AN IMPROVEMENT LOCOMOTIVE STEAM ENGINES
Year: 1846

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, we, GEORGE
STEPHENSON, of Tapton House, Chesterfield, in the County of Derby, Engineer,
and WILLIAM HOWE, of Newcastle-upon-Tyne, in the County of Northumber-
land, Mechanic, send greeting.
ALI
WHEREAS we did, by Petition, humbly represent unto Her present most
Excellent Majesty Queen Victoria, that we had invented "AN IMPROVEMENT
LOCOMOTIVE STEAM ENGINES," and Her said Majesty, being willing to give
encouragement to all arts and inventions which may be for the public good,
was graciously pleased, by Her Royal Letters Patent under the Great Seal of
the United Kingdom of Great Britain and Ireland, bearing date at West-
minster, the Eleventh day of February, One thousand eight hundred and
forty-six, in the ninth year of Her reign, for Herself, Her heirs and successors,"
to give and grant unto us, the said George Stephenson and William Howe,
our executors, administrators, and assigns, Her especial license, full power,
sole privilege and authority, that we or they, by ourselves or themselves, or
by our or their deputies, servants, or agents, or such others as we or they
should agree with, and no others, during the term of fourteen years from the
date of the said Letters Patent, should and lawfully might make, use, exercise,
and vend our said Invention within that part of Her said Majesty's Dominions
called England, Her Dominion of Wales, and Town of Berwick-upon-Tweed,
in such manner as to us, our executors, administrators, and assigns, shall seem
meet, and that as we or they shall enjoy the whole profit and advantage:
arising by reason of the said Invention during the said term of fourteen
years; and for that end Her said Majesty requires and strictly commands

page_text: all Her subjects whatsoever, within England, Wales, and Berwick-upon-Tweed
aforesaid, that they shall not, neither directly, nor indirectly, make, use, or
put in practice our said Invention, or any part thereof, nor in anywise
counterfeit, imitate, or resemble the same, nor make any addition thereto
or subtraction therefrom, whereby to pretend himself or themselves to be
the inventor or inventors thereof. And whereas the said Letters Patent
contain a proviso obliging us, the said George Stephenson and William Howe,
particularly to describe and ascertain the nature of our said Invention, and
in what manner the same is to be performed, by an instrument in writing
under our hands and seals, or under the hand and seal of one of us, 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
Letters Patent, as in and by the same (reference being thereunto had) will
more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
George Stephenson, for myself, and on behalf of the said William Howe, do
hereby declare that the nature of our Invention, and the manner in which
the same is to be performed, is fully described and ascertained in manner
following, and with the aid of the two sheets of Drawings hereunto annexed,
that is to say:-
.
Locomotive steam engines, as heretofore usually constructed, have. been,
two, horizontal or nearly horizontal steam cylinders, with pistons fitted therein,
to be actuated, by the impelling force of high-pressure steam, with double
action of that steam for impelling, each piston to move within its cylinder,
that is to say, the high-pressure steam proceeding from the boiler is first
admitted through a suitable valve. into one end of one of the cylinders, in,
order to impel the piston of that cylinder to move in one direction therein,
and, after it has been so moved as far as the length of the cylinder, will permit,
then the steam is admitted into the opposite end of the same cylinder, in order
to impel, the same piston to return, and move in a contrary direction therein,
so that each piston is, impelled by the steam alternately backwards and for-
wards within its steam cylinder, and the alternate reciprocating motion. so
given to each piston is; transmitted by intervention of a piston rod and a
connecting rod to, a suitable crank pin, in such manner as to urge that pin to
move round in a circular orbit, concentric with the horizontal central line of
the main axis of the principal wheels of the locomotive engine, and by such
action of the two. pistons and their connecting rods on, the two crank pins the.
said, axis and wheels are turned round, in a, suitable manner for causing the
whole engine to travel along the, railway or road on which the said. principal

