IMPROVEMENTS IN DUPLEX PUMPING ENGINES, OR STEAM PUMPS
Year: 1884

page_text: COMPLETE SPECIFICATION.
"
I ARTHUR WILLIAM LOVELL REDDIE of the Office for Patents, 6 Bream's
Buildings Chancery Lane in the County of Middlesex Patent Agent, do hereby
declare the nature of my invention for IMPROVEMENTS IN DUPLEX PUMPING
ENGINES, OR STEAM PUMPS, and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement :-
This invention relates to duplex pumping engines or steam pumps in which the
valve of each engine or pump is operated, by means of connections from the piston
rod of the other engine or pump.
In duplex pumping engines or steam pumps as heretofore generally constructed
the valves have been arranged to open and close by a movement lengthwise of the
cylinders or in the direction of movement of the pistons. Such valves have been
operated by a system of rock shafts and levers which are arranged between the
water and steam cylinders, or by means of long rods or connections, extending.
outside of or between the two steam cylinders to the rear ends, thereof, and there
connected to levers for operating the valves.
In carrying out this invention I employ rocking or reciprocating rotary valves,
one for each steam. cylinder, which are arranged with their axes parallel with the
axes of the steam cylinders and which are preferably of approximately the same
length as the steam cylinders.
The stems of these valves are extended forward considerably beyond the front
ends of the two steam cylinders, and the valves have no longitudinal movement
and are susceptible of a rocking or reciprocating rotary movement only. Each
piston rod is furnished with an upwardly projecting arm, and during the whole
length of piston stroke this arm moves in a slotted valve cam which oscillates
on a rod extending parallel with the piston rod, and which bas a slight swinging
movement imparted to it in a direction transverse to the piston rod, by the
movement of said arm in its slot. The said valve cam of each engine is connected
by a rod with an arm on the valve stem of the other engine, and through said rod
imparts a slight rocking movement to the valve. The parts above described for
-

page_text: operating the valves are simple and inexpensive of construction, and by them the
necessary movements of the valves are accomplished with very little friction and
wear, Each valve rocks on a concave sent which forms the are of a circle, and by
making the valve of about the same length as the cylinder I am enabled to
construct and arrange the ports in the valve seat so that their greatest dimensions 5
shall be lengthwise of the cylinder; while their width or dimensions in the direction
. of movement of the valve is very little. Hence I can provide very large ports and
still control them by a valve having very little movement.
The invention consists in certain novel combinations of parts hereinafter described
and referred to in the claims.
1
In the accompanying drawing Fig: 1 is a side elevation partly in soction of a
duplex pumping engine embodying the invention; Fig: 2 is a plan of the engine
the valve chests of the two steam cylinders being in horizontal section and the
valves being removed to show the arrangement of ports in the valve seats; Figs 3
and 4 represent inverted plans of the two valves; Fig: 5 is a transverse section of 1
the valve chests, valves, and portions of the two steam cylinders; and Fig: 6 is a
longitudinal section on the dotted line y y Fig: 5.
Similar letters of reference designate corresponding parts in all the figures.
A A¹ designate the two water cylinders of the duplex engine or pump and B B¹
designate the corresponding steam cylinders. As here shown the water cylinders
are formed in a single casting as also are the steam cylinders. I do not however
make any claim to the construction of those cylinders and the rear portions of the
water cylinders and their chests are omitted.
The cylinders are secured to a bed plate or base frame A².
C C¹ designate the two piston rods which move in opposite directions as in all
duplex pumps.
D, DI, designate tie-rods or braces which connect the steam and water cylinders;
.the rod D serving to connect the cylinders A, B, and the rod D¹ serving to connect
the cylinders A¹ B.
It is usual to employ rods to tie together or connect the oppositely arranged:
cylinders of pumps and hence I make no claim to the rods D D' in themselves; but
in this engine they serve other purposes in addition to their functions as tic-rods or
braces as will be hereinafter described.
E, E¹ designate arms which extend upwardly from the piston rods C, C³, and are
rigidly secured thereto. They may be adjusted to their proper place on the piston
rods when the pump is set up and there secured by set screws a, a, or other
means.
The rods D D are arranged above and parallel with the two piston rods C C' and
the arms E E¹ at their upper ends are bored to fit said rods and slide freely thereon,
as they move with the piston rods. The arms E E¹ being guided on the said tie
rods D D¹, are always maintained in an upright position and move in vertical
planes. The tie rods therefore serve also as guides for the said arms.
The arms E E¹ might each consist of a single piece but as here shown each arm
consists of two pieces a¹ a³ fitted telescopically together as shown in section in
Fig. 1.
The upper portion a³ comprises a socket into which the lower portion a¹ extends
and although said portions move with the piston rod as one arm, yet they may
move relatively to each other in the direction of their length in order to compensate
for any differences in the measurement between the piston rod and the tie rod
above it. Hence the arm may fit snugly on the tie rod D D' and still there will
be no liability of its binding thereon in case the tie rod and piston rod are not.
absolutely parallel.
On the portion a¹ of each arm E E' may be placed a roller a³ best shown
in Fig: 1 and for a purpose hereinafter described.
F, F, designate two valve cams one for each pump and which are substantially
alike in their construction. Each cam comprises a long slot b in which the

