IMPROVEMENTS IN THE SLIDE VALVES AND PISTONS OF STEAM AND OTHER ENGINES
Year: 1869

page_text: LETTERS PATENT to Thomas Adams, of No. 1, Laurel Grove, Penge,
in the County of Surrey, for the Invention of "IMPROVEMENTS IN
THE SLIDE VALVES AND PISTONS OF STEAM AND OTHER ENGINES."
Sealed the 22nd December 1869, and dated the 5th October 1869.
PROVISIONAL SPECIFICATION left by the said Thomas Adams at the
Office of the Commissioners of Patents, with his Petition, on the
5th October 1869.
I, THOMAS ADAMS, of No. 1, Laurel Grove, Penge, in the County of
Surrey, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN THE SLIDE VALVES AND PISTONS OF STEAM AND OTHER ENGINES," to be
as follows:-
This Invention has for its object improvements in the slide valves and
pistons of steam and other engines.
In constructing slide valves I form in the back of the valve an
annular groove into which a metal ring is fitted; this ring is pressed up to

page_text: the bonnet or valve box cover by springs; the steam is admitted by
passages formed for it under the ring, and a metallic packing prevents
the steam passing the ring. This being the general construction of the
valve, I make the surface of the ring on which the steam acts smaller in
area than the surface which bears against the bonnet.
According to another arrangement I form at the back of the valve a
cylindrical cavity, and I fit into it a piston suitably packed; this piston
projects from the cylindrical cavity, and its head or end, which is of
larger diameter than the cylindrical cavity, bears against the bonnet or
cover of the valve box, a bearing surface being formed around its cir-
cumference, and the steam is free to act against this bearing surface,
but not over its full width, so that as in the arrangement first described
the area acted upon by the steam is less than that which is in contact
with the bonnet or cover of the valve box, and this is an important
element in the combination.
In constructing pistons I cause the packing ring to be at all times
exposed at its back to the pressure of the exhaust steam. I make a
passage through the piston, to which I fit a double valve having a face
on either side of the piston. The steam on entering the cylinder closes
the valve on the side of the piston on which it acts, opening at the same
time the passage on the other or exhaust side of the piston which leads to
the back of the packing ring. When the steam is admitted on the other
side of the piston immediately the double valve is reversed in position,
and the back of the packing ring is exposed to the pressure of the
exhaust steam as before.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Adams in the Great Seal Patent Office
on the 4th April 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
ADAMS, of No. 1, Laurel Grove, Penge, in the County of Surrey, send 3
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifth day of October, in the year

page_text: of our Lord One thousand eight hundred and sixty-nine, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Thomas Adams, Her special licence that
I, the said Thomas Adams, my executors, administrators, and assigns,
or such others as I, the said Thomas Adams, my executors, adminis-
trators, 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 THE SLIDE
VALVES AND PISTONS OF STEAM AND OTHER ENGINES," upon the condition
(amongst others) that the said Thomas Adams, 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 Thomas Adams, 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 the slide valves and
pistons of steam and other engines.
In constructing slide valves I form in the back of the valve an
annular groove into which a metal ring is fitted; this ring is pressed up
to the bonnet or valve box cover by springs; the steam is admitted by
passages formed for it under the ring, and a metallic packing prevents
the steam passing the ring. This being the general construction of the
valve, I make the surface of the ring on which the steam acts smaller in
area than the surface which bears against the bonnet.
According to another arrangement I form at the back of the valve a
cylindrical cavity, and I fit into it a piston suitably packed; this piston
projects from the cylindrical cavity, and its head or end, which is of
larger diameter than the cylindrical cavity, bears against the bonnet or
cover of the valve box, a bearing surface being formed around its cir-

page_text: .cumference, and the steam is free to act against this bearing surface,
but not over its full, width, so that as in the arrangement first described
the area acted upon by the steam is less than that which is in contact
with the bonnet or cover of the valve box, and this is an important
element in the combination.
Having thus stated the nature of my Invention, I will proceed to
describe the manner of performing the same.
.
Figure 1 is a plan of valve looking on its back shewing displacement
and packing rings, and spring and buckle; Figure 2 is a section of the
same; Figure 3 is another section of displacement ring. The letters
on any Figure refer to the same on any other Figure.
V is the valve; D, the displacement ring; R, the packing ring; S, a
spring; H, exhaust steam communication holes; h, initial steam com-
munication holes; F, the face of steam chest cover or face of division
plate; B, the buckle. The right use of D is to displace so much of the
steam from the back of the valve as will produce an instantaneous
balance between the positive and negative forces acting on the back and
face of the valves at any given instant of the valve's position in its
stroke, to determine which (Figure 4) draw the outer and inner edges
of the valve face V, V, V, V, v, v, v, v. Let A, B, be the centre line of
motion, and C the centre of the valve; on C, as a centre, describe the
circle X, Y, Z. Let the valve be represented, as in Figure 2, at the
commencement of the stroke, and V, VI, becomes an instantaneous axis.
Set off the spaces P, P, as representing the positive unbalanced forces,
and N, N, as those representing the negative unbalanced forces; find
'the centre of action of each space respectively; find also their areas, and
multiply the area of each space by the distance of its centre of
'action from the instantaneous axis V, VI, and by the measure of its
force, which is represented by the temperature of its surface relative
'to the absolute zero of heat, make the sum of the negative forces equal
to those of the positive, and the moment which ensures the balance will
be correct, and the face of the valve working on the cylinder face and
exposed to negative force will always have a greater area than the back
of the valve exposed to positive force. B, D, has also got a surface &
exposed to a constant initial force, and it has also got a surface S¹
working against another surface F, and having exposed to a pair of