page_text: ör impelled wheels' rest.. The two crank pins on which the two pistons
operate by intervention of their piston rods and connecting rods in nianner
aforesaid are both attached by suitable' cranks to the said main axis; but at
different places in the length thereof, suitably for the places of the two cylin-
ders, and the said two crank pins are disposed in their respective circular
orbits aforesaid so as to be at right angles one to the other as regards their
relative positions around the main axis of the impelled wheels, that is to say:
if a radial line is supposed to be drawn in each of the said orbits from the
centre of each crank pin respectively to the centre of the orbit, or to the
central line of the axis (and at right angles to the latter) the directions of those
two radial lines will form a right angle one with the other, so that whenever
one of those radial lines points from the central line in a horizontal direction
the other will point from the same central line in a vertical direction, and con-
sequently whenever either of the pistons has arrived at the extreme end of its
alternating motion within its steam cylinder, and is' about to return (at which
time its connecting rod cannot exert any tendency to urge its crank pin
further round in the circular orbit wherein that pin is to move), the other
piston will at that same time be near to the midway of its motion within its
steam cylinder, and its connecting rod will be acting with full force to urge its
crank pin onwards in the circular orbit wherein that pin is to move, and
thereby to turn the axis and the wheels round, so that at all times when the
position of one crank pin' in' its circular orbit is less favourable for being urged
onwards in that orbit' by' the action of its piston and connecting rod; the
position of the other crank pin in its circular orbit will at the same time be
more favourable for being urged onwards by the action' of the other piston and
connecting rod, and therefore the two steam cylinders, pistons' connecting rods,'
and crank pins between them will keep up a continuous action, for the forcë
which is exerted by the steam against one or other or both of the pistons is'
always operative for turning round the axis and the wheels; and propelling the
engine along the rails, all which, being the common system of locomotive
engines, is well known. And our improvement thereon consists in substituting
for one of the said steam cylinders; with its' valve, double-acting pistoni, piston
rod; connecting rod; and crank pin aforesaid (as usually employed) two small
steam cylinders, with suitable valves, and double-acting pistons and pistón' rods,
connecting rods, and crank pins, so that in locomotive engines: constructed
according to our improvement there will be three steam cylinders;' valves;
pistons, piston rods, connecting rods; and crank pins, instead of two such, as
heretofore; but the two small steam cylinders which are so substituted' as
aforesaid will be of such dimensions as that the contents or capacity of the

page_text: two together will be equal to the contents or capacity of the one larger steam
cylinder for which the said two are substituted, consequently the force where-
with the two small pistons are impelled to move within the said two small
cylinders the steam will be equal to the force wherewith the one larger
piston for which the two are substituted would be impelled; and the motion
wherewith the said two small pistons are so impelled is to be simultaneous, and
in the same direction one as the other in their respective cylinders, so that
whenever one small piston has arrived at either end of its cylinder the other
small piston will also have arrived at the corresponding end of its cylinder,
the said simultaneous motion of the two small pistons in the same direction
one as the other taking place at the same time and in the same direction as
the motion of the one larger piston for which the two are substituted would take
place. And the said two small steam cylinders, pistons, piston rods, connecting
rods, and crank pins which are so substituted are to be disposed at each side
of the central line or middle of the breadth of the locomotive engine, and at
equal distances from that central line, measuring crossways and horizontally.
Also the usual steam cylinder, piston, piston rod, connecting rod, and crank
pin, which is retained, is to be disposed in the said central line, instead of
being at one side thereof, as usual. Wherefore a locomotive engine con-
structed according to our improvement will have one of its steam cylinders,
with the piston, piston rod, connecting rod, and crank pin, thereof, of the usual
size, and disposed nearly as usual, and acting nearly in the usual manner,
except as to being situated in the central line of the breadth of the engine
as aforesaid (and therefore we call the same the central cylinder, piston, piston
rod, connecting rod, and crank pin); and the same engine will have two other
smaller steam cylinders, each being half the capacity of the said central one,
these two small cylinders being disposed at opposite sides of the said central
line, at equal distances therefrom; and the pistons, piston rods, and con-
necting rods of the said two small cylinders, acting on their respective
crank pins simultaneously, and in the same direction one as the other, for
urging those crank pins round in their circular orbits, but not acting simul-
taneously with the piston, piston rod, and connecting rod of the central cylinder;
for the three crank pins are disposed in their respective circular orbits so
that radial lines being drawn therein as herein-before mentioned from the
centre of each crank pin respectively to the centre of the orbit or to the
central line of the axis (and at right angles to that line), the said radial lines
of the two crank pins for the connecting rods of the two small cylinders will
both point in the same direction; suppose, for instance, vertically downwards
towards the ground, in which case the radial line of the crank pin for the

