IMPROVEMENTS IN AND APPLICABLE TO SLIDE VALVES
Year: 1867

page_text: LETTERS PATENT to Thomas Adams, Engineer, and George John Parson,
Gentleman, both of No. 5, Duke Street, Adelphi, in the County of
Middlesex, for the Invention of "IMPROVEMENTS IN AND APPLICABLE TO
SLIDE VALVES."
PROVISIONAL SPECIFICATION left by the said Thomas Adams and
George John Parson at the Office of the Commissioners of Patents,
...with their Petition, on the 18th September 1867.
We, THOMAS ADAMS, Engineer, and GEORGE JOHN PARSON, Gentleman,
both of No. 5, Duke Street, Adelphi, in the County of Middlesex, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN AND
APPLICABLE TO SLIDE VALVES," to be as follows:-
Our Invention has for its object the formation of steam-tight joints applied
to the working surfaces of slide valves, and consists in the adaptation
and application of metallic packing rings to the steam displacement rings, or
to the seating of the valve, or to the valve itself. The steam-tight joint may
be formed by the insertion of a single packing ring in or about the middle of
'the' depth of the steam displacement ring, but a greater number may be
distributed over the surface thereof. 'And in applying the said packing rings
to the valve or the valve seating one or more packing rings may be inserted in

page_text: the middle or distributed over the rubbing surfaces as required. The spring
or springs for keeping the valve in close contact with the cylinder face is or
are by preference applied in such a manner as to cause the fulcrum or point
of resistance of each spring to be taken on the steam displacement ring, and
the ends of the springs to exert their force on each end of the valve in the
line of its motion.
In order to meet the variations of lap and stroke of valve as well as breadth
of bar or cylinder faces the valve is placed in that position of the stroke
where the moment of the common centre of gravity of the negative forces
although tending in the greatest degree to press the valve away from the
cylinder face yet does not exceed the moment of the common centre of gravity
of the positive forces tending to keep the valve in contact with the cylinder
face.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Adams and George John Parson in the Great Seal
Patent Office on the 18th March 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, THOMAS
ADAMS, Engineer, and GEORGE JOHN PARSON, Gentleman, both of No. 5,
Duke Street, Adelphi, in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of September, in the year of our Lord
One thousand eight hundred and sixty-seven, in the thirty-first year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us, the
said Thomas Adams and George John Parson, Her special licence that we,
the said Thomas Adams and George John Parson, our executors, adminis-
trators, and assigns, or such others as we, the said Thomas Adams and George
John Parson, our 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
AND APPLICABLE TO SLIDE VALVES," upon the condition (amongst others) that we,
the said Thomas Adams and George John Parson, our executors or adminis-
trators, 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

page_text: 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 Thomas Adams, on behalf of myself,
and of the said George John Parson, 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,..
reference being had to the Drawings hereunto annexed, and to the letters
and figures marked thereon (that is to say) :-
Our Invention of " Improvements in and applicable to Slide Valves" has.
for its object the formation of steam-tight joints applied to the working
surfaces of, slide valves, and consists in the adaptation and application of
metallic packing rings to the steam displacement rings, or to the seating of:
the valve,, or to the valve itself. The steam-tight joint may be formed by the
insertion of a single packing ring in or about the middle of the depth of the
steam displacement ring, but a greater number may be distributed over the
surface thereof; and in applying the said packing rings to the valve or the
valve seating one or more packing rings may be inserted in the middle or
distributed over the rubbing surfaces as required. The spring or springs for
keeping the valve in close contact with the cylinder face is or are by preference.
applied in such a manner as to cause the fulcrum or point of resistance of each
spring to be taken on the steam displacement ring, and the ends of the
springs to exert; their force on each end of the valve in the line of its..
motion.
In order to meet the variations of lap and stroke of valve as well as breadth:
of bar or cylinder faces the valve is placed in that position of the stroke.
where the moment of the common centre of gravity. of the negative forces.
although tending in the greatest degree to press the valve away from the
cylinder yet does not exceed the moment of the common centre of gravity
of the positive forces tending to keep the valve in contact with the cylinder
face.
Having thus stated the nature of the said Invention, we will proceed to
describe more particularly in what manner the same is to be performed by
reference to the accompanying Drawings, in which are represented the parts
above referred to.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 is a section of a valve laid in its middle position over the ports;
Fig. 2 is a plan or horizontal view of the same shewing three displacement
rings applied thereto; Fig. 3 is a section of a valve laid in its position at the

