IMPROVEMENTS IN STEAM ENGINES, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO HYDRAULIC RAMS AND PUMPS
Year: 1872

page_text: LETTERS PATENT to Walter Charles Church, of Brixton, in the County
of Surrey, Engineer, for the Invention of "IMPROVEMENTS IN STEAM
ENGINES, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO HYDRAULIC
RAMS AND PUMPS."
Sealed the 19th April 1872, and dated the 21st February 1872.
PROVISIONAL SPECIFICATION left by the said Walter Charles Church
at the Office of the Commissioners of Patents, with his Petition,
on the 21st February 1872.
I, WALTER CHARLES CHURCH, of Brixton, in the County of Surry,
Engineer, do hereby declare the nature of my said Invention for
WHICH IMPROVEMENTS ARE
"IMPROVEMENTS IN STEAM ENGINES, PARTS OF
APPLICABLE TO HYDRAULIC RAMS AND PUMPS," to be as follows:-
-
This Invention relates more particularly to the pistons, packing rings,
and slide valves of steam engines, and has for its object the increasing
the power of the engine, the prevention of waste of steam, the facilitating
the balancing or removal of the back pressure on the slide valve, the
A

page_text: of the steam passages.
According to my Invention I propose to employ a piston having
convex or hemispherical top and bottom surfaces in lieu of having flat
faces as heretofore, whereby I obtain an increased effective area for the
steam pressure to act upon. I propose to pack my improved piston or
an ordinary piston by means of two or more packing rings of a peculiar
section, such rings being so shaped in transverse section as that the
surface in actual contact with the sides of the cylinder shall have a less
area than the surface contained within the groove in the body of the
piston itself, whereby I obtain an excess of expanding force, tending
to press the packing ring or rings outwards over that which tends to
press it inwards, and hence I prevent leakage. One or more openings
or passages is or are so made in the body of the piston as that the steam
shall exert a pressure tending to force the ring or rings against the
forward side of the annular groove in the piston at the same time that
it expands or forces the ring or rings outwards. A fish piece is to be
placed across the joint in each ring, in order to make good the same.
I propose to make the slide valves of steam engines of a circular, in
lieu of a rectangular form, and to make the valve ports in the cylinder
of a correspondingly curved form, whereby I am enabled to reduce the
length of the steam passages. This form of valve admits of the removal
or balancing of the pressure on the valve more easily than when using
a rectangular shaped valve. I propose to balance or remove the back
pressure on the valve by the employment of a cap or ring of smaller
diameter than the valve itself, fitting over a junk ring secured by a
central bolt to the back of the valve, a packing ring similar to the one
herein-before referred to being interposed between the said junk ring
and the inner parallel sides of the cap, in order to make the joint steam
tight. The cap is kept pressed against the steam chest cover when
the steam is out by an S shaped spring fitted on to a central bolt, the
contact surfaces of the spring and the cap being bevelled or inclined.
The junk ring has a number of holes made round its outer circum-
ference to allow of the escape of any steam which may leak past the
side of the packing ring. The pressure of the steam when in the valve
chest against the annular area of the cap next the valve keeps the
said cap firmly against the steam chest cover, and thus prevents back
pressure.

page_text: It is obvious that the same arrangement used in duplicate may be
applied to a rectangular slide valve.
Although I have described my improved packing ring in reference to
the piston of a steam engine, they are obviously equally applicable to
the rams of hydraulic presses, to the pistons and plungers of pumps,
and to other similar purposes.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Walter Charles Church in the Great Seal Patent
Office on the 21st August 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WALTER
CHARLES CHURCH, of Brixton, in the County of Surrey, Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-first day of February, 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 suc-
cessors, give and grant unto me, the said Walter Charles Church, Her-
special license, that I, the said Walter Charles Church, my executors,
administrators, and assigns, or such others as I, the said Walter Charles
Church, my executors, administrators, or 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 "IMPROVEMENTS IN STEAM ENGINES, PARTS OF WHICH IMPROVEMENTS ARE
APPLICABLE TO HYDRAULIC RAMS AND PUMPS," upon the condition (amongst
others) that I, the said Walter Charles Church, my executors or
administrators, by an instrument in writing under my hand and seal,
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

