IMPROVEMENTS IN PISTONS FOR Steam and othER ENGINES AND PUMPS
Year: 1872

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
in the County of Middlesex, Patent Agent, for the Invention of
"IMPROVEMENTS IN PISTONS FOR Steam and othER ENGINES AND PUMPS."-A
communication from abroad by Frédéric Jean Falcimagne, of Paris,
France.
Sealed the 30th July 1872, and dated the 10th June 1872.
PROVISIONAL SPECIFICATION left by the said Alexander Melville
Clark at the Office of the Commissioners of Patents, with his
Petition, on the 10th June 1872.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN PISTONS FOR STEAM AND OTHER ENGINES
AND PUMPS," to be as follows :—
This Invention relates to an improved construction of piston for steam
and other cylinders and pumps. This piston is provided with a means
of adjustment which may be placed outside of the cylinder, besides
which it is lighter, of greater strength, and capable of being more
accurately filled than the pistons now in use.

page_text: This improved piston is furnished with a metallic annular clastic
packing, the expansion of which is effected without interruption to the
motion of the piston, by pressure applied simultaneously in opposite
directions on the double inclined surfaces of the packing by means of a
hollow piston rod, through which passes an inner rod. To the outer rod
is attached the nearer of the two plates of which the piston is composed,
the other plate being attached to the inner rod. The tubular piston rod
is attached at the other end to the cross head, and the inner rod is con-
tinued through and provided with a screw nut on its end for tightening
up the two plates of the piston.
Figure 1 of the accompanying Drawing shows a central vertical
section of the improved piston with piston rod in position in a cylinder;
Figure 2 is an elevation of the piston; Figure 3, a horizontal section on
line 1, 2, Figure 2; while Figure 4 shows a plan of the piston in dotted
lines.
The piston is composed of two plates l, m, having their edges made
conical, or bevelled in opposite directions, as shown, between which the
piston packing is placed. The packing consists of three concentric rings
of which p, q, are external rings bevelled to correspond to the bevelled
edges of plates l, m, both rings being in perfect contact with each
other throughout. r is an inner ring, bevelled on both sides, and with
which the outer rings q, m, are in contact. Each of the rings is cut, as
shown in Figure 2, so that they may all be expanded by the pressure
of the plates 1, m; n is the hollow piston rod, attached at one end
to plate 1, and at the other to cross head i, as shown; o, rod fixed
at one end to the plate m and passing through n, said rod being screw
threaded at its other end to receive a nut g which works within or
against a socket h fixed to the cross head i, through which the end of
rod e passes.
In a slightly modified arrangement a solid piston rod is used, and
plate is fixed directly to said rod, which is prolonged through. the
plate m, and screw-threaded at that part on which works a screw socket
fitted concentrically in plate m, and secured by a nut so as to be free to
turn in said plate, whereby the plates l, m, may be drawn together, as
required, to expand the packing rings as before.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Melville Clark in the Great Seal Patent
Office on the 9th December 1872.
. TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Tenth day of June, in the year of
our Lord One thousand eight hundred and seventy-two, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Alexander Melville Clark, Her special
licence that I, the said Alexander Melville Clark, my executors, adminis-
trators, and assigns, or such others as I, the said Alexander Mel-
ville Clark, my executors, administrators, 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 PISTONS FOR STEAM AND OTHER ENGINES AND PUMPS,"
a communication to me from abroad by Frédéric Jean Falcimagne,
of Paris, France, upon the condition (amongst others) that I, the said
Alexander Melville Clark, my executors or administrators, by an instru-
ment in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said In-
vention, 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 Alexander Melville Clark, .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, reference being had to the accom-
panying Sheet of Drawings, and to the letters and figures marked
thereon (that is to say) :-
:-
This Invention relates to an improved construction of piston for steam
11
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navida
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page_text: of adjustment placed in one arrangement outside of the cylinder, besides
which it is of lighter construction, greater strength, and capable of being
more accurately fitted than the pistons now in use.
This improved piston is furnished with a metallic annular packing,
the expansion of which may be effected, if necessary, without inter- 5
ruption to the motion of the engine by pressure applied simultaneously
in opposite directions on the inner beveled surfaces of the packing rings
by tightening up the two plates of which the piston is composed, by means
of a hollow piston rod attached to the nearer of the two plates, and
through which an inner rod passes attached to the other plate. The 1
tubular rod is attached at the other end to the cross head, and the inner
rod is continued through and provided with a screw nut on its end for
tightening up the two plates of the piston.
This Invention is illustrated in the accompanying Drawing, Figure 1
of which shows a central vertical section of the improved piston with 1
piston rod in position in a cylinder; Figure 2 is an elevation of the piston
removed; Figure 3, a horizontal section on line 1-2, Figure 2; while
Figure 4 shows a plan of the piston in dotted lines.
l, m, are the two plates or discs of which the piston is composed.
Their edges are beveled in opposite directions, so as to form a V shaped 2
opening around the piston, as shown, in which the piston packing is
placed. The packing consists of three concentric rings, of which p, q,
are external rings, each bevelled on one side to correspond to the beveled
edges of plates l, m, and flat on the other side, so that both rings will be
in perfect contact with each other throughout. ☞ is an inner ring
bevelled on both sides to correspond to the bevelled edges of plates l, m,
and with which ring the outer rings p, q, are in contact. Each of the
rings is cut, as shown in Figure 2, so that they may all be expanded
simultaneously by tightening up the plates l, m; n is the hollow piston
rod attached at one end to piston plate 7, and screwed at the other end a
to cross head i, as shown; o, rod fixed at one end to the piston plate m,
and fitted within n, said rod being screw-threaded at its other end to
receive a round nut g, which works within or against a yoke-shaped
socket or guide & fixed to the cross head i by screw nuts, and through
which the end of rod o passes; k, k, arc circular springs or cupped discs a
-

page_text: nuts g, z, for adjusting the packing rings, the whole arranged as described,
and illustrated in Figure 5 of the Drawings.
In witness whereof, I, the said Alexander Melville Clark, have
hereunto set my hand and seal, this Ninth day of December,
in the year of our Lord One thousand eight hundred and seventy-
tavo