Improvements in Duplex Pumping Engines.
Year: 1889

page_text: Date of Application, 5th June, 1889
Complete Specification Left, 1st Mar., 1890-Accepted, 5th Apr., 1890
PROVISIONAL SPECIFICATION.
Improvements in Duplex Pumping Engines.
We TANGYES Limited of Cornwall Works Soho in the County of Stafford
Engineers and EDWARD BARNES of No. 44 Villa Road Handsworth in the County of
Stafford Mechanical Engineer do hereby declare the nature of this Invention to be as
follows:
The said invention has reference to duplex pumping engines worked by steam
or compressed air and consists of the improvements hereinafter described whereby
the loss of steam or compressed air which occurs in the said engines as ordinarily
constructed is avoided.
We will describe the said invention as worked by steam.
In duplex pumping engines of the type to which this invention relates it is usual
to provide two ports or passages at each end of each cylinder one of the said two
ports being for the admission of steam and the other which is placed nearer the
middle of the cylinder for the double purpose of exhaust and (as the piston passes it
in continuation of its travel) to confine and compress the steam remaining between
the piston and cover and thus form a cushion to arrest the motion of the piston
and prevent it from striking the cover. As the energy to be absorbed however
varies considerably with the conditions under which these engines have to work it
is found necessary to place the exhaust port far enough in to meet the worst case
that can occur the result being large clearance spaces and consequent loss of steam
as a small amount of compression in addition to the load will suffice to stop the
piston when working under normal conditions. To overcome this defect adjustable
bye pass valves are often placed between the admission and exhaust ports to allow
the compressed steam to escape and enable the piston to approach nearer the cylinder
cover.
In addition to the loss of steam due to clearance there is a further loss due to
the additional port. When the piston is worn and travels much over the exhaust
or compression port there is a still further loss of steam by its escape past the
piston in consequence of the steam being maintained in the cylinder at initial
pressure while the opposite piston is making its stroke.
The object of the said invention is to provide duplex pumping engines with
valves and valve operating mechanism capable of adjustment by hand or auto-
matically which will close both the inlet and exhaust at that part of the stroke of
the piston found most suitable for the conditions under which the engine has to
work the said adjustable valve and mechanism constituting an integral part of the
engine.
The
The said invention consists of motor cylinders provided at each end with induction
ports or passages and also provided with the usual eduction or exhaust ports as in an
ordinary steam engine. In conjunction with each cylinder a main valve a stationary
valve plate and a cut off valve are employed the valves being worked by means of
slide rods passing through stuffing boxes in the steam chest in the usual manner.
main valve which is preferably of the flat type (although a piston may be employed)
is arranged to work between the valve face of the cylinder and the valve plate and
the cut off valve is arranged to work on the top of the valve plate or on the outside
of the valve cylinder when a piston valve is used. The cut off valve is of the
ordinary D type and the valve plate is provided with a central exhaust port two
induction ports and two intermediate exhaust ports. The central exhaust port is
always open and the cut off valve is so constructed as to close one induction port
with the opposite intermediate exhaust port alternately as the piston travels to one or
other end of its stroke. The main valve is constructed with two induction ports as in

page_text: an ordinary valve with an expansion valve at its back but with the exhaust port also
carried right through. These ports are made at the bottom side of the valve together
with the corresponding ports in the steam cylinder about equal to the travel of the
valve in width so that they are always open and with the maximum stroke either way
will give the required area of steam passage.
The induction ports are tapered upwards to about half this width at the top but the
exhaust ports are taken through with the same or about the same width at top.
To give motion to these valves levers are employed each having a long and short
arm and the fulcra of the said levers are situated between the two slide rods the
long arm being connected to its piston rod and the short arm being connected by
adjustable gear to the cut off valve of the same cylinder. One of these levers is
secured to one end of a solid rocking shaft to which is connected at the opposite end
a cam or short arm for operating the main slide valve of the other cylinder and the
opposite lever is secured to a hollow rocking shaft of a length proper to form a bearing
on its outside to fit the fulcrum bracket and on its inside to form a bearing for the
rocking shaft of the other or opposite lever.
Parallel to the main lever shafts and at the required distance in the same plane and
having its fulcrum situated in the same relative position between the slide valves a
second rocking shaft is situated. This rocking shaft has a cam or short arm to work
the other main valve. This shaft is driven by the lever having the hollow shaft and
for this purpose the side of the lever has the figure of a segment of a circle with
spur teeth gearing into a similar segment secured to the second rocking shaft so that
as the long arm of the lever moves with its piston in one direction the cam or short
arm at the other end moves and operates the main slide valve in the opposite direction.
Other equivalent gearing may be employed.