page_text: NOW KNOW YE, that I, the said Walter Charles Church, do hereby
declare the nature of my 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 accompanying
Drawings, and to the letters and figures marked thereon, that is to
say:
My said Invention relates more particularly to improvements on the
pistons, packing rings, and slide valves of steam engines, and is in part
based upon my Patents numbered respectively 1974, A.D. 1867, and
3169, A.D. 1868, and has for its object the so improving the pistons and
slide valves as to increase the power of the engine, prevent waste of
steam, balance or remove the back pressure on the slide valve, reduce
the cost of manufacture of the piston and valve, and diminish the length
and width of the steam passages in the cylinder.
According to my present improvements I propose to pack the piston
of a steam engine by means of two or more metallic packing rings
of an L shaped section cut through on one side and disposed so that
the surface in actual contact with the internal working surface of the
cylinder shall have a less area than the surface contained within the
groove in the body of the piston itself, and which is subjected to the
direct pressure of the steam admitted through holes in both faces of
the piston alternately at each stroke of the piston, whereby I obtain an
excess of expanding force, tending to press the packing ring or rings
outwards against the internal working surface of the cylinder over that
which tends to press them inwards, and hence I prevent leakage. In
conjunction with this action the steam also exerts a pressure which
forces the forward side of the ring or rings against the central belt or
flange situate between the annular grooves in the piston at the same
time that it expands or forces the ring or rings outwards, the said ring
or rings being free laterally in their grooves. A segmental joint piece
such as is herein-after described is to be placed across the joint in each
ring, in order to make good the joint and prevent leakage through the
same.
Although I have described my improved mode of packing in reference
to the piston of a steam engine, it is obviously applicable to the rams

page_text: I propose to employ a peculiar construction and arrangement of
equilibrium slide valve for steam engines, such valve being of a circular
in lieu of the ordinary rectangular form, and capable of rotating within
a circular buckle or clip such as is herein-after described when running
with or without steam. I also propose to make the valve ports in the
cylinder of a peculiarly curved form herein-after fully described, whereby
I am enabled to reduce the length and width of the steam passages
whilst I increase the length of the port for the lead. The peculiar
construction of slide valve herein-after described admits of the removal
or balancing of the pressure on the valve more effectually and easily
than when an ordinary rectangular shaped valve is used. I propose to
balance or remove the pressure acting on the back of the valve by the
employment of a cap or ring of smaller diameter than the valve itself
fitting over a junk ring secured by a central bolt to the back of the
valve; an L shaped packing ring similar to the one herein-before referred
to with reference to the piston and acting in the same manner being
interposed between the under side of a projecting flange on the upper
surface of the said junk ring and the body of the slide valve, and pressed
against the inner parallel surface of the cap and against the junk ring
by the pressure of the steam in the valve chest, thus making the said
surfaces in contact steam tight. The cap is kept pressed against the
steam chest cover when the steam is out by an S shaped spring fitted
on to a central stud, the contact surfaces of the spring and the cap being
bevelled or inclined. The junk ring has a number of holes or radial
slots made round its outer circumference to allow of the escape of any
steam which may leak past the contact surfaces of the metallic packing
ring. The pressure of the steam when in the valve chest against the
annular area of the cap next the valve keeps the said cap firmly against
the steam chest cover, and thus reduces the area subject to pressure on
the back of the valve. The same arrangement of cap, junk ring, S
shaped spring, and packing ring used either singly or in duplicate may
be applied to a rectangular slide valve.
And in order that my said Invention may be fully understood I shall
now proceed more particularly to describe the same, and for that pur-
pose shall refer to the several Figures on the annexed three Sheets of
Drawings, the same letters of reference indicating corresponding parts
in all the corresponding Figures.
Figure 1 (Sheet 1) of my Drawings represents a transverse section of
a 16 inch locomotive engine cylinder with my improved slide valve and

page_text: piston drawn to a scale of three inches to the foot, these sizes being
given by me as an example of the application of my Invention; Figure
2 is a corresponding longitudinal vertical section of the same; Figure 3
is a view of the back of the improved slide valve corresponding to Figure
2 (the cover of the valve chest being removed). Figure 4 is a view
shewing the improved cylinder ports corresponding to Figure 1. The
rest of the Figures on Sheet 1 are details which I shall herein-after more
particularly describe and refer to.
Figure 9 on Sheet 2 is a vertical longitudinal section of the improved
steam passages and steam and exhaust ports, and Figure 10 is a corre-
sponding plan of the said steam and exhaust ports adapted to a 12 inch
circular slide valve as herein-after described and drawn to a scale of one
half the full size.
A is the cylinder which with the exception of the steam and exhaust
ports a, a, and b, and steam passages as herein-after described may be of
the ordinary construction. B is the piston, which is packed by two
or more metallic packing rings c, c, of the section shewn more clearly
in the enlarged detail, Figure 5. These rings are cut as shewn at d
in the detail, Figure 6, and the cut or opening is covered by a seg-
mental piece e secured to one of the ends of the ring and overlapping
the other end. The section of the ring is L shaped," and the outer and
narrowest surface is that which is in actual contact with the internal
working surface of the cylinder, the inner and larger surface being
contained within a groove or annular chamber formed in the piston and
exposed to direct steam pressure from within the said rings, being free
laterally in their grooves. The segmental joint piece e is of a thickness
sufficient to fill the recess or rebate round the ring, so that it will with
the ring fit into and nearly fill the transverse area of the annular
groove in the piston; f, f¹, are holes in the two sides of the piston
for the admission of steam to act upon the larger areas of the said
packing rings alternately both outwardly and laterally at each stroke of
the piston.
The body of the piston is grooved out as shewn in my Drawing
(Figure 2), and in the enlarged detail (Figure 5) for the purpose of
admitting steam to act upon the ring or rings alternately, so as to press
them outwardly against the internal working surface of the cylinder,
and at the same time laterally against the central belt or flange g' in

