Improvements in and relating to Steam and other Fluid Engines and Pumps.
Year: 1888

page_text: Date of Application, 6th Nov., 1888
Complete Specification Left, 2nd Aug., 1889-Accepted, 7th Sept., 1889
PROVISIONAL SPECIFICATION.
Improvements in and relating to Steam and other Fluid Engines
and Pumps.
We, ARTHUR GEORGE MUMFORD, of the Culver Street Iron Works, Colchester, in
the County of Essex, Engineer, and ALFRED ANTHONY, Draughtsman at tho
aforesaid Works, do hereby declare the nature of this invention to be as follows :-
:-
Our invention relates to engines or pumps having duplex cylinders, the pistons of
which act as distributing valves to the said cylinders, thus dispensing with the use
of slide valves, and it has for its objects;-First, balancing the pistons in the
cylinders; Secondly, constructing the pistons so that the whole bore of the cylinders
is swept by the said pistons in such a manner as to equalize tho wear in the cylinders
and prevent shoulders being formed therein, and Thirdly, certain improvements in
the several parts whereby increased efficiency is obtained.
We are aware that engines and pumps have already been made having duplex
cylinders each piston of which acts as a distributing valve to the other cylinder, but
such engines and pumps have not been a success owing to certain faults in their
construction which it is the object of our present invention to remedy. In the first
place no attempt has been mado to balance the pistons so as to equalize the pressure of
the steam on the exhaust recesses, the result of which is that engines and pumps of
this type will not work satisfactorily unless the exhaust recesses are reduced to the
smallest possible area, and then only under a moderate pressure of steam. By this
hitherto necessary reduction of the areas of the exhaust recesses, it has not been
possible to obtain a synchronous reciprocation of the pistons, thus proventing the said
pistons from being coupled to a crank shaft to transmit rotary motion. Now by our
invention this difficulty is overcome, as by balancing the pistons the exhaust recesses
may be made of any desired area. Again in engines or pumps of the type to which
our invention relates it is necessary to use hollow pistons of greater length than
the stroke, the consequence of which is, that the bore of the cylinder is not swept by
the piston rings at the ends of the said piston, and by wear, shoulders are formed
therein. This defect we also overcome in a manner hereinafter described.
Our invention is applicable to all types of both single and duplex cylindered
engines and pumps. In the latter case the cylinders are made of equal area and both
pistons are provided with piston rods adapted to be coupled indirectly to a crank shaft
or directly to the pistons of pumps.
In the former case the one cylinder is made smaller than the other and is used
entirely as a steam-moved distributing valve to the other and larger cylinder.
We arrange the two cylinders side by side, or otherwise in close proximity to each
other, and we form suitable ports or passages between the cylinders either as described
in the specification of our prior application for a Patent No. 14166 of 1887, or in
any other suitable manner to obtain the shortest and most direct passages from, the
one cylinder to the other. A convenient modification of the arrangement of the ports
or passages as described in our aforesaid prior application for a Patent is to arrange
the three ports or passages in the centre of each cylinder, at the inner side thereof
instead of at the bottom, thus avoiding the sinuosity of the said ports or passages.
Each cylinder is fitted with a piston of the necessary length, made skeleton in
form so as to be practically hollow and provided with suitable piston rods-if for a
duplex engine or pump. Each piston has four expansion rings one at or near
each end of the said piston, and one at or about the inner end of each exhaust recess
in the said piston, thus cutting off each exhaust recess from the other, and forming
a space in the centre of the piston for a purpose that will hereinafter be disclosed.
It will be seen that by the use of the four expansion rings on each piston arranged

page_text: as described, the whole length of the bore of each cylinder will be swept by the said
rings and so will be uniformly worn. Suitable slots are made in the pistons for the
admission of steam thereto from the steam chest, which is preferably made common to
both cylinders, and to admit the steam from the pistons to the ports or passages
leading to the alternate ends of the cylinders. Suitable holes are also provided in the
pistons in advance of the steam slots to facilitate starting the engine or pumps from a
state of rest. The pistons are guided so as to prevent their rotation by means of
studs or guides bolted to the cylinder covers and extending within the bores
of the respective cylinders to engage with suitable recesses in the said pistons.
