Improvements in and connected with Valves for Steam Engines.
Year: 1889

page_text: Date of Application, 23rd Sept., 1889
Complete Specification Left, 23rd June, 1890-Accepted, 23rd Sept., 1890
PROVISIONAL SPECIFICATION.
Improvements in and connected with Valves for Steam Engines.
I, JOHN THOM, of Inverkip, in the County of Renfrew, Engineer, do hereby
declare the nature of my said invention to be as follows:
The improvements in valves for steam engines, the subject of the present invention,
concern more particularly valves constructed under Letters Patent granted to me
No. 4087 A.D. 1883 and No. 9617 A.D. 1884. In the inventions the subject of my
said former Patents, I conveyed the steam from one side of the piston of the cylinder
at the end of each stroke for re-use at the other side of the piston, by leading the
steam through a passage in the valve and arranging the ports so that a communication
is opened between the ends of the cylinder at the end of the stroke. To this end the
valves are constructed with what is known as a "Trick " passage, the inside edges
of the ports of which are formed and arranged so as to have a negative lap, thereby
effecting the required communication between the ends of the cylinder at the end of
the stroke of the piston.
According to my present invention I provide a negative lap on the inner edges
of the "Trick" ports and a less amount of positive lap on the edges of the valvo
controlling the exhaust from the cylinder; so that at the time communication by way
of the trick passage is made, there will be negative exhaust lap. The result of this
is that a much freer exhaust of steam from the cylinder through the valve or cylinder
exhaust ports is obtained, and also an advantage is obtained in causing a more rapid
movement of steam from one end of the cylinder through the "Trick
"
passage to
the other end, due to the current obtained by putting the passage in the back of
the valvo momentarily in communication with the exhaust port, or condenser, as the
case may be.
The operations taking place in the cylinder and valve according to my present
invention, may be enumerated or set out as follows:-
a. Steam cut off and expansion commences.
6. Steam passes through "Trick". passage to opposite end of cylinder and partly
and momentarily to exhaust port or condenser.
c. Exhaust passages, at compression end of cylinder closed and opposite ones open
a little afterwards.
d. Trick" passage closed, compression commences.
e. Initial or working steam enters compression end of cylinder and valve keeps
open till cut off.
The invention herein described is alike applicable to "Slide Valves" and to “ Piston
Valves."
Dated this Twenty-first day of September 1889.
COMPLETE SPECIFICATION.
Improvements in and connected with Valves for Steam Engines.
I, JOHN THOM, of Inverkip, in the County of Renfrew, Engineer, do hereby
declare the nature of this invention and in what manner the same is. to be
performed, to be particularly described and ascertained in and by the following
statement :-
The improvements connected with distribution valves for steam engines, the subject
of the present invention, have reference more particularly to the inventions covered
under Letters Patent granted to me No. 4087 A.D. 1883, and No. 9617 A.D. 1884.

page_text: In these inventions, the subject of my said former Patents, I conveyed the steam from
one side of the piston of the cylinder at the same end of each stroke for re-use at the
other side of. the piston, by leading the steam through the valve, and arranging the
ports so that a communication is opened between the ends of the cylinder at the end
of the stroke.
To this end, according to one arrangement, the valves were constructed with, what
is known as, a Trick passage, the inside edges of the ports of which were formed
and arranged so as to have a negative lap, thereby effecting the required communi-
cation between the ends of the cylinder at the end of the stroke of the piston.
::
According to my present invention, I effect a more rapid movement of steam from
one end of the cylinder to the other end, through the valve, by way of the "Trick,"
or other passage and I do this by putting the passage, by which said communication
is made between the opposite ends of the cylinder, momentarily in communication
with an exhaust port. This action is carried out in a valve having
22
Trick or like
passage, and according to this invention-by providing a negative lap on the inner
edges of a "Trick" or other equivalent passage, and a less amount of positive lap
on the edges of the valve controlling the exhaust from the cylinder; so that at the
time communication by way of the Trick" or other passage is first made, there will
be negative exhaust lap.
The operations taking place in a cylinder and valve having a "Trick" or other
equivalent passage, according to my present invention, may be "enumerated or set out
as follows:-
a. Steam cut off and expansion commences.
b. Steam passes through valve (by way of a
"Trick or other passage), to opposite
end of the cylinder, and partly and momentarily to exhaust port, or condenser, or
other outlet.
c. Exhaust passage at compression end of cylinder closed and opposite ones open
a little afterwards.
d. "Trick or other passage through the valve closed and compression commences.
e. Initial or working steam enters compression end of cylinders and valve keeps
open till cut off.
