AN IMPROVEMENT IN PISTON VALVES AND OTHER PISTONS
Year: 1863

page_text: LETTERS PATENT to William Clark, of 53, Chancery Lane, in the
County of Middlesex, Engineer and Patent Agent, for the Invention
of "AN IMPROVEMENT IN PISTON VALVES AND OTHER PISTONS." -A com-
munication from abroad by Thomas Shrimton Davis, of Jersey, City in
the County of Hudson, and State New Jersey, United States of America,
Machinist.
Sealed the 16th June 1868, and dated the 22nd January 1863.
PROVISIONAL SPECIFICATION left by the said William Clark at the.
Office of the Commissioners of Patents, with his Petition, on the 22nd
January 1863.
I; WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex,
Engineer and Patent Agent, do hereby declare the nature of the said Inven-
tion for "AN IMPROVEMENT IN PISTON VALVES AND OTHER PISTONS," to be as
follows:-
This improvements is more especially designed for piston valves, but may be
adopted in other kinds of pistons. It consists in the construction of such a
valve, or of any piston with an expanding ring having the head and follower
fitted to its interior, and with a dovetail wedge so applied in connection with
the ring head and follower as to make the valve or piston as much like a
solid block as is desirable, yet capable of being set out to fit the cylinder in
which it works and compensate for wear.
In the accompanying Drawing, which forms part of this Specification,
Fig. 1 is a central section of the piston valve constructed according to the
Invention; Fig. 2, a transverse section of the same.

page_text: A is the single ring of cast iron, brass, or other metal of a depth equal to
the whole depth of the piston or valve, turned up externally to a cylindrical
form to fit the cylinder or cylindrical seat, and having its interior turned out
at one side concentrically to its exterior, as shown at a, for the reception
within it of the flange b, of the solid head B of the piston, and turned out at
the opposite side in a similar manner as shown at c, in Fig. 1, for the reception
of the follower. The said ring has cut in its exterior, at any point in its
circumference, a taper dovetail groove d, d, for the reception of a dovetail
wedge D, which is to be movable parallel with the piston rod, and from the
middle of the back of said groove the said ring is cut through, as shown at e,
to permit it to be set out by the dovetail wedge, the outer face of which
combines with the periphery of the ring to make a complete cylinder. The
solid head B is driven tightly on, or otherwise firmly secured to the rod E,
and the follower C is fitted to the rod, and secured by a nut G, fitted
to the screw thread on the rod, the said nut holding it close up to the
face of the head B, and to the shoulder at the back of the recess c. The
flange b has projecting from its periphery a short pin f to enter a notch 9, in
the interior of the recess a of the ring, and the follower C has a similar pin to
enter a similar notch in the recess c. These notches and pins prevent the
head B, the follower C, and ring A, from turning independently of each
other. The head B and follower C are received entirely, or almost entirely,
within the ring A, so that the peripherical surface of the piston is unbroken,
except at the junction of the wedge D, and the piston is almost like a solid
block, though it can be expanded or set out against the interior of its cylinder
or cylindrical seat, as required, to make it fit and compensate for wear by
means of the wedge D. To provide for the convenient adjustment of the
wedge D there is applied a screw H, screwing through a tapped hole in the
lug at one end of the wedge, and having a journal i so fitted to a bearing
in the follower C as to be capable of turning freely, but not moving longi-
tudinally. This screw is fitted with a jam nut j to secure the wedge in any
position in which it may have been adjusted.
In applying piston valves for the introduction of the steam to and from the
cylinders of steam engines there is provided within the steam chest a cylindrical
casing or seat bored for the reception of the valves, which are two in number,
and attached to the same stem or rod E, and the steam ports and exhaust
As the outer. ends
port are arranged substantially as for the D slide valve.
of both valves are exposed to the pressure of the steam in the chest, and the
inner ends of both are exposed to the pressure of the exhausting steam, or of
the atmosphere, the valves are perfectly balanced in a direction parallel with

page_text: their axis and to provide for balancing them in all directions radial to the
axis there are grooves of a width corresponding with the width of the ports,
and communicating with said ports cut all round the seat.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Clark in the Great Seal Patent Office on the 17th
July 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
CLARK, of 53, Chancery Lane, in the County of Middlesex, Engineer and
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of January, in the year of our Lord
One thousand eight hundred and sixty-three, in the twenty-sixth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said William Clark, Her special licence that I, the said William Clark,
my executors, administrators, and assigns, or such others as I, the said
William Clark, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times there-
after 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 "AN,
IMPROVEMENT IN PISTON VALVES AND OTHER PISTONS," a communication to me.
from abroad by Thomas Shrimton Davis, of Jersey City, in the County of
Hudson, and State of New Jersey, United States of America, Machinist,
upon the condition (amongst others) that I, the said William Clark,
my executors or administrators, by an instrument in writing under my,
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 I, the said William Clark, do hereby declare
the nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being had to the Sheet of Drawings hereunto annexed,
and to the letters and figures marked thereon (that is to say):-
This improvement is more especially designed for piston valves, but may be
adopted in other kinds of pistons. It consists in the construction of such a