page_text: commencement of the stroke; Figures 4 and 5 represent the mode of finding
the area of displacement. In these several Figures the same letters of reference
indicate corresponding parts.
V is the valve; R is the displacement ring; R¹, the metallic packing ring,
which in Fig. 1 is shewn recessed into the displacement ring and pressing
against the valve; these metallic packing rings may however be increased in
number and distributed over the surface of the displacement ring or the valve..
The fulcrum of the spring S is in this case resting on the valve, the ends
pressing the displacement ring against its working surface, whether this be the
door or a division plate, but the said spring may be inverted with its fulcrum.
resting on the displacement ring and the ends against the valve; a, a, (Fig. 2),
are apertures to allow the exhaust pressure to act equally on both sides of the
exhaust cavity and on both ends of the inside of the displacement ring. Fig. 4
is a plan of the valve shewing the outer and inner edges thereof, and Fig. 5
is a diagram representing the stroke of the piston and of the valve, and also
the pressures; both positive and negative, on the valve.
In Fig. 5 x is the point of suppression of steam, and y the point of exhaust
representing a diminution of pressure equal to forty-four per cent. In order to
determine the area of displacement a space equal to forty-four per cent. of the
area of the admission port is set off from the inner edges of the valve from. A
to A¹, and from B to B¹ (see Fig. 4), then the area bounded by the letters-
A, B, C, D¹, becomes the area of displacement for the whole-valve, which in
the Figure is distributed between the three rings. The per-centage of the
area of the admission port to be added to the area bounded by the inner edges
of the valve is determined by the difference between the final pressures of
admission and exhaust, which are determined by the proportions of the outer
and inner edges of the valve.
Fig. 6 shews a form of head of a displacement ring with a recess in it;
Fig. 7 shews the ring with the exhaust cavity formed in it; Fig. 8 shews
at the left-hand side a plain ring without a head with a metallic packing
ring in the valve pressing against the ring, and at the right-hand side the
Figure shews a metallic packing ring in the displacement ring and pressing
against the valve. The Figure also shews in the one case a spiral spring S
and in the other case a flat spring S.
Fig. 9 is a plan of a portion of the head of a ring, shewing the proportion
of areas at the top and bottom at the point where it would leave its working
surface. A and B are the centres of gyration, and supposing the temperature
at A to be three hundred and eighty degrees, and at B three hundred degrees,
then three hundred multiplied by the distance A, B, and divided by the sum

page_text: of both temperatures will give the distance A, C; then C is the common
centre of the forces, and A, C, is the proportion of the under surface of the
displacement ring exposed to the action of the steam in the valve chest and
C, B, the proportion of surface exposed to the working face at the instant
when the ring would leave its working face.
Having thus described the nature of the said Invention, and in what
manner the same is to be performed, we hereby declare that what we claim
as of our Invention, is,-
First. The formation of steam-tight joints by the insertion of metallic
packing rings either in one or more pieces in the steam displacement rings or
in the valve or the valve seating.
Secondly. The mode herein-before described of determining the area of
displacement of steam on the valve.
Thirdly. The mode described of determining the point at which the ring
will leave its working surface.
And lastly. The arrangement of the working surfaces of both the valve and
displacement ring in such a manner that the moment of the forces holding
them respectively against their working surfaces must be equal to or greater
than the areas of the working surfaces multiplied by their pressures, and this
result may be attained either by the action of the steam alone, or by mechanical
means such as springs, or by both combined.
In witness whereof, I, the said Thomas Adams, on behalf of myself
and of the said George John Parson, have hereunto set my hand and
seal, this Seventeenth day of March, in the year of our Lord One
thousand eight hundred and sixty-eight.
Witness,
WILLIAM SPENCE,
8, Quality Court,
Chancery Lane.
THOMAS ADAMS. (L.S.).