page_text: central cylinder will point horizontally; for in all cases the direction assumed·
by the radial lines of the crank pins of the two small cylinders will be at*
right angles to the direction which will at the same time be assumed by the
radial line of the crank pin of the central cylinder. And the intention and
effect of our said improvement is to counteract or neutralize any tendency
that the oblique action of the several connecting rods on their respective crank
pins may have to produce a lateral vibration or raking motion of the loco-
motive engine from side to side upon its supporting spring when it is travelling
very rapidly; because the oblique direction wherewith each of the connecting
rods acts when the piston is near to the midway of its course must have the
effect of exerting a force either to lift up (or else to press down) the guides
which retain the joint at the end of the connecting rod, and of the piston rod,
in its intended rectilinear motion. And in the common system of locomotive
engines with two horizontal (or nearly horizontal) cylinders, pistons, piston
rods, connecting rods, and crank pins, the said effect of the oblique action of
the two connecting rods to lift up (or to press down) the said guides will be
operative alternately at opposite sides of the central line or middle of the
breadth of the engine, and consequently operative with a tendency to produce
a lateral vibration or rocking motion of the whole engine from side to side
upon its supporting springs, such tendency being greater or less according to
circumstances, but chiefly according as the two cylinders are farther apart,
and consequently as their connecting rods and crank pins are farther removed
from the said middle of the breadth of the engine so as to give greater activity
to the said lifting (or depressing) force for producing a rocking motion as
aforesaid. Some locomotive engines in common use have the two steam
cylinders outside the breadth of the rails, in order that their connecting rods
may act on crank pins projecting out from the central parts of the main
impelled wheels, those wheels being fastened on the two extreme ends of the
main axis; which is not in such case a cranked axis. In such engines the
two cylinders being outside, and far apart, the oblique action of the connecting
rods, and the lifting (or depressing) force resulting therefrom as aforesaid, is
exerted at a considerable distance from the middle of the breadth of the engine
so as to have much more tendency to produce a lateral rocking of the engine,
as aforesaid than is the case in other locomotive engines (also in common use) '
which have the two steam cylinders disposed near together within the breadth
of the rails, and their connecting rods acting on the pins of cranks formed on
the main axis of the main impelled wheels, and which is therefore a cranked
axis. But whatever may be the amount of the said tendency of the oblique
actions of the connecting rods to produce lateral vibration or rocking motion

page_text: of a locomotive engine as aforesaid, such tendency will be wholly counteracted.
or neutralized in locomotive engines constructed according to our improve-
ment; because the central steam cylinder with its connecting rod is operative
at the middle of the breadth of the engine, and therefore the lifting (or
depressing) force resulting from the oblique action of that connecting rod can.
have no tendency to produce lateral rocking. And the same of the two small
steam cylinders, whatever their distance apart and from the middle of the
breadth of the engine may be, they act simultaneously one with the other,
and in the same direction at the same time, so that the lifting (or depressing)
forces which may result from the oblique actions of their connecting rods, are
equally operative at the same instant of time and in the same direction at
opposite sides of the said middle of the breadth, and at equal distances.
therefrom, and will therefore have no tendency to produce lateral rocking.
Also the force exerted by each small piston and its connecting rod, and
consequently the lifting (or depressing) force resulting from the oblique action
of each such rod on its crank pin, will be only half as great as would be
exerted by one large cylinder, piston, and connecting rod, such as the central
one. The nature and effect of our said improvements. being. as aforesaid, the
manner of performing the same may be varied to suit the kind of locomotive
engines which are to be constructed according to our said improvement; and
by way of example we have hereunto annexed Drawings of a locomotive
engine adapted to travel upon railways of the ordinary gage or width between
the rails, namely, a width of four feet eight and one half inches, or four feet
nine inches, the said engine being mounted on six wheels, whereof only two
are impelled or turned round by the force exerted by the engine, in order to
cause the whole to advance, along the rails; the other four wheels are of a
smaller size, and act only as bearing wheels, to sustain part of the weight of
the engine.
Figure 1 Sheet I. is a lateral elevation of the whole engine, and Figure 2,
a horizontal plan of the lower parts of the engine, the boiler (or the greater
part thereof) being supposed to be removed in order to expose those said
lower parts to view. The said two Figures in Sheet I. are drawn to a scale
of one and a quarter inches to a foot. And in Sheet II. Figure 3 is a trans
verse vertical section of the three, steam cylinders with their valves and
accessaries; and Figure 4 a corresponding horizontal section, and plan
of the same parts. Figure 5 is an elevation of the main axis of the
two large impelled wheels. The said three Figures in Sheet II. are drawn
to a scale of two inches to a foot. In all the said Figures the same
letters of reference are used to denote the same parts. A Figures

