IMPROVEMENTS IN STEAM ENGINES
Year: 1843

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
CONNISON, of Everett Street, Brunswick Square, in the County of Middlesex,
Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Third day of March, in the sixth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Alexander Connision, Her especial licence, full power, sole privilege and
authority, that I, the said Alexander Connison, my exors, admors, and assigns,
or such others as I, the said Alexander Connison, my exors, admors, or
assigns, should at any time agree with, and no others, from time to time and
at all times during the term of years therein expressed, should and lawfully
might make, use, exercise, and vend, within England, Wales, and the Town of.
Berwick-upon-Tweed, my Invention of "IMPROVEMENTS IN STEAM ENGINES;" in
which said Letters Patent is contained a proviso that I, the said Alexander
Connison, shall cause a particular description of the nature of my said Inven-
tion, and in what manner the same is to be performed, to be inrolled in Her
said 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
Alexander Connison, do hereby declare that the nature of my said Invention,.
and the manner in which the same is to be performed, are fully described and
ascertained in and by the following statement thereof, reference being had to
the Drawings hereunto annexed, and to the figures and letters marked thereon
(that is to say)-
My Invention consists in so constructing a steam engine that a three-throw
crank is combined with two pistons, which work in the steam cylinder, and
also with pistons or surfaces which bound endwise the steam cylinder, and in
such manner that steam acts in three compartments of the same cylinder, the
working parts of each compartment being put in connection with their respec-
tive cranks, whereby rotatory motion is obtained to the three-throw crank
shaft by means of three impulses of steam acting within one steam cylinder;
by means of which I avoid the prejudicial effects of dead points in the rotation
of the cranks, and steam may be used expansively to a more valuable extent
than usual, and without occasioning so great an inequality of pressures in
different parts of the revolution, as commonly occurs when steam is used
expansively in other constructions of engines. I adopt two different modes of
carrying this improvement into practice; in one of which the cylinder itself is
moveable, being mounted on slides and connected by suitable means to one of
the three cranks; in the other modification the cylinder is stationary, being
affixed to the framing of the engine, while that particular portion of its length
which is in use at any given instant of the revolution of the crank is bounded
by two pistons (or ends sliding within the cylinder in manner of pistons) which
are firmly connected together, and which are attached to one of the cranks, as
in the former case was the cylinder itself. I first describe my Invention under
the former modification.
In Figures 1 and 2, A, A', A", is the cylinder; B and C are pistons; D, D,
is the rod of the piston C, which passes through E, E, the hollow rod of the
piston B, and slides steam-tight through a stuffing box on the hollow rod
E and F, the hollow rod E sliding in like manner through the stuffing box G
on the cylinder cover H; the cover at the other end of the cylinder is denoted
by I. P, P, P, P, is the framing; N, N, N, N, are projections on the cylinder
ends or covers, which fit and slide in the. mortices 0, 0, 0, 0, in the fraining
P, P, P, P, and by which the cylinder is supported and correctly guided in its
vibrations. The crank shaft J, K, T, S, K, J, turns in bearings affixed to the
frame, as shewn in the Drawing. The cranks K, K, are in one plane, and to
them is connected the cylinder A, A', A", by means of the connecting rods I., L,
embracing the studs M, M, which are prolongations of the projections N, N, on