page_text: the body of the piston, which belt or flange g¹ is turned to a smaller.
diameter than the internal working surface of the cylinder. On admit-
ting steam to either end of the cylinder the said steam enters one or
other of the two annular grooves or chambers through the openings
for f as the case may be, at each stroke of the piston, and acts on the
entire lateral area of the metallic packing ring or rings c, pressing the
annular reduced area on the forward side of the ring of rings c against
the central belt or flange g¹ in the body of the piston as well as the
reduced outward annular area of the metallic packing ring or rings c
against the internal working surface of the cylinder A.
The central belt or flange g¹ of the body of the piston is turned to a
less diameter than the internal working surface of the cylinder A. as
shewn in Figure 5, in order that when the metallic packing ring or
rings care first put to work in the cylinder, any steam that might escape
past the reduced lateral area on the forward side of the ring or rings c,
by reason of the surface or surfaces not being tightly pressed against
the central belt or flange g¹, or any steam that might escape past the
reduced outer annular area of the ring which might not be in contact
with a portion of the internal working surface of the cylinder when first
put to work on the engine, will pass between either of the surfaces herein-
before mentioned, and cannot exert a sufficient amount of pressure on
the recessed or rebated area of the ring or rings c to balance the pressure
on the opposite side. The leakage if any passes between the central
belt g¹ in the body of the piston and the cylinder, and as the metallic
packing rings c are a slack fit laterally they allow any steam that might
thus escape past the said surface or surfaces not in tight contact to at
once force the ring c on the exhausting side of the piston in a forward
direction, thereby allowing any pressure of steam caused from leakage
to escape past the reduced lateral surface of the ring c on the exhaust,
ing side of the piston and through the holes fas shewn by the arrow,
in Figure 5, so long as the exhausting side of the steam port is open
to the atmosphere or condenser. After working a short time the said
surface or surfaces in contact with the internal working surface of the
cylinder and the central belt or flange in the body of the piston become
tight, thereby preventing any waste of steam or loss of power to the
engine while working. The recess or rebate in the rings c will vary
in width and depth according to the diameter of the ring or rings adopted,
as this recess or rebate regulates the proportions of the outward annular

page_text: area pressed against the internal working surface of the cylinder A as
well as the lateral area pressed against the central belt or flange g¹ in
the body of the piston B.
According to the Drawings of my improved piston the internal area
of each metallic ring c is about 23 square inches acted upon at each
stroke of the piston by the pressure of steam or other fluids in the
cylinder, and the external area of the ring or rings c pressed against
the working surface of the cylinder is about 19 square inches, thereby
showing an excess of about 4 square inches more than the external
area. The lateral area of each ring or rings c acted upon at each stroke
of the piston by the pressure of steam or other fluids in the cylinder is
about 30 square inches, and the lateral area pressed against the central
belt or flange g¹ in the body of the piston is about 10 square inches,
giving an excess of 20 square inches also acted upon by the pressure
of steam or other fluids in the cylinder. By these means I insure a
perfectly tight contact of the annular area of the ring or rings c pressed
against the central belt or flange g¹ in the body of the piston, and also
of the outward annular area of the ring or rings c pressed against the
internal working surface of the cylinder. I thus prevent any escape of
steam or other fluids past the surfaces of the piston ring or rings c at
each stroke of the piston whilst working.
The areas herein-before given will vary according to the depth, width,
and diameter of ring or rings adopted.
I shall now proceed to describe my improved circular slide valve,
which is of peculiar construction. It is left free to revolve during its
travel within the clip or buckle D on the valve rod or spindle E, by
which arrangement the relative surfaces of the valve and port faces are
continually varying, thereby preventing the formation of grooves, and
consequently producing a greater uniformity of wear and a longer
duration of both valve and port faces. The circular slide valve C may
be economically made by turning it up and facing it in the lathe; Fis
a junk ring shewn in detail plan in Figure 7 which is also turned in
a lathe. This ring is fixed on to the back of the valve by a central bolt
and nut G; above and around this junk ring there is adjusted the loose
cap H, also turned up and faced in the lathe, which cap slides against
the face of the steam chest cover thereby preventing the pressure of
steam or other fluids from acting on the area contained in the inside
diameter of the cap H in contact with the metallic packing ring 9. A