From the foregoing description it will be understood that the main valve of one
cylinder is operated by the piston and lover of the other or opposite cylinder and at
the same time is operating its own cut off valve.
When the engine exhausts into a condenser a supplementary passage is made in the
cut off valve so as to effect a communication between the ends of the cylinder and
thereby supply the steam required for cushioning.
Dated this 5th day of June 1889.
W. T. WHITEMAN,
Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Duplex Pumping Engines.
We TANGYES Limited of Cornwall Works Soho, in the County of Stafford Engineers
and EDWARD BARNES of No. 44 Villa Road, Handsworth in the County of Stafford
Mechanical Engineer do hereby declare the nature of the said invention and the
manner in which the same is to be performed to be particularly described and
ascertained in and by the following statement:-
The said invention has reference to duplex pumping engines worked by steam or
compressed air, and consists of the improvements hereinafter described whereby the
loss of steam or compressed air which occurs in the said engines as ordinarily
constructed is avoided.
We will describe the said invention as worked by steam.
In duplex pumping engines of the type to which this invention relates, it is usual
to provide two ports or passages at each end of each cylinder, one of the said two
ports being for the admission of steam and the other, which is placed nearer the
middle of the cylinder for the double purpose of exhaust, and (as the piston passes
it in continuation of its travel) to confine and compress the steam remaining between
the piston and cover and thus form a cushion to arrest the motion of the piston and
prevent it from striking the cover. As the energy to be absorbed however varies
considerably with the conditions under which these engines have to work it is found

page_text: necessary to place the exhaust port far enough in to meet the worst case that can
occur; the result being large clearance spaces and consequent loss of steam, as a
sinall amount of compression in addition to the load will suffice to stop the piston
when working under normal conditions. To overcome this defect adjustable bye
pass valves are often placed between the admission and exhaust ports to allow the
compressed steam to escape and enable the piston to approach nearer the cylinder
cover.
In addition to the loss of steam due to clearance there is a further loss due to
the additional port. When the piston is worn and travels much over the exhaust
or compression port there is a still further loss of steam by its escape past the piston
in consequence of the steam being maintained in the cylinder at initial pressure
while the opposite piston is making its stroke.
The object of the said invention is to provide duplex pumping engines with valves
and valve operating mechanism, capable of adjustment by hand or automatically,
which will close both the inlet and exhaust passages at that part of the stroke of
the piston found most suitable for the conditions under which the engine has to
work, the said adjustable valve and mechanism constituting an integral part of the
engine.
The said invention consists of motor cylinders provided at each end with induction
ports or passages and also provided with the usual eduction or exhaust ports as in
an ordinary steam engine. In conjunction with each cylinder a main valve, a
stationary valve plate and a cut off valve are employed the valves being worked by
means of slide rods passing through stuffing boxes in the steam chest in the usual
manner. The main valve which is preferably of the flat type (although a piston
valve may be employed) is arranged to work between the valve face of the cylinder
and the valve plate and the cut off valve is arranged to work on the top of the valve
plate or on the outside of the valve cylinder when a piston valve is used. The
cut off valve is of the ordinary D type and the valve plate is provided with a central
exhaust port, two induction ports and two intermediate exhaust ports. The central
exhaust port is always open and the cut off valve is so constructed as to close one
induction port with the opposite intermediate exhaust port alternately as the piston
travels to one or other end of its stroke. The main valve is constructed with two
induction ports as in an ordinary valve with a cut off or expansion valve at its back
but with the exhaust port also carried right through. These ports are made at the
bottom side of the valve together with the corresponding ports in the steam cylinder
about equal to the travel of the valve in width so that they are always open and
with the maximum stroke either way will give the required area of steam passage.
The induction ports are tapered upwards to about half this width at the top but
the exhaust ports are taken through with the same width from top to bottom or
expanding from bottom to top.
To give motion to these valves, levers are employed each having a long and short
arm and the fulcra of the said lovers are situated between the two slide rods, the long
arm being connected to its piston rod and the short arm being connected by
adjustable gear to the cut off valve of the same cylinder. One of these levers is
secured to one end of a solid rocking shaft to which is connected at the opposite end
a cam or short art for operating the main slide valve of the other cylinder and the
opposite lever is secured to or made in one piece with a hollow rocking shaft of a
length proper to form a bearing on its outside to fit the fulcrum bracket and on
its inside to form a bearing for the rocking shaft of the other or opposite, lever.
Parallel to the main lever shafts and at the required distance in the same plane
and having its fulcrum situated in the same relative position between the slide valves,
a second rocking shaft is situated. This rocking shaft has a cam or short arm to
work the other main valve.