page_text: roller a moves during the whole length of piston stroke, and which is somewhat
oblique to the piston rod, as best shown in Fig: 2.
Each valve cam F F is formed with upwardly extending arms cc' at its opposite
ends, and at the upper ends of these arms are hubs or eyes which are fitted to the
tie rod D or D', and which are free to turn thereon, thus allowing the cam For F
to be swung in a direction transverse to the piston rod by the action of the arin E
or E in the slot b.
The tie rods D D¹ therefore form fulcrums on which the valve cams F F¹ may
swing, but said cans have no movement lengthwise of the tie rods.
I will now describe how these tie-rods are made and secured in place.
Each tie rod is formed with a head d at one end, a screw thread d' adjacent to
the head, and a screw thread d³, at the other end, and in the flange of each
cylinder B or B' is a hole d³ through which the rod D or D' is inserted, while in
each water cylinder A or A' is a threaded socket into which the rod is screwed.
In order to assemble the parts the rod D or D¹ is inserted from the right
through the hole d³ and is then slipped through a nut d³, then through the hubs or
eyes on the arms c, c', of the valve cam F or F', and through the arm E or E' and
a collar do, and finally its end is screwed into the socket d'. The nut d³ is then
tightened thereby clamping the flange of the cylinder B or B¹ tightly between the
nut do and head d. The valve cam F or F' is held against longitudinal movement
by its arm c' being held between the collar do and the end of the socket d'. *
GG' designate the two valve stems which are provided with arms e e¹, and these
arms are connected by rods H H¹ with ears f on the inner sides of the two valve
cams F F; the valve cam F being connected by the rod H with the arm e¹ on the
valve stem G¹, and the valve cam F being connected by the rod H' with the arm c
on the valve stem G.
From the above description it will be understood that the reciprocating movement
of the piston rods of the engine produces a slight swinging movement of the valvo
cams, and a movement of the rods H H¹ and valve stems G G¹, all in a plane
transverse to the line of movement of the piston rods.
I, 1' designate the valve chests and 12 is a steam chamber or chest which is in.
full communication with the valve chests, and to which steam is supplied from an
inlet f. J, J, designate the the two valves from which the stems GĜ' project, and
which are shown in Figs: 3, 4, 5 and 6.
The front heads 13 1 of the valve chests are formed with housings or skeleton
frames which comprise bearings f for the outer ends of the valvo stems G, G¹, as
shown best in Figures 1 and 2, and afford adequate support therefor.
The portions g g of the valve stems G G¹ arc rectangular in transverse section as
shown in Figs 5 and 6 and are fitted to a corresponding recess in the back of the
valve. This connection between the valve and its stem insures the turning of the
valve by its stem and allows the valve to be kept to its seat without causing any
sido strain on the stem.
Below the steam chest or chamber 1 is an exhaust chest or chamber I* from.
which leads the exhaust pipe Iº.
The steam and exhaust ports for cach cylinder are alike and hence a description
of those of one cylinder and valve chest will suffico.
and separate exhaust
being employed to
piston covering the
dimension of all the
At opposite ends of the cylinder are steam supply ports
ports jj best shown in Fig: 6, the separate exhaust ports
cushion the piston at each end of its stroke by reason of the
exhaust ports. Where they enter the cylinder the greatest
ports is in a direction around the cylinder as is usual, but at their ends which are
presented in the valve seat all the parts have their greatest dimensions in tho
direction of the length of the cylinder. In fact those ends of the ports which are
presented in the valvo seat are so spread in the direction of the length of the
cylinder that they occupy the entire length of the valve seat, with the exception of
the necessary bridges. Consequently the ports are very narrow and long, and whilo,