page_text: the cylinder end H; by this means the cylinder is made to vibrate by the
rotation of the crank shaft. The crank S is at 120 degrees from the plane of
the cranks K, K, and is embraced by one end of the connecting rod Q, which
connects it with the cross head U, V, U, and by means of it with the piston
rod D, D, and the piston C. In like manner the crank T, which is at 120
degrees from the cranks K, K, and S, is connected with the hollow piston rod
E, E, and the piston B by means of the connecting rod R, R, and the cross
head W. The cross heads U and W are supported and guided by the frame
P, P, P, P, into whose mortices 0, 0, 0, 0, their respective ends X, X, and
Y, Y, are duly fitted; in the cross head U, U, is formed a ring or opening at V,
as shewn in Figure 3, to allow the passage through it of the connecting rod R, R.
By these parts and arrangements the cylinder is divided into three chambers
or compartments, which are extended and contracted by the relative motions
of the cylinder and pistons produced by the rotation of the cranks, and these
extensions and contractions happen in the manner I will now describe :-That
point in the further side of the circle described by the cranks, where it is cut
by that diameter which coincides with the axis of the piston rods, I call its
vertex; it corresponds with one of the dead points in steam engines, as com
monly constructed. When the crank S has passed to a point 30 degrees
beyond the vertex, and the crank T is 150 degrees beyond the same point,
their respective pistons C and B will be in their nearest position to each other;
and when on the other side of the circle the crank T shall have reached the
point which is 30 degrees from the vertex, and the crank S shall have reached
that which is 150 degrees from the same point, the said pistons will be the
farthest possible from each other, and their greatest distance will be twice the
length of the side of an equilateral triangle, inscribed in the crank circle.
In these statements, however, I have supposed the connecting rods to be
always parallel with the piston rods, their obliquity slightly affects the places of
the aforesaid points, but differently so, by different lengths of connecting rods
the constructor of the engine may choose to employ. The steam, by whose
elastic force the said pistons are to be separated and the cranks made to rotate,
is to be admitted between them when the cranks are in or near the former of the
aforesaid positions, and to be discharged when they are in or near the latter.
The same description applies to the other pistons and cranks, their relative
positions and distances and the admission and discharge of the steam operating
on them, considering the two covers of the cylinders to act as one piston, and
each cover as standing in the relation of one to the piston which is nearest to
it. It is necessary to remark here, that each piston if made of only the
ordinary length or thickness would pass the opening by which steam is admitted

page_text: into the cavity between them, and suffer the steam to flow into the compart-
ment behind the piston, to prevent which they are made of greater length or
thickness than is usually the case; only part in width of their peripheries being
packed, the remainder of the bulk of the pistons merely fills up the space
which would otherwise exist at their nearest approach to each other. Z, Z, are
notches cut in the last-mentioned part of each piston opposite the steam
passage, to facilitate the ingress and egress of the steam. The steam is con-
veyed to the engine from the boiler by a steam pipe S', which enters the steam
chest a, a, through a stuffing box. The valve which duly admits and discharges
the steam to and from each compartment is placed within the same steam
chest, and is fully described hereafter, it being only necessary to remark here,
that when the cylinder is made to vibrate the steam chest and the pipe S¹
must be of dimensions which will allow of the necessary extent of motion, and
that the shaft S2, which carries the wheel S³, by which the valve is worked, is
to slide through the wheel S while making it revolve by any known and
sufficient contrivance. When a condenser is used another chest may be affixed
to the lower side of the cylinder with which the proper passage of the valve
may communicate, and into which the pipe to the condenser may slide through
a stuffing box, as described in the case of the steam chest; if no condenser is
used no such chest will be required.
I now proceed to describe the modification of my Invention, in which the
cylinder is stationary. In Figures 4 and 5, A, A¹, A", is, as before, the cylinder;
B and C are pistons, whose rods are respectively E and D. The brackets
11, 11, serve to affix the cylinder to the base plate or other foundation.
H and I, which in the former modification were the covers of the cylinder,
are now in form and appearance pistons moving within the cylinder, but they
really perform the same office as before, videlicet, that of bounding endwiso
the cylindrical space within which the elastic force of the steam is exerted.
The piston rod E, belonging to the piston B, passes through the hollow piston
rod M, belonging to the end piston H, and through the stuffing box f, with
which it is furnished. It is then secured to the joint slide e which moves in
the slides 2, 3, and which is attached to the crank T by the connecting rod R.
The piston rod D of the piston C in like manner passes through the hollow
piston rod M¹ of the end piston I, and its stuffing box f¹, it is then secured in
the curved cross head d, and through it gives motion to the rods m, m, which
slide in supports like k, k; but which, being on the other side of the cylinder,
do not appear in the Drawing; they are united at their other ends by the
cross head d¹, which is properly formed to move in the slides 1 and 2, and
to receive the connecting rod Q, by which it is attached to the crank S.