In the centre of each piston in the space formed by and between the inner pair of
expansion rings as herein before described is formed a groove or recess in its outer
face opposite to the exhaust recesses. This groove or recess we call the balancing
recess, and it is connected by a suitable passage or passages with the said exhaust
recesses and is so proportioned that the pressure of the steam on the exhaust recesses
is wholly or partially balanced by the pressure of the steam in the contrary direction
and on the aforesaid balancing recess. It will be seen that by placing this balancing
recess in the centre of the length of the piston, and between the two expansion rings,
the live steam in the hollow pislon is prevented from gaining access to the said
recess while the piston can be made an easy fit in its cylinder.
Dated this 6th day of November 1888
ROBT. ED. PHILLIPS, M.I.M.E.,
Consulting Engineer and Patent Agent, 70, Chancery Lane, London, W.C.,
Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in and relating to Steam and other Fluid Engines
and Pumps.
We, ARTHUR GEORGE MUMFORD, of the Culver Street Iron Works, Colchester,
in the County of Essex, Engineer, and ALFRED ANTHONY, Draughtsman at the
aforesaid works, do hereby declare the nature of our said invention and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement:-
Our invention relates to engines or pumps having duplex cylinders the pistons of
which act as distributing valves to the said cylinders, thus dispensing with the use of
slide valves; and it has for its objects; First, balancing the pistons in the cylinders;
Secondly, constructing the pistons so that the whole bore of the cylinders is swept by
the said pistons in such a manner as to equalize the wear in the cylinders and prevent
shoulders being formed therein, and Thirdly; certain improvements in the several parts
whereby increased efficiency is obtained.
We are aware that engines and pumps have already been made having duplex
cylinders each piston of which acts as a distributing valve to the other cylinder and
therefore we do not claim such generally as our invention, but such engines and
pumps have not been a success owing to cortain faults in their construction which it
is the object of our present invention to remedy. In the first place, no attempt has
been made to balance the pistons so as to equalize the pressure of the steam on the
exhaust recesses, the result of which is that the engines or pumps of this type will
not work satisfactorily with high pressure steam, unless the exhaust recesses are
reduced to the smallest possible area. By this hitherto necessary reduction of the
areas of the exhaust recesses it has not been possible to obtain a synchronous recipro-
cation of the pistons except with very low pressure steam, thus preventing the said
pistons from being coupled to a crank shaft to transmit rotary motion. Now by our
present invention this difficulty is overcome, as by balancing the pistons, the exhaust
recesses may be made of any desired area. Again in engines or pumps of the type
to which our invention relates, it is necessary to use pistons of greater length than
the stroke, the consequence of which is that the whole length of the bore of the

page_text: cylinder is not swept by the piston rings at the ends of the said piston, and
consequently by wear shoulders are formed therein. This defect we overcome by
using one or more rings at or about the centre of the length of each piston.
Our invention is applicable to all types of both single and duplex cylindered engines
and pumps. In the latter case the cylinders are made of equal area, and both pistons
are provided with piston rods adapted to be coupled indirectly to a crank shaft, or
directly to the pistons of pumps. In the former case the one cylinder is made
smaller than the other and is used entirely as a steam moved distributing valve to
the other and larger cylinder.
We arrange the two cylinders side by side, or otherwise in close proximity to each
other, and we form suitable ports or passages between them, either as described in
the Specification of our prior Patent No. 14166 of 1887, or in any other suitable
manner to obtain the shortest and most direct passages from the one cylinder to the
other. Each cylinder is fitted with a piston of the necessary length, made either
skeleton in form so as to be practically hollow, or solid with suitable annular recesses
round it. Each piston is provided with a suitable piston rod if for a duplex engine
or pump.
Each piston has three or more expansion rings, one at or near each end
of the said piston, and one or more at or about the centre of the length of the piston,
between the exhaust recosses in the said piston, thus cutting off the one exhaust
recess from the other.
