IMPROVEMENTS IN STEAM ENGINES
Year: 1838

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
WALKER, of Birmingham, in the County of Warwick, Clock Maker, 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 Thirty-first day of May, in the first year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Thomas Walker, Her especial licence, full power, sole privilege and authority,
that I, the said Thomas Walker, my exors, admors, and assigns, or such
others as I, the said Thomas Walker, my exors, adiňors, 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 Thomas Walker,
shall cause a particular description of the nature of my said Invention, 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.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Thomas Walker, do hereby declare the nature of my said Invention, and
the manner in which the same is to be performed, are fully described and

page_text: 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 relates to
to be worked by steam.
certain improved constructions of rotatory engines
And, in order to give the best information in my
power, I will describe the Drawings hereunto annexed, in which the same
letters indicate the same parts wherever they occur.
DESCRIPTION OF THE DRAWING MARKED No. 1.
Figure 1 is a plan of an engine constructed according to the first part of my
Invention. Figure 2 are two longitudinal sections of the engine, showing the
pistons in different positions. Figure 3 is a plan of the engine in section.
Figure 4 shows a transverse section taken between the two cylinders of which
the engine is composed. Figure 5 shows an elevation of the engine. Figure 6
shows the inside view of one of the covers of the steam cylinders. And
Figure 7 shows the pistons and slide separately. A, B, are two cylinders, each
having a slit or opening at C, by which means steam can flow into and from
the steam cylinders A, B, as will be hereafter explained. D, E, are, two
pistons, the piston D being in the cylinder A, and the piston Ẹ being in the
cylinder B; and the external figure of the pistons is such that any number of
lines drawn through a given point (the centre of the shaft) would be of nearly
equal lengths, such figure in geometry being called cardioidal hence; the two
pistons D, E, being affixed on two axes F, and in such manner that the
surfaces of the pistons against which the sliding abutment acts are at all times
at the same distance from each other, and the shafts F are to be so geared or
caused to work together as to keep the two pistons at all times in such relative
position; hence the surfaces of the two pistons will at all times be at the same
distance apart, and allow of a sliding steam stop or abutment to be employed at
the openings C of the steam cylinders, which will prevent steam passing from
G to H, or from H to G, without driving the two pistons round. I is the sliding
abutment, which slides in grooves or recesses formed in the two end covers of
the steam cylinders, as is clearly shown in the various Figures of the Drawing
No. 1. It should be remarked, that at the circumference of each piston at its
longest radius for some length the surface of the piston is concentric with the
steam cylinder in which it works, the object of which is, that the surface so
produced shall be sufficiently wide to cover the slits or openings C in the steam
cylinders, and thus produce a closing of steam from that cylinder in which
the longer radius is next the opening C of its cylinder, as will readily be
traced in Figure 2. And it will also be seen that the slide I is also so formed

page_text: at its ends as to close the opening C when driven into such openings. G, H,
are the steam pipes leading to and from the engine; and there is to be a
suitable arrangement of other pipes, with suitable cocks or valves applied
thereto, in order to enable the person attending the engine readily to reverse
the action of the engine, as is well understood by engineers, and consists in
causing the steam to enter in opposite directions. And, further, when the
engine is worked by condensation, then a suitable condenser is to be applied to
the eduction way of the engine, all which I have not thought it necessary to
show, they forming no part of my Invention, and, being well understood, will
readily be applied to my improved engines, both in respect to those under
description and those hereafter to be described. The Drawing shows the
two shafts F geared together by cog wheels J, which is a convenient means of
keeping the two pistons in their relative and correct positions in respect to each
other, as above described, though I do not confine myself thereto, as other
means may be resorted to. The Drawings show the parts, and the mode of their
going together, and also the means of packing the same steam tight by metallic
packing, but all which may be varied, provided the principle of my Invention
be retained which relates to the mode of using two pistons of the description
shown in two cylinders having a sliding abutment, as above explained.
Having thus explained the nature of the first part of my Invention, I will
describe the manner of action of the parts. In doing so I will suppose that
steam is being admitted at the pipe or inlet G in the lower section at
Figure 2. The steam would press on the sliding abutment I, and cause it to
be pressed steam tight into its grooves or recesses; and the steam would pass
in the direction of the arrows, and press on the two pistons, and force them
round; and ultimately the steam would escape at H, and this would be the
continued action of the engine so long as steam was permitted to flow in that
direction. And it will be seen by this arrangement of machinery a constant
uniformity of action and power would be the result of the working of the two
pistons; for it will readily be understood, that although each piston, sepa-
rately considered, is working with a varying power, the two together so work
that as the one decreases in power the other increases in exact proportion, and
the slide I, in whatever position of the pistons, will at all times touch the
surface of the two pistons, and keep the touching surfaces steam tight. And
it only remains to be stated that the power thus obtained to the shafts or axes
F may be communicated from either to the machinery or purposes desired, or,
if wished, both axes F may become driving axes.
I will now proceed to describe the second part of my Invention, which
relates to another arrangement of parts to produce a rotatory engine.

