CERTAIN IMPROVEMENTS IN STEAM ENGINES
Year: 1853

page_text: LETTERS PATENT to James Griffiths, of Wolverhampton, in the
County of Stafford, Engineer, for the Invention of "CERTAIN
IMPROVEMENTS IN STEAM ENGINES."
Sealed the 30th January 1854, and dated the 29th September 1853.
PROVISIONAL SPECIFICATION left by the said James Griffiths at
the Office of the Commissioners of Patents, with his Petition,
on the 29th September 1853.
I, JAMES GRIFFITHS, of Wolverhampton, in the County of Stafford,
Engineer, do hereby declare the nature of the said Invention for
"CERTAIN IMPROVEMENTS IN STEAM ENGINES" to be as follows:-
The said Invention applies to the slide valves of steam engines, and
consists, firstly, in a mode of relieving the back of the slide or valve
from the pressure of the superincumbent steam, so as to place it nearly
in a condition of equilibrium. The valve or slide is sufficiently deep in
section to occupy the whole depth of the valve box, and it is made with
two opposite faces or working surfaces, which are in steam-tigh
contact with the upper and lower sides of the valve box. But a con-
siderable portion of the transverse sectional area of the valve box is left

page_text: open at each side of the valve or slide, so that the steam can circulate
freely round it. The valve is in two parts, the junction of which is in
a plane parallel or nearly so to those of its faces, and is rendered im-
pervious to the surrounding steam by an elastic and steam-tight packing
and spring cushion of vulcanised india-rubber, the elastic force of
which, tending to separate the two parts of the valve presses their faces
into close contact with the corresponding surfaces of the valve box or
chest. By this arrangement the faces of the valve are kept in close
contact with their seats by the elastic force exerted by the india-rubber
cushion in lieu of the pressure of the steam.
Secondly, the said Invention consists in forming the valve so as to
afford an enlarged and more free passage for the escape of the exhaust
An opening is made in the upper side of the valve, and one in
the upper side or lid of the valve box, and these openings are so situated
and proportioned that an aperture of considerable area is always open
for the passage of the exhaust steam through the top or lid of the valvė
chest in every position of the valve, the extent of which aperture is
sufficient to obviate the throttling to which the steam is subject under
the usual arrangement, in which the exhaust port is necessarily of con-
tracted dimensions.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said James Griffiths in the Great Seal Patent Office
on the 25th March 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
JAMES GRIFFITHS, of Wolverhampton, in the County of Stafford,
Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-ninth day of September,
One thousand eight hundred and fifty-three, in the seventeenth
year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said James Griffiths, Her special license
that I, the said James Griffiths, my executors, administrators, and
assigns, or such others as I, the said James Griffiths, my executors,

page_text: administrators, or 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 "CERTAIN IMPROVEMENTS IN
STEAM ENGINES," upon the condition (amongst others) that I, the said
James Griffiths, by an instrument in writing under my hand and seal,
should particularly describe and ascertain the nature of the said Inven-
tion, 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 I, the said James Griffiths, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement (that is to say):
My Invention applies to valves used for opening and closing passages
for steam, and specially to that class of them commonly known as
"slides or "slide valves." In valves of this description it is well
known that the friction between the working surfaces, caused by the
pressure of the steam on the back of the slide or box which changes
the communications between the ports or passages, is considerable. The
first object of the present Invention is to relieve the slide from the
pressure of this superincumbent steam, the contact of the working faces \
being preserved by the substitution for such pressure of the elastic force
or re-action of a layer or washer of vulcanized caoutchouc or india-
rubber. Its second object is to afford a more free and enlarged passage
for the exhaust steam than is generally obtainable in valves of this kind,
as commonly constructed.
The improvement whereby I carry into effect the first object consists
in constructing the slide in two parts, the conjoint depth of which is
equal to the whole depth of the valve chest. The upper side or face of
the slide moves in contact with the inner surface of the cover of the
valve chest. The lower side or face slides on the lower surface of the
valve chest, covering the steam ports or passages in the usual manner.
One of the parts into which the slide or box is divided contains a

page_text: groove, which receives the corresponding sides of the other part. The
bottom of this groove is occupied by a strip or layer of caoutchouc or
india-rubber, vulcanized, which acts as a steam-tight packing, rendering
the junction of the two parts of the slide or box impervious to the sur-
rounding steam, and forming at the same time an elastic spring cushion,
the repellent force of which, tending to separate the two parts, presses
their outer faces into close contact with the corresponding surfaces of
the valve chest, against which they slide. The pressure of the steam
is thus removed from the upper side of the slide or box, the elastic force
exerted by the india-rubber acting as its substitute in keeping the
working faces in contact.
The improvement whereby I accomplish the second of the before-
'named objects, namely, to afford a more free and enlarged passage for
the exit of the exhaust steam, consists in permitting such steam to
escape through the interior of the slide or box, and thence through the
cover of the valve chest. By this arrangement a passage for the
exhaust steam can be afforded of larger proportions than common, and
the steam subjected to less throttling than under the usual arrangement,
in which the area of the exhaust port is narrowed in its dimensions by
the necessity for limiting the area of the upper side or back of the slide,
to prevent the exposure of too large a surface to the pressure of the
steam in the valve chest. The first improvement is, however, equally
capable of being applied with steam passages arranged in the usual
manner as with those last described, the latter improvement applying
to the discharge passages being incidental to the form adopted for car-
rying into effect the former, but not necessarily combined with it.
I have appended to this statement a Sheet of Drawings representing
the arrangement and construction of a slide valve made according to
this my Invention for the purpose of better illustrating and explaining
the details thereof. Of these Fig. 1, is a plan view, the cover of the
valve chest and upper part of the slide being removed so as to expose
the interior. Figure 2, is a longitudinal vertical section through the
middle at the line marked A, B, in the plan. Figure 3, is a transverse
vertical section at right angles to the former, and at the line marked
C, D, in the plan. Figure 4, represents the upper half of the slide

