Improvements in Direct-acting Duplex Valves for Pumping Engines.
Year: 1890

page_text: COMPLETE SPECIFICATION.
Improvements in Direct-acting Duplex Valves for Pumping
Engines.
I, MARSHALL TEN BROECK DAVIDSON of Brooklyn, Kings County, in the State
of New York, United States of America, 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:-
My invention relates to that class of direct acting duplex pumping engines which
can be instantly converted into two independent pumping engines without requiring
any change in the mechanical construction of the valve gears.
My improvement consists mainly in providing each engine with a supplemental
valve operated by the other engine for governing the supply of live steam to the
induction valve of the main valve pistons of its own engine, and the discharge of the
exhaust steam from the same, said supplemental valve being so constructed and
arranged that it will give at the will of the operator either a continuous supply to
both steam cavities of the induction valve and a continuous discharge from the
exhaust ports of the valve, or an intermittent supply and exhaust alternately to one
induction cavity and exhaust port and to the other induction cavity and the exhaust
port thereof. My invention further consists of certain details of construction and
arrangement of parts which will be pointed out more particularly hereinafter.
In order that my invention may be clearly understood I have illustrated in the
annexed drawings so much of a direct acting duplex pumping engine as is necessary
for a clear understanding of my invention, it being understood that the valve device
shown is, in the present instance, intended to be applied to what are known as
"Davidsons Pumping Engines."
In the said drawings:-
Fig. 1 is a vertical section through the main valve and the supplemental valve
mounted thereon.
Fig. 2 is a similar view (broken) showing the supplemental valve in a different
position.
Fig. 3 is a similar vertical section at right angles to the first.
Fig. 4 is a plan view of the supplemental valve shown in section in Fig. 1 and in
end view in Fig. 2, and
Figs. 5, 6 and 7 are respectively end, sectional, and plan views of a positive valve
which may be used in place of the negative valve shown in the supplemental valve
chamber.
In pumping engines heretofore used the supplemental valve is arranged to control
only the admission of steam to the steam cavities or ports of the main valve, the
exhaust steam being in nowise controlled by the supplemental valve. I have found
in practice that under certain circumstances, as for instance when the packing of the
pistons of the main valve becomes worn, some steam is liable to leak past the pistons
into the ends of the valve chest, one end of the chest being closed and the other open
to the exhaust, the balance of the valve is destroyed and the main valve is thus liable
to move before the supplemental valves open the ports to control the steam. This is
particularly disadvantageous when the pumps are acting as duplex pumping engines
and the supplemental valve of one engine is controlled by the movement of the piston
of the other engine, as it is evident that the exact time of operation of the pumps is
liable to be disarranged. I overcome this difficulty by providing a supplemental
valve that will control both the supply of live steam and the exhaust steam to and
from the main valve.
In the drawings 1 is the steam chest and 2 is the inlet admitting steam to the chest.
The main valve 3 is shown in the present instance as a slide valve consisting of two

page_text: plates connected together and provided with a stem or pin 5 which is adapted to be
connected to some operating part of the engine to be controlled thereby, and mounted
upon the upper end of the stem or pin 5 is a plate 6 which is held in place by a
spring 7 surrounding the pin and pressing the two portions of the valve closely
to their seats. To each plate 4 of the valve is attached a piston 8, each provided
with proper packing 9 and serving to complete the movement of the main valve in a
manner well understood in this class of valves.
Mounted upon the valve chest 1 is the valve chest 11 of the supplemental valve 10,
and passing through and connected to the head 12 of the chest is a stem or rod 13
provided with a lever or connection 14 by which the valve 10 is operated by the other
engine of the pair. Passing through the other head. 15 of the valve chest is a
hand screw 16 which is connected to the valve 10, and by which it may be moved
longitudinally in the chest so as to bring the ports of the valve in operative con-
nection with the ports of the chest or to bring them in such a position that the ports
shall always remain open, as before described; that is to say, when the engines are
operating singly or independent of each other the valve 10 is moved so that the
induction and eduction ports are always open notwithstanding the fact that it may be
oscillated by the adjacent engine, but when the two engines are operating as duplex
engines the valve 10 is moved so that both the induction and eduction ports are
controlled by the oscillating movement imparted to the valve by the complementary
engine. The valve 10 may be either what is known as a positive or as a negative
valve, the negative form of the valve being shown in Figures 1, 2, 3 and 4, and the
positive form in Figures 5, 6 and 7.
A
The valve 10 is shown as having a recess or slot 17 in the top portion thereof, and
one end is cut away at 18 to allow a free passage of the steam through the channel
and around the end except where the extension 19 acts as the cut-off proper of the
valve controlling the admission of steam to the opposite side of the main valve.
recess 20 substantially of the form shown in Figures 4 and 7, as the case may be,
serves to control the passage of the exhaust steam from the exhaust ports of the
main valve. The steam is admitted to the supplemental chest through the main valve
chest, the port 21, and goes through a passage 22 formed in the chest and protected
by a cylinder 23 between the valve and chest so that the steam enters the recess 17
of the valve from an opening 24 in the cylinder, and thence passes to both ends of
the valve 10, and when either one of the ports 25 is opened by the face of the
extension 19, Fig. 3, being oscillated one way or the other the steam passes from
the cavity 26 in the main valve to the passage 27, extending to one end or the
other of the valve chest, so that the steam will enter the chest at a point 28
between the head and piston and move the main valve as required. The exhaust
steam from the main valve passes from the end of the chest through a port corre-
sponding to the port 28, opening into a passage 29, thence through the cavity 30
to the port 31, which, when the exhaust is open corresponds to the portion 32 of
the opening or recess 20 in the valve 10, whence it passes through the port 33
to the exhaust pipe or discharge 34. It will of course be understood that there
is an induction passage connected to the ports in each end of the main valve chest,
and one or the other is opened or closed as the valve 6 is oscillated.
In Fig. 2 I have shown the supplemental valve as being moved by the hand wheel
or otherwise, so that although it may be operated by the adjacent engine it will
not in any way effect the admission or emission of steam to the main valve as the
ports are always open. In this way the two engines may be operated as independent
engines, the main valve alone controlling the passage of steam. When, however, it
is desired to have the engines operate as duplex engines it is only necessary to again
move the valve 10 to the position shown in Fig. 1, when the ports both controlling
the admission and emission of steam to the main valve pistons will be controlled by
the supplemental valve. It will be seen that in both positions of the supplemental
valve the cylinder or lining 23 remains in the same position relative to the ports in
the valve chest, and the steam is delivered above the valve as before.
Heretofore it has been common in duplex engines to make the supplemental valves

