IMPROVEMENTS IN THE CONSTRUCTION AND METHOD OF OPERATION OF THE SLIDE VALVES AND EX- PANSION GEAR OF STEAM ENGINES
Year: 1882

page_text: LETTERS PATENT to Edmund Edwards, of the firm of Edwards and Co:-
1
Patent Agents and Engineers, of 40, Southampton Buildings, Chancery Lane,
in the County of Middlesex for an invention of "IMPROVEMENTS IN THE
CONSTRUCTION AND METHOD OF OPERATION OF THE SLIDE VALVES AND EX-
PANSION GEAR OF STEAM ENGINES" A communication from abroad by Ernst
PROVISIONAL SPECIFICATION left by the said Edmund Edwards at the
Office of the Commissioners of Patents on the 19th April 1882..
EDMUND EDWARDS, of the firm of Edwards and Co-Patent Agents and
Engineers, of 40 Southampton Buildings, Chancery Lane, in the County of
Middlesex "IMPROVEMENTS IN THE CONSTRUCTION AND METHOD OF OPERATION
OF THE SLIDE VALVES AND EXPANSION GEAR OF STEAM ENGINES" [A communication
from abroad by Ernst Sonntag of Lauban, in the Empire of Germany]
This invention relates to Steam Engines in which a slide valve is. used for the
purpose of distributing the steam in the cylinder, such slide valve being actuated
directly by the pressure of the steam itself.
It has for its objects, first, improvements in the method of arranging steam
passages and valves by which the slide valve is actuated, so that the latter operates
with great regularity and efficiency, and second, improved methods of constructing
and arranging apparatus by which the steam admitted to such slide valve is inade
to work expansively as desired.
In order to put the invention in operation I take a cylinder provided with a
piston reciprocating backward and forward in the usual way, the cylinder covers
being provided with suitable projections or attachments containing the passages
and valves hereinafter described.
The cylinder is provided with a cylindrical steam chest having admission and
exhaust ports of the usual well known kind, and the slide valve is formed of two
pistons fitting and working in the ends of the steam chest and connected together

page_text: by a bar the centre of which is semi-cylindrical in end view and forms' the dis-
tributing slide valve, being provided with two cavities which communicate
alternately with a central exhaust port as the valve and pistons reciprocate.
Each of the pistons described has a very small hole completely through it, and
a projection is formed upon the back of the valve so that the latter can be
actuated when desired by a fork upon a spindle, passing through a stuffing box
and fitted with a wheel or handle so that the valve can be operated by hand if
desired.
In each of the cylinder covers is fitted a conical valve opening outward, the stem
of which projects into the cylinder so that they are struck and opened alternately
by the main piston at the ends of its stroke, and a passage is formed at each end
of the cylinder, one end opening into the steam chest and the other end opening
into a space above the conical valves. Two similar passages are also formed of
which one end opens into the seat of the conical valves, and the other end into the
cylinder in which the pistons connected to the slide valve work.
Two other similar passages are also formed of which one end opens into the
seat of the conical valves, and the other end into the exhaust port of the Engine.
The operation of the apparatus constructed and arranged as described is as
follows If the slide valve with its pistons is at the left hand end of its stroke,
steam is admitted to the left hand end of the cylinder and drives the main piston
from left to right, the steam in the other end of the cylinder escaping through the
exhaust port. If now an opening into the right hand small cylinder at the back
.of the piston in it is uncovered so as to communicate with the external air, the
two small pistons with the slide valve will travel from left to right until the
opening so uncovered is closed by the right hand piston.
In the position of the slide thus attained, the left hand main steam port is closed
'whilst the exhaust port continues.uncovered, and the main piston therefore con-
tinues its stroke by the expansion of the steam in the cylinder.
:
When in this way it reaches the end of its stroke it strikes the stem of the valve
in the right hand cylinder cover and raises it from its seat into which it is pressed
by the steam above it. The valve thus raised opens a communication through the
second of the passages above described from the small right hand cylinder to the
seat of the valve, and thence through the third of the passages described from the
seat of the valve to the exhaust port of the 'Engine. The slide valve with its
pistons therefore again moves from left to right until the right hand piston covers
the opening into the second passage described; the slide valve then admitting
steam to the right hand of the main cylinder and opening a communication
from its left hand to the exhaust port, and the direction-of movement of the piston
is thus reversed.
A similar series of movements then takes place at the left hand end of the
main and, small cylinders, and the continuous reciprocation of the piston is thus
.effected.
A small quantity of steam being always admitted through the very small holes
through the small pistons, ensures the movement of the pistons with their slide
valve gradually and without shock.
It will be seen therefore that the point at which the admission of steam through
the slide valve is cut off, and the consequent degree of expansion in the cylinder,
depend upon the point of the stroke at which a communication is made between
the back of each smaller piston alternately and the open air. For this purpose
two expansion valves are arranged in the following manner.
Into each of the small cylinders described a small opening is made in such a
position as to be closed by the small piston when the slide valve has travelled
sufficiently far to cut off the admission of steam as above described. A pipe from
each of these openings is carried back to a sufficient distance parallel with the
main piston rod which latter is extended back between them through a stuffing
box in the back cylinder, cover. The outer end of each pipe passes through a
stuffing box in a concentric outer tube, the latter tubes or projections upon them

page_text: being arranged to slide longitudinally in suitable guides, and being connected by
links or other equivalent means with a handle pivotted between them, so that
when the handle is moved by hand or any suitable governor, one of the tubes is
moved toward the cylinder of the engine whilst the other is moved from it and
vice versa. A small valve is arranged transversely at a suitable point on the
inner side of each such moveable tube, the valves being held in their seats by
springs and their stems projecting through stuffing boxes so that when either is
pressed in, an opening is made between the interior of the tube and the open air.
These valves, therefore, partake of the movement of the tubes and are made to
approach or recede from each other as the handle above described is moved.
The outer end of the main piston rod extended as described carries a socket
turning freely, but incapable of moving lengthways, upon the rod, and this socket
is provided with two curved longitudinal projecting pieces one of which operates
upon and opens each of the projecting valve stems described.. These projecting
pieces are not arranged diametrically opposite to each other but at such an angle
that when one of them is in a position to operate upon the stem of its valve, the
other one is clear of and passes freely the opposite valve.
In order to turn the socket, with the curved projecting pieces backward and
forward sufficiently at each end of its stroke, so that each piece operates its valve
during its stroke in one direction, but escapes it during the return stroke, a pro-
jecting rib helically curved is formed upon the socket between the projecting
pieces and strikes against and is twisted round by corresponding helical cams
fixed, one at each end of the stroke, upon the frame or support which carries
the guides for the tubes already described, which support may also carry a guide
for the piston rod.
In order to retain the socket with the two curved projecting pieces in the
positions into which it is alternately moved by the curved cams as described, a
spring catch may be fixed upon the socket, fitting into one or other of two
corresponding notches in a ring upon the piston rod.
As has been already explained; the opening of a communication between one or
other of the tubes described and the open air determines the point of the stroke
at which the slide valve moves and cuts off the steam from the main cylinder, and
this point can be varied as desired by moving the handle and thus shortening or
lengthening the space travelled by the socket and its projecting pieces before the
latter operate upon the stems of the valves in the tubes.
Where it is not desired that the Engine should work expansively, cocks fixed
upon the outlets for the valves last described may be closed, or the socket with its
curved projecting pieces may be removed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edmund Edwards in the Great Seal Patent Office on the 19th October
1882.
EDMUND EDWARDS, of the firm of Edwards and Co-Patent Agents and
Engineers, of 40, Southampton Buildings, Chancery Lane, in the County of
Middlesex "IMPROVEMENTS IN THE CONSTRUCTION AND METHOD OF OPERATION
OF THE SLIDE-VALVES AND EXPANSION GEAR OF STEAM ENGINES" (a communication
from abroad by Ernst Sonntag, of Lauban, in the Empire of Germany)
This invention relates to steam Engines in which a slide valve is used for the
purpose of distributing the steam in the cylinder, such slide valve being actuated
directly by the pressure of the steam itself.
It has for its objects, first, improvements in the method of arranging steam
passages and valves by which the slide valve is actuated so that the latter operates
with great regularity and efficiency, and second, improved methods of constructing
and arranging apparatus by which the steam adınitted to such slide valve is made
to work expansively as desired.
In order to put the invention in operation I take a cylinder provided with a
piston reciprocating backward and forward in the usual way, the cylinder covers
being provided with suitable projections or attachments containing the passages
and valves hereinafter described. The cylinder is provided with a cylindrical
steam chest, having admission and exhaust ports of the usual well known kind,
and the slide valve is formed of two pistons fitting and working in the ends of the
steam chest and connected together by a bar the centre of which is semi-cylindrical
in end view and forms the distributing slide valve, being provided with two
cavities which communicate alternately with a central exhaust port as the valve
and pistons reciprocate. Each of the pistons described has a very, small hole
completely through it, and a projection is formed upon the back of the valve so
that the latter can be actuated when desired. by a fork upon a spindle passing
through a stuffing box and fitted with a wheel or handle so that the valve can be
operated by hand if desired. In each of the cylinder covers is fitted a conical
valve opening outward, the stems of which project into the cylinder so that they
are struck and opened alternately by the main piston at the ends of its stroke, and
a passage is formed at each end of the cylinder, one end opening into the steam
chest and the other end opening into a space above the conical valves. Two
similar passages are also formed of which one end opens into the seat of the
conical valves, and the other end into the cylinders in which the pistons connected
to the slide valve work.
Two other similar passages are also formed of which one end opens into the seat
of the conical valves, and the other end into the exhaust port of the Engine.
The operation of the apparatus constructed and arranged as described is as
follows: If the slide valve with its pistons is at the left hand end of its stroke,
steam is admitted to the left hand end of the cylinder and drives the main piston
from left to right, the steam in the other end of the cylinder escaping through the
exhaust port. If now an opening into the right hand small cylinder at the back
of the piston in it is uncovered so as to communicate with the external air, the
two small pistons with the slide valve will travel from left to right until the
opening so uncovered is closed by the right hand piston. In the position of the

page_text: slide thus attained the left hand main steam port is closed whilst the exhaust port
continues uncovered, and the main piston therefore continues its stroke by the
expansion of the steam in the cylinder.
When in this way it reaches the end of its stroke it strikes the stem of the
valve in the right hand cylinder cover and raises it from its seat into which it is
pressed by the steam above it. The valve thus raised opens a communication
through the second of the passages above described from the small right hand
cylinder to the seat of the valve, and thence through the third of the passages
described from the seat of the valve to the exhaust port of the Engine. The slide
valve with its pistons therefore again moves from left to right until the right
hand piston covers the opening into the second passage described, the slide valve
then admitting steam to the right hand of the main cylinder and opening a com-
munication from its left hand to the exhaust port, and the direction of movement
of the piston is thus reversed. A similar series of movements then takes place at
the left hand end of the main and small cylinders, and the continuous recipro-
cation of the piston is thus effected. A small quantity of steam being always
adınitted through the very small holes through the small pistons, ensures the
movement of the pistons with their slide valve gradually and without shock. It
will be seen therefore that the point at which the admission of steam through the
slide valve is cut off, and the consequent degree of expansion in the cylinder,
depend upon the point of the stroke at which a communication is made between
the back of each smaller piston alternately and the open air. For this purpose
two expansion valves are arranged in the following manner. Into each of the
small cylinders described a small opening is made in such a position as to be
closed by the small piston when the slide valve has travelled sufficiently far to cut
off the admission of steam as above described. A pipe from each of these openings
is carried back to a sufficient distance parallel with the main piston rod which
latter is extended back between them through a stuffing box in the back cylinder
The outer end of each pipe passes through a stuffing box in a concentric
outer tube, the latter tubes or projections upon them being arranged to slide
longitudinally in suitable guides, and being connected by links or other equivalent
means with a handle pivotted between them, so that when the handle is moved by.
hand or any suitable governor, one of the tubes is moved toward the cylinder of
the engine whilst the other is moved from it and vice versa. A small valve is
arranged transversely at a suitable point on the inner side of each such moveable
tube, the valves being held in their seats by springs and their stems projecting
through stuffing boxes, so that when either is pressed in an opening is made
between the interior of the tube and the open air. These valves therefore, partake
of the movement of the tubes and are made to approach or recede from each other
as the handle above described is moved. The outer end of the main piston rod
extended as described carries a socket turning freely but incapable of moving
lengthways upon the rod, and this socket is provided with two curved longitudinal
projecting pieces one of which operates upon and opens each of the projecting
valve stems described. The projecting pieces are not arranged diametrically
opposite to each other but at such an angle that when one of them is in a position
to operate upon the stem of its valve, the other one is clear of and passes freely
the opposite valve. In order to turn the socket with the curved projecting pieces
backward and forward sufficiently at each end of its stroke so that each piece
operates its valve during its stroke in one direction, but escapes it during the
return stroke, a projecting rib helically curved is formed upon the socket between
the projecting pieces and strikes against and is twisted round by corresponding
belical cams fixed, one at each end of the stroke, upon the frame or support which
carries the guides for the tubes already described, which support may also carry a
guide for the piston rod.
cover.
In order to retain the socket with the two curved projecting pieces in the
positions into which it is alternately moved by the curved cams as described, a

page_text: spring catch may be fixed upon the socket, fitting into one or other of two
corresponding notches in a ring upon the piston rod.
As has been already explained the opening of a communication between one or
other of the tubes described and the open air determines the point of the stroke at
which the slide valve moves and cuts off the steam from the main cylinder, and.
this point can be varied as desired by moving the handle and thus shortening or
lengthening the space travelled by the socket and its projecting pieces before the
latter operate upon the stems of the valves in the tubes.
Where it is not désired that the engine should work expansively, cocks fixed
upon the outlets from the valves last described may be closed, or the socket with
its curved projecting pieces may be removed.
The accompanying drawings are in illustration of the invention :-
Figure 1 is a longitudinal section of the entire machine, Figure 2 a plan and
Figure 3 a vertical section of the machine, Figure 4 is an end view of the
expansion gear; Figure 5 a section through the line v, w, (figure 2), Figure 6 a
section through the line x, y, (figure 1). Figures 7 and 8 are detailed views of a
detached part of the machine.
In Figures 9, 10, 11, and 12 the different positions of the slide valve are
shewn.
The steam piston f.
Similar letters refer to similar parts throughout the several drawings.
The steam enters the valve chest b through the pipe a.
works in the cylinder c.
The cylinder covers have projections for receiving the several steam passages
hereinafter referred to. The steam distributing ports 1 and 2, leading from the
steam chest to the cylinder, are arranged in the usual manner. There are in
addition the following steam passages bored or formed in the cylinder c:-(1). The
passages 1, 1, leading from the steam chest b to the upper faces of the conical
valves ii. (2), the passages 2; 2, leading from the steam chest to the conical scats
of the valves i, i. (3), the passages 5 5 leading from the seats of the valves i, i,
to the steam exhaust port . (4), the passage 3 leading from the steam chest to
the expansion valve p² hereinafter referred to. (5) the passage 4 leading from the
steam chest to the other expansion valve p'.
The slide valve is forined by means of two pistons r, r, united together by the
semi-cylindrical connecting piece 8. This latter is provided with two annular
recesses y, y, and two cavities z, z, and the two pistons r, r, have two very narrow
holes v, v, By means of the hand wheel w, the fork u and the tappet t fixed to
the pieces the slide valve may also, if desired, be moved by hand. The distribution
of steam and the expansion is effected and operated as follows :-
In the position of the slide valve, shewn in figure 9 the steam enters the port /,
whilst the piston f travels from left to right-and the steam escapes through the
port k².
If now by means of a device hereinafter explained the expansion valve p¹ is
opened, the compartment x¹ of the steam chest communicates through the passage 4
with the outer air.. A reduction of pressure is therefore necessarily produced in
the compartment x¹ and the slide valve r, r, will advance, until it covers the
passage 4 and by so doing occupies the position shewn in figure 10.
:
In this position no further steam is admitted to the port and the steam at the
left side of the piston will therefore expand. At the end of its stroke the piston f
raises the valve i from its seat, into which it is constantly pressed by the steam
entering through the passage. 1.
As soon as the valve i is raised out of its seat, the passage 2 comes into communi-
cation with the passage
leading to the exhaust port and therefore a second
time a reduction in pressure is produced in the compartment of the steam chest
and the slide valve advances, until it covers the passage 2 at the right hand and
occupies the position shewn in figure 11. The steam enters the port and by
this means the movement of the piston f is reversed. During the back motion of

page_text: In this
the piston, the expansion valve p² communicating with the passage 3 is opened, a
reduction of pressure takes place in the compartment x of the steam chest and the
slide valve advances from right to left until it covers the passage 3.
position (figure 12) the expansion begins, which is terminated when the steam
piston pushes back the left valve į and in the manner already described the slide
valve advances until it covers the passage 2, so occupying again the first position.
shewn in figure 9. Through the narrow holes vv of the slide valve r, r, a small
quantity of steam is always admitted to the compartments x and x and the slide.
valve will therefore advance toward the compartiment in which the pressure has
been reduced gradually and without any shock..
The two expansion valves p¹ and p2 are opened and closed by means of the
following mechanism. The passage 4 communicates with the pipe c¹ screwed to the
cylinder cover, and outside the pipe c' fits and slides another pipe d' at the end of
which the valve p¹ is disposed.
The prism secured to the bottom of the pipe d¹ (figure 4) slides in a guide upon
the standard g'. The parts c², d², p², g², as to construction and operation exactly
correspond with the parts c¹, d¹, p¹, g¹.
The outer end of the piston rod a carries the socket b¹ turning freely round the
piston rod and provided with two semi lunar shaped ribs m', m², and moreover
provided with a short square threaded piece 7.
The two arms of the standard h¹, which latter by one of these two arms guides
the piston rod a carry the triangles i, 2. the helicoidal edges of which are shewn in
the top view of the machine (figure 2).
In accordance with the reciprocating motion of the piston rod, the helicoidal
edges of the thread will push against the helicoidal edges of the triangles ', ..
and in this way the socket b' will alternately be turned round the piston rod a¹
from the position shown in figure 4 into the other position, represented by dotted
lines in the same figure, or vice versa.
'
If the socket b¹ during the outstroke of the piston occupies the position shewn
in figure. 4, the rib m¹ will catch the projecting centre pin of the valve p¹ and
press the latter out of its seat, to which it then returns by the pressure of a spiral
spring; the other rib m² passes by the pin of the valve p². But during the
instroke of the piston the rib m² catches the valve p² and the rib m² does not
touch the valve p'. In order that the socket b¹ at the end of each stroke may be
maintained more steadily in one or other position the spring n' (figure 8) fixed to b¹
catches into one or other of the two notches of the ring o¹ of the piston rod.
The lever'e pivoting on the cross piece f', secured to the standard h¹, serves to
determine the degree of the expansion. For this purpose the ends of the lever e¹
are united by the links to the sliding pipes d'; which contain the valves p¹
and p2. If now the lever e¹ is brought into any determined position on the
quadrant y' the valves p' and p² will also be opened at a'defined point' of the course
of the piston and therefore the degree of the expansion will be determined.
The motor works also as an ordinary steam pump without expansion if the
outlet cocks q, q2, of the valves p¹, p², are closed or if the socket b¹ is detached.
I am aware that, prior to this invention, steam motors in which the distributing
valve is actuated directly by the steam have been used. I therefore do not claim
such an arrangement broadly, but what I do claim as my invention and desire to
secure by letters Patent is:-
(1) The combination in a steam motor with steam actuated valve, of the valves i, i,
the steam passages 1, 2, and 5, the slide valve r, r, with the holes v, v¹, working in
the steam chest b, the compartments x and x¹ of which. communicate with the seats.
of the valves i, i, all substantially as set forth, and shewn.
(2) In order to adapt an expansion-gear to a steam-motor with steam-actuated
slide-valve the following elements in combination, the steam passages 3 and 4,
communicating with the valves p¹ and p2 at the ends of the pipes d' and d², which
slide over the pipes c' and c², the socket 61 turning upon the piston rod and turned

page_text: by pressure against the triangles 1, 2, and having the ribs m', m², which, open the
valves p', p², producing by so doing reduction of pressure in the compartments x, x¹,
of the steain chest b, all substantially as described and shewn..
In witness whereof; I, the said Edmund Edwards, have hereunto set my hand
and seal this 18th day of October in the year of Lord 1882.
.
("SUT)

page_text: LETTERS PATENT to Edmund Edwards, of the firm of Edwards and Co:-
Patent Agents and Engineers, of 40, Southampton Buildings, Chancery Lane,
in the County of Middlesex for an invention of IMPROVEMENTS IN THE
66
LETTERS PATENT to Edmund Edwards, of the firm of Edwards and Co:-
1
Patent Agents and Engineers, of 40, Southampton Buildings, Chancery Lane,
in the County of Middlesex for an invention of IMPROVEMENTS IN THE
CONSTRUCTION AND METHOD OF OPERATION OF THE SLIDE
AND
PANSION GEAR OF STEAM ENGINES" A communication from abroad by Ernst.
Sonntag of Lauban, in the Empire of Germany
PROVISIONAL SPECIFICATION left by the said Edmund Edwards at the
Office of the Commissioners of Patents on the 19th April 1882..
EDMUND EDWARDS, of the firm of Edwards and Co-Patent Agents and
Engineers, of 40 Southampton Buildings, Chancery Lane, in the County of
Middlesex "IMPROVEMENTS IN THE CONSTRUCTION AND METHOD OF OPERATION
OF THE SLIDE VALVES AND EXPANSION GEAR OF STEAM ENGINES" [A communication
from abroad by Ernst Sonntag of Lauban, in the Empire of Germany]
This invention relates to Steam Engines in which a slide valve is used for the
purpose of distributing the steam in the cylinder, such slide valve being actuated
directly by the pressure of the steam itself.
It has for its objects, first, improvements in the method of arranging steam
passages and valves by which the slide valve is actuated, so that the latter operates
with great regularity and efficiency, and second, improved methods of constructing
and arranging apparatus by which the steam admitted to such slide valve is made
to work expansively as desired.
In order to put the invention in operation I take a cylinder provided with a
piston reciprocating backward and forward in the usual way, the cylinder covers
being provided with suitable projections or attachments containing the passages
and valves hereinafter described.
The cylinder is provided with a cylindrical steam chest having admission and
exhaust ports of the usual well known kind, and the slide valve is formed of two
pistons fitting and working in the ends of the steam chest and connected together
"

page_text: by a bar the centre of which is semi-cylindrical in end view and forms the dis-
tributing slide valve, being provided with two cavities which communicate
alternately with a central exhaust port as the valve and pistons reciprocate.
Each of the pistons described has a very small hole completely through it, and
a projection is formed upon the back of the valve so that the latter can be
actuated when desired by a fork upon a spindle, passing through a stuffing box
and fitted with a wheel or handle so that the valve can be operated by hand if
desired.
In each of the cylinder covers is fitted a conical valve opening outward, the stem
of which projects into the cylinder so that they are struck and opened alternately
by the main piston at the ends of its stroke, and a passage is formed at each end
of the cylinder, one end opening into the steam chest and the other end opening
into a space above the conical valves. Two similar passages are also formed of
which one end opens into the seat of the conical valves, and the other end into the
cylinder in which the pistons connected to the slide valve work.
Two other similar passages are also formed of which one end opens into the
seat of the conical valves, and the other end into the exhaust port of the Engine.
The operation of the apparatus constructed and arranged as described is as
follows If the slide valve with its pistons is at the left hand end of its stroke,
steam is admitted to the left hand end of the cylinder and drives the main piston
from left to right, the steam in the other end of the cylinder escaping through the
exhaust port. If now an opening into the right hand small cylinder at the back
.of the piston in it is uncovered so as to communicate with the external air, the
two small pistons with the slide valve will travel from left to right until the
opening so uncovered is closed by the right hand piston.
In the position of the slide thus attained, the left hand main steam port is closed
whilst the exhaust port continues.uncovered, and the main piston therefore con-
tinues its stroke by the expansion of the steam in the cylinder.
When in this way it reaches the end of its stroke it strikes the stem of the valve
in the right hand cylinder cover and raises it from its seat into which it is pressed
by the steam above it. The valve thus raised opens a communication through the
second of the passages above described from the small right hand cylinder to the
seat of the valve, and thence through the third of the passages described from the
seat of the valve to the exhaust port of the 'Engine. The slide valve with its
pistons therefore again moves from left to right until the right hand piston covers
the opening into the second passage described; the slide valve then admitting
steam to the right hand of the main cylinder and opening a communication
from its left hand to the exhaust port, and the direction of movement of the piston
is thus reversed.
A similar series of movements then takes place at the left hand end of the
main and,small cylinders, and the continuous reciprocation of the piston is thus
.effected.
:
A small quantity of steam being always admitted through the very small holes
through the small pistons, ensures, the movement of the pistons with their slide
valve gradually and without shock.
It will be seen therefore that the point at which the admission of steam through
the slide valve is cut off, and the consequent degree of expansion in the cylinder,
depend upon the point of the stroke at which a communication is made between
the back of each smaller piston alternately and the open air. For this purpose
two expansion valves are arranged in the following manner.
Into each of the small cylinders described a small opening is made in such a
position as to be closed by the small piston when the slide valve has travelled
sufficiently far to cut off the admission of steam as above described. A pipe from
each of these openings is carried back to a sufficient distance parallel with the
main piston rod which latter is extended back between them through a stuffing
box in the back cylinder, cover. The outer end of each pipe passes through a
stuffing box in a concentric outer tube, the latter tubes or projections upon thei

page_text: being arranged to slide longitudinally in suitable guides, and being connected by
links or other equivalent means with a handle pivotted between them, so that
when the handle is moved by hand or any suitable governor, one of the tubes is
moved toward the cylinder of the engine whilst the other is moved from it and
vice versa. A small valve is arranged transversely at a suitable point on the
inner side of each such moveable tube, the valves being held in their seats by
springs and their stems projecting through stuffing boxes so that when either is
pressed in, an opening is made between the interior of the tube and the open air.
These valves, therefore, partake of the movement of the tubes and are made to
approach or recede from each other as the handle above described is moved..
The outer end of the main piston rod extended as described carries a socket
turning freely, but incapable of moving lengthways, upon the rod, and this socket
is provided with two curved longitudinal projecting pieces one of which operates
upon and opens each of the projecting valve stems described.. These projecting
pieces are not arranged diametrically opposite to each other but at such an angle
that when one of them is in a position to operate upon the stem of its valve, the
other one is clear of and passes freely the opposite valve.
In order to turn the socket, with the curved projecting pieces backward and
forward sufficiently at each end of its stroke, so that each piece operates its valve
during its stroke in one direction, but escapes it during the return stroke, a pro-
jecting rib helically curved is formed upon the socket between the projecting
pieces and strikes against and is twisted round by corresponding helical cams
fixed, one at each end of the stroke, upon the frame or support which carries
the guides for the tubes already described, which support may also carry a guide
for the piston rod.
'al
In order to retain the socket with the two curved projecting pieces in the
positions into which it is alternately moved by the curved cams as described, a
spring catch may be fixed upon the socket, fitting into one or other of two.
corresponding notches in a ring upon the piston rod.
As has been already explained; the opening of a communication between one or
other of the tubes described and the open air determines the point of the stroke
at which the slide valve moves and cuts off the steam from the main cylinder, and
this point can be varied as desired by moving the handle and thus shortening or
lengthening the space travelled by the socket and its projecting pieces before the
latter opérate upon the stems of the valves in the tubes.
Where it is not desired that the Engine should work expansively, cocks fixed
upon the outlets for the valves last described may be closed, or the socket with its
curved projecting pieces may be removed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edmund Edwards in the Great Seal Patent Office on the 19th October
1882.
EDMUND EDWARDS, of the firm of Edwards and Co-Patent Agents and
Engineers, of 40, Southampton Buildings, Chancery Lane, in the County of
Middlesex "IMPROVEMENTS IN THE CONSTRUCTION AND METHOD OF OPERATION
OF THE SLIDE-VALVES AND EXPANSION GEAR OF STEAM ENGINES (a communication
from abroad by Ernst Sonntag, of Lauban, in the Empire of Germany)
"
This invention relates to steam Engines in which a slide valve is used for the
purpose of distributing the steam in the cylinder, such slide valve being actuated
directly by the pressure of the steam itself.
It has for its objects, first, improvements in the method of arranging steam
passages and valves by which the slide valve is actuated so that the latter operates
with great regularity and efficiency, and second, improved methods of constructing
and arranging apparatus by which the steam adimitted to such slide valve is made
to work expansively as desired.
In order to put the invention in operation I take a cylinder provided with a
piston reciprocating backward and forward in the usual way, the cylinder covers
being provided with suitable projections or attachments containing the passages
and valves hereinafter described. The cylinder is provided with a cylindrical
steam chest having admission and exhaust ports of the usual well known kind,
and the slide valve is formed of two pistons fitting and working in the ends of the
steam chest and connected together by a bar the centre of which is semi-cylindrical
in end view and forms the distributing slide valve, being provided with two
cavities which communicate alternately with a central exhaust port as the valve
and pistons reciprocate. Each of the pistons described has a very small hole
completely through it, and a projection is formed upon the back of the valve so
that the latter can be actuated when desired by a fork upon a spindle passing
through a stuffing box and fitted with a wheel or handle so that the valve can be
operated by hand if desired. In each of the cylinder covers is fitted a conical
valve opening outward, the stems of which project into the cylinder so that they
are struck and opened alternately by the main piston at the ends of its stroke, and
a passage is formed at each end of the cylinder, one end opening into the steam
chest and the other end opening into a space above the conical valves. Two
similar passages are also formed of which one end opens into the seat of the
conical valves, and the other end into the cylinders in which the pistons connected
to the slide valve work.
.
Two other similar passages are also formed of which one end opens into the seat
of the conical valves, and the other end into the exhaust port of the Engine.
The operation of the apparatus constructed and arranged as described is as
follows-If the slide valve with its pistons is at the left hand end of its stroke,
steam is admitted to the left hand end of the cylinder and drives the main piston
from left to right, the steam in the other end of the cylinder escaping through the
exhaust port. If now an opening into the right hand small cylinder at the back
of the piston in it is uncovered so as to communicate with the external air, the
two small pistons with the slide valve will travel from left to right until the
opening so uncovered is closed by the right hand piston. In the position of the

page_text: slide thus attained the left hand main steam port is closed whilst the exhaust port
continues uncovered, and the main piston therefore continues its stroke by the
expansion of the steam in the cylinder.
When in this way it reaches the end of its stroke it strikes the stem of the
valve in the right hand cylinder cover and raises it from its seat into which it is
pressed by the steam-above it. The valve thus raised opens a communication
through the second of the passages above described from the small right hand
cylinder to the seat of the valve, and thence through the third of the passages
described from the seat of the valve to the exhaust port of the Engine. The slide
valve with its pistons therefore again moves from left to right until the right
hand piston covers the opening into the second passage described, the slide valve
then admitting steam to the right hand of the main cylinder and opening a com-
munication from its left hand to the exhaust port, and the direction of movement
of the piston is thus reversed. A similar series of movements then takes place at
the left hand end of the main and small cylinders, and the continuous recipro-
cation of the piston is thus effected. A small quantity of steam being always
adınitted through the very small holes through the small pistons, ensures the
movement of the pistons with their slide valve gradually and without shock. It
will be seen therefore that the point at which the admission of steam through the
slide valve is cut off, and the consequent degree of expansion in the cylinder,
depend upon the point of the stroke at which a communication is made between
the back of each smaller piston alternately and the open air. For this purpose
two expansion valves are arranged in the following manner. Into each of the
small cylinders described a small opening is made in such a position as to be
closed by the small piston when the slide valve has travelled sufficiently far to cut
off the admission of steam as above described. A pipe from each of these openings
is carried back to a sufficient distance parallel with the main piston rod which
latter is extended back between them through a stuffing box in the back cylinder
cover. The outer end of each pipe passes through a stuffing box in a concentric
outer tube, the latter tubes or projections upon them being arranged to slide
longitudinally in suitable guides, and being connected by links or other equivalent
means, with a handle pivotted between them, so that when the handle is moved by.
hand or any suitable governor, one of the tubes is moved toward the cylinder of
the engine whilst the other is moved from it and vice versa. A small valve is
arranged transversely at a suitable point on the inner side of each such moveable
tube, the valves being held in their seats by springs and their stems projecting
through stuffing boxes, so that when either is pressed in an opening is made
between the interior of the tube and the open air. These valves therefore, partake
of the movement of the tubes and are made to approach or recede from each other
as the handle above described is moved. The outer end of the main piston rod
extended as described carries a socket turning freely but incapable of moving
lengthways upon the rod, and this socket is provided with two curved longitudinal
projecting pieces one of which operates upon and opens each of the projecting
valve stems described. The projecting pieces are not arranged diametrically
opposite to each other but at such an angle that when one of them is in a position
to operate upon the stem of its valve, the other one is clear of and passes freely
the opposite valve. In order to turn the socket with the curved projecting pieces
backward and forward sufficiently at each end of its stroke so that each piece
operates its valve during its stroke in one direction, but escapes it during the
return stroke, a projecting rib helically curved is formed upon the socket between
the projecting pieces and strikes against and is twisted round by corresponding
helical cams fixed, one at each end of the stroke, upon the frame or support which
carries the guides for the tubes already described, which support may also carry a
guide for the piston rod.
In order to retain the socket with the two curved projecting pieces in the
positions into which it is alternately moved by the curved cams as described, a

page_text: spring catch may be' fixed upon the socket, fitting into one or other of two
corresponding notches in a ring upon the piston rod.
As has been already explained the opening of a communication between one or
other of the tubes described and the open air determines the point of the stroke at
which the slide valve moves and cuts off the steam from the main cylinder, and.
this point can be varied as desired by moving the handle and thus shortening or
lengthening the space travelled by the socket and its projecting pieces before the
latter operate upon the stems of the valves in the tubes.
Where it is not désired that the engine should work expansively, cocks fixed.
upon the outlets from the valves last described may be closed, or the socket with
its curved projecting pieces may be removed.
The accompanying drawings are in illustration of the invention :-
Figure 1 is a longitudinal section of the entire machine, Figure 2 a plan and
Figure 3 a vertical section of the machine, Figure 4 is an end view of the
expansion gear; Figure 5 a section through the line v, w, (figure 2), Figure 6 a
section through the line x, y, (figure 1). Figures 7 and 8 are detailed views of a
detached part of the machine.
-
In Figures 9, 10, 11, and 12 the different positions of the slide valve are
shewn.
Similar letters refer to similar parts throughout the several drawings.
The steam enters the valve chest b through the pipe a.
works in the cylinder c.
The steam piston f
The cylinder covers h have projections for receiving the several steam passages
hereinafter referred to. The steam distributing ports and k³, leading from the
steam chest to the cylinder, are arranged in the usual manner. There are in.
addition the following steam passages bored or formed in the cylinder c-(1). The
passages 1, 1, leading from the steam chest b to the upper faces of the conical
valves i i. (2), the passages 2; 2, leading from the steam chest to the conical seats
of the valves i, i. (3), the passages 5 5 leading from the seats of the valves i, i,
to the steam exhaust port L. (4), the passage 3 leading from the steam chest to
the expansion valve p² hereinafter referred to. (5) the passage 4 leading from the
steam chest to the other expansion valve p¹.
The slide valve is formed by means of two pistons r, r, united together by the
semi-cylindrical connecting piece 8. This latter is provided with two annular
recesses y, y, and two cavities z, z, and the two pistons r, r, have two very narrow
holes v, v, By means of the hand wheel w, the fork u and the tappet t fixed to
the pieces the slide valve may also, if desired, be moved by hand: The distribution
of steam and the expansion is effected and operated as follows:-
In the position of the slide valve, shewn in figure 9 the steam enters the port k,
whilst the piston f travels from left to right and the steam escapes through the
port k².
If now by means of a device hereinafter explained the expansion valve p¹ is
opened, the compartment a¹ of the steam chest communicates through the passage 4
with the outer air.. A reduction of pressure is therefore necessarily produced in
the compartment x¹ and the slide valve r, r, will advance, until it covers the
passage 4 and by so doing occupies the position shewn in figure 10.
In this position no further steam is admitted to the port % and the steam at the
left side of the piston will therefore expand. At the end of its stroke the piston f
raises the valve i from its seat, into which it is constantly pressed by the steam
entering through the passage.1.
As soon as the valve i is raised out of its seat the passage 2 comes into communi-
cation with the passage 5 leading to the exhaust port and therefore a second
time a reduction in pressure is produced in the compartment x¹ of the steam chest
and the slide valve advances, until it covers the passage 2 at the right hand and
occupies the position shewn in figure 11. The steam enters the port 2 and by
this means the movement of the piston f is reversed. During the back motion of

page_text: In this
the piston, the expansion valve p² communicating with the passage 3 is opened, a
reduction of pressure takes place in the compartment x of the steam chest and the
slide valve advances from right to left until it covers the passage 3.
position (figure 12) the expansion begins, which is terminated when the steam
piston pushes back the left valve į and in the manner already described the slide
valve advances until it covers the passage 2, so occupying again the first position
shewn in figure 9. Through the narrow holes vv of the slide valve r, r, a small
quantity of steam is always admitted to the compartments x and x' and the slide
valve will therefore advance toward the compartiment in which the pressure has
been reduced gradually and without any shock.
The two expansion valves p¹ and p³ are opened and closed by means of the
following mechanism. The passage 4 communicates with the pipe c¹ screwed to the
cylinder cover, and outside the pipe c' fits and slides another pipe d' at the end of
which the valve p¹ is disposed.
The prism secured to the bottom of the pipe d¹ (figure 4) slides in a guide upon
the standard g'. The parts c², d², p², g², as to construction and operation exactly
correspond with the parts c¹, d², p², g¹.
The outer end of the piston rod a¹ carries the socket b¹ turning freely round the
piston rod and provided with two semi lunar shaped ribs m', m², and moreover
provided with a short square threaded piece l¹.
The two arms of the standard h¹, which latter by one of these two arms guides
the piston rod a carry the triangles, the helicoidal edges of which are shewn in
the top view of the machine (figure 2).
In accordance with the reciprocating motion of the piston rod, the helicoidal
edges of the thread will push against the helicoidal edges of the triangles i¹, ¿².
and in this way the socket b' will alternately be turned round the piston rod a
from the position shown in figure 4 into the other position, represented by dotted
lines in the same figure, or vice versa.
'
If the socket during the outstroke of the piston occupies the position shewn
in figure 4, the rib m¹ will catch the projecting centre pin of the valve p¹ and
press the latter out of its seat, to which it then returns by the pressure of a spiral
spring; the other rib m² passes by the pin of the valve p². But during the
instroke of the piston the rib m² catches the valve p² and the rib m¹ does not
touch the valve p'. In order that the socket b¹ at the end of each stroke may be
maintained more steadily in one or other position the spring n' (figure 8) fixed to b¹
catches into one or other of the two notches of the ring o' of the piston rod.
The lever 'e pivoting on the cross piece f', secured to the standard h¹, serves to
determine the degree of the expansion. For this purpose the ends of the lever e¹
are united by the links to the sliding pipes d¹; which contain the valves pl
and p2. If now the lever e¹ is brought into any determined position on the
quadrant y' the valves p³ and p² will also be opened at a defined point of the course
of the piston and therefore the degree of the expansion will be determined.
The motor works also as an ordinary steain pump without expansion if the
outlet cocks q, q2, of the valves p¹, p², are closed or if the socket b' is detached.
I am aware that, prior to this invention, steam motors in which the distributing
valve is actuated directly by the steam have been used. I therefore do not claim
such an arrangement broadly, but what I do claim as my invention and desire to
secure by letters Patent is
(1) The combination in a steam motor with steam actuated valve, of the valves i, i,
the steam passages 1, 2, and 5, the slide valve r, r, with the holes v, v¹, working in
the steam chest b, the compartments x and x¹ of which. communicate with the seats.
of the valves i, i, all substantially as set forth, and shewn.
(2) In order to adapt an expansion-gear to a steam-motor with steam-actuated
slide-valve the following elements in combination, the steam passages 3 and 4,
communicating with the valves pl and p² at the ends of the pipes d' and d², which
slide over the pipes c' and c², the socket b¹ turning upon the piston rod and turned

page_text: by pressure against the triangles 1, 2, and having the ribs m', m², which, open the
valves p', p², producing by so doing reduction of pressure in the compartments x, x¹,
of the steain chest b, all substantially as described and,shewn..
In witness whereof, I, the said Edmund Edwards, have hereunto set my hand
and seal this 18th day of October in the year of Lord 1882.