IMPROVEMENTS IN STEAM ENGINES
Year: 1852

page_text: WALKER, of Birmingham, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent, under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twenty-third day of
February, One thousand eight hundred and fifty-two, in the fifteenth year
of Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Thomas Walker, my exors, admors, and assigns, 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, adiñors, 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 con-
tained 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, by an instrument in writing under my hand and
seal, 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 that the nature of my said Invention, and

page_text: 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 relates to an improved construction of rotary engines. In
order that the nature of the Invention may be clearly understood I will proceed
to describe the Drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 shows a plan. Figure 2 a horizontal section. Figures 3, 4, and 5
are somewhat similar vertical sectional views, but shewing the pistons in
different positions. Figure 6 is a transverse section. Other views show some
of the parts separately. a, a, are the cylinders in which the pistons b, b, work.
These pistons b, it will be seen, are cylindrical, but placed eccentrically upon
their axes 61, 61, and it is the so arranging the slide or valve to act simulta-
neously upon the cylindrical pistons thus placed excentrically upon their axes,
which constitutes one peculiarity of the Invention. The slide or valve c, it
will be seen by reference to the views, Figures 3, 4, and 5, is so broad upon
its surfaces c¹, c, c, c, that in whatever position of their rotary motions the
pistons b, b, may for the time be situated, they are constantly borne against
by some part of those surfaces of the slide c. In order to compensate for
the wear of the surfaces (c', c) of the slide c, I make that slide in two
parts, as shewn, with a tendency for the parts of the slide to be forced away
from each other and against the pistons b, b, by means of the packings a', which
are borne against by springs, with a tendency to force them together. By this
arrangement of the slide c, that slide will constantly adjust itself, and
maintain contact with the piston as it becomes worn on its surfaces. The
slide c has recesses formed in its sides, by which it acts in connection with
the packings a¹, a', as a slide valve to conduct steam into and from the respec-
tive steam chambers or cylinders ȧ, that is, one of such recesses will
conduct steam into the chambers a to act upon the pistons b, whilst the other
will serve to conduct away the steam after it has been used in the chambers ȧ.
d is the inlet pipe for the steam, conducting it to the chamber e, thence to one
or other of the chambers f, through one of the passages ġ formed in the
packings a. The steam is conducted into one or other side of the slide c, by
means of the slide valve i, as shewn more clearly by the sections, Figure 3 & 6.
jis the exhaust passage. The direction in which, according to the position
shewn of the valve i, the steam is now supposed to be passing into the engine,
is shewn by red arrows; the black arrows shew the steam passing away. The

page_text: pistons b, b, do not fit tightly on their axes, except at or near their centres,
there being enlarged parts 6' formed, as shown, upon those axes; and they.
have ribs or keys 6s which pass into grooves formed in the interior of those
pistons, by which the axes are controlled to revolve with the pistons. By this
arrangement of the axes 61, 6¹; greater freedom of action in the working of the
pistons between the cylinder covers: is obtained: One of the. covers: (a) of
each of the cylinders a is: formed with a loose flange a; to facilitate packing:
As the end surfaces of the pistons. wear away, I am, by placing extra thick-
nesses of suitable packing between the parts,a, as, at z,, enabled to maintain
closeness of contact between the ends of the pistons b,; b,, and the two moveable
covers a³, a².
I would remark, that I do not confine myself to such a combination of
cylinders when of equal diameters, as the cylinders may be of different
diameters so long as the amount of the eccentricity of the pistons remains the
same for the working of a slide,, as above explained..
I would remark that although I have shown the axes of the pistons. to be
geared together by the wheels k, k,. by which the. pistons will be. constantly
travelling in opposite directions, I do not confine myself to that arrangement,
and sometimes I introduce an intermediate wheel between and gearing into the
wheels upon the axes of the pistons 6; or the simultaneous movement of the
piston may be obtained by connecting rods and excentrics, as shewn
by the diagram, Figures 7, 8, 9, 10, & 11, (Drawing B.) connecting them
together, so that in place of the pistons 6 revolving in opposite directions, they
revolve in the same direction.
b
In thus arranging the pistons, so that they may revolve in the same direc-
tion, I find it desirable to adopt the modification of valves and passages shown
by Drawing B.
The same letters of reference are used to indicate like parts described in
respect of the various Figures shown on Drawings A.
Having thus described the nature of my said Invention, I would have it
understood that I do not confine myself to the precise details shown and
described, so long as the peculiar character of any part of the Invention
be retained. But what I claim is,―
First, the mode herein described of combining two cylindrical pistons fixed
excentrically on their axes, in two steam cylinders contiguous to each other,
and having a slide between the two pistons.
Secondly, I claim the making of the slide of two parts, so that as the
surfaces wear they may be set up as herein explained, and constantly be in
contact with the two pistons.

page_text: Thirdly, I claim the mode herein described of constructing the slide, whereby
it acts as a slide valve for admitting the steam to flow into and from the steam
cylinders, and at the same time as an abutment to the steam.
Fourthly, I claim the mode herein described of constructing one of the end
covers of each, of the steam cylinders in separate parts.
And, fifthly, I claim the mode herein described of affixing the pistons on
their axes, by enlarging the axes at their middle portions.
In witness whereof, I, the said Thomas Walker, have hereunto set my
hand and seal, this Twenty-third day of August, in the year of our
Lord One thousand eight hundred and fifty-two.