page_text: 1 and 2, is the fire-box. C, the cylindrical part of the boiler. .D, the.
smoke box. 0, 0, the foremost of the wheels, and o, o, their axis. K, K,
the large main impelled wheels, and k, k, l, l, their cranked axes; shewn sépa-.
rately in Figure 5. M, M, the middlemost of the wheels, and m, m, their
axis. x, x, x, x, x, x,. are the six springs which sustain the weight of all.
the parts which are above the several bearings of the axis of the six wheels.
U, U, is the framework of the engine. The parts aforesaid being nearly the
same as are in comnion use in locomotive engines, and being well known,
need not be further explained, than as they are exhibited in the Drawings;
and the same may be said of many other minor parts which are apparent on,
the Drawings; and are sufficiently explained by the writing thereon, without
more particular reference thereto. In Figure. 2 (also Figures 3 and 4), E is.
the steam cylinder, herein-before mentioned as the central cylinder, which is
situated beneath the boiler, and with a piston fitted to move within it. e,
Figure 2, is the uppermost of the two guides for retaining the ends of the
central piston rod, to move with its intended rectilinear motion. That piston.
rod is itself concealed beneath the said guide.. P is the central connecting
rod, forked at that end which is jointed to the said piston rod, in order to
admit the guides e in the space between the prongs of the fork. The other.
end of the connecting rod P is jointed around the crank pin of the crank 1, ?,
on the main cranked axis k; k, l, l, (also Figure 5,) of the large impelled:
wheels K, K. F, F 1, Figures 1, 2, 3, and 4, are the two small steam.
cylinders, each with its piston fitted to move within it; and f, f, Figures.
1 and 2, are, the guides for retaining the ends of the two piston rods to move
as aforesaid, with their intended rectilinear motions. Q; Q, are the two con-
necting rods for the said two small cylinders, each one being forked at one end
as aforesaid, and their other ends are jointed to the crank pins g, g, which are
fastened to central parts of the main impelled wheels, K, K, and project out
therefrom, so as to move round in circular orbits respectively when the said
main axes revolves. And note, the term crank pin has been herein-before
used to mean that pin around which the end of the connecting rod is jointed,
and which crank-pin is moved around in a circular orbit concentric to the
horizontal central line of the main axis of the principal wheels of the loco-
motive engine, such crank pin being attached by some suitable crank to the
main axis; so as to be carried round in such orbit, with an angular, motion of
the herein-before mentioned radial line theréof around: the centre of the orbit
(or the central line of the axis), and that angular motion corresponding. pre-
cisely with the angular motion wherewith the said main axis and crank and
principal wheels are at the same time turning around the said central line.

page_text: And the same results as herein-before described will follow, whether the crank
pin and crank are a part of the main axis itself, bended into a crank form, as
shewn at 1, 1, Figure 5, (and called a cranked axle,) or whether the crank pin
is a pin such as g, Figures 1 and 2, fastened into and projecting out from a
central part of one of the principal wheels K, which latter is firmly fastened
on the extreme end of the main axis k. The Drawings shew that the radial
lines of the two crank pins 9, 9, Figures 1 and 2, are both pointing in the same
direction from the central line of the axis k, k; and if a horizontal line is
susposed to be drawn in Figure 2 from the centre of one crank pin g to the
centre of the other crank pin 9, as shewn by a red dotted line, that supposed
line would be parallel to the horizontal central line of the main axis k, k; and
it follows that the two connecting rods Q, Q, will have simultaneous motions,
so as to be in all cases parallel one to the other; also, the two small pistons
will move with simultaneous motions backwards and forwards in their respec-
tive small steam cylinders F, F 1, so that whenever one of those pistons has
arrived at either end of its course, and is beginning to return, the other of
them will have arrived at the corresponding end of its course, and will be
beginning to return. The two small pistons moving thus simultaneously
operate by their piston rods, connecting rods Q, Q, and crank pins g, g, to
turn the principal wheels K, K, and their axis k, k, round in the same manner
and with the same force as one large steam cylinder, piston, piston rod, con-
necting rod Q, and crank pin g would do, if it were disposed in the place of
either one of the two small cylinders F or F 1, and acted wholly at one end of
the main axis k, k, as is commonly the case in locomotive engines with outside
cylinders; but according to our said improvement the same force that would
in the usual way be exerted by one large piston as aforesaid is divided and
exerted by two small pistons, and is equally operative at both ends of the main
axis k, k, and upon each of the main wheels K, K, at the same time and in
the same direction for turning the same round. The central cylinder E is so
much larger than the two small cylinders F, F 1, as to be equal in capacity to
the capacity of both the said small ones together; and the large piston
operates by its piston rod and connecting rod upon the crank pin of the
crank l, l, at the middle of the length of the main axes k, k, to turn the same
round together with the wheels K, K. But the direction in which the radial
line of the crank 1, 1, is at any time pointing from the central line of the main
axis k, k, is at right angles to the direction in which the two radial lines of the
two crank pins g, 9, are at the same time pointing therefrom, see Figure 2,
where the pin of the crank 1, 1, for the central cylinder is pointing downwards
beneath the axes towards the ground, whilst the two crank pins 9, 9, are both