page_text: unequal and interchanging forces, and to balance which (Figure 5) let
A, B, be the centre line of motion, and D, E, an axial line. Let C be
the centre of formation: On C, as a centre with radius equal to the
outer circumference line of the body of D, Figure 2, or head of D,
Figure 3, describe the circle A, E, B, D. On the same centre with radius
equal to the inner circumference line of body of Figure 2 or outer line
of body of Figure 3 inscribe the circle a, e, b, d; find the centre of
action of the concentric space bounded by the outer and inner radii just
described and represented by the dot line on either side of the axis D, E;
set off the angles D, C, D, E, C, F, each equal to 60 degrees; draw
D', D, E, E; join E", D", E, D'; then the area of the concentric
space bounded by the angle E', C, D', multiplied by the distance of its
centre of action from the axis D, E, is equal to the combined concentric
spaces bounded by the angles E, C, E', D, C, D', multiplied by the dis-
tances of their centres of action from the axis D, E, and C, F; C, C, is
therefore the static leverage with which the two unequal forces of
initial and exhaust pressures act on either side of D, E. Let F repre-
sent the temperature of the initial steam, and G that of the exhaust
steam, both measured. from the absolute zero of heat; then G mul-
tiplied by the distance F, G, and divided by the sum of the forces F and
G will give the fulcrum O. Set off O, F, into any number of equal
parts, and O, G, into any number of the same parts; then the number of
parts contained in O, F, will be the proportion of the surface S exposed
to initial force, and the number of parts in O, G, will be the proportion
of the surface S¹ exposed to the two unequal initial and exhaust forces,
and the area S¹ working against F and exposed to two unequal forces
must, in order to maintain the balance, be greater than the arca S
exposed to a constant force equal to the greater of the other two, and
hence the greater area of working surface to surface exposed. II, H, are
communication holes to allow the exhaust pressure within the cavity of
valve to pass freely through and exert its force equally on both sides of
the valve on the area contained within the displacement area, and also
to act equally on the inner sides and ends of D not in contact with the
surface F, and so maintain the balance internally. R is a metallic
packing ring having a small piece cut out of it, by preference before
being turned, the joint to be held close in chuck while being turned; when
freed it has a natural self-contained spring to press itself against V or D.
S is a three or more armed spring to secure V against the cylinder face,

page_text: and D against F when running without steam. h, h, are holes to admit
initial steam under D, but where D does not come in contact with B
the outer part of V may be dispensed with, and S become exposed to the
steam in the chest.
What I claim as regards this part of my Invention is, constructing
slide valves substantially as herein described, the proportion of their
surfaces being such as to maintain the balance between the positive and
negative forces and between equal and unequal forces, as herein set
forth, for by the proportion of surfaces alone can a slide valve be
balanced.
In constructing pistons I cause the packing ring to be at all times
exposed at its back to the pressure of the exhaust steam. I make a
passage through the piston, to which I fit a double valve having a face
on either side of the piston. The steam on entering the cylinder
closes the valve on the side of the piston on which it acts, opening at
the same time the passage on the other or exhaust side of the piston
which leads to the back of the packing ring. When the steam is admitted
on the other side of the piston, immediately the double valve is reversed
in position, and the back of the packing ring is exposed to the pressure
of the exhaust steam as before.
Figure 6 shews a transverse section, and Figure 7 a plan view of a piston
with a valve applied to it as above described. P is the piston, and V the
valve. The valve is double seated and joined in the middle, so that when
the initial pressure enters the cylinder the steam will close the valve on its
seating by reason of the difference between the outer and inner areas of
the head of valve exposed to the force, and in closing the end on which the
steam acts it opens the end exposed to the exhaust pressure, allowing
the exhaust steam in the cylinder to enter in behind the packing ring or
rings R and press it to the cylinder side, and as the same pressure is
acting between the packing ring and cylinder sides the outer surface of
the packing ring is greater than the inner, but the angular force is the
same in both cases, and the packing ring or rings is balanced against the
cylinder sides.

page_text: propelling side, and opens to the exhaust side, allowing the exhaust
pressure to act behind the packing ring or rings, and so balancing the
packing rings.
In witness whereof, I, the said Thomas Adams, have hereunto
set my hand and seal, this Twenty-first day of January, in the
year of our Lord One thousand eight hundred and seventy.