This shaft is driven by the lever having the hollow shaft and for this purpose the
side of the lever has the figure of a segment of a circle with spur teeth gearing into
a similar segment secured to the second rocking shaft so that as the long arm of the
lever moves with its piston in one direction the cam or short arm at the other end

page_text: moves and operates the main slide valve in the opposite direction. Other equivalent
gearing may be employed.
From the foregoing description it will be understood that the main valve of one
cylinder is operated by the piston and lever of the other or opposite cylinder and
at the same time is operating its own cut off valve.
When the engine exhausts into a condenser a supplementary passage is made in
the cut off valve so as to effect a communication between the ends of the cylinder
and thereby supply the steam required for cushioning.
We will now proceed to describe with reference to the accompanying Drawings
the manner in which the said invention is to be performed.
Figures 1. 2. and 3. illustrate the application of the said invention to a direct
acting duplex pumping engine having simple cylinders, but the said invention may
also be applied to duplex pumping engines having compound cylinders.
The two engines are marked A. and B. in the Drawings.
Figure 1 represents a longitudinal vertical section taken through the valves and
cylinder of the engine A, together with its actuating gear.
Figure 2 represents a longitudinal vertical section taken through the valves and
steam chest of the duplicate or sister engine B. together with its actuating gear.
Figure 3 represents in plan, the valve gears of both the engines A. and B. and a
portion of the cylinder of the engine A. and Figure 4. represents the duplex engine
in transverse vertical section taken on the liue C. D. Figure 3.
The corresponding parts of each engine are marked with the same letters of
reference, but the parts appertaining to the engine B. are distinguished by the addition
of a dash to the letters. The cylinders of the duplex pumping engine are alike in
construction and it will be seen by an examination of the cylinder A Figure 1. that
its ports or passages are of the kind used in the cylinders of ordinary steam engines,
that is, each cylinder has at each end an induction port or passage and at the middle
the usual exhaust port.
a is the main valve of the engine A and a¹ is the main valve of the other engine B.
working in the steam chests of the said engines; b. b' are respectively the stationary
valve plates of the said main valves a. and a¹.
The said valves a. and a¹ are of the flat type and work or slide between the valve
plates b. and 6 and the valve faces of the cylinders as represented: c. is the cut off
valve of the engine A working on the top of the stationary valve plate b and c¹ is
the cut off valve of the engine B. working on the top of the stationary valve
plate 6. Each of the cut off valves c and c¹ is of the D type and each of the
stationary valve plates b. and is provided with a middle exhaust port, two outer
induction ports and two intermediate exhaust ports. The middle exhaust port in the
valve plate is always open and each of the cut off valves is so constructed as to close
one of the outer induction ports together with the opposite intermediate exhaust port
alternately as the main piston in the steam cylinder travels to one or other end of its
stroke as will be understood by an examination of the sections Figures 1. and 2.
where it will be seen that the left hand induction port in each plate 6, 6' is closed and
the intermediate exhaust port on the right hand side is also closed. Each of the
main valves a and a¹ has two induction ports as in an ordinary slide valve and a
middle exhaust port open at top and bottom as represented. The induction ports at
the bottom face of the main valves a. and a¹ are wider than the tops of the said ports,
the width of the said induction ports together with the corresponding ports in the
steam cylinder being about equal to the travel of the main valve so that they are
always open, the admission of steam to the said induction ports being regulated by
the motion of the main valve and cut off valve as hereinafter described.
are the
The middle exhaust ports in the main valves a, and a¹, are widest at top.
The main and cut-off valves are worked by the following mechanism.,
slide rods by which the cut-off valves c and c¹ are worked and m, m' are the slide rods
by which the main valves a, a¹ are worked.
On the rod i are adjustable collars e, e, fixed to the rod by set screws and on the
rod ¹ are corresponding adjustable collars e¹, e¹. Sliding between the pairs of collars e, e,

page_text: and e', el are blocks d. d' connected by the rods 7. ' to the short arms of the levers g.g',
the long arms of which are actuated by any suitable means from the reciprocating
piston rods p. p' of the two engines; fare cams or arms working in the slotted
heads of the main valve rods m, m²; h is a fulcrum shaft or axis to which are keyed
the lever g. at one end and the cam flat the opposite end; k. is a second and parallel
fulcrum shaft or axis on one end of which is keyed the cam and on the other end
the toothed sector q which gears with another toothed sector g' on the lever g¹. The
lever g¹ is also provided with a sleeve (see Figure 4.) for fitting accurately the tubular
part of the fulcrum bracket n. the said tubular part of the bracket forming a bearing
for the shaft h as represented in Figure 4.
The action of the mechanism is as follows:-
:―
The parts being in the respective positions represented in Figures 1. 2. and 3, that
is with the pistons of both cylinders A and B. at the end of their outward strokes, it
will be seen that the steam and exhaust ports of the engine A Figure 1. are closed
while the front steam port and back exhaust port of the engine B. are fully open.
