IM- DRAVEMENTS IN SLIDE VALVES
Year: 1870

page_text: LETTERS PATENT to James Grafton Jones, of Blaina, near Newport,
in the County of Monmouth, and George William Elliott, of
Chesterfield, in the County of Derby, for the Invention of "IM-
DRAVEMENTS IN SLIDE VALVES.'
"
Sealed the 7th June 1870, and dated the 19th April 1870.
PROVISIONAL SPECIFICATION left by the said James Grafton Jones
and George William Elliott at the Office of the Commissioners of
Patents, with their Petition, on the 19th April 1870.
We, JAMES GRAFTON JONES, of Blaina, near Newport, in the County
of Monmouth, and GEORGE WILLIAM ELLIOTT, of Chesterfield, in the
County of Derby, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN SLIDE VALVES," to be as follows:-
This Invention has for its object improvements in slide valves. In
order to relieve the slide valve from the pressure of the steam or fluid
upon its back, so as to lighten the friction against the valve face as far as
is consistent with maintaining a sufficient contact, we form the valve
with a passage through it and a face at its back which works steam-

page_text: tight upon a plate carried by a cylinder passing through the bonnet or
steam chest cover by a suitably packed gland. This cylinder excludes
the steam from the back of the valve more or less according to its area.
If the engine be non-condensing the area of the cylinder will be
somewhat less than that covered by the valve. For a condensing engine
the cylinder may be of larger area than the valve, and apparatus will
then be provided to prevent the cylinder receding from the back of the
valve when there is no proper vacuum in the condenser.
According to another arrangement the back of the valve and the face
are in separate parts connected by a telescopic joint suitably packed, so
that whilst the face of the valve works steam tight over the ports the
back may also work steam tight against the bonnet or back of the steam
chest in which there is a cavity in connection with the centre port or
with the air. The centre port may be a steam port, and in this case the
cavity behind the valve will be somewhat less in area than the interior
surface of the back of the valve which is exposed to the pressure. The
front portion of the valve is so proportioned that the steam may hold it
against the face with a suitable pressure.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said James Grafton Jones and George William Elliott
in the Great Seal Patent Office on the 19th October 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JAMES
GRAFTON JONES, of Blaina, near Newport, in the County of Monmouth,
and GEORGE WILLIAM ELLIOTT, of Chesterfield, in the County of Derby,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Nineteenth day of April, in the year of
our Lord One thousand eight hundred and seventy, in the thirty-third
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto us, the said James Grafton Jones and George William
Elliott, Her special licence that we, the said James Grafton Jones and
George William Elliott, our executors, administrators, and assigns, or
such others as we, the said James Grafton Jones and George William
Elliott, our executors, administrators, and assigns, should at any time agree

page_text: ..
⚫ I■-
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
PROVEMENTS IN SLIDE VALVES," upon the condition (amongst others) that
we, the said James Grafton Jones and George William Elliott, our
executors or administrators, by an instrument in writing under our or
their hands and scals, or under the hand and seal of one of us or them,
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 I, the said James Grafton Jones, on behalf of
myself and the said George William Elliott, do hereby declare the nature
of the said Invention, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following
statement thereof, that is to say :-
This Invention has for its object improvements in slide valves. In
order to relieve the slide valve from the pressure of the steam or fluid
upon its back, so as to lighten the friction against the valve face as far as
is consistent with maintaining a sufficient contact, we form the valve
with a passage through it and a face at its back which works steam
tight upon a plate carried by a cylinder passing through the bonnet or
steam chest cover by a suitably packed gland. This cylinder excludes
the steam from the back of the valve more or less according to its area.
If the engine be non-condensing the area of the cylinder will be
somewhat less than that covered by the valve. For a condensing engine
the cylinder may be of larger area than the valve, and apparatus will
then be provided to prevent the cylinder receding from the back of the
valve when there is no proper vacuum in the condenser. It is essential
that the packing employed to prevent the escape of steam between the
cylinder and steam chest cover should be of such a nature that the
cylinder shall at all times be able to move freely endwise to and fro, so
that the plate carried by the cylinder shall at all times be free to move
and be pressed with an even pressure against the back of the slide
valve; if an ordinary stuffing box be employed the cylinder as it has no

