IMPROVEMENTS IN THE SLIDE VALVES OF STEAM ENGINES
Year: 1858

page_text: LETTERS PATENT to John Dodd, of Ruabon, in the County of Denbigh,
Engineer, and Thomas Phillips, of the same Place, Painter, for the Inven-
tion of "IMPROVEMENTS IN THE SLIDE VALVES OF STEAM ENGINES."
Sealed the 7th December 1858, and dated the 6th July 1858.
PROVISIONAL SPECIFICATION left by the said John Dodd and Thomas
Phillips at the Office of the Commissioners of Patents, with their Petition,
on the 6th July 1858.
We, JOHN DODD, of Ruabon, in the County of Denbigh, Engineer, and
THOMAS PHILLIPS, of the same Place, Painter, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE SLIDE VALVES OF STEAM ENGINES,"
to be as follows (that is to say):-
Our Invention which has reference to an improved form and construction of
slide valve for locomotive or other steam engines, consists in reducing the
friction and pressure upon the outer surfaces of the said valves, by causing
them to work within open chests or jackets in place of closed ones as at present,
whereby the pressure of the steam upon the said surfaces, as heretofore, is
wholly removed, and the valve retained in its position, and the requisite
pressure supplied and adjusted by the employment of set screws.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Dodd and Thomas Phillips in the Great Seal Patent
Office on the 6th January 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JOHN
DODD, of Ruabon, in the County of Denbigh, Engineer, and THOMAS PHILLIPS,
of the same Place, Painter, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixth day of July, in the year of our Lord One
thousand eight hundred and fifty-eight, in the twenty-second year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto us, the said
John Dodd and Thomas Phillips, Her special licence that we, the said John
Dodd and Thomas Phillips, our executors, administrators, and assigns, or such
others as we, the said John Dodd and Thomas Phillips, our executors, adminis-
trators, and assigns, should at any time agree with, and no others, from
time to time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle of Man,
an Invention for "IMPROVEMENTS IN THE SLIDE VALVES OF STEAM ENGINES,"
upon the condition (amongst others) that we, the said John Dodd and Thomas
Phillips, our executors or administrators, by an instrument in writing under
our, or their, or one of their hands and seals, should particularly describe and
ascertain the nature of the said Invention, and in what manner the same
was to be performed, and cause the same to be filed in the Great Seal
Patent Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that we, the said John Dodd and Thomas Phillips do
hereby declare the nature of our said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained in
and by the following statement, and the Drawings therein referred to, (that
is to say)
Our Invention which has reference to an improved form and construction
of slide valve, whereby the operation of conducting the steam to and from the
cylinders of steam and other motive power engines is more readily effected,
and the wear and tear of the valves consequent on the friction greatly reduced
by the same being subjected only to the pressure necessary for keeping the
sliding surfaces together, and rendering them steam-tight, consists in the steam
being only admitted to the sides of the valve, so that the pressure of the same
on the back thereof, as heretofore, is wholly removed; to effect which object

page_text: the valve chest or jacket is provided with a moveable surface plate, by means
of which the pressure of the steam is prevented from acting on the back of
the slide which is kept in contact with the valve seat by the employment of set
screws.
But in order that our said Invention may be more fully understood and readily
carried into effect, we now proceed to describe it by the aid of the accompanying
Drawings, reference being had to the letters and figures thereon marked.
(that is to say):-
Fig. 1 represents a back view of our improved valve, showing its application
to an oscillating steam cylinder; Fig. 2 a longitudinal vertical section taken
through the dotted line in Fig. 1, showing the slide in its position for admitting
steam for the up stroke of the piston; Fig. 3 a transverse section taken through
the dotted line in Fig. 2; Fig. 4 an end view of the moveable surface plate
separately shown; and Fig. 5 a corresponding view of the slide. In each
Figure the same letters of reference denote similar corresponding parts.
A, A, steam cylinder; B, B, valve chest or jacket bolted to the exterior
face thereof, and containing the short slide steam valve C, C, which receives
motion in the usual manner from an eccentric on the crank shaft through the
medium of the slide rod D, D; E and E¹ spaces into which the steam flows
from the boiler through the hollow F, F, of the steam belt G, G, and one of
the hollow trunnions of the cylinder; H and H¹ steam ways for conducting
the steam, or otherwise, alternately above and below the piston; I, I, eduction
passage through which the steam is conveyed into the condenser, or blown off
into the air by means of the opposite trunnion; J, J, valve port or opening;
K, K, steam ports; L, L, moveable surface plate or back to the valve chest
capable of being adjusted through the medium of the nuts and bolts M and M';
N, N, bearing bars, through which the said bolts work; 0, 0, plates, against
which the ends of the screws rest; P, P, packing; Q, Q, glands or stuffing
boxes for securing the same; R, R, nuts and bolts for flanging the valve
chest together.
In conclusion to the foregoing description, it may be here necessary to note,
that our improved valve may be fitted to the cylinders of any steam or other
motive power engines, in lieu of oscillating ones, as represented, and further-
more that valves of the present construction may in like manner be provided
with adjustable surface plates and moveable glands with similar advantages, by
substituting the same for the ordinary valve chest or jacket cover.
Having now fully described and ascertained the nature of this our said
Invention, and the manner in which the same is to be performed and carried
into effect, we would have it clearly understood, that we do not intend to

page_text: confine ourselves to the precise details herein-before described, as the same
may be varied without departing from the general principle of these our said
improvements; but that which we do claim as new and of our said Invention
is, the general construction and employment of the several parts in con-
nection with the mode of relieving the surface pressure of steam upon the
back of the slide in the manner and for the purposes herein-before set forth
and described.
In witness whereof, we, the said John Dodd and Thomas Phillips have
hereunto set our hands and seals, this Fifth day of January, in the
year of our Lord One thousand eight hundred and fifty-nine.
Witness,
JOHN DODD.
(L.S.)
THOMAS PHILLIPS. (L.S.)
F. R: DARKIN CAMPBELL,
Clerk to Messrs. Weatherdon & Co.,
77, Chancery Lane.