The invention herein described is alike applicable to "Slide Valves" and to "Piston
Valves."
Having thus stated generally the nature of this invention I will now describe it
with reference to the drawings hereto annexed, which illustrate several examples of
valves and ports in connection with which they work, arranged, constructed, and
adapted to operate, according to the invention; that is to say in these various
arrangements one or more of the improvements involved in this invention, are
embodied.
In the drawings, the same letters and figures of reference are used throughout
to denote the same or equivalent parts wherever they occur.
In Figure 1, there is shewn a valve of the "Trick " type, and a cylinder valve
face with its ports, so arranged and constructed that at the time communication from
one end of the cylinder to the other is made, by way of the "Trick" passage, there
will be negative exhaust lap, so that the steam will pass to the exhaust port.
'
•
In this Figure, a is the cylinder valve face, having ports b, c, and d, d being
the exhaust port; e is the "Trick " passage of the valve, and el, e, are the walls
forming the said passage; are bars on the inside edges of the "Trick " passage e
and gare bars across the valve, which control the ports c, which ports are provided
for the exhausting purpose only; that is to say, whilst steam is admitted to the
ports b, from the valve casing, past the edges e, when these edges uncover such
ports, and through the "Trick passage e, the main exhaust takes place from the
cylinder, through the double ports b, c, of the cylinder face, and the ports h and i of
the valve. Generally speaking, this method of operation is the sume as that set forth
with reference to Figures 1 to 8 of my former Letters Patent No. 4087 of 1883;
but in this arrangement, the bars f are made of such a width, relatively to the width
of the port b, and so arranged in relation thereto, that at the time communication

page_text: 23
between the opposite ends of the cylinder, by way of the "Trick
passage is made,
there will be negative exhaust lap; that is to say, the odge fl of the bar at that
end of the cylinder to which steain is to be transferred will stand at a point somewhere
between the edges of the metal forming the port b (i.e. such port will be partly
uncovered by the bar f), and steam from the cylinder will be free to flow, by way of
the space between said edges (ie. the port so uncovered), to the exhaust port d. The
bars g and port a would also be so arranged that the bar y also uncovers the port c
at this time.
33
It will be seen, therefore, the action is that a rapid movement of steam from one
end of the cylinder to the other through the "Trick passage, as abovo stated, will
take place, and that a much freer exhaustion of steam from the cylinder through the
valve and cylinder exhaust ports will also take place.
In the arrangement in Figure 2, the bar is made much smaller than that shewn
in Figure 1, in relation to the port b, so that when the valve is in its central position,
there will be negative exhaust lap at both of the exhaust edges f¹ of the valve. This
will provide an extra amount of opening for the exhaust during the latter part of the
stroke. The direction of flow of the steam when the valve is in its central position is
indicated by the arrows.
By this mode of working and arrangement of parts, the passage e in the back of the
valve serves for carrying off exhaust steam at a portion of the stroke, as well as a
steam inlet; also by this arrangement, the negative lap at the edge e¹ of the passage e
being greater than the negative lap at the edge of the bar f, the steam passing
through the passage e from one end of the cylinder towards the other, will still flow
into this latter end for the purpose of being compressed therein (as in my former
Patent No. 408783), after the edge has closed the port c, in an analogous manner
to the bar facts with respect to the port d.
It will thus be seen that this arrangement is similar in general operation and effect
to that shewn in Figure 1, but that a still more rapid flow or transference of steam,
from one end of the cylinder to the other, is set up through the "Trick" passage e,
during the time such flow of steam is momentarily opened to the exhaust port, by the
negative lap at f¹, as described. This causes the filling of the end of the cylinder with
steam about to be compressed, to be very rapidly effected.
In carrying out this invention, with respect to the mode or method by which a more
rapid movement and transference of steam, from one end of the cylinder to the other
through the valve, is caused, that is to say, by putting the end of the cylinder from
which steam is to be transferred to the other, for the purpose of compression, for a
short duration of time prior to the closing of the exhaust, in communication with the
cylinder or other exhaust port, it is to be understood, that the steam so exhausted may
be carried directly to the atmosphere or to a condenser belonging to the engine, or a
separate one, or a water heater, or other thing, and used for any useful purpose."