page_text: steam-tight metallic packing ring is established between the junk ring
and the top of the valve and the inner parallel bored surface of the cap
H, by the interposition of the L shaped packing ring 9 (shewn in detail
in Figure 6), the said ring being forced outwards and at the same time
forced against the under or inner side of the projecting flange of the
junk ring so as to maintain a tight joint and prevent leakage of steam
by the pressure of the steam in the valve chest. When the steam is out
of the valve chest the cap H is held in contact with the steam chest
cover by the S shaped spring I (Figure 8), which is placed centrally on
a stud or pap turned on the end of the bolt G, whilst the extremities of
its two arms which are bevelled or inclined so as to fit the inner bevelled
or inclined surface of the cap are made to press against such bevelled or
inclined surface, and consequently the horizontal and vertical tension
of the spring forces upwards the said cap or caps. The said S shaped
spring can be cast either in gun metal, iron, or steel, or forged out of
ordinary spring steel as may be required, and is made larger in diameter
across the arms than the internal diameter of the bevelled or inclined
surface of the cap or caps as required. The action of the spring is so
designed that in case one of the arms should accidentally break the
remaining arm still retains its elastic action, both horizontally and
vertically as the spring being bored out centrally to fit on the stud or
pap turned on the end of the bolt G; it forms a kind of fulcrum for the
action of each arm, so that one can work independently of the other.
I have found it necessary in practice to make the metal of the metallic
packing ring or rings g of the valve much softer than either that of the
cap H or junk ring F, that is to say, that if the cap H and the junk
ring F are made of gun metal the metallic packing ring 9 should be
made of soft brass so as to prevent the outer surface of the metallic
packing ring g from wearing or forming grooves in the internal parallel
surface of the cap H as well as in the surface of the projecting flange
of the junk ring F, by reason of the extension and compression of the
rings whilst working. In the centre of the steam chest cover a pipe. K
is fitted leading into the atmosphere, such pipe forming the vent for
any steam that may escape between the cap H and the valve chest
cover, or may leak past the packing ring 9. A number of holes or
radial slots are made round the edge of the junk ring (as shewn in
Figure 7) to allow of the free escape of any steam that may momentarily
leak past the surfaces of the metallic packing ring when the steam first

page_text: enters the valve chest, and other openings are made through the cap H,
such openings communicating with an annular groove or channel h
(Figure 3) made in the sliding face of the cap, which groove or channel
in conjunction with other channels or sunk parts at i, i, also serve as
free vents for any steam that may leak behind the cap H when first
put to work on the engine.
It will be seen by referring to the plan (Figure 3) that the clip or
buckle D surrounding the circular slide valve C is bored out so as to
be an easy fit over the back part of the valve to allow the valve to
rotate freely within it. The semicircular ends of the buckle D are
struck with the same radius as the diameter of the valve face C, each
being struck from a separate centre for the purpose of giving a greater
sectional area on the longitudinal centre line, the section of which is
shewn in the longitudinal section, Figure 2, so as to keep the buckle D
from springing and thereby allow the valve C to rotate freely within the
buckle D during the reciprocal motion of the valve. A flat surface is.
provided on each side the total depth of the buckle D, so as to form a
guide between the projecting surface h¹ on each side of the steam chest
to keep the valve C always central over the ports and thus prevent any
lateral motion of the buckle D by the rotation of the valve C. These
projecting surfaces h¹, h', are suitably faced on the inner side and also
serve to impart a rotatory motion to the slide valve when travelling
without steam by reason of the periphery of the face of the valve rolling
against one or other of the said surfaces. The same rotatory motion of
the valve C is also obtained when under steam if one side of the valve
face or port face should become dry for want of more lubrication than
the other side, as a greater amount of friction will be caused on that
part of the port face or valve face through a deficiency of lubrication,
thereby creating a greater amount of cohesion between the parts in
contact, and by the reciprocal motion of the valve C this excess of
cohesion on one side of the valve face over the other will cause the
valve C to rotate in its buckle D, thereby causing a uniformity of wear
between the surfaces in contact.
The following proportions of the acting surfaces of the metallic
packing ring g for a 12-inch circular slide valve constructed according
to my Invention will be found to, answer well in practice. The outer
reduced annular area of the metallic packing ring 9 in contact with the
internal parallel surface of the cap H is about 9 square inches, and the