page_text: continuous motion through its stuffing box is very apt to stick fast and
to become inoperative. We employ for this purpose a ring of thin sheet
metal or other flexible material, the outer edge of which is clamped to
the cover of the steam chest, whilst the inner edge is clamped to the
top of the cylinder. The flexibility of the ring allows the cylinder to
play to and fro to the required extent. The cylinder is made to pass
quite freely through the cover and cannot bear against it as all endway
movement of the plate is stopped by the ends of the plate bearing
against planed surfaces at the ends of the valve chest.
Figure 1 shows a longitudinal section of a slide valve constructed as
above described and suitable for a non-condensing engine. a is the
reciprocating valve with a passage formed through it as above-mentioned;
b is the valve face against which it works; 6' are the ports in the valve
face leading to the two ends of the cylinder of the engine; and 6 is the
central port open to the exhaust; c is the plate against which the face
on the back of the valve works; d is the cylinder on the back of this
plate the cylinder d passes freely through an opening in the bonnet or
steam chest cover e; and is a ring of flexible material such as thin
sheet lead or copper. The outer edge of this flexible ring is fixed steam-
tight to the steam chest cover by a metal ring g screwed down on to it,
and the inner edge of the flexible ring is similarly fixed by a ring / to
the top of the cylinder d. The ring g on the steam chest cover is formed
to overlap the joint so as to form a backing to the flexible joint ring f
all end way motion of the plate c is prevented by projections c' upon it
coming against planed surfaces at the end of the valve chest as shown.
By the arrangement above described of forming a steam-tight joint
between the cylinder d and steam chest cover e the relieving plate c is
always free to follow up and press against the back of the reciprocating
valve as the valve faces wear away; the thin joint ring giving way as
the surfaces wear the inner edge of the joint on the steam chest cover is
chamfered off, as shown, to admit of this motion of the flexible ring; the
reciprocating valve will thus practically have always the same pressure
upon it, and remain steam-tight without any further attention.
condensing engines the relieving cylinder d should be made larger in
proportion than for high pressure engines as the vacuum as well as the
pressure of the steam will then be acting on the relieving plate c which
presses on the back of the valve.
In
In this case provision should be made

page_text: for holding the plate on to the back of the valve until a vacuum is formed
at the time of starting the engine.
What we claim as regards this part of our Invention is, the combined
arrangement above described for relieving the back of a slide valve from
an excess of pressure, such combination consisting of the plate a for the
back of the valve to work against the cylinder and packing plate c,
substantially as herein described.
According to another arrangement the back of the valve and the face
are in separate parts connected by a telescopic joint suitably packed, so
that whilst the face of the valve works steam tight over the ports the
back may also work steam tight against the bonnet or back of the steam
chest, in which there is a cavity in connection with the centre port or
with the air. The centre port may be a steam port, and in this case the
cavity behind the valve will be somewhat less in area than the interior
surface of the back of the valve which is exposed to the pressure. The
front portion of the valve is so proportioned that the steam may hold it
against the face with a suitable pressure.
At Figure 2 is shewn a longitudinal section of a slide valve arranged
as above described, the cavity in the steam chest cover being in con-
nection with the central port which in this Figure is an exhaust port;
the back of the reciprocating valve and its face are marked respectively a
and b; the two are connected together by a telescopic joint as shown; c
is the valve face with the steam and exhaust ports formed in it; d is the
cavity in the steam chest cover, which cavity is in communication with
the central port. The areas of the two parts a and b of the reciprocating
valve which are acted upon respectively by the steam and exhaust are
so proportioned as to press them up to the faces against which they
work sufficiently to obtain steam-tight joints. In place of the cavity d
being in communication with the central port it might be open to the
air. In the arrangement shewn at the longitudinal section, Figure 3, the
central port is a steam port, so that there will be a pressure of steam in
the cavity d of the bonnet or valve chest cover.
What we claim as regards this part of our Invention is the combined
arrangements of slide valve above described and shewn at Figures 2
and 3 of the Drawings annexed, the face and back of the reciprocating
valve being in two separate pieces coupled by a steam-tight telescopic
joint, and there being a cavity in the valve chest cover above the back

page_text: of the reciprocating valve open to the central port or to the air, sub-
stantially as described.
In witness whereof, I, the said James Grafton Jones, have here-
unto set my hand and seal, this Nineteenth day of October,
in the year of our Lord One thousand eight hundred and 5
seventy.
J. GRAFTON JONES. (L.s.)