page_text: DESCRIPTION OF THE DRAWING MARKED No. 2.
Figure 1 is an elevation of an engine constructed according to the second
part of my Invention. Figure 2 is a section of Figure 1. Figure 3 is a plan,
with part of the steam chamber (in which the piston works) removed, in order
make the construction more clear. Figure 4 is an end view. Figure 5 is an
internal view of one half of the steain chamber in which the piston works.
Figure 6 shows the piston separately. Figure 7 shows the part of the shaft or
axis with the circular partition and steamways separately; and Figure 8
shews the circular partition, the piston, and the steamways, separately.
It should, in the first place, be stated that the steam chamber a, a, in which
the piston works is of somewhat peculiar form, and is such, that although it
proceeds in an inclined direction around the axis, a section through any number
of places from the shaft to the periphery will produce the same figure, and
may be closed by the same piston. The steam chamber, as shown in the
Drawing, consists of two end surfaces a', a², the surfaces of which for a time
proceed for a certain length in parallel lines, but in an inclined direction in
respect to the shaft or axis 6; the sides then proceed still in parallel lines to
each other, but for a time at right angles across the shaft or axis b; then
again the sides of the steam chamber proceed in parallel lines to each other,
but in an inclined direction in respect to the shaft or axis b, such second
inclined direction being of a length equal to the one first described at the
opposite side of the shaft or axis 6; then the sides of the steam chamber
proceed parallel to each other, but at right angles to the shaft or axis b; and
the sides or surfaces a', a², are at all parts perpendicular to the axis, all which
is shewn in the Drawing. This steam chamber a, a, is cylindrical on its outer
circumference, the inclined and plane parallel surfaces above explained in fact
forming the ends or what may be called the covers of the steam chamber or
cylinder a, such covers or ends having equal inclined surfaces opposed to
inclined surfaces, and plane surfaces opposed to plane surfaces. Hence, sup-
posing a piston of a size just sufficient to touch the shaft or axis b, and capable
of sliding longitudinally in a groove formed in the axis b, and supposing the
piston to touch the two ends a¹, a³, of the cylinder or steam chamber, and the
outer circumference of the steam chamber and the axis 6 caused to
revolve, the steam cylinder a, a, remaining fixed and stationary, the
effect would be that the piston so arranged would first move for a time
in one direction lengthwise of the axis so long as the two ends of the
piston were governed by the first inclined parrallel sides of ends of the steam
cylinder, then the piston for a time would revolve without moving lengthwise
of the axis; then it would come to the second inclined surfaces, and be caused