page_text: inner area of the metallic ring exposed to the pressure of steam in
the steam chest is about 13 square inches, showing an excess of about
4 square inches for forcing the outer reduced annular area against the
internal parallel surface of the cap H by the pressure of steam in the
steam chest. The reduced annular area of the metallic packing ring g
on the upper side next, the junk ring F is about 6 square inches, and
the area of the lower slide of the ring next the valve exposed to the
pressure of steam in the steam chest is about 17 square inches, showing
an excess of about eleven square inches for forcing the upper reduced
surface of the ring against the projecting flange of the junk ring F by
the pressure of steam in the steam chest. By these means I ensure a
perfectly tight contact, and thus prevent any escape of steam or other
fluids past the said surfaces when working. The proportions will vary,
and consequently the areas, according to the width, depth, and diameter
of ring or rings adopted.
Figure 11, Sheet 3, of my Drawings represents a longitudinal vertical
section of an ordinary rectangular slide valve, the back pressure on
which is avoided or reduced by the application thereto of my improve-
ments consisting of the junk ring, cap, S shaped spring, and metallic
packing ring acting as herein-after described.
Figure 12 is a corresponding plan or view of the back of the slide
valve with the valve chest cover removed showing a duplicate arrange-
ment of caps, one cap being in its working position and the other
cap removed, and Figure 13 is a corresponding transverse setion of
the same taken through the centre thereof and showing both caps in
their places. In cases where the rectangular slide valve is nearly
square a single arrangement of cap, junk ring, packing ring, and S
shaped spring may be used. C is the rectangular slide valve, which is
connected to the valve rod E by eyes D, D, formed on the back of the
valve, through which eyes the rod E is passed, and is secured therein by
a nut at one end and a loose collar at the other, as shown by dotted lines
in longitudinal section Figure 11. It will be seen that the valve
spindle E is flattened on the top side in the centre part of the valve as
shown in dotted lines in the longitudinal section, Figure 11, and in full
lines in plan (Figure 12), also in transverse section Figure 13, for the
purpose of allowing the caps to be placed closer together, and thereby
obtaining a greater area for displacement of steam on the back of the
rectangular valve due to the inside diameter of the caps H, or more

page_text: strictly speaking the line of contact between the outer diameter of each
metallic packing ring g and the internal diameter of its cap H. A pair
of junk rings F, F, are secured by means of the bolts G, G, to the back
of the valve, and in combination with each junk ring there is provided
a cap H, an S shaped spring I, and a metallic packing ring g, all
arranged and operating precisely as described in reference to the circular
slide valve. K, K, are the two vent pipes (one for each junk ring and
cap), one of which I have also previously referred to.
When either of the herein-before described. slide valves are under
steam the steam in the steam chest presses upon that part of the annular
area of the cap or caps H next the valve, which area is due to the
difference of its inner and outer diameters, and as this annular area is
greater than that on the top of the cap or caps H which is outside the
annular channel or groove h, h, the steam consequently forces the cap or
caps H tight against the steam chest cover, and by the position and
formation of the annular groove h, h, any steam pressure from small
leakage caused by the surfaces not accurately fitting one another when
first put to work on the engine is prevented from being realized on the
additional wearing surfaces on the cap face pressed against the steam
chest cover,
and contained within the annular channel or groove h, since
such leakage will pass off by the channels i to the vent pipe or pipes K.
The surfaces of the cap or caps H and steam chest cover after working
for a short time will become perfectly tight. Should the spring I not
force the surface of the cap face tight against the surface of the steam
chest cover when the steam is shut off from the steam chest, the moment
the steam is readmitted into the steam chest the pressure of steam
acting upon the annular area of the said cap or caps next the valve
instantly forces the cap or caps against the steam chest cover by reason
of the annular area of the cap or caps next the valve being greater than
the annular area on the cap face pressed against the steam chest cover
which is outside the annular groove h, h. All leakage is carried off by
the annular groove h, h, and sunk parts i, i, and escapes through the
pipe or pipes K. into the atmosphere, as shown on the Drawings, there
being always a free communication through the pipe or pipes K to the
atmosphere when the valve C is working as an equilibrium slide valve,
thereby gaining the remaining area or areas contained within the
groove or passages i on the cap face H for additional wearing surface,
and diminishing the friction and pressure per square inch between these