page_text: on a level with the main axis k, k, and both pointing towards the cylinders
F, F 1. And when the said parts are in those positions, the large central
piston is near to the middle of the length of its course in its cylinder E, and is
exerting its force with the greatest advantage to turn the crank 1, l, axes k, k,
and the wheels K, K, round; and at the same time the two small pistons are at
the extreme ends of their courses within their respective cylinders F, F 1, and
are beginning to return, and are not exerting any force for turning their crank
pius g, g, round. But after the wheels K, K, and axis k, k, have made one
fourth of a revolution from the position represented in Figure 2, then the central
piston will have arrived at the extreme end of its course in its cylinder E, and
will be beginning to return, so as to exert no force for turning the crank 1, l, round,
and at the same time the two small pistons will then be near to the middle of
the length of their courses within their respective cylinders F, F 1, so as to exert
their force with the greatest advantage to turn the two crank pins g, g,
and the wheels K, K, and axis k, k, l, l, round; all which is the same as
has been herein-before stated. The requisite distribution of the steam of
the respective steam cylinders E, F, F 1, in order to impel their pistons.
backwards and forwards therein, may be performed by means of sliding valves,
and working gear for moving those valves, in the usual manner, but so as that
the sliding valves of the two small cylinders F, F 1, will always be moved simul-
taneously in the same direction one as the other, which may be done by the
working gear, without requiring any other excentrics on the main axis k, k,
than usual in ordinary locomotive engines, because the same excentric (or pair
of excentrics) which serves for actuating the sliding valve of one of the small
cylinders F may also serve for actuating the sliding valve of the other of
those small cylinders F 1. The Drawings represent the sliding valves to be
applied to slide against vertical surfaces at the sides of the respective cylinders,
in order that the several valve rods which pass through stuffing boxes in the
valve boxes, for giving motion to the valves within those boxes, may point
directly to the central line of the main axis k, k, which arrangement of valves-
(as well as the arrangement of all the six wheels O, O, M, M, K, K, beneath
the cylindrical part C of the boiler) is part of certain improvements for which
a Patent was granted to Robert Stephenson on the Twenty-third day of June,
One thousand eight hundred and forty-one. But although that arrangement
of valves (and of the six wheels) is very suitable for engines constructed
according to our present improvement, the sliding valves may be applied to
slide against horizontal surfaces (and the six wheels may be arranged beneath
the engine) in the usual manner.
In Figures 3 and 4. Sheet II., a represents the steam chest or valve hor