It will be seen that by the use of three or four expansion rings in each piston
arranged as described, the whole of the bore of the cylinders will be swept by the said
rings, and so will be uniformly worn.
Suitable slots if the pistons are hollow-or annular recesses-if the pistons are
solid are made in or around the pistons for the admission of steam from a chamber
or chest, preferably common to both cylinders, and from the pistons to the ports or
passages leading to the alternate ends of the cylinders. Suitable holes or slots are also
provided in the pistons in advance of the steam slots to facilitate starting the engine or
pump from a state of rest.
The pistons are guided so as to prevent their rotation by means of studs or guides
screwed into the cylinder covers, and extending within the bores of the respectivo
cylinders to engage with suitable recesses in the said pistons.
"
In each piston, in the space formed by and between the expansion rings as herein-
before described, are formed one or more grooves or recesses in its outer face
opposite to the exhaust recesses. These grooves or recesses we call "balancing
recesses, and they are connected by suitable passages with the exhaust recesses, and
are so proportioned that the pressure of the steam on the exhaust recesses is wholly or
partially balanced by a corresponding pressure in the opposite direction.
In the accompanying drawings which illustrate the application of our invention to
some types of duplex engines, the views on Sheet 1. show the application of our
invention to the type of engine having hollow pistons as described and illustrated in
our prior Patent No. 14106 of 1887. Figure 1, being a sectional elevation through
one of the cylinders, Figure 2. a sectional plan through the centre of the cylinders,
Figure 3. a transverse section through the centre ports of the cylinders, and Figures 4
and 5. views of one of the pistons, the former showing the steam slots or ports and
the exhaust grooves or recesses, and the latter the balancing recess.
The views on Sheet No. 2. of the accompanying drawings illustrate the application
of our invention to an engine having solid pistons and having the steam and exhaust
ports or passages arranged in such a manner as to give them the shortest possible
length, and to decrease as much as possible the sinuosity of the said ports or passages.
Figure 6. is a sectional elevation through one of the cylinders with the piston
removed. Figure 7 is a sectional plan through the centre of the cylinders. Figure 8
is a transverse section through the centre ports of the cylinders. Figure 9. is a view
of one of the pistons (having three expansion rings) showing the annular recesses
for the steam and the exhaust recesses, and Figure 10 is a view of a piston (with
four expansion rings) showing the annular recesses for the steam, the exhaust
recesses, the balancing recesses, and the holes for the guide studs.

page_text: Throughout the several views similar parts are marked with like letters of
reference.
Referring to Figures 1. 2. 3. 4. and 5. Sheet No. 1. of the accompanying drawings.
A and A¹ designate the cylinders which are preferably cast in one piece and are fitted
with covers A² A² back and front, the latter being fitted with stuffing boxes and
glands of the usual construction. B and B designate the hollow pistons fitted with
piston rods B2 B² which pass out through the stuffing boxes on the covers A². C desig-
nates the steam chamber common to both cylinders A and A', from which the steam
or other fluid is admitted into the hollow pistons B and B by means of the holes c and c¹
in the cylinders and the slots 6 in the pistons. designate the expansion rings in the
ends of the pistons as usually fitted, and 6262 designate the additional expansion rings at
or about the centre of the lengths of the pistons. D designates the exhaust chamber
common to both cylinders, and in communication therewith by the ports and d¹.
A3 and A³ designate the guides or studs which engage with recesses B³ and B³ in the
pistons to prevent their rotation. E and E designate the slots or ports in the piston B,
and E, E designate the slots or ports in the piston B', to admit the steam therein to the
ports e and e of the cylinder A, and the ports e¹ and e¹ of the cylinder A respectively.
