IMPROVEMENTS IN SLIDE VALVES AND VALVE PORTS OR FACINGS FOR STEAM AND OTHER MOTIVE ENGINES
Year: 1878

page_text: LETTERS PATENT to Francis William Webb, of Crewe, in the County of
Chester, Mechanical Engineer, for the Invention of "IMPROVEMENTS IN SLIDE
VALVES AND VALVE PORTS OR FACINGS FOR STEAM AND OTHER MOTIVE
ENGINES."
Sealed the 10th December 1878, and dated the 21st August 1878.
PROVISIONAL SPECIFICATION left by the said Francis William Webb at the
Office of the Commissioners of Patents on the 21st August 1878.
FRANCIS WILLIAM WEBB, of Crewe, in the County of Chester, Mechanical
Engineer. "IMPROVEMENTS IN SLIDE VALVES AND VALVE PORTS OR FACINGS FOR
STEAM AND OTHER MOTIVE ENGINES."
Firstly. My Invention refers to the improved slide valves described in the
Specification of Letters Patent granted to me, numbered 3403, dated the 25th day
of November 1869.
In the said Specification, a circular valve is described so as to be free to move
round or change its place in a hoop formned on the valve spindle which gives
reciprocating motion to it, the effect of such arrangement as that described in the
said Specification, and shown by the Drawings, being that the valve rotates or
moves round, or to and fro in the hoop without any special mechanism to produce
such movement other than that which results from the arrangement described in
my said Specification, and the result and advantage of the said Invention is that
the valve and port facings wear perfectly smooth and even without any tendency
to become grooved, as is the case with slide valves arranged in the ordinary
manner.
My present Invention relates to the above-named valves, and consists in an
improved form or construction of such valves and their ports or facings, having the
object above explained, namely, in arranging the inlet and outlet ports upon the
cylinder so that the outer edges of the inlet ports are or may be made to a curve
formed by a radius equal to the semi-diameter of the flange part of the valve, the
centre from which the curve is struck being in the centre line in which the valve
Din 1

page_text: slides, but at a distance equal to the "lap" from the centre of the middle or outlet
port. The curve of the inner edges of the inlet ports are or may be struck from the
centre of the middle or outlet port with a radius equal to the semi-diameter of the
interior of the valve, or, in other words, with a radius equal to the semi-diameter of
the outer flange of the valve, less the width of the inlet port at the middle or centre
line of the valve.
The outlet port is or may be made circular, with clearances cast at each side of
the port; or it is or may be of such form that there is no part of the port face over
which the valve does not work.
Clearance is also cast in each side of the face of the middle port; one of these
spaces or clearances, in the case of valves, working with their faces vertical, is used
for lubrication, and they also serve to reduce the pressure between the valve and
port faces.
Secondly. Another part of my Invention refers to valves intended to work
compound engines, in which the valves are arranged in chambers or chests common
or open to the backs of both valves, and in this case I admit the steam or other
elastic fluid to one cylinder through the interior of the valve, and exhaust it from
the exterior edge of the valve into the common chamber, and thence in the ordinary
way through the second valve to the second cylinder.
Thirdly. My Invention relates to ordinary slide or rectangular valves for steam
and other motive engines, and its object is to arrange them in such manner that a
grooving action upon their faces will be prevented, and it consists in placing the
valve in its hoop or buckle so that it can move to and fro across its line of motion
when working, and in connecting the valve with a piston or diaphragm that will
give a lateral movement or change in the lateral position of the valve as the steam
or motive power varies in pressure. Or the valve is arranged in its buckle so as to
be free and capable of being slightly oscillated or moved in the lengthway of the
ports by arranging space in the buckle and shaping the exterior of the valve to
allow a slight oscillation, or by arranging rollers or connecting links between the
buckle and valve.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Francis William Webb in the Great Seal Patent Office on the 20th
February 1879.
FRANCIS WILLIAM WEBB, of Crewe, in the County of Chester, Mechanical
Engineer. "IMPROVEMENTS IN SLIDE VALVES AND VALVE PORTS OR FACINGS FOR
STEAM AND OTHER MOTIVE ENGINES."
Firstly. My Invention refers to the improved form of slide valves described in
the Specification of Letters Patent granted to me, numbered 3403, dated the 25th
day of November 1869.
In the said Specification, a circular valve is described so as to be free to move
round or change its place in a hoop formed in the valve spindle which gives
reciprocating notion to it, the effect of such arrangement as that described in the
said Specification, and shown by the Drawings, being that the valve rotates, or
moves round, or to and fro in the hoop without any special mechanism to produce
such movement other than that which results from the arrangement described in
my said Specification, and the result and advantage of the said Invention is that
the valve and port facings wear perfectly smooth and even without any tendency
to become grooved, as is the case with slide valves arranged in the ordinary
manner.
My present Invention relates to the above-named valves, and consists in an
improved form or construction of the ports or facings of such valves having the
object above explained. The inlet and outlet ports upon the cylinder are arranged
according to one modification described in the Specification of my said Patent, that
is, so that the outer edges of the inlet ports are made to a curve formed by a radius
equal to the semi-diameter of the flange part of the valve, the centre from which
the curve is struck being in the centre line in which the valve slides but at a
distance equal to the lap (if lap is used) from the centre of the middle or outlet
port. The curve of the inner edges of the inlet ports are struck from the centre of
the middle or outlet port, with a radius equal to the semi-diameter of the interior
of the valve, or, in other words, with a radius equal to the semi-diameter of the
outer flange of the valve less the width of the inlet port at the middle or centre
line of the valve, with the lap added, when lap is used.
The outlet port is made circular, but is improved by extended clearances cast at
each side of the port so that a portion of the valve face is always exposed to the
exhaust, there being no part of the port face over which the valve does not work.
Clearance is also cast in each side of the face of the middle port, one of these
spaces or clearances, in the case of valves, working with their faces vertical, is used
for lubrication, and they also serve to reduce the pressure between the valve and
.port faces.
Secondly. Another part of my Invention refers to valves intended to work
compound engines, that is, engines where the steam passes through a high and low
pressure cylinder. The valves are arranged in chambers or chests common or open
to both valves, and by my Invention I admit the steam or other elastic fluid to one
cylinder through the interior of one valve, and exhaust it from the exterior edge of
this valve into the common chamber, and thence in the ordinary way through the
second valve to the second cylinder.
Thirdly. My Invention relates to ordinary slide or rectangular valves for steam
and other motive engines, and its object is to arrange them in such manner that a
grooving action upon their faces will be prevented, and it consists in placing the
valve in its hoop or buckle so that it can move to and fro across its line of motion
when working, and in connecting the valve with a piston ram or diaphragm that
will cause a lateral movement or change in the lateral position of the valve when
the steam or motive power varies in pressure. Or the valve is arranged in its
buckle so as to be free and capable of being slightly oscillated or moved in the

page_text: -
lengthway of the ports by arranging spaces in the buckle and shaping the exterior
of the valve to allow a slight oscillation; or by arranging rollers or connecting links
between the buckle and valve.
Fig. 1 is an elevation of the port faces on a cylinder, and Fig. 2 is a longitudinal
section through the valve ports and steam chest.
The above Figures represent a primitive valve (a), that is, a valve without
"lap," and the outer and inner edges of the inlets port (b) and the outlet or exhaust
port (c) are all struck with radii from the common centre, that is, the centre of the
exhaust port (c), the outer curve of the inlet ports (b) being struck with a radius
equal to the semi-diameter of the outer flange part of the valve (a), and the inner
edge of the inlet ports (b) being struck with the same radius, less the width of the
inlet ports.
d are extended clearance spaces; e is a space for the lubricant; d' is a small hole
passing into the exhaust cavity, shown in section in Fig. 4, to be herein-after
described.
The valve (a) in Figs. 1 and 2 is perfectly circular and is free to rotate in the
buckle a¹, as described in the Specification of my said Patent.
Fig. 3 is an elevation showing the port facings for a valve having lap, and Fig. 4
is a cross sectional elevation through the valve, exhaust port, and steam chest.
In this case, the curves of the outer edges of the inlet ports (b) are struck
according to one modification, described in the Specification of my said Patent, with
a radius equal to the semi-diameter of the outer flange of the valve (a), but from a
centre at one side of the common centre, and in the line of the valve's motion equal
to the lap.
Extended clearance spaces d are formed, as described in reference to Fig. 1, and
there is a space (e) for lubricant, which passes through a hole (e') in the valve
chest, part of the lubricant passing between the buckle and valve, as shown in
Fig. 4. There is also a small hole (d') between the clearance space and the exhaust
cavity to allow the escape of liquid or surplus moisture.
Fig. 5 is a view of the back of the valve (a).
Fig. 6 is an elevation of a port face, similar to Fig. 3, but with different clearance
spaces (d).
In all the modifications above described there are extended clearance spaces (d)
so as to leave a part of the under face of the valve exposed to the exhaust in every
position of the valve; these clearance spaces tend to condense and retain moist
steam which can get upon the exposed under surface of the valve opposite the
extended clearance spaces, which moisture acts as a very efficient lubricant, being
carried on the face of the valve as it moves round.
In some cases, I prefer to drill the surface of the valve with numerous small
holes, partially through the metal, to facilitate the spreading of the lubricating
medium more evenly over the rubbing surfaces.
That part of the extended clearance spaces (d) which exposes the under face of
the valve to the exhaust is shown in the Drawings, sectioned in dotted lines.
In Figs. 1, 2, 3, and 4, the extended clearance spaces (d) are of equal extent on
each side of the valve, but in the modification shown by Fig. 7 there is a greater
extent of clearance space on one side than on the other. This is so arranged to
cause the valve to have more friction or adhesion on one side than the other, which
has a tendency to promote a greater movement in it.
Fig. 7 is a sectional elevation showing the valve chest for a compound engine.
Fig. 8-is a view of the valve chest looking towards the facing of the port
through which the steam enters in the part which forms a portion of the valve
chest.
Fig. 9 is a cross section.
The high-pressure valve is of the equilibrium class, formed by two circular parts,
the cylindrical portion of one part fitting into the cylindrical portion of the other
part as a piston, being provided with packing rings to keep it steam-tight.
The part a³ is the valve prones and works acainet nort facings atmak unan the

page_text: principle herein-before stated; except that as the "lap" is inside the valve; the curve
of the inner edge of the inlet ports has to be struck by a radius equal to the semi-
diameter of the interior of the valve, but from a centre at a distance equal to the
lap on that side of the common centre nearest the port being struck.
The steam acts on the cylindrical edges of the parts a³ and a forming the equi-
librium valve to force them apart, and each part against its ports or facings; a
spring (g) may also be inserted to keep the valves up to their faces when the steam
is shut off..
The steam enters at f, passes through the interior of the valve a³, a¹, and enters
the inlet ports b of the high-pressure cylinder, and exhausts from these ports from
the outer edge of the valve a³ into the steam chest, and is then admitted to and
allowed to exhaust from the other or low-pressure cylinder through the valve a,
which is a circular valve like that illustrated by Figs. 3 and 4, or it may be an
ordinary rectangular slide valve, or an ordinary rectangular slide valve arranged as
herein-after described, and illustrated by Figs. 10 to 14 inclusive.
Fig. 10 is a sectional elevation, and Fig. 11 a cross section, illustrating one mode
of carrying out the third part of my Invention.
a is an ordinary rectangular slide valve and a' its buckle. This valve is arranged
with a space in its buckle so that it can move to and fro laterally..
The side of the valve chest (b) is formed, or a part is attached to it, to carry a
T piece (c) which supports the lower edge of the valve. The upright of this T piece
comes into a thimble-formed port that rests upon a diaphragm d secured as
shown. The steam from the valve chest can get past the thimble (c!) to the dia-
phragm, and when it exceeds the pressure exerted by the diaphragm the latter is
forced outwards, and consequently the valve allowed to fall, but when the
pressure of the steam on the diaphragm is less than its upward elastic force, or
when steam is entirely shut off, the valve will be lifted, and thus in each-case will
work over a different part of the port face.
The diaphragm (d) has or may have a supplementary spring to help to sustain
the pressure of the steam and lift the valve, and this spring has or may have a
screw or screws for adjusting the pressure of the spring upon the diaphragm. The
supplementary spring may be similar to that herein-after described as applied to
the ram modification shown by Figs. 12 and 13, but with a connecting piece secured
between the spring and the under side of the diaphragm.
Fig. 12 is a cross section, and Fig. 13 an elevation illustrating another mode of
applying this part of my Invention in the case of two valves working back to
back.
c is a ram of sufficient area, with a cross head supporting the under edge of each
valve (a), as shown. This ram is in a cylinder formed in the valve chest, or in a
part attached thereto, and it is packed by a gland on the exterior of the chest, as
shown. The end of the ram is acted upon by any suitable spring in the example
shown; it is a flat spring e held and adjusted by two bolts, as shown.
Fig. 14 is a sectional elevation showing another modification where the inclined
end of a ram is made to act upon the end of the T piece upon which the edges of
the valve or valves rest.
a are valves; c, the Ṭ piece; d, ram; d, ram cylinder, formed with or attached
to the valve chest b; d, packing gland; ³, end cover; e, spring to act on ram to
push it inwards, the pressure of which spring is or may be adjusted by a screw e¹,
as shown. The steam passes to the ram cylinder through a small hole d. d is a
cock for blowing off steam or water when desired, and by which movement can be
given to the ram d.
When the pressure of th esteam is in excess of that of the spring (e), the ram (d) is
forced outwards, and the incline on the end of the ram raises the T piece (c) and
the valve or valves upwards, and when the pressure of the steam is reduced at any
time, or by opening the cock d³, the spring e will force the ram back, and the
weight of the valve or valves will cause them to descend. A ram or piston is or
may be used to act upon a lever to force up the T piece, if desired.

page_text: Fig. 15 is a cross section and Fig. 16 is a sectional elevation showing another
mode of applying this part of my Invention in arrangements of two inclined valves
working back to back, a being the valves; c, the inclined rest supporting the valves
(before described as a T piece in Fig. 14); d, the ram; d', the ram cylinder open to
'the steam chest, and either attached to or cast with the chest; e, the spring to
thrust back the ram; d², the packing gland; and f, a plate to resist the spring
which is adjusted by the nuts f¹.
The area of the diaphragms, rams, or pistons, and the elastic force of the springs
are made, at least in the case of the modifications shown by Figs 10 to 16, sufficient
to lift the valve or valves to their highest position when the steam is shut off from
the valve chest, so that when steam is admitted the valves will reciprocate in their
highest positions, and will gradually work down, but will be again lifted when the
regulator is shut, and so on, and thus the same parts of the valves will not be
continually working over the same parts of the port or facings.
By making the ram d, Figs. 14, 15, and 16, of sufficient area, and the spring (e)
of sufficient power, the valve or valves will be forced upwards when the steam is at
high pressure in the valve chest, and it will be allowed to descend when the
pressure diminishes, to again be forced up when the pressure increases.
Fig. 17 is an elevation and Fig. 18 a cross section illustrating another modifi-
cation under the third part of my Invention.
The sides of that part of the valve held within the buckle are shaped as shown,
and the middle parts of these sides touch the sides of the buckle, which is large
enough to allow the valve to oscillate in it and give way slightly in the case of
extra friction, and thus to some extent vary the relative positions of the surfaces
working together.
I have now particularly described my Invention, and the mode in which the same
is to be carried into effect, and claim as my Invention,-
. Firstly. The combination of a circular valve (a) free to rotate in its buckle (a¹),
with port faces formed with extended clearance spaces (d) and lubricant spaces (e),
as herein-before described, and illustrated by the Drawings.
Secondly. The combination of an equilibrium valve, through the interior of which
steam is admitted to the cylinder, with improved circular or ordinary slide valves
for compound engines, substantially as herein-before described, and illustrated by
the Drawings.
Thirdly. The arrangement of rectangular slide valves so as to be moved laterally
when the pressure of the steam comes into and passes from the valve chest, or when
the pressure of the steam increases or diminishes in the valve chest, substantially as
herein-before described, and illustrated by the Drawings.
Fourthly. The arrangement of rectangular slide valves in their buckles, for the
purpose and substantially in the manner herein-before described, and illustrated by
Figs. 17 and 18 of the accompanying Drawings.
In witness whereof, I, the said Francis William Webb, have hereunto set my
hand and seal, this Seventeenth day of February, in the year of our Lord
One thousand eight hundred and seventy-nine.