page_text: wherein the sliding valve 6 for the central cylinder E is contained; and ris
the valve rod, which passes through a stuffing box, as appears in Figure 4, for
communicating motion to the valve 6, within the said box a. s represents the
steam chest or valve box, wherein the sliding valve t, for one of the small
cylinders F, is contained; and z is the valve rod passing through a stuffing
box for communicating motion to that valve t within its said box s; the
space a and s within the said steam chests is one space for containing
steam, which is conveyed from the boiler into that space through the
steam pipe N, and that steam serves for both the cylinders E and F,
according as it may be admitted into one or other by the sliding valves
b and t, belonging to those cylinders respectively. The other small cylinder
F1, Figures 3 and 4, has its own sliding valve, exactly the same as t,
but it is not seen. The valve rod for giving notion to that valve is seen at v,
coming out of the steam chest u, through its stuffing box. The steam chest u
is for the said sliding valve of the small cylinder F 1 solely, and has no com-
munication with the other steam chest a, s; but steam is conveyed by the
steam pipe R from the boiler into the steam chest u, for the supply of the
small cylinder F 1. The eduction passage for conveying the waste steam
away from the large central cylinder E is marked W in Figure 3, and is
continued by an eduction pipe W, Figures 1 and 2.
The eduction passage
from the small cylinder F is marked X in Figure 3, and that of the other
cylinder, F 1, is similar but not seen; but both the said passages are con-
tinued by eduction pipes X, X, Figures 1 and 2, which two pipes X, X,
together with the aforesaid eduction pipe W of the central cylinder E, turn
upwards within the smoke box D, in order to discharge the whole of the
waste steam up the chimney in the usual manner of ordinary locomotive
engines. And note-The two steam pipes N and R come down within the
smoke box D from one common steam pipe, whereof they are two branches.
That common steam pipe is not seen, but it passes in the usual manner within
the boiler C to the highest part of the elevated steam head, from whence it
takes away the steam, and the passage of the steam through that steam pipe
is intercepted by the steam-regulating valve, whereof the handle is seen at the
end of the boiler, within reach of the engine-man, as usual in ordinary
locomotive engines. And that steam regulator regulates the supply of steam
through both the steam pipes N and R to the steam chests a, s, and u, of all
the three steam cylinders. The steam pipe N is of a large size, because it
has to convey steam for the supply of the large central cylinder E, as well as
of the small cylinder F; but the steam pipe R is smaller, having only to
supply steam. for the small. cylinder F 1; and as to the working gear for

page_text: actuating the said three sliding vales, the same is represented in the Drawing.
with four excentrics, 1, 2, and 3, 4, Figure 2, fastened on the main axis h, k,
for actuating the working gear for the three cylinders, two of those excentrics,
1 and 3, being adapted when brought into action to move the sliding valves
suitably for causing the engine to advance forwards upon the railway, and the
other two excentrics, 2 and 4, being adapted when brought into action to move
the same sliding valves suitably for causing the engine to run backwards along
the railway; all which is well known in modern locomotive engines. The two
excentrics 1 and 2 are provided for moving the sliding valve 6 of the large
central cylinder E, one or other of those excentrics (but not both) being rendered.
operative upon the valve rod r of the said valve b, according as the engine is
required to run forwards or to run backwards along the railway, and both of the
excentrics 1 and 2 are rendered inoperative on the rod r when the engine is
intended to remain at rest. The end of the rod r is connected with a square
sliding bolt p, Figure 2, which is retained and guided in a suitable stationary.
socket for permitting the bolt p to move endways, and it is upon the opposite
end of the said bolt p that one or the other of the excentrics 1 or 2 is rendered
operative as aforesaid, when required. The other two excentrics, 3 and 4,
are provided for moving the two sliding valves of the two small cylinders
F, F 1, with simultaneous motion of those two valves, and in the same.
direction one valve as the other, at the same time. For this purpose the
respective valve rods z and v of those two valves are connected, as may be
seen in Figure 2, by suitable jointed links, with the upper ends of two
short lever arms, which are both fastened upon one horizontal cross axis
w, at the two extreme ends thereof, and both stand upwards therefrom;
and there is another similar lever arm also standing upwards at y from the
same axis w, and the upper end of the lever army is connected by suitable
jointed links with one end of a sliding bolt q, which is of the same kind and
is mounted in a like socket as the bolt p, already described; and any endway
motion which may be given to the said sliding bolt q in its said socket will be
duly transmitted, by means of the cross axis-w and its three lever arms afore-
said, to both the valve rods and v (and consequently to the respective sliding.
valves of the two, small cylinders F and F 1, at the same time, in the same
direction, and with the same extent of motion. And it is; upon, the opposite
end of the said sliding bolt q that one or other of the two excentrics 3 or 4 is
rendered operative when required. The only peculiarity in the said working
gear from what is in common. use and well known in ordinary locomotive
engines is the circumstance of having two lever arms, on the horizontal cross.
axes w connected with two valve rods and, of two, sliding valves of two
3.