F and F designate the exhaust recesses in the piston B, and F, F those in the piston B¹
to connect the ports e and e with the exhaust port d, and the ports e and e¹ with the
exhaust port respectively. ee² etc. designate small auxiliary starting holes, and ³ ³
small auxiliary steam holes in the pistons, to facilitate starting the engine when the
pistons remain at a state of rest at or about the centre of the length of the
cylinders.
area
G and G designate the balancing recesses in the centre of the pistons between the
expansion rings 62 62. Each pair of exhaust recesses F F and F¹ F¹ are put in
communication by means of the holes or passages f and f¹, and also into communi-
cation with the balancing recesses by means of the holes or passages g and g¹ thus
balancing the pressure of the steam on the exhaust recesses by a corresponding pressure
exerted in the opposite direction, the balancing recesses being made of an
approximately equal to that of the exhaust recesses. Referring to Figures 6. 7. 8.
9 and 10 Sheet No. 2. of the accompanying drawings A and A¹ designate the cylinders
fitted with covers A² having stuffing boxes and glands of the usual construction.
Band B¹ designate the pistons fitted with pistons rods B2, the usual expansion rings 'b',
and with either one additional expansion ring 62 as illustrated by Figures 7 and 9 or
with two such rings as illustrated by Figure 10. A3 A3 designate the guide studs
which engage with recesses B³ B³ in the pistons to prevent their rotating. designates
the steam chamber common to both cylinders A and A from which steam is admitted
by the ports c and c¹ into the annular recesses B³ B³ extending partially round the
pistons B and B'.
D designates the exhaust chamber common to both cylinders, and in
communication therewith by the ports d and . ee designate the ports or passages
leading from the centre of the cylinder A to the opposite ends of the cylinder A¹,
and ee designate the ports or passages leading from the centre of the cylinder A¹ to
the opposite ends of the cylinder A. E, E, and E¹, E', designate recesses in the
pistons B and B respectively running into annular recesses B³. These recesses are
of a width equal to the width of the steam ports e and e¹ and are of a sufficient length
to open the said steam ports to the exhaust ports d and d. F, F, and F¹, F
designate the exhaust recesses in the pistons B and B' respectively. G, G and G,
G₁
designate the balancing recesses in the respective pistons, and 9 and g¹ the passages
connecting the said balancing recesses with the exhaust recesses. ee designate the
small auxiliary starting grooves in the pistons.
It will be understood that when the pistons are coupled up, or connected to, a crank
shaft to form a motor engine, the auxiliary starting holes or grooves e² e² etc. in the
pistons may be dispensed with.
When the engine is used as a direct pumping engine we provide cushioning ports
as described in our prior Patent No. 14166 of 1887.
The "cut off " may be varied as required by increasing or reducing the length of
the various ports of recesses.
L-

page_text: The action of the engine is the same as set forth in our prior Patent No. 14166 of
1887, and will be clearly understood from the accompanying drawings.
We wish it to be clearly understood that we do not limit our invention to the precise
construction and arrangement of parts as herein described and shown, but hold
ourselves at liberty to make such changes and alterations as fairly fall within the
spirit and scope of our invention.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is;
1st. The improvements in steam and other fluid engines and pumps, substantially as
described and shown.
2nd. In a duplex engine, the pistons of which act as distributing valves to the
cylinders, balancing the pressure on the exhaust recesses by means of recesses of
equivalent areas on the opposite side of the pistons, as and for the purpose set
forth.
3rd. In a duplex engine the pistons of which act as distributing valves to the
cylinders, the use of one or more additional piston rings placed at or about the centre of
the length of each piston, as and for the purpose set forth.
4th. In a duplex engine the pistons of which act as distributing valves to the
cylinders, and having additional piston rings at or about the centre of their lengths,
preventing the rotation of the pistons in their cylinders by means of studs fixed to the
cylinder covers and engaging in recesses formed longitudinally in the said pistons, as
set forth.
5th. In a steam or other fluid engine having duplex cylinders and pistons, the
latter acting as distributing valves to the former, the combination with the balanced
pistons, of the additional piston rings placed at or about the centre of the length of
the pistons, the guide studs A3 A³, and the auxiliary starting holes or slots a² a² etc.
as and for the purpose set forth.
Dated this 2nd day of August.1889.
ROBT. ED. PHILLIPS, M.I.M.E.,
Consulting Engineer & Patent Agent, Royal Courts Chambers,
70, 71 & 72, Chancery Lane, London, W.C.,
Agent for the Applicants.