page_text: to move for a time lengthwise of the axis or shaft 6 in an opposite direction to
which it was caused to move by the first inclined surfaces till it came to the
second plane surface, when it would for a time revolve with the shaft or axis b
without moving along it till it again came to the first inclined surfaces.
Hence it will be seen that the two surfaces of the ends a', a³, of the steam
cylinder or chamber a act as two cams of like figures opposed to each other.
The nature of the steam chamber in which the piston works being understood,
the remainder of the parts and their action will readily be traced. d is the
piston, the inner end of which moves in a groove formed in the axis or shaft b
in the following manner:-e is a tube to receive the axis 6 through it. f is the
groove in which the piston moves lengthwise of the axis b. The tube e has
the steamways g, h, formed therein, as is shewn in the Drawing, and the tube
e is keyed or otherwise affixed to the axis b. On the tube e is cast the circular
partition i, which divides the steam cylinder a into two compartments,
the circular partition i being packed steam-tight in respect to the steam
cylinder a, and there is an opening formed in the circular partition i,
through which the piston d works freely; and the nature of the piston
being clearly shown in the Drawing, it will not be necessary to enter into
a further description of it other than to state that it is to be carefully
packed steam tight. k is the induction way, and the eduction way. It will
now readily be understood that the circular partition i, in dividing the steam
cylinder a, rests constantly against the two portions of the ends a², a³, of the
cylinder, which are plane surfaces; that is, the parts which cross the shaft at
right angles, and thus form steam abutments, against which and the piston d
the pressure of the steam acts; and as the piston in this arrangement is
capable of movement, the steam drives round the piston, and with it the shaft
or axis 6, and the steam will constantly be acting or pressing on the same area
of piston throughout the whole revolution of the axis 6, all which will readily
be traced aided by the foregoing description. And all that need further to be
said in respect to this engine is, that although I have only described one
arrangement of parts as working on the same shaft or axis, it will be evident
that any desired number of chambers a may be formed in the same cylinder,
and work the same shaft or axis b. And, further, it will be evident that in
place of the circular partition and piston d revolving, and consequently
driving the shaft or axis 6, the cylinder a and the partition i may remain
stationary, and the ends a', a² of the cylinder a revolve and be keyed to the
shaft; in such case the piston d would be (excepting in its sliding action) a
stationary abutment.
I will now proceed to describe the third part of my Invention, which is also

page_text: shewn in Drawing marked No. 2, Figure 9 being au elevation, Figure 10 an
elevation in section, and Figure 11 a transverse section of so much of an
engine as will enable me to describe the third part of my Invention. m is the
steam cylinder, and n an eccentric axis. o is a sliding abutment. p, q, are
the steamways, and it will be seen that the surface of the piston where it
touches the inner surface of the steam cylinder m is concentric with that
cylinder, and is of a width greater than the width of the opening into the
cylinder m, to admit steam; hence the piston, when opposed to the opening,
will close the same, and prevent the passage of steam into the cylinder till the
piston has passed beyond the steam port or opening into the steam cylinder;
and it is this mode of closing the steamways in rotatory steam engines by means
of the piston which constitutes the novelty of this part of the Invention. In
using this engine, when a single-acting one, a fly-wheel should be employed;
or otherwise an uniform motion may be obtained by having two pistons
and cylinders on the same axis, the pistons being at right angles.
I will now proceed to describe the fourth part of my Invention, which
relates to another arrangement of rotatory steam engines. Figure 12 is a
transverse section, and Figure 13 a view of the piston shown separately. q is
the steam chamber or cylinder, and r is the piston affixed on a hollow axis,
there being two steam slides or abutments s. It will be seen that the steam-
ways, in passing through the axis, pass also on either side of the piston, as is
shown; and the novel feature of this Invention consists in the lengthening the
steamways on the surface of the piston in such manner, that immediately or
just before the piston begins to raise the slides or steam abutments, the steam
will pass on either side equally of the abutment, and allow of the free moving
of the abutments.
I would remark in respect to the steam abutments of Figures 10, 11, 12, &
18, that they may be pressed constantly into the steam cylinder by the force of
steam, or by springs aided by their own weight, but to which I lay no claim;
neither do I make any claim to the form of cylinders and pistons, or modes
of working other than is herein-before described and hereafter particularly
claimed.
Having thus described the nature of my Invention, and the manner of
performing the same, I would have it understood that what I claim as my
Invention is,
First, the mode of combining the pistons D, E, in two steam cylinders
having a sliding stop I, as above described.
Secondly, I claim the mode of producing a rotatory steam engine by means
of the peculiar construction of steam chamber a, a, a², the circular partition,
and the piston d, as above described.

page_text: Thirdly, I claim the mode of arranging the pistons of rotatory steam engines
in such manner that the steamway into the cylinder is stopped by the piston,
as above described.
And, Fourthly, I claim the mode of arranging the steamways in the pistons
of rotatory steam engines in such manner that when they come to operate on
the sliding abutments, the steamways allow of equalization of the pressure of
the steam on both sides of the abutments, as above described.
In witness whereof, I, the said Thomas Walker, have hereunto set my
hand and seal, this Thirtieth day of November, One thousand eight
hundred and thirty-eight