page_text: of each engine precisely alike, and this being so it was necessary to arrange the
mechanical connections between the valves and the operating portion of the other
engine reversely to each other. To avoid this arrangement I prefer to construct the
supplemental valves of the two engines differently, or in other words, to make one a
positive valve and the other a negative valve, so that they can both be operated by
the same direct movement from the adjacent engine. This construction is clearly
indicated in the drawings which show the arrangement of parts so that while both
valves oscillate in the same direction they will open opposite ports leading to opposite
ends of the main valves, so that they will be moved in a direction opposite to each
other to cause the engines to operate in accordance therewith.
It is not absolutely necessary to provide each engine with a supplemental valve for
governing the supply of steam to the induction valve of its chest cylinder, since
where only one of the engines is provided with such a valve the two engines may
still be worked either duplex or independently, but I prefer the described use of a
supplemental valve for each engine for various reasons, among which I may cite that
the engines are then both under positive control when working duplex, and that
the capability of the engines of working duplex is still preserved in case one of the
supplemental valves or its gear gets out of repair.
From the above it will be seen that while I do not claim to be the first to use in
connection with a pair of direct acting engines supplemental valves for governing the
induction of steam to one of the engines, I do believe myself to be the first to auto-
matically control the induction and eduction of the steam in a valve arrangement of
this character, and I therefore do not confine myself to the exact details of con-
struction and arrangement herein set forth, as it is evident that this may be varied by
those skilled in the art without departing from the spirit of my invention.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I.
claim is :-
:-
1. In a duplex engine, the combination with the main valve of one engine, of a
single supplemental valve for governing the supply of steam to the induction ports
and the exhaust steam from the eduction port, the valve piston of the main chest
cylinder, said supplemental valve being controlled by the other engine, substantially
as described.
2. In a duplex engine, the combination with the main valve of one engine, of a
supplemental valve for governing the supply and exhaust steam to the chest cylinder
in accordance with the movements of the other engine, the said valve being shiftable
so that the induction and eduction ports will be opened and closed alternately or will
be open continually, substantially as described.
3. The combination with the valve chest, of the valve moving therein, and the
cylinder arranged between the valve and chest, substantially as described.
4. The combination with the valve chest having induction and eduction ports, of a
valve having a channel in its upper part and induction and eduction ports on its lower
part and a cylinder interposed between the valve and chest and arranged to deliver
the steam to the channel in the valve, substantially as described.
5. In a duplex pumping engine the combination with the valve chamber, of a valve
having one end cut away to form a passage for the live steam, a channel in the upper
portion of the valve communicating with the steam passage, and a recess in its lower
portion for the passage of the live steam, substantially as described.
6. The combination with the steam chest, of a supplementary valve having
induction and eduction ports for the live and exhaust steam, of a shiftable valve
having one end cut away for the passage of the live steam, and having a recess
in its under side for the exhaust steam, the arrangement being such that the ports.
may be continuously open or alternately opened and closed according to the position
of the valve, substantially as described.
7. The combination with a main valve chest having ports in its upper portion for
the live and exhaust steam, of a supplementary valve chest having corresponding

page_text: ports, and a shiftable valve in the supplementary valve chest arranged to maintain all
the ports open in one position, and to afternately open and close the live steam and
exhaust steam ports in another position, substantially as described.
8. The combination with the steam chest having passages and ports in the upper
portions thereof for the live and exhaust steam, of a valve having cavities in its
upper portion corresponding to the said passages and ports, substantially as
.described.
9. In a duplex engine, the combination with each main valve, of a supplemental
valve arranged to be operated by the other engine, the said supplementary valves
being positive and negative with respect to each other, substantially as described.
Dated this 2nd day of July 1890.
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, Applicant's Agent.