. The boiler is of a quadrangular
form, and the opposite sides are supported against the pressure of the steam
by stays which pass through spaces between the tubes. This form of
boiler it will be observed, admits of the insertion of a much larger number of
tubes than it is possible to introduce where the form is cylindrical, or such as
not to require the use of transverse stays. The upper part of the boiler is
expanded in width in order to afford additional room for steam, and the
following means are adopted to lessen the liability to what is technically
termed "priming," viz*:-
Firstly, the steam is drawn off by two collectors, occupying those two
angles of the boiler which are least liable to be reached by the ebullition, and
is admitted into each collector through a narrow opening extending from end
to end thereof, so as to distribute the gathering up of the steam over an
extended surface of water.
Secondly, a steam receiver or "equalizing chamber," as it is herein-after
designated, communicating with the boiler on the one side, and the cylinders
on the other, is placed on the under side of the engine. The object of this
chamber is to correct or lessen the tendency to priming, which the irregular
draught of steam to the cylinders is liable to produce when the supply is taken

page_text: direct from the boiler, and its operation in neutralizing inequalities in the flow
of steam from the boiler is in a great measure analogous to that of an air
vessel in equalizing an irregular flow of water through a pipe. It alternately
supplies a deficiency of steam and accumulates a surplus as the draught to the
cylinders at each successive instant exceeds or falls short of the average flow,
and thus an equable discharge of steam is maintained from the boiler. To
produce this effect, it is necessary, however, slightly to throttle the steam prior
to its entering the equalizing chamber; and this may be done to any desired
extent by means of the regulating valve which governs the admission of steam
to the engine, and which is placed upon the steam pipe between the equalizing
chamber and the boiler. The eccentrics, the feed pumps, and the slot links
for reversing the engine and regulating the expansive action of the steam are
all placed outside of the frame of the engine, and the motion of the eccentrics
is communicated to the valve spindles by means of levers and arbors.
Instead of the customary mode of lifting and lowering the links by means of
a lever, a screw motion is used which is more precise and powerful in its action
than the lever.
Having thus described the general features of the engine, I shall now pro-
ceed to describe in detail those parts of the same which require to be further
explained. Note. That in the following description, similar letters are used to
denote similar parts in all the Figures. Referring to Figure 1, on Sheet No. 1
of the Drawings, Figure 2, on Sheet No. 2, and Figures 3 and 4, on Sheet
No. 3, A is the boiler; B, the pipe by which the steam is conveyed to the
equalizing chamber; C, the regulating valve; D, the lever for working the
same; E, the equalizing chamber; F, F, the cylinders; G, G, the piston
slide valves, for opening and shutting the induction and eduction passages of the
cylinders; H is a cylindrical vessel, through which the water from the feed
pumps is passed on its way to the boiler and where it is heated by contact with
tubes conveying the waste steam from the cylinders into the funnel I. The
eccentrics for working the feed pumps and slide valves are fixed upon the ends
of the driving axle, as shewn in Figures 1 and 2. J is the feed pump
belonging to one side of the engine; K, K, are the pipes for conveying the
cold water from the pumps into the heating chamber H; and L is the pipe
for conveying the heated water from the same to the boiler. The eccentrics,
the pumps, and the valve gear are the same on both sides of the engine, but
the Drawings only shew them on one side. M is the handle for working the
screw by which the slot links are lifted or lowered; N, N, are two tubes con-
nected with the boiler for the purpose of forming still water receptacles, in