page_text: steam cylinders, for transmitting equal motions at the same time and in the
same direction of those two sliding valves. Whenever a similar horizontal
cross axis (or axes) with lever arms has (or have) been heretofore used in the
working gear of locomotive engines, it has (or they have) been for transmitting
motion to only one sliding valve by each such axis and its lever arms, instead of
to two valves by one such axis, as is the case in locomotive engine represented
in the Drawing. And as to the means whereby one or other of two excentrics
(but not both) may be rendered operative upon each of the said sliding bolts p
or q, for running the engine either backwards or forwards along the railway,
those means are well known, being in common use, and operating in different
ways in different locomotive engines; but those means, not being part of our
present improvement, need not be minutely described. The engine repre-
sented in Figures 1 and 2 is provided with the most modern of the said means,
but any other of those means may be used instead. The excentric rod 6 of
the excentric 3, Figure 2, is jointed to the upper end 5, Figure 1; and the
excentric rod 8 of the excentric 4, Figure 2, is jointed to the lower end 7,
Figure 1, of a curved grooved piece 5, 7, into the groove whereof a head at
the end of the sliding bolt q is received, and the said grooved piece 5, 7, is
connected by an upright link (shewn dotted in Figure 1) with the end of a
lifting lever arm 9 (dotted in Figure 1), which is fastened on near to one end
of a horizontal cross axis 10, having another similar lifting lever arm 11
fastened on the other end of the same axis 10, in order to connect by another
upright link from that lever arm 11 with another curved grooved piece corre-
sponding to 5, 7, but belonging to the other pair of excentrics 1 and 2. Also
the said cross axis 10 has a third lever arm 12, Figure 1, fastened upon the
extreme end of it, and connected by a long rod 13 with the lever handle Z,
the upper end of which is within reach of the engine man. When the afore-
said parts are in the positions shewn in the Drawings, the curved grooved piece
5, 7, is let down, and the upper end 5 of it (which is jointed to the excentric
rod 6 of the excentric 3) is on a level with the head at the end of the sliding
bolt g, which is in that case solely actuated by the excentric rod 6 and
excentric 3, and that in a suitable manner for moving the sliding valves of the
two small cylinders, so as to cause the engine to advance forwards along the
railway, the other sliding bolt p being at the same time and in like manner
solely actuated by the excentric 1, for moving the sliding valve of the central
cylinder suitably for going forwards. If the engine man moves the lever
handle Z into a vertical position, it will operate by its rod 13, lever arm 12,
cross axis 10, the lever arms 9 and 11 thereof, and their respective upright
links, to raise up the two curved groove pieces (5, 7, and its fellow), so that the

page_text: midlengths thereof will be brought opposite to the heads of the bolts 9 and p,
which will in that case receive no sensible motion from either of the excentric
rods and excentrics, because of the contrary motions which the two excentrics
1 and 2 or 3 and 4 of each pair thereof are at the same time giving to the
upper and to the lower end of each curved grooved piece, which contrary
motions neutralize each other at the midlength of each curved grooved piece;
or, if the engine man moves the upper end of the lever Z farther, so that it
will incline contrary way to that represented, then the two curved grooved pieces
will be raised up so high as to bring their lower ends (which are jointed to the
excentric rods of the excentrics 2 and 4, on a level with the bolts q and p, which
will in such case be wholly actuated by the said excentrics 2 and 4, and that
in a suitable manner for noving the several sliding valves so as to cause the
engine to run backwards along the railway. The lever arms 9 and 11 have
weights applied to the tail ends of them for balancing their weight and that of
their links and of the curved grooved pieces, and so much of the weight of the
excentric rods as bears thereon. The above brief description of the working
gear of the engine represented in the Drawings is sufficient to identify the.
same with what is now in common use and well known. And note, in case of
locomotive engines, which are to be adapted to travel upon railways of the
broad guage of seven feet, being constructed according to our said improve-
ment, there will be width enough within the framing of such engines to place
the two small cylinders F and F 1 within the framing, and within the width of
the rails, if that is preferred, to having them outside, as represented in the
Drawings; and in case of the said small cylinders being inside, as aforesaid,
their pistons, piston rods, and connecting rods must act upon the crank pins of
two cranks formed on the main axis between the middle of its length and each
end thereof, both those cranks projecting out from the said axis on the same side
thereof one as the other, but the central crank, such as 1,1, Figure 5, projecting
out from the axis in a direction at right angles to the direction in which the afore-
said two cranks project out therefrom, so that the axis will have three cranks
formed upon it. And note, although it has been herein-before described and:
represented that there is to be one central steam cylinder (such as E) in a loco-
motive engine constructed according to our improvement, nevertheless there
may be two small steam cylinders substituted for that one central cylinder E, if.
preferred. In which case those two small cylinders would be disposed on each
side of the central line of the breadth of the engine, very nearly in the usual
places for the two steam cylinders of an ordinary locomotive engine, with:
cranked axis, and having its steam cylinders withinside the framing of the
engine. The pistons and the slide valves of the said two small steam