page_text: surfaces, consequently increasing the durability of the cap face as the
total areas of the cap face sliding on the steam chest cover are greater
than the annular area of the cap H next the valve C exposed to the
steam pressure in the steam chest.
It will be seen from the Drawings that the cap or caps H are kept
central by their inner parallel part fitting over the junk ring or rings F
either on the circular or rectangular valves, and are independent and
free to have a rotatory motion round the junk ring or rings F when
travelling without steam, especially on locomotive engines, since one
side of the S shaped spring will in practice press one side of the cap or
caps H against the steam chest cover with a greater pressure than the
other, thereby causing a greater amount of cohesion between the sur-
faces in contact, and by the reciprocal motion of the valve C this excess
of cohesion on one side of the cap over the other will cause the cap or
caps H to rotate around the junk ring or rings F, thereby causing a
uniformity of wear between the surfaces of the cap or caps Hand the
surface of the steam chest cover. The sanie rotatory motion of the cap
or caps H is obtained when under steam, if one side of the cap or caps
in contact with the steam chest cover should become dry for want of
lubrication, as a greater amount of friction is thereby caused on that
part of the cap or caps, thus creating a greater amount of cohesion
between the parts in contact, and by the reciprocal motion of the valve C
this excess of cohesion on one side over the other will cause the cap or
caps to rotate round the junk ring or rings F, and insure a greater
uniformity of wear between the surfaces in contact.
The S shaped
spring by fitting loosely on to a central stud or pap turned on the head
of the bolt G is left free to rotate with the cap or caps if required.
By referring to the Drawings it will be seen that by the formation of
the metallic packing ring 9 the upper reduced area of the said ring
which is pressed against the under side of the projecting flange of the
junk ring F is less than the area exposed to steam pressure on the side
next the valve C, also that the internal area of the packing ring acted
upon by steam pressure is greater than the reduced external area which
is pressed against the internal parallel surface of the cap or caps H, and
that the metallic packing ring or rings 9, g, which are also cut on one
side, as shown at d in Figure 6, are covered by a segmental piece e,
which fills the annular rebate or recess on the top side of the ring, as
shewn in the Drawings. The said segmental piece is bevelled slightly

page_text: along its entire length and depth on the outter side so that its entire
length and depth shall not bear against the inside parallel surface of
the cap or caps H, thereby ensuring a uniform contact between the
inner bored parallel surface of the cap or caps and the upper part of the
outer reduced area of the packing ring even should the surfaces of
the port face and steam chest cover not be perfectly parallel. As the
segmental piece e is pressed tight against the projecting flange of the
junk ring or rings F it prevents any steam from escaping at the part
where the cut in the ring g is made. The holes or radial slots in the
edge of the junk ring (see Figure 7) for carrying off any leakage of
steam that may escape past the surfaces of the metallic packing ring or
rings g through the pipe K in the steam chest cover to the atmosphere are
so drilled that the inner edges of these holes or slots are about 3 of an
inch clear of the outside annular bearing surface of the packing ring,
which is pressed up against the projecting flange of the junk ring or
rings F so as to prevent any leakage of steam passing through the
opening or cut in the ring 9, and which is not covered by the segmental
piece e before described, since the said segmental piece e only fills the
recess which is turned on the side of the metallic packing ring or
rings 7 next the junk ring, which recess will vary in width and depth
according to the size of ring adopted. The pressure of steam acting on
the annular area of the cap or caps H next the valve will hold them
tight against the steam chest cover, and the pressure acting on the
larger annular area of the metallic packing ring or rings g next the
valve will hold them also tight against the inner surface of the pro-
jecting flange of the junk ring or rings F, thereby providing against any
want of parallelelism between the port face and steam chest cover, so
that by the reciprocal motion of the valve C the cap or caps H will
adjust themselves over the outer diameter of the metallic packing ring
or rings g, and thus accommodate themselves to any want of parallelism
which may exist between the surfaces of the port face and the steam
chest cover, thereby preventing the surface of the cap or caps H from
being displaced from the surface of the steam chest cover and ensuring a
tight contact between the surfaces described. The valve ports in lieu of
being rectangular are of the peculiar curvilinear form shown in Figures 4
and 10 of my Drawings, the ports are also angled or inclined below the
port face to suit their curvilinear form as shown by the dotted lines z
in Figures 2 and 9, which angle or inclination extends round the
exhaust side and accross the ends of the steam ports, as shown at Z in