page_text: which the sediment of the water will, upon known principles, be collected.
These sediment collectors are attached to the boiler in a manner to be easily
removed for the purpose of being emptied of the deposit formed therein; but
they may in a great measure be kept clear of such deposit by occasionally
blowing off a little water through them. 0, 0, 0, 0, is the platform or foot-
board, which descends in steps at the back end of the engine, and at each side
thereof, to the level at which the fire door P is reached. In Figure 4 the
steps are omitted to avoid concealing the parts beneath. Q, Q, are the
driving cranks; R, R, are the connecting rods between the cranks and the
piston rods; S is the slot link appertaining to the eccentrics seen on one side
of the engine; T is a cranked lever connected with the sliding piece within
the link, and communicating motion through the arbor U to the lever V,
which works the valve spindle to which it is shewn as connected; W is the
arbor, to the opposite ends of which are affixed the levers for lifting and
lowering the slot links; X, X, is a casing (shewn in plan in Figure 2, and
in section in Figure 1), which encloses the cylinders, the valves, and the
vessel for heating the feed water. The safety valves, steam whistle, and water
guage are all placed at the front end of the boiler, the latter being shewn
at Y in Figure 2, but not seen in the other Drawings on the Sheets now
under description. Z is the steam pipe communicating between the equalizing
chamber and the cylinders.
Figure 5, on Sheet No. 3, is a section through the screw apparatus for
lifting and lowering the slot links. a is the screw spindle, having a collar and
nut at the lower end, to prevent an upward or downward motion in the
spindle; is a fork-ended lever, fixed upon the arbor W, to which is also
affixed the lever from which the slot links are suspended. The lever b, being
double ended, is connected by a link on each side of the screw spindle with
a nut worked by the screw, which is prevented from turning round by the
guide piece c. By turning the spindle, therefore, the nut is screwed upwards
or downwards, and thus motion is communication to the lever b, and thence by
the arbor W to the lever from which the slot links are suspended. d, d, are
small toothed wheels, for the purpose of communicating a slower motion from
the spindle to an index pointer fixed upon a hollow axis, within which the
screw spindle is contained. This pointer traverses an index plate upon the
top of the pillar e, and denotes the extent to which the screw spindle must be
turned in either direction to produce the desired effect upon the slide valves.
The Figures from 6 to 14, both inclusive, will be found on Sheet No. 4.
Figure 6 represents a vertical longitudinal section passing through the boiler

page_text: and equalizing chamber between the two cylinders, and through the vessel for
heating the feed water. Figure 7 is a plan of the same, shewing the boiler
with the top plate removed, and Figure 8 is a vertical transverse section
through the boiler and one of the chimneys. f is the fire-box; g, g, the
tubular flues, placed vertically, and having stays passing between them to
support the opposite sides of the boiler; h is a pipe from the boiler for
supplying two jets of steam projected from the points i, i, into the chimneys
j,j, for the purpose of producing an increased draught of air through the fire,
to which pipe a cock is affixed for stopping the jets or regulating their force;
k, k, are annular plates, which turn upon a spindle, so as to admit of being
placed either vertically or horizontally. When these plates are in a vertical
plane they present no material impediment to the natural draught through the
fire, and when placed horizontally they give increased effect to the steam jets
by contracting at the points where they are placed, the sectional area of the
chimneys, and preventing a return current of air down the same. These
annular plates are seen in section in Figures 6 and 8, and in plan in Figure 9.
Where a more powerful draught is required than can be advantageously
obtained by one jet in each chimney, a second jet may be employed near the
top of the chimney, which will greatly aid the operation of that below.
1, l, are dampers, to be used when necessary to deaden the fire; m, m,
are the steam collectors, occupying the two side angles at the top of the
boiler, and into each of which the steam is admitted through a narrow
opening between the roof of the boiler and the upper edge of the plate
forming the collectors. These openings extend from end to end of the
collectors, and by their means the stean is drawn off at the highest attainable
level; along each side of the boiler n, is the steam course connecting the two
collectors with the steam pipe B. This form of boiler may be varied by
increasing the length as well as breadth of the boiler in the upper part,
and the collectors may be carried all round the boiler, or along any one or
more of the upper angles thereof. Figure 10 is an end view of the engine
cylinders, the valve cylinders, and the chamber o which connects the escape
passages of the valve cylinders with the vessel for heating the feed water, the
whole forming a connected group cletached from the engine frame. Figure 11
embraces on the one hand a section through the middle of one of the cylinders
and slide valves, shewing the course p, p, pursued by the steam into the valve
cylinder through a belt cast upon the engine cylinder, and represents on the
other side a section through one of the exhaust passages of the slide valve into
the chamber o, communicating with the vessel for heating the feed water.

page_text: Figure 12 is a longitudinal section cutting the axis of one of the engine
cylinders and its connected valve cylinder; 7, 9, are the steam ports having the
piston slides shewn upon them by dotted lines; the passages from the valve
ports to the cylinders are contained in belts formed round the valve cylinders,
the exterior of one of these belts is shewn at r, (Figure 11) and sections of
the interior at the most contracted points may be seen at r, r, (Figure 12);
s, 8, are the passages which conduct the exhaust steam from the valve ports to
the chamber o. The action of these valves may be explained as follows:-
The steam entering the valve cylinders between the two pistons presses
equally upon each and maintains an equilibrium between them. The pistons
are fixtures upon the spindle t, t, and when they are caused to slide backwards
and forwards by the action of the eccentrics, they alternately open the steam
ports to the pressure and to the exhaust sides of the pistons. The packing of
the valve pistons consists of a single metallic ring pressed out by steel springs
behind, and having an intercepting tongue piece where the ring is cut to
prevent a passage of steam at that point; u, u, arc what I term "relief
valves," the purpose of which is to relieve the engine from strains and shocks
in consequence of water lodging in the cylinders. Each valve consists of a
clack or falling lid, which in its natural condition is kept shut by the pressure
of the steam acting upon its upper side through the connecting passage v; but
in the event of water lodging in the cylinder and filling a larger space than the
steam passage and clearance room at each end of the stroke, then the excess
will force its way back into the valve cylinder without any violence to the engine,
inasmuch as it will only meet with a resistance equal to the pressure of the
steam. The true position of these relief valves may be seen in Figures 10
and 11, but in Figure 12 they are shewn as brought a little forward, in order
to bring them into a position where they could be more clearly delineated.
Figure 13 represents a section, and Figure 14 a plan, of the piston used in
the engine cylinders; w, w, are the packing rings, having circular steel springs
behind them to press them out; a, a, is a cylindrical passage through the
piston; and y is a ball clack which closes the passage against the escape of
steam through the piston but maintains a communication between the steam
acting on either side of the piston and the back of the packing rings contained
within it. The object of this provision is to effect a constant equilibrium
between the steam acting in the cylinders and the steam which must under any
circumstances find admission into the cavities of the piston, for without such a
provision there must necessarily be a continual tendency either for the springs
to be thrust inwards when the pressure in the cylinder is in excess, or to be

page_text: pressed outwards with an undue force when the pent-up steam in the piston
attains the ascendency, which it must always do when the pressure of the
steam in the cylinder diminishes by expansive action.
Figure 15, on Sheet No. 5, is an elevation of an upright tubular boiler of a
cylindrical form, which I propose to apply to locomotive engines of a lighter
class than those to which the quadrangular form of boiler would be adapted.
Figure 16 is a vertical section, and Figure 17 a plan of the same, with the
top plate of the boiler removed. The upper part of this boiler is expanded all
round to a larger diameter than the lower part in order to increase the steam
room, and the steam is drawn off into a circular collector occupying the
angular space at the top, and constructed upon the same principle as the
steam collectors already described in connection with the quadrangular form
of boiler.
Having now described the nature of my Invention, and the manner in
which the same is to be performed, I hereby declare that what I claim as my
Invention, and as constituting my improvements in steam engines so far as the
same apply to steam engines in general, are as follow:-
Firstly, the application to a steam engine piston of a ball, clack, or other
valve of the like nature, for the purpose of opening a passage, as herein-
before described, between the interior of the piston and the steam acting in the
cylinder on either side of the piston, so as to prevent the steam in the cylinder
from thrusting back the packing rings, or the steam contained in the piston
from pressing out the same with undue force against the sides of the cylinder.
Secondly, the application of the "relief valve," herein-before described, to
the passages of a steam engine cylinder, for the purpose of preventing
injurious shocks upon the piston and the cylinder covers in the event of a
larger quantity of water lodging in the cylinder than the steam passage and
clearance space at each end of the stroke will contain.
And I hereby further declare, that what I claim as my Invention, and as
constituting my improvements in steam engines, so far as the same relate to
locomotive steam engines adapted for railways, consist of,-
Firstly, the application to such engines of upright tubular boilers of forms
other than cylindrical, having their sides supported by stays passing from side
to side through spaces between the tubes, by which means the said boilers may
be sufficiently strengthened to allow of their being used of a quadrangular or
other form, affording a larger space for the insertion of tubes than is attain-
able where the form is cylindrical, or such as not to require the use of such
stays.