page_text: The hollow piston rods M and M', belonging respectively to the end pistons
H and I, pass through the stuffing boxes g and g', in the cylinder ends V, V¹,
and are secured to the rods j, j, j, j, by the bent cross heads h and i, by which
means they are kept at the same invariable distance from each other. The
rods jjjj, are supported by the slides k, k, k, k, affixed to the cylinder, and
are extended to the cross head h³, which unites their ends, and moves in the
slides 3, 4, receiving the connecting rod L, by which it is attached to the
crank K.
From the foregoing description it will readily be seen that the motion of
each piston relatively to the rest and to the whole cylindrical space employed is
in this modification precisely the same as in that before described, and that
whatever may be said of the points of contact or distance of separation of the
pistons, or the times and places of the admission and discharge of steam, in that
case, applies to this also. In this modification it is not necessary to make the
pistons so long as in the former case, but they are to be long enough to nearly
meet each other without passing the steamways. The action of the engine
would be quite complete if the cylinder heads V, V', were omitted, since steam
is never admitted in the spaces v, v¹, between them and the head pistons H and I;
their purpose is to prevent the access of cold air and dust to the outer faces of
the end pistons, and to those parts of the cylinder which the movements of the
end pistons leave exposed. The pipe y, y, serves as a passage for the air from
one of those spaces to the other, according to the motion of the head pistons;
and thus the same volumn of air is always retained, by which means waste
of heat is in a great degree prevented. 5, 6, 7, are the standards and bearings
which support the crank shaft J, J, and in which it turns. It may be proper
to remark here, that a fly wheel may be used with this engine or omitted,
according to the nature of the work to be performed and the extent to which
the steam is used expansively. Where great exactness of speed is required,
and the steam is to be used with great expansion in the cylinder, it will be
advisable to place a fly wheel on the crank shaft, especially if but one cylinder
be employed; but that fly wheel may be much lighter than is usual, and
very many cases may occur in which it will not be necessary to use a fly wheel
at all.
In the Drawings I have not shown a condenser or a pump of any descrip-
tion, since they may be readily adapted to this engine according to the usual
practice of engineers.
I now proceed to describe a valve which will duly distribute the steam to
the several compartments of the cylinder, and provide for its escape; but I
prémise I do not describe this valve as the only one capable of answering

page_text: the purpose, since various others may be adopted according to the size or
destination of the engine or the opinion of the engineer. It is necessary to
admit-the steam' alternately to the three compartments of the cylinder, and to
admit it to each during half the revolution of the cranks; except it be sooner cut
off, to be used expansively; the eduction from each compartment may always
continue during a semi-revolution. The three steamways to the several
compartments of the cylinder I bring to the circumference of a circle whose
centre is at a, in which I place these openings or steamways at one hundred
and twenty degrees apart; the openings are of equal size, and bounded by ares
and radii, as in the Figure 5. The face in which the openings are placed is
attached to or forms a part of the cylinder, and is made true, so that the
principal or lowest plate of the valve I am about to describe may revolve
on it steam-tight.. On this face I secure a steam chest a, a, of sufficient
capacity to contain the valve, and in the side of it is the steam pipe (S¹).
The shaft and sockets of the valve pass through a stuffing box in the lid
of the steam chest, and carry on their upper ends the parts for moving thein,
and regulating their relative positions as hereafter described. Motion is com-
municated to the valve from the crank shaft by means of the wheels and shafts,
as shewn in. the 'Drawings, the valve making one revolution for one of the
crank shaft. The lower or principal plate of the valve is shewn at c¹,
Figure 4, and at c', c, c³, c, in Figure 6, these exhibiting its under surface
section, upper surface, and side view respectively; through this plate' is cut a
circular mortice a¹, which, extends nearly to a semicircle, and which, in radius
and width, corresponds with the openings to the steamways; through it the
steam has access to any steam 'way or ways over which it comes at any period
of the revolution: In the under face of this plate is sunk a groove x², occupy-
ing nearly all the remainder of the same circle as the mortice," already
described; and from this 'groove a mortice passes parallel with the flat faces
of the plate to the hole (x) in tlie centre of the plate, which corresponds with
the hole (a) in the plate on which the valve revolves, forming the entrance to
the discharge pipe or way to the condenser; when, therefore, the said groove
comes over any of the steamways it allows of the steam passing to the atmo-
sphere or to the condenser. The mortice and groove just described are
separated from each other by the solid parts (³, a³,) which are each made
rather larger than one of the openings to the steamways, in order that they
may safely prevent the occurrence of a direct passage from the boiler to the
atmosphere or the condenser. If it were only desired to work the engine with
full steam this plate would form a sufficient valve, and in the 'Drawing of the
engine with a moving cylinder this part only is shewn, but the parts hereafter

