AN IMPROVED ROTARY STEAM ENGINE AND PUMP.
Year: 1874

page_text: LETTERS PATENT to William Cooper, of Clarendon House, Bridge
Road, Southampton, in the County of Hants, Chief Engineer,
Peninsular and Oriental Steam Navigation Company, for the Inven-
tion of "AN IMPROVED ROTARY STEAM ENGINE AND PUMP.
Scaled the 5th March 1875, and dated the 8th September 1874.
PROVISIONAL SPECIFICATION left by the said Willian Cooper at the
Office of the Commissioners of Patents, with his Petition, on the
8th September 1874.
I, WILLIAM COOPER, of Clarendon House, Bridge Road, Southampton,
in the County of Hants, Chief Engineer, Peninsular and Oriental Steam
Navigation Company, do hereby declare the nature of my said Invention
for "AN IMPROVED ROTARY STEAM ENGINE AND PUMP," to be as follows:-
The object of my Invention is the construction of a rotary engine
which shall be free from the great defects that have hitherto been found
in this class of engine, that is to say, