IMPROVEMENTS IN AND RELATING TO THE SLIDE VALVES OF STEAM-ENGINES
Year: 1885

page_text: Engines.
I, EDWARD GARDNER COLTON; of the firm of Popplewell, Colton, and Company,
of Victoria Chambers, Southampton Buildings, in the County of Middlesex, Fellow
of the Institute of Patent Agents, do hereby declare the nature of my invention
for "IMPROVEMENTS IN AND RELATING TO THE SLIDE VALVES OF STEAM-ENGINES,"
(a communication to me from abroad, by George Schuhmann; of Staats Zeitung
Building, Tryon Row, in the City, County, and State of New York, United States
of America, Mechanical Engineer), to be as follows:-
:
--
This invention has reference to steam engines using double-seated slide valves in
connection with a stationary distance-piece, and the invention consists of a steam
cylinder, having admission and exhaust ports, a distance-piece supported in a bridge
of the steam supply passage, a box-like slide valve having ports and passages and
a covering plate.
The steam cylinder has ports at the end by which communication is formed
alternately and at intervals by means of the slide valve between the cylinder and
the valve chest which forms an exhaust chamber communicating with the exhaust
pipe.
8 C
A steam chamber is formed in the cylinder and communicates with the inlet
pipe. A casting or distance-piece is secured to a bridge of the steam chamber.
This distance-piece is formed with seats for a covering plate which is secured to
and forms part of the slide valve.
The slide valve is a box-like structure closed on each end and at the opposite
sides, the interior of the slide valve being always in communication with the steam
chamber.
The said slide valve has two inwardly extending plates in each of which is
arranged a port for directing the steam from the interior of the valves to the ports
in the cylinder.

page_text: A valve stem passing through a stuffing box, is secured to the valve and is
operated by the usual eccentric or other valve gear,
It will be seen that the hollow box-like slide valve forms really a reciprocating
steam-chest contained in an exhaust chamber.
The manner in which the slide-valve performs its function is the same as in
slide-valves in use, and requires no special description. As regards the balancing
of the slide-valve, the steam acts on the exposed surface of the covering plate, in
opposition to the action of the steam on the plates of the valve and hence, if the
area, of the plates minus that of the ports and overlapping parts equals the area of
the exposed portions of the covering plate, the pressure tending to force the valve
to its seat will be exactly counteracted by the pressure to force it from the same.
As in certain positions of the valve, however, the steam in one or other of the
ports in the steam cylinder tends to force the valve from its seat, and as it is
necessary in order to keep the valve steam-tight to have a preponderance of
pressure on the seats, it is best to make the area of the plates of the valve some-
what larger than the exposed portion of the covering plate.
For the same reason the sides of the slide-valve are arranged to project
inwardly.
It is
When the valve is in its central position, it should lap over its seats to the extent
of about half the throw of the valve, so that the difference in the area of the plate
exposed to the pressure of steam and the exposed area of the covering plate will
remain constant at each end of the valve und in every position of the same.
important that when the box-like valve is expanded by the live steam, the distance-
piece should be similarly expanded in order that the valve shall always fit tight
both to its seat on the cylinder and to the covering plate. For this reason the
distance-piece is depressed and an opening provided in the covering plate, whereby
one side of the distance piece is exposed to the exhaust steam, while the other side
is exposed to the live steam, the valve itself being similarly exposed. The metal
of the distance piece, moreover, is made of about the same thickness as that of the
valve, hence, the expansion and contraction of both pieces will be alike.
When the slide valve is combined with a cut-off valve the plates on the valve
are provided with seats for the cut-off valves which are placed on a spindle passing
through a tubular spindle moving the slide valve.
Instead of the ports passing through the plates of the valve they may be made
to communicate with two or more smaller ports the cut off valves having ports to
suit.
The distance-piece has a slot formed to allow of the passage of the cut-off valve
spindle.
If desired the steam cylinder might have an exhaust port at each end which may
be made to communicate with an exhaust outlet opposite to the steam inlet. This
slide valve is as before, but has an exhaust passage at each end communicating
with the exhaust ports.
The exhaust chamber is thus dispensed with and if desirable a hot air jacket
may be substituted.

page_text: Improvements in and relating to the Slide Valves of Steam
Engines.
"
I EDWARD GARDNER COLTON of the firm of Popplewell Colton & Co of Victoria
Chambers Southampton Buildings in the county of Middlesex Fellow of the
Institute of Patent Agents, do hereby declare the nature of the said invention for
"IMPROVEMENTS IN AND RELATING TO THE SLIDE VALVES OF STEAM ENGINES
(a communication to me from abroad by George Schuhmann of Staats Zeitung
Building Tryon Row in the City County and State of New York United States
of America Mechanical Engineer) and in what manner the same is to be per
formed to be particularly described and ascertained in and by the following
statement:-
This invention has reference to an improved balanced slide valve for steam;
engines of that class in which a double seat slide valve has been used in connection
with a stationary distance piece, and the invention consists of a steam cylinder
having admission and exhaust ports, a distance piece supported in a bridge of the
steam supply passage, a box-like slide valve having ports and passages, and a
covering plate as will appear more fully hereinafter described.
In the accompanying drawings Fig. 1 represents a vertical longitudinal section
of a steam cylinder with the improved balanced slide valve and exhaust chest.
Fig. 2 is a vertical transverse section of the same.
Fig. 3 is a vertical longitudinal section of the balanced slide valve combined with
a cut-off valve, and
Fig. 4 is a vertical longitudinal section of a steam cylinder with the balanced
slide.valve and exhaust-passages in the cylinder in place of the valve chest.
Similar letters of reference indicate corresponding parts.
;
Referring to the drawings C represents a steam cylinder having ports i i one
near each end, by which ports communication is formed alternately and at intervals
by means of the slide valve between the cylinder and the valve chest H which
latter forms an exhaust chamber communicating with the exhaust pipe E. A steam
chamber S is formed in the cylinder A and is in communication with the steam
inlet J as shewn in Fig. 2.
A casting D which may be termed the "distance-piece" and which is sub-
stantially of the form shewn in Fig. 1, is secured to a bridge B of the steam
chamber S. The distance-piece D is formed with seats for a covering plate P,
which is secured to and forms a part of the slide-valve A. The plate P is provided
with an opening. O...The slide valve A has two faces and is a box-like structuré
closed on each end and at the opposite sides fƒ (Fig. 2).
.
The interior of the slide valve A is always in connection with the steam
chamber S. The slide valve A has two inwardly extending. plates q q in each of

page_text: which is arranged a port g for directing the steain from the interior of the valves
to the ports ii. A valve stem w passes through a stuffing box on the chest H and
is secured to one end of the valve which may be reciprocated by the usual eccentric
or other valve gear.
It will be seen that the hollow box-like slide valve forms really a reciprocating
steam chest, contained in an exhaust-chamber.
The manner in which the slide-valve performs its function is the same as in all
slide valves in use, and requires no special description..
.
As regards the balancing of the slide valve, the steam acts on the exposed
surface of the covering plate P, in opposition to the action of the steam on the
plates qq of the valve and hence, if the area of the plates minus that of the ports
and overlapping parts equals the area of the exposed portions of the covering
plate P. the pressure tending to force the valve to its scat will be exactly counter-
acted by the pressure to force it from the same.
As in certain positions of the valve however, the steam in one or other of the
ports i, in the covering plate, tends to force the valve from its seat, and as it is
necessary in order to keep the valve steamtight to have a preponderance of
pressure on the seats, it is best to make the area of the plates 9 of the valve, some-
what larger than the exposed portion of the covering plate P. For the same reason
the sides ff of the slide valve are arranged to project inwardly.
When the valve is in its central position as shewn in Fig. 1, it should lap over
its seats to the extent of about half the throw of the valve, so that the difference
in the area of the plate q exposed to the pressure of steam and the exposed area of
the covering plate k will remain constant at each end of the valve and in every
position of the same..
"
.
It is important that when the box-like valve A is expanded by the live steam,
the distance-piece D should be similarly expanded, in order that the valve shall
always fit tight both to its seat on the cylinder, and to the covering plate P. For
this reason the distance-piece is depressed and an opening O provided in the
covering plate P whereby one side of the distance piece is exposed to the exhaust
steam, while the other side is exposed to the live steam, the valve itself being
similarly exposed. The metal of the distance-piece morever is made of about the
same thickness as that of the valve, hence the expansion and contraction of both
pieces will be alike.
In Fig. 3, the slide-valve A is combined with a cut-off valve; the plates qq are
in this case provided with seats for the cut-off valves N N which are attached to
the. spindle the spindle w.of the slide valve A being made tubular to admit the
said spindle v of the cut-off valves.
The ports g g instead of passing through the plates q q may be made to
communicate with two or more smaller ports the cut-off valves having ports to
suit.
The distance-piece D has a slot X cast in to allow the passage of the spindle v.
In fig. 4, the steam-cylinder C, has in addition to the steam chamber S and
ports ii, an exhaust-port y at each end, which may be made to communicate with
an exhaust outlet opposite the steam inlet.
The slide-valve is substantially like that described, but has an exhaust-passage m
at each end, communicating with the exhaust-ports y y.
The manner in which these passages perform their duty, will be easily understood
by referring to the drawing. The exhaust-chamber H is dispensed with and if
desirable a hot-air jacket may be substituted.
Having now particularly described and ascertained the nature of the said
invention as.communicated to me by my foreign correspondent and in what manner
the same is to be performed I. declare that what I claim is
Firstly. The combination of a steam cylinder C, having steam ports i i, a steam
chamber or passage S, situated between said ports, an exhaust chamber H; a box

page_text: like slide valve A, having ports and passages and a distance piece D forming a seat
for the covering plate of the valve substantially as described.
Secondly. In combination with the box like valve A and depressed distance
piece D, the covering plate P having an opening O, substantially as described.
Thirdly. In combination with the box like valve A and its ported plates q q, the
cut off valves N N, having their seats on the said plates substantially as described
with reference to Fig. 3 of the accompanying drawings.
Fourthly. The combination of a steam cylinder C having ports ii and y y, a
steam chamber S, a distance piece D, a covering plate P and a balanced box-like
valve A having exbaust passages m m substantially as described.