page_text: nverted. The same letters of the alphabet are used to denote the
ame parts in all the Figures. a, a, is the interior of the valve chest,
which varies from the usual form in having its sides made to bulge
outwards, so as to afford room for the steam to circulate freely round
he slide, a provision rendered necessary by the circumstance of the
apper face or surface of the slide being in close contact with the cover
of the steam chest, so that the steam cannot occupy the space above it,
as in valves of the common form. 6, is the cover of the valve chest, the
inner face of which is planed or ground and set parallel with the lower
surface of the valve chest c, c. Between these parallel faces the slide
or box d, d, works. It is made in two parts. The lower one consists
of four upright sides d', d', d', d', forming a parallelogram, and having
an expanded base or flanch d, d, whose inferior surface slides in con-
tact with the bottom of the valve chest.
e, e, are the adit, and f, the
embraces the slide, and con-
exit ports. g, g, is the iron strap which
nects it with the valve stalk or spindle h. The upper part of the slide
consists of a rectangular plate k, surrounded by a grooved rim project-
ing downwards, the sectional form of which is shewn at 1, 1, Figures 2,
and 3. The groove in this rim is of a figure and dimensions to fit
accurately, but without friction, over and enclose the upper edges of the
vertical sides d', d', of the lower part of the slide. m, m, are four
guide pieces projecting downwards, and having their straight edges or
faces fitted to slide against the ribs or chipping pieces n, n, which pro-
ject inwardly from the sides of the lower part of the slide d', d', and
have their faces reduced to parallel planes to receive the guide pieces
m, m, which serve to keep the upper part of the box or slide in its
true position while working. The bottom of the groove in the rim 1, 1, of
the upper part is occupied by a washer or packing ring of vulcanized
india-rubber, shewn by the dotted part o, o, which is tightly compressed
between the inner sides of the groove and the upper edges of the
sides d', d', so as to form at the same time a steam-tight packing and
a spring. The relative positions of the several parts which compose
the upper portion of the slide are shewn in Figure 4. In the Drawing
- a circular portion of the upper plate is shewn removed, so as to leave
a considerable aperture in it. By this construction the area of rub.

page_text: bing surface is diminished; but when steam of high pressure is to be
used I prefer leaving the upper plate of the box or slide entire, as in
that case the pressure of the exhaust steam aids the elastic force of the
india-rubber in keeping the working faces of the valve in close and
steam-tight contact. s, is the steam pipe, by which the steam is con-
ducted from the boiler to the valve chest, where it circulates round the
sides and ends of the slide, as at a, a, and finally enters the cylinder by
one of the passages leading thereto, as.at e, while the interior of the slide
or box forms a communication or passage between the other port or
passage and the discharge pipe at f, through which the exhaust steam
escapes from the opposite end of the cylinder.
According to the arrangement shewn in the Drawing the exhaust
steam is made to occupy the whole interior of the slide or box. This
construction may be modified so as to confine the passage of the steam
to the lower part of the slide only, by placing a partition or division
across the interior of the slide in the position shewn by the faint or
dotted lines at r, in Figures 2, and 3. The part of the slide below this
division then represents the interior of a common slide, and the escape
of steam from the valve chest directly to the discharge pipe is more
effectually prevented in case of any slight temporary leakage or defect
in the packing 0, 0.
By an inspection of the Drawing it will be seen that if the middle
portion of the upper part of the slide, bounded by the dotted lines
p', p, p, p, Figure 4, be removed, and if a corresponding opening be
made in the lid or cover of the valve chest to the extent indicated by
the dotted lines p, p, p, p, Figures 2, and 3, the interior of the slide
will form a passage to conduct the steam from the cylinder to the out-
side of the valve chest, where a suitable pipe may be fixed to conduct
it away. In this case the upper plate of the slide would require to be
extended in length, as at q, q, to cover the enlarged opening and the
exhaust port f, and discharge pipe connected with it would be dispensed
with. This arrangement constitutes the second of the improvements
herein-before mentioned.
Having now described the nature and objects of my Invention, and
explained the manner of carrying it into effect, I shall close this state-

page_text: ment by declaring that what I claim as new and of my Invention in
the arrangements herein-before described are,-
Firstly, the mode or method described of relieving the slide from the
pressure, or from a portion of the pressure, exerted thereupon by the
steam in the valve chest, by causing the slide to fill the whole depth of
the valve chest, and by the use of a packing or clastic cushion of
vulcanized india-rubber, inserted between the moveable parts or
divisions of such slide, for the purpose of pressing the upper and
inferior faces or surfaces thereof against the inner corresponding
surfaces of the valve chest, and of preventing the access of the steam
to the interior of the slide.
Secondly, the arrangement described, whereby a passage is opened
through a slide constructed as above, and through the cover of the
valve chest, for the discharge of the exhaust steam.
In witness whereof, I, the said James Griffiths, have hereunto
set my hand and seal, this Twenty-fourth day of March, in the
year of our Lord One thousand eight hundred and fifty-four.
JAMES GRIFFITHS. (L.S.)
Signed, sealed, and delivered by
the herein-before named
James Griffiths, in the pre-
sence of
JOHN TAYLER,
Engineer,
Manchester.