page_text: they may be made or ample arca, a comparative slight rocking movement of the
valve will control them.
At the side of the exhaust ports jj' in the valve seat are ports which lead to
the exhaust chest I'; and the valve J or J' is provided with an exhaust cove j¹
whereby the ports are brought into communication and with an exhaust cove j³
whereby the ports are brought into communication.
The piston K in Fig: 6 being about to move in the direction of the arrow, it
will be observed that the valve J is in such a position that steam is admitted
through the port while the steam may exhaust from the opposite side of the piston
through the ports which are brought into communication through the exhaust
cove of the valve J.
When the several moving parts are in the position shown in Figs 1 and 2 the
valve J will occupy a position corresponding to that shown in Fig 6; that is to say,
the supply port in the valve chest I will be closed, the exhaust ports jj will be in
communication, the exhaust ports j' j³ will be closed, and the supply port i will be
open At the same time the supply port i in the valve chest I will be open, the
exhaust portsja will be closed, the exhaust ports j j³ will be in communication,
and the supply port will be closed. The condition of all the ports as above
described would produce the movement of the piston rod C towards the left hand
of Figs 1, 2 and 6, and the movement of the piston rod C' towards the right hand
of Figs 1 and 2.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what
I claim is :-
1. The combination with the two piston rods and cylinders of a duplex engine,
and arms extending from said piston rods, of two valves susceptible of a rocking
movement and having their axes lengthwise of the cylinders, valve stems extending
from said valves, two valve cams wherein the said arms travel as the piston rods
are reciprocated, and rods extending transversely to the piston rods and connecting
the valve cam of each engine with the valve stem of the other engine substantially
as herein described.
2. The combination with the two piston rods and cylinders of a duplex engine or
pump and tie rods connecting each steam cylinder with its opposite pump cylinder,
of two slotted valves cams pivotted on said tie rods, arms extending from the piston
rods through the slotted cams and guided by tho said tio rods, rocking valves having
their axes lengthwise of the cylinders, and rods extending transverse to the piston
rods and connecting the valvo cam of each engine with the stem of the valve of the
other engine substantially as herein described.
3. The combination with the piston rod C and cylinders A. B, of the tie rod D
connecting said cylinders, the slotted valvo cam F pivotted on said tie rod and held
against movement lengthwise thereof, and the arm E for actuating said cam
extending from the piston rod and guided by the tie rod, and consisting of upper
and lower portions a' a' telescoped together, substantially as herein described.
4. The combination with the piston rod C and cylinders A, B, of the tie rod D,
the slotted valve cam F pivotted on said rod and held against movement lengthwise
thereof, and the armi E for actuating said cam extending from the piston rod and
guided by the tie rod, and composed of portions a¹ a³ telescoped together, and a
roller a³ on the portion a', substantially as herein described.
5 The combination of the piston rod C the cylinders A B, the tie rod D having a
head d at one end and a thread dat the other, and the nut d' and collar do, the
slotted valve cam F forined with arms c c¹ fulcrummed on said rod and the arm E,
working in said cam and guided by said tie rod, substantially as herein described.
6. In a duplex engine or pump the combination of the cylinders B B¹ and valve
chests I, 1¹, extending lengthwise thereof, the cylinders being furnished with supply
ports which at the valve soats have their greatest dimensions in the direction of
the length of the cylinders and the valves J Ji of approximately the same length as

page_text: the cylinders and susceptible of a rocking movement only, substantially as herein
described.
7. In a duplex engine or pump the combination of the cylinders B B' and valve
chests II constructed with supply ports i i¹, and exhaust portsj, j. j. arranged
as described, and the valves J, J₁, constructed with exhaust coves j j³ and
susceptible of a rocking movement only, substantially as herein described.
Dated this 3rd day of October 1884