Thus, the piston of the engine B. having steam admitted to its front side and being
exhausted on its rear side, will make a stroke inwards, at the same time causing the
cut off valve c¹ to be closed, by means of the short arm of the lever gi connecting
rod and slide block d' in contact with the front collar e¹ on the rod, and thereby
reversing by means of the toothed sector q' on the lever g', operating through the
toothed sector the fulcrum shaft k. and cam f, the main valve a. of the engine A.
The valves of the said engine A. being now in the same relative positions as those of
the engine B. Figure 2, the piston of the engine A. makes an inward stroke, closing
its cut off valve c, by the action of the lever g and reversing by means of the shaft h
and cam f1, the main valve a' of the engine B.
Both the valves of the engine B. being now in the opposite positions to those in
which they are shown in Figure 2, the piston of the engine B makes an outward
stroke operating its cut-off valve e¹ as before described but in the opposite direction,
and at the same time operating the main valve a of the engine A as before described
also in the opposite direction, when the piston of the engine A. will make an outward
stroke thus bringing its cut off valve c. and the main valve a¹ into their original
positions, or the positions represented in Figures 1. and 2. and thus completing the
cycle.
By adjusting the positions of the collars e, e, and e', e¹, on their rods, the cut-off
valves c, cl, may be made to cut off the steam early or late as may be desired.
The positions of the collars e, e, e¹, el, may be adjusted by hand or automatically
adjusted as hereinafter described.
Figure 5. represents in longitudinal vertical section and Figure 6. in plan an
arrangement for adjusting automatically the position of the collars or stops e e, el el
on the cut-off valve rods i, i so as to regulate the cut-off of the steam; Figure 7.
represents in plan a modified arrangement of the same.
is a cylinder provided with an adjustable cataract z; p. is a piston fitted in the
cylinder and kept back or pressed towards the back end of the cylinder by the coiled
spring s.
The rod of the spring pressed piston in the cylinder x has at its outer end a rack
gearing with the pinion w. on the cross shaft t on the ends of which shaft are keyed
the bevil pinions w¹, w¹ gearing with the bevil pinions v₁, vl, on the slide rods i, ¹. The
said slide rods i, i', are provided with feathers f. f1 on which the bevil pinions v, v
work (or in the case of the modified arrangement Figure 7. the pinions w³, w²) and
also with right and left hand screws working in corresponding screwed holes in the
stops e, e, el, e¹.
To put the automatic gear described into operation two ordinary double acting
pumps may be employed driven from any convenient parts of the engines, and
arranged to deliver pressure water through the pipe n. into the cylinder a. and thus
by the retarding action of the cataract z in combination with the varying speeds of
the engines a variable pressure on the piston is set up in opposition to the
springs. As this pressure overcomes the power of the springs the rack a¹. acting

page_text: through the pinion w, shaft t. and hevil wheels w¹, w³, vl, v¹, Figure 6. (or through the
racks and pinions w², w2, Figure 7.) will turn the valve rods i, il and cause the space
between the stops e, e, e¹, e¹ to be contracted and the valves c. c' closed earlier, or as
the pressure in the cylinder . diminishes the spring s. acting in opposition will draw
back the piston and cause the valve rods to be turned in the opposite direction
thereby increasing the space between the stops e, e, e¹, e¹, and cause the valves to be
closed later.
In place of the double acting pumps described the pressure water from the main
may be used in some cases and in place of the spring s. dead weights or weighted levers
may be employed.
By extending the piston rod of the piston in the cylinder z. and connecting it to a
throttle valve the automatic gear described and represented may be made to shut off
the steam in addition to varying the cut off.
When the engines are made to exhaust into a condenser the small passage y,
(Figure 5.) in the valve c, c¹ may be employed by which to make connection between
the steam and exhaust side of the pistons in the main cylinders.
Having now particularly described and ascertained the nature of the said inven-
tion and the manner in which the same is to be performed we declare that we claim
as the said invention ;-
First The combination in duplex pumping engines of main slide valves and
stationary valve plates of the kinds herein before described and illustrated in the
accompanying Drawings.
Secondly The combination in duplex pumping engines of the main slide valves
and stationary valve plates referred to in the preceding claim with cut-off valves con-
structed and operating substantially in the manner herein before described and illus-
trated in the accompanying Drawings.
Thirdly The construction and combination of the parts of the valve operating
mechanism of duplex pumping engines hereinbefore described and illustrated in the
accompanying Drawings.
Lastly The construction and combination of the parts of automatic cut-off
mechanism for duplex pumping engines hereinbefore described and illustrated in the
accompanying Drawings.
Dated the 27th day of February 1890.
W. T. WHITEMAN,
Agent for the Applicants.