An arrangement for separating this exhaust from the main exhaust, and conveying
it away by a separate conduit or pipe, is illustrate in sectional elevation and cross
section in Figures 3, and 3ª, respectively. It consists in providing a passage ex in
connection with the passage e, and having a face k, with a port k therein, which face
slides upon a fixed face 7, having in it a port ; and in communication with the
porta passage is provided, by which steam flowing from the passage e
through ex, and ", is carried off from the engine. In this figure, this passage l
and the passage ex are arranged within the main exhaust port d and within the valve
respectively, but they may be arranged on the side, as hereinafter described and
illustrated, or in any suitable position. Passages n are formed through the passage ex
to provide for free cominunication of steam to either side of such passage ex, and to
allow for a free and unrestricted exhaust.
In Figure 4, 4 and 4, is shewn a valve having the same main characteristics as
those set forth with reference to Figures 3 and 3ª, but the passage ex for effecting a
momentarily exhaust of steam at terminal pressure is arranged at one side of the
valve instead of right across it, as in Figures 3 and 3ª.

page_text: 4
In these Figures, Figure 4 is a longitudinal section through the valve and cylinder
valve face at A. A. Figure 4, whilst Figure 4 is a longitudinal section through the
valve and cylinder valve face at B. B. Figure 4*.
It will be seen in these Figures that the valve is a double ported steam one, having
steam pockets or ports m arranged in it in the ordinary way.
In this arrangement the breadth of the ports
and is limited to the breadth
' of the passage ex, whilst the passage e extends over the whole breadth of the
valve.
In Figures 4 and 4 on the left hand side of the valve the passage e is shewn taken
from the outside edge of the ports, whilst on the right hand side of the valve it is
shewn taken from the inside edge: either of these plans may be adopted; but in the
case of the passage e, is used as a "Tricksteam port for admission of steam, as at
the left hand side of Figures 4 and 4", then the steam pockets or ports, m, may be
dispensed with. The Figures show the valve in the central position.
In Figures 5, 5, and 5b, I shew an ordinary double ported steam valve with its
passage e arranged entirely at the side of the valve, and running from one end of
valve to the other. In this case the port e serves to transfer the steam from one end
of the cylinder to the other in the same manner as previously described, and at the
same time the momentarily exhaust to a condenser or other thing is carried out by
providing the faces and with ports and therein; that is to say, these ports
and passages are so arranged in the valve, that the steam passes from one end of the
cylinder to the oilier, and also to the condenser, water heater, or other thing,
case may be, by way of the ports k, l, and passago 12, in the same manner as sot.
forth with reference to Figures 3 to 4.
as the
The arrangement of passage e shewn in these Figures may also be applied and used
in a valve wherein the momentarily exhaust provisions are not employed.
Figures 6 and 6 shew a piston valve and valve casing constructed and adapted to
operate according to this invention, the valve itself being shewn in two positions ;
one position, namely that shewn on the right, being that at which steam is passing to
one of the cylinder ports b by way of the central annular steam passage or port P₂
and the inner "Trick" passage e, whilst the other shewn the valve in its central
position..
The annular bars between the edges and the outside edge of the passage e, are
made of such width, in relation to the port b, and so arranged to operate in connection
therewith, that negative exhaust lap exists at that end of the valve and cylinder to
which steam is to be transferred, at the time communication by way of the "Trick"
passage e is made between the two ends of the cylinder, and a quick transference of
steam from one end of the cylinder to the other and a free exhaustion of steam from
the cylinder through the valve and cylinder exhaust ports is effected, as described with
reference to the valves described under Figures 1 and 2.
In Figures 7, 7" I shew a single ported piston valve and valve casing, wherein
the exhaust takes place at the centre, and steam is admitted at either end of the
casing.
In this arrangement the annular portion is so made and arranged and adapted to
operate, with, and in relation to the ports, that negative exhaust lap exists on the
edges at the time communication, by way of the Trick" passage é, is made at the
opposite ends of the cylinder, substantially as in the case described with reference to
Figure 1.
Figure 7 is a diagrammatic view to an enlarged scale of a part of Figure 7, and
shows the negative lap of exhaust at the edge of the valve, at the moment of
transference of steam through the port e from the opposite end of the cylinder.
In Figure 8 there is illustrated an ordinary double ported "Trick "slide valve
adapted to make communication with the opposite ends of the cylinder at the proper
time, and having negative exhaust lap at the edges and g'at that end of the cylinder
to which steam is to be transferred at the same time as such communication is made.
It will be plain that the provisions for passing steam through a valve from one end

page_text: of a cylinder to the other and the momentarily exhaust herein specified, can be effected
and carried out in a valve in which the main exhaust is taken through the back of the
valve and the valve casing cover instead of through the cylinder.