page_text: described may be applied to that modification, if necessary. In order, however,
to provide for cutting off the steam at any desired period of the stroke I place
on the aforesaid principal plate another, fitted steam-tight to it on its upper
face, and capable of partially revolving on it. In this second plate (d', Figure 4
and, Figure 7) is a mortice y¹, exactly corresponding with that in the lower
plate, and at that extremity of the mortice which comes last to a steamway is
a stud (y), which projects and exactly fits into the mortice of the lower plate,
its end coinciding accurately with the lower surface of that plate, and with it
fitting steam-tight on the surface of the fixed plate (2); in which are the open-
ings to the steamways. When it is desired to work steam at full pressure
nearly throughout the stroke this plate d¹ is so placed on the other c¹ that the
said stud (y) is at the hinder extremity of the mortice in the lower plate, and
when it is intended to cut off the steam before the conclusion of the stroke the
second plate is moved on the first so as to advance the stud y; and thus:to
shorten the mortice through which the steam is admitted. The plates, so far
described, would suffice, if the engine were designed always to work in one
direction; but to cut off the steam correctly, when its motion is reversed' the
contraction of the mortice should take. place from its other end, to perform
which is the office of the third plate (e¹), Figure 4 and Figure 8, and its
stud (), which third plate fits steam-tight on the upper face of the
second, and its stud reaches, as did the other, to the fixed plate (z)
fitting upon it, and in the mortice of the lower plate (c'); in this
third plate the mortice corresponds with those in the other two, but
its stud (*) is placed at the opposite end of the mortice. It is further
necessary in reversing the engine to change the position of the valve relatively
to any given position of the cranks by an exact semicircle, to effect which is
the object of the clutch box (a), whose two projections are each a quadrant; the
hand wheel (x) furnishes convenient hold for turning the valve about, and
that part of the clutch box which is affixed to the bevil wheel S³ turns loose
upon the shaft S² to allow of the necessary reversing motion. The mode I adopt
to give the requisite rotatory motion to the several plates of the valve, without
endangering the correct application of their surfaces to each other, is as follows:-
The shaft (a), to which is affixed the bevilled wheel S at its upper end, and
by which it is turned, rests by its lower end, which is rounded, in the step
formed in the upper surface of the lower plate c'; its projections (a) fit into
the corresponding recesses of the plate c', and serve as carriers; by this means
the plate is made to revolve without danger of lifting it from the face to which
it should closely apply. To carry the second plate d', I use a socket (as,) which
fits the shaft (a), and whose rounded lower end and projections fit into a seat

page_text: and recesses in the plate d', like those in the first plate c', and to the same
effect; and so also do I provide for the motion of the third plate by a socket
fitting on the second, resting on and moving its plate as before. On the upper
end of each of these sockets I secure an arm (a) and (0), by which it may
be turned together with its plate to any position relative to the lower plate c',
and consequently its stud placed at any desired part of the mortice in it; when
put into the desired position it is secured there by a stud which passes through
the arm and the opposite hole in the wheel (a). This description applies with
equal correctness to either plate and its socket and arm, and therefore need not
be repeated. By these means the several plates of the valve are adjusted to
their true positions, relatively to the cranks and to each other, and, when
adjusted, are made to revolve together. The valve may be correctly kept to
its place on the fixed plate z by a ring z¹, formed on the fixed face (2) which
shall correctly fit the outside of the lower plate (c¹).
Having thus described my Invention, and the best means I am acquainted
with for performing the same, I would wish it to be understood, that I do not
confine myself to the details herein described so long as the peculiar character
of the Invention be retained, whereby the steam cylinder of a steam engine is
divided into three compartments, and the pistons or working parts are in
combination with three cranks, as above described.
In witness whereof, I, the said Alexander Counison, have hereunto set my
hand and seal, this First day of September, in the year of our Lord
One thousand eight hundred and forty-three.
ALEXANDER (L.S.) CONNISON.