page_text: cylinders would act simultaneously, with like motions one as the other, in their
respective cylinders and valve boxes, and in the same direction at the same
time as the central piston and sliding valve move in the engine represented in
the Drawings, and the two connecting rods of the said two small pistons
would in the case aforesaid act upon the two crank pins of two cranks, like
the crankl, 1, Figure 5, formed on the main axis k, k, and both projecting out
from the same side thereof as the one crank 1, 1, projects out from the axis in
Figure 5; the two outside small cylinders F, and F, 1, would be the same
as herein-before described; therefore the engine would in such case have four
small steam cylinders acting in pairs with simultaneous motion of the two
pistons and sliding valves of each pair. And note-Our said improvement is
applicable to locomotive engines having only four wheels, also to locomotive
engines whereof four (or six) of their wheels are to be impelled instead of
only two of the wheels being impelled, as represented in the Drawings. The
principal wheels k, k, on the axis whereof are the three cranks' l and 9, 9, (for
receiving the impelling actions of the three connecting rods P'and Q, Q)
should in such case be the middlemost of the six wheels, the three steam
cylinders. being situated further forwards beneath the smoke box D. The
hindmost wheels nearest the fire box- must be of the same size as the said
middlemost: wheels, and those hindmost wheels and the middlemost wheels
must be coupled together by means of outside crank rods acting on suitable
crank pins attached to the central parts of the several wheels, in the usual and
well known: manner of coupled wheels. in' locomotive engines; and they may,
if required, be in some cases further coupled by means of an inside crank röd
(or rods) acting on the crank pins of cranks on the axes of the said middle-
most and hindmost wheels. The engine represented in Figure 2 has its
two feeding pumps. worked by two excentrics fastened on the main axis
k, k, as is apparent in the Drawing; but that is no part of our present
improvement..
Having now described our said improvement, I, the said George Stephenson;
for myself and on behalf of the said William Howe, do hereby declare that
the new Invention, whereof the exclusive use is granted to us by the said
Letters Patent, consists in the improvement herein-before described of
applying the steam cylinders, with their pistons, piston rods, connecting rods;
and crank pins; in a locomotive engine, so as that there shall be two steam
cylinders, connecting rods, and crank pins (such for instance as F, F 1, Q, Q
and g, g, Figure: 2,.): disposed at equal distances on each side of the middle-of
the breadth of the engine (or of the rails whereon it is to travel), those two
connecting rods Q; Q, acting on the said crank pins g, g, with like motion in

page_text: the same direction one as the other at the same time, to urge their crank
pins g, g, onward in their respective circular orbits; and also so as as that
there shall be one large steam cylinder, with its piston, piston rod, connecting
rod, and crank pin, (such for instance as E, P, and 1, Figure 2), situated at
the said middle of the breadth of the engine or of the rails, in the manner of
what has been herein-before termed a large central steam cylinder; or other-
wise, in place of such large central cylinder, two small steam cylinders, with
their pistons, piston rods, connecting rods, and crank pins, disposed at equal
distances on each side of the said middle of the breadth, but as near thereto as
conveniently can be, in order by such application of the three or four con-
necting rods and corresponding crank pins as aforesaid (and as herein-before
fully described) to counteract or neutralize all tendency that the oblique action
of the several connecting rods on their respective crank pins may have to pro-
duce a lateral vibration or rocking motion of the locomotive engine from side
to side on its supporting springs when it is travelling very rapidly.
In witness whereof, I, the said George Stephenson, for myself and on
behalf of the said William Howe, have hereunto set my hand and
seal, this Tenth day of August, One thousand eight hundred and