In conclusion I wish it to be understood that the invention herein described is not
confined to the particular valves and ports set forth with reference to the drawings, as
it is susceptible of modification, and being carried out in various different ways, without
departing from the controlling features involved hereunder and that the improvements
are capable of being applied, one or more of them, to valves differing in types and
forms to those represented in the drawings; and that what I claim in respect of the
herein described invention is :-
1. The herein described improvement connected with steam distribution valves of
steam engines, consisting in causing, by such valve, steam at terminal pressure to be
transferred from one end of the cylinder to the other, and at the same time causing
the end of the cylinder to which the steam is flowing to be momentarily in communi-
cation with an exhaust port or passage.
2. In a steam distribution valve of a steam engine, by which steam at terminal
pressure from one end of the cylinder is transferred or caused to flow therethrough to
the opposite end, for reuse and compression therein, effecting the rapid flow of such
steam by so arranging and constructing the valve and cylinder valve ports, that
negative exhaust lap exists at the exhaust passage at the time communication by way
of the valve is first made.
3. A steam distribution valve of a steam engine constructed and adapted to operate
substantially in the manner set forth with reference to Figure 1.
4. In a steam distribution valve of a steam engine in which the steam at terminal
pressure is transferred from one end of the cylinder to the other for the purposes
described, by a passage in such valve, the arrangement and construction of valve,
substantially as described with reference to Figure 2, by which communication
between both ends of the cylinder and the exhaust port effected, and the exhaust
partially takes place through such transferring passage.
5. In a steam distribution valve of a steam engine, whereby steam is transferred
from one end of the cylinder to the other for the purposes described, and a
momentarily communication between the valve, or passage therein, and an exhaust
port or passage, is made, the combination with the valve, of an exhaust passage
or port, separate from the main exhaust port, and by which the steam released at
said momentarily communication is conveyed away by such passage from the engine.
6. In a steam distribution valve of a steam engine whereby steam is transferred
from one end of the cylinder to the other for the purposes described, and a
momentarily communication between the valve or passage therein and an exhaust
port or passage, is made, the combination of a passage, such as e, in the back of
the valve, a passage e* and an exhaust passage or port substantially as set forth.
7. A steam distribution valve of a steam engine having at one side of it a passage
(such as e in Figures 5 5 and 5b) by which communication between the opposite ends
of the cylinder is made, for effecting the transference of steam from one end thereof to
the other to be compressed and reused therein.
8. A steam distribution valve of a steam engine, arranged and adapted to operate
substantially as set forth with reference to Figures 3 and 3.
9. A steam distribution valve of a steam engine arranged and adapted to operate
substantially as set forth with reference to Figures 4, 4" and 4°.
10. A steam distribution valve of a steam engine, arranged and adapted to operate
substantially as set forth with reference to Figures 5, 5º, and 5'.
11. In a piston steam distribution valve of a steam engine, in which the steam
enters at the centre thereof, such as that shewn in Figure 7, the combination of an
annular port such as p and an interior annular "Trick" port such as e; adapted to
operate substantially as set forth.
12. A piston valve of a steam engine arranged and adapted to operate, in the
manner set forth with reference to Figure 7 and 7", wherein and whereby at the

page_text: moment of transference of steam from one end of the cylinder to the other, a negative
exhaust lap exists at that end of the cylinder and valve at the time the steam trans-
ference communicating passage is first made.
13. The particular construction and arrangement of slide valve, with ports and
passages connected therewith, as set forth with reference to Figure 1.
14. The particular construction and arrangement of slide valve, with ports and
passages,connected therewith, as set forth with reference to Figure 2.
15. The particular arrangement and construction of slide valve with ports and
passages connected therewith, as set forth with reference to Figures 3, and 3.
16. The particular construction and arrangement of slide valves with ports and
passages connected therewith; as set forth with reference to Figures 4, 4°, and 4°.
17. The particular construction and arrangement of slide valve with ports and
passages connected therewith, as set forth with reference to Figures 5, 5 and 56.
18. The particular construction and arrangement of slide valve, with ports and
passages connected therewith, as set forth with reference to Figures 6 and 6".
19. The particular construction and arrangement of slide valve, with ports and
passages connected therewith, as set forth with reference to Figures 7, 7° and 7°.
Dadal this 31st day of June 1800
CHEESBROUGH & ROYSTON,
15, Water Street, Liverpool, Applicant's Patent Agents.