page_text: valve or of any piston with an expanding ring, having the head and follower
fitted to its interior and with a dovetail wedge, so applied in connection with
the ring head and follower as to make the valve or piston as much like a
solid block as is desirable, yet capable of being set out to fit the cylinder in
which it works and compensate for wear.
In the accompanying Drawing, which forms part of this Specification,
Fig. 1 is a side view of the piston valve constructed according to the Invention;
Fig. 2 is a central section of the same; Fig. 3 is a transverse section of the
same; Fig. 4 is a face view of the packing ring, and Fig. 5 is a central
longitudinal section of the cylinder and steam chest of a locomotive, having a
pair of such piston valves. Similar letters of reference indicate corresponding
parts in the several Figures.
A, Figs. 1, 2, 3, 4, is a single ring of cast iron, brass, or other metal, of a
depth equal to the whole depth of the piston, or valve turned up externally
to a cylindrical form to fit the cylinder or cylindrical seat, and having its
interior turned out at one side concentrically to its exterior as shown at a, a,
in Figs. 2 and 4 for the reception within it of the flange 6 of the solid head B,
of the piston, and turned out at the opposite side in a similar manner as
shown at c, in Fig. 2, for the reception of the follower C. The said ring has
cut in its exterior at any point in its circumference a taper dovetail groove d, d,
for the reception of a dovetail wedge D, which is to be movable parallel
with the piston rod, and from the middle of the back of said groove the
said ring is cut through as shown at 1, in Figs. 2, 3, and 4, to permit it
to be set out by the dovetail wedge, the outer face of which combines with
the periphery of the ring to make a complete cylinder. The solid head B,
is driven tightly on, or otherwise firmly secured to the rod E, and the
follower C is fitted to the rod and secured by a nut G, fitted to a screw
thread on the rod, the said nut holding it close up to the face of the head B,
and to the shoulder at the back of the recess c. The flange has projecting
from its periphery a short pin f to enter a notch g in the interior of the
recess a of the ring, and the follower C has a similar pin to enter a similar
notch in the recess c. These notches and pins prevent the head B, the
follower C, and ring A, from turning independently of each other. The
head B and follower C are received entirely or almost entirely within the
ring A, so that the peripherical surface of the piston is unbroken, except
at the junction of the wedge D, and the piston is almost like a solid block,
though it can be expanded or set out against the exterior of its cylinder or
cylindrical seat as required to make it fit and compensate for wear by means
of the wedge D. To provide for the convenient adjustment of the wedge D,

page_text: there is applied a screw H screwing through a tapped hole in a lug h, at one
end of the wedge, and having a journal i so fitted to a bearing in the follower
C as to be capable of turning freely, but not moving longitudinally. This
screw is fitted with a jam nut j to secure the wedge in any position in which
it may have been adjusted.
In applying piston valves for the induction of the steam to and from the
cylinders of steam engines, there is provided within the steam chest S (Fig. 5)
a cylindrical casing or seat T bored for the reception of the valves, which
are two in number, and attached to the same stem or rod E, and the steam
ports S, S', and exhaust port t, are arranged substantially as for the D slido
valve. As the outer ends of both valves are exposed to the pressure of the
stream in the chest, and the inner ends of both are exposed to the pressure of
the exhausting steam or of the atmosphere, the valves are perfectly balanced
in a direction parallel with their axis, and to provide for balancing them in all
directions radial to the axis, there are grooves u, u', of a width corresponding
with the width of the ports s, s', and communicating with said ports cut all
round the seat T.
Having described the nature of this Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein-before in part recited Letters Patent is, the construction of a piston
valve or other piston with an expanding ring A, having the head B and
follower C fitted to its interior, and furnished with a dovetail wedge D, the
whole combined substantially as herein described.
In witness whereof, I, the said William Clark, have hereunto set my
hand and seal, this Seventeenth day of July, in the year of our Lord
One thousand eight hundred and sixty-three.
Witness,
W. G. E. SWINNOCK,
53, Chancery Lane,
London.
W. CLARK. (L.S.)