page_text: Figure 10). These last-mentioned dotted lines also show the clearance
requisite below the port face for the tool to clear in slotting them out
as each arc can be slotted under a circular slotting machine. This form
of steam port a enables the steam passages to the cylinders to be
shortened and reduced in width, as shown in plan in Figures 4 and 10,
whilst at the same time a larger area and uniform lead are obtained
throughout the entire length of port.
In Figures 9 and 10 I have also shewn the method of setting out the
various curves requisite for a valve 12 inches diameter which is as
follows, reference being had to the figured dimensions on the said Figures:
f First describe the circle of the valve C of the diameter fixed upon,
which as shown in the Drawing (Figures 9 and 10) is 12 inches diameter
or 6 inches radius; within this circle mark off on each side from the
circumferential line on the centre line the outside lap and the width of
the steam port a, which are respectively 2 of an inch and 1 inch, as
shown in Figure 10. This gives the width of valve face, namely, 1
inches. This dimension will vary according to the outside lap of the
valve and the width of the steam port a, also of the inside lap if adopted.
The diameter of the exhaust opening in the valve is found by sub-
tracting the width of the valve face on each side from the diameter of
the valve C, namely, 12 inches minus 3 inches, which leaves 8 inches
for the diameter of the exhaust opening in the valve C. The radius
for the outer edges of the port face is the same as that of the valve,
namely, 6 inches, and the width from the outside of the port face to the
outer arc of the steam port a is 1½ inches. This dimension will vary
according to the travel and outside lap of the valve. The radius for
the outer arc or curve of the steam port a is 16th of an inch greater
than that of the valve face C, and is therefore 6 inches, as shown in
the Drawing (Figure 10), giving a uniform opening of 8th of an inch
for the entire length of the arc of the steam port a, which is 14 inches
long and allowing the port to commence opening at the two extremities
of the arc or curve in lieu of on the centre line. The same result occurs
on the exhausting side of the steam port. This dimension also varies
according to the lead decided upon. When a greater amount of uniform.
lead is required the radius of the outer arc of the steam port a will
increase in a greater proportion to the radius of the valve face C, as
the valve face being circular its motion causes the steam port a to open,
more quickly on the centre line whilst travelling over the port face,,

page_text: thereby requiring the outer arc of the steam port a to be struck with a
greater radius than that of the valve C, thus giving a greater opening
with a uniform lead on the entire length of the arc of the steam
port a and thereby accomplishing any amount of uniform lead required.
The width of the steam port a on the centre line is one inch and the
radius of the arc of the inside of the steam part a is 1/16th of an inch
less than the radius of the exhaust opening in the valve C, namely,
4 inches, which produces a uniform opening throughout the entire
length of the arc on the exhaust side of the steam port a, and as
the valve C travels over the steam port a and opens the exhaust
side thereof at the same time, the length of the exhaust are of the
valve C increases in such a rapid manner over the inner arc of the
steam port a as to allow the steam to escape freely from the cylinder.
The exhaust opening in the valve C being of a circular form it opens
more quictly on the centre line, and therefore the arc on the exhaust
side of the steam port a is struck with a less radius than that of
the valve C (which is 4½ inches) as shewn in Figure 10. The
width of the bars between the steam and exhaust ports on the centre
line is 1 inches, and the radius of the arc of the exhaust port 6 is
the same as that of the exhaust opening in the valve C, namely 41
inches, so that when the valve C works expansively only opening the
steam port a on the centre line 38th of an inch, the inside of the circular
exhaust opening in the valve C will be flush with the arc or curve of
the exhaust port 6 (see Figures 9 and 10), thereby producing a uniformity
of wear on the surfaces whether working in full throw or expansively.
It will be seen on referring to the Drawings of the circular and
rectangular slide valves that the area on the back of the valve not
acted upon by the pressure of steam in the steam chest is equal to the
area of the inside diameter of the cap or caps H, or more strictly
speaking is equal to the area bounded by the line of contact between
the outer diameter of the metallic packing ring or rings 9, and the
internal diameter of the cap or caps H.
It will also be seen that there is a provision made for compression
in the cylinder, which compression is caused by the boiler priming,
or by an accumulation of condensed water in the cylinder, when the
engine is first started by a clearance being allowed between the top
of the junk ring F and the under side of the cap or caps H, also between
the top side of the valve C and the lower annular edge of the said cap or

page_text: caps. The pressure of steam in the steam chest acting upon the lower
annular area of the cap or caps H next the valve C will hold the said
cap or caps tight against the steam chest cover, so that when compression
takes place in the cylinder one side of the valve C being raised from
the port face at each stroke of the piston B, the valve C causes the
metallic packing ring or rings g to rise inside the cap or caps H, and
when the piston B arrives at the end of its stroke compression ceases,
and this side of the valve C again falls on to the port face without
moving the surface of the cap face H from the surface of the steam
chest cover, thereby preventing the surface of the cap or caps H from
being displaced from the surface of the steam chest cover and insuring
a tight contact between the surfaces described.
'
The practical rule adopted for giving additional outside lap on ordinary
rectangular slide valves over the steam ports increases the width of the
valve face, thereby giving an increased area on the back of the valve
exposed to the pressure of steam in the steam chest, tending to press it
to the port face, but in a circular slide valve of my improved construction
as herein-before described the outside lap of the valve may be increased
without increasing the area on the back of the valve acted upon by
the pressure of steam in the steam chest, by bringing the outer curves
or arcs of the steam ports a, a, closer together on the centre line,
leaving nevertheless a sufficient area between the two curves or arcs
of the exhaust port 6 for the steam to escape freely from the cylinder,
also leaving an uniform opening throughout the entire length of the
curve or arc of the steam port a (which is 14 inches long as herein-
before described, and illustrated by Figures 9 and 10), hence the
superiority of my method for setting out the ports on the port face
for circular valves will be obvious.
It will be seen on referring to the Drawings that in my improved
slide valves there is no communication between that portion of the back
of the valve enclosed by the cap or caps H and the exhaust port 6 in
the port face of the cylinder for the passage of any leakage that may
take place from defects in the surfaces of the cap or caps H and metallic
packing ring or rings g into the exhaust, as this leakage would pass
through the pipe or pipes K into the atmosphere, but should there be
any such leakage as would cause a waste of steam from the engine the
attendant by closing a tap or taps attached to the pipe or pipes K in
R