page_text: Secondly, the application to such engines of upright tubular boilers having
the upper part widened beyond the limits imposed in the lower part, by the
restricted space between the side frames and wheels of the engine, so as to
obtain additional room for steam.
Thirdly, the employment of what I have termed "steam collectors" in the
angular space formed between the top and side plates of upright tubular
boilers, as applied to such engines, in order to gather the steam over an
extended space, and as much as possible beyond the reach of the ebullition.
Fourthly, the application to such engines of what I have designated an
"equalizing chamber," for the purpose of neutralizing irregularity in the
draught of steam from the boiler to the cylinders, and thereby preventing or
lessening the tendency to priming which arises from such irregularity.
And I also further claim the improvements embraced under the following
heads as constituting part of my said Invention, so far as the same relate to
locomotive steam engines adapted for railways; but I only claim the same
when applied in combination with upright tubular boilers :-
Firstly, the placing of the driving cranks between the boiler and the
cylinders.
Secondly, the production of the necessary draught of air through the fire by
a jet or jets of steam supplied direct from the boiler, and projected into the
chimney or chimneys in the direction of the current of air.
Thirdly, the employment of the exhausted steam from the cylinders to heat
the feed water in its course to the boiler.
.
Fourthly, the employment of piston slide valves for the purpose of alter-
nately opening and shutting the induction and eduction passages of the
cylinders.
Fifthly, the casting of the two engine cylinders in one piece.
Sixthly, the employment of a screw power, for the purpose of lifting. and
lowering the slot links.
Seventhly, the employment of closed vessels, fixed externally to the boiler,
and communicating with the interior thereof, for the purpose of forming still
water receptacles, in which a large portion of the sediment, which would
otherwise be thrown down in the boiler, may be collected.
And such my Invention being, to the best of my knowledge and belief,
entirely new, and never before used within that part of Her said Majesty's
United Kingdom of Great Britain and Ireland called England, Her Dominion
of Wales, or Town of Berwick-upon-Tweed, I do hereby declare this to
be my Specification of the same, and that I do verily believe this my said

page_text: Specification doth comply in all respects fully and without reserve or disguise
with the proviso in the said herein-before in part recited Letters Patent
contained; wherefore I hereby claim to maintain exclusive-right and privi-
lege to my said Invention.
Specification doth comply in all respects fully and without reserve or disguise
with the proviso in the said herein-before in part recited Letters Patent
contained; wherefore I hereby claim to maintain exclusive-right and privi-
lege to my said Invention.
in witness whereof, 1, the said William George Armstrong have here-
unto set my hand and seal, the twenty-sixth day of May, in the year
Que thousand sight hundred and forty-nine
Signed, sealed, and delivered, (being first
duly stamped) by the within named
William George Armstrong, in the
presence of
W. G. (L.S.) ARMSTRONG.
AND BE IT REMEMBERED, that on the Twenty-sixth day of May, in
the year of our Lord 1849, the aforesaid William George Armstrong came
before our said Lady the Queen in Her Chancery and acknowledged the
Specification aforesaid, and all and everything therein contained and specified
in form above written. And also the Specification aforesaid was stamped
according to the tenor of the Statute made for that purpose.
Enrolled the Second day of June, in the year of our Lord One thousand
eight hundred and forty-nine.