page_text: the steam chest cover allows the pressure of the steam escaping from
the steam chest to be exerted on that portion of the back of the valve
enclosed within the cap or caps H, thus reducing the valve for the time
being to an ordinary slide valve.
In a rectangular valve C, supposing one tap only to be closed from
the causes before described, the enclosed area within the cap H would
be acted upon by the pressure of steam in the steam chest, but if both
taps were closed from the causes before described the pressure of steam
would act upon the back of the valve in the same manner that it would
with a slide valve of the ordinary construction.
Thus it will be seen that under the most unfavorable circumstances
(as in case of accidents) my improved equilibrium slide valves can
never become more objectionable than the ordinary slide valve at present
in use, as they can either work as equilibrium or ordinary valves until
an opportunity can be obtained for rectifying any part or parts that may
have become deranged, thereby insuring their certainty of working in
all cases and on all classes of engines either as equilibrium or ordinary
slide valves.
The advantages to be derived from the adoption of my peculiar circular
equilibrium slide valves and curved ports as compared with the rect-
angular valves now in ordinary use may be exemplified to a certain
extent by taking a circular valve of 12 inches diameter, as shewn on the
Drawings (Sheets 1 and 2), containing an area of about 113 square inches
on the back of the valve having steam ports for admitting steam on the
lead 14 inches in length, with an area of about 13 square inches, the
area of the exhaust port being about 37 square inches. The rectangular
valve now in use, which is taken as a comparative example, is 16 inches
long and 9 inches wide, having an area on the back of the valve of
156 square inches with steam ports only 13% inches in length, about
18 square inches area, the exhaust port being about 37 square inches
area. On comparing the above dimensions it will be seen that my
circular slide valve steam port is half an inch greater in length on the
lead than the rectangular one, with an area of about 43 square inches
less on the back of the valve to be acted on by the pressure of the steam
in the steam chest, which diminishes the power required for working it a
compared to an ordinary rectangular slide valve of the dimensions given

page_text: at the same time gaining where most required a large amount of steam
supply to the cylinders, as well as economising its consumption by
reason of the formation of the ports through diminishing the width and
length of the steam passages into the cylinder.
I
may observe that I am aware that it has been proposed to employ
a circular slide valve in conjunction with lunar shaped ports, that is to
say, with crescent shaped steam ports and a circular exhaust port in the
port face, also with curved steam ports having their outer and inner
sides struck from one common centre, forming also the centre of a
circular exhaust port, also with curved steam ports and a circular
exhaust port in which the outer curve of the said steam ports is struck
with a radius as much larger than the radius of the common centre as
the lap of the valve, but in all these arrangements the opening on the
lead is not uniform throughout the entire length of the curve, and the
length of such opening is less than it would be with a circular valve of
my improved construction of the same diameter.
Having now described and particularly ascertained the nature of my
said Invention, and the manner in which the same is or may be used or
carried into effect, I would observe in conclusion that what I consider
to be novel and original, and therefore claim as the Invention secured to
me by the herein-before in part recited Letters Patent is,―
1st. The use of recessed or rebated metallic packing rings in combina-
tion with segmental joint pieces for pistons of steam engines and other
like purposes, such as for plungers of hydraulic rams, &c. when arranged
and operating substantially as herein-before described and illustrated in
the Drawings annexed.
2nd. The peculiar construction and arrangement of equilibrium
circular slide valves and their combination with the peculiar curvilinear
steam and exhaust ports as herein-before described.
3rd. The peculiar construction of curvilinear steam and exhaust ports
as and for the purposes herein-before described and illustrated more
particularly by Figures 9 and 10 of my Drawings.
4th. The combination with a circular or with a rectangular slide valve
of the junk ring or rings, the cap or caps, the metalic packing rings,
and the springs, such as are above described, all arranged and operating

page_text: together substantially as and for the purposes herein-before set forth
and as illustrated in the Drawings annexed.
In witness whereof, I, the said Walter Charles Church, have to this
my Specification set my hand, and seal, this Twentieth, day of
August One thousand eight hundred and seventy-two.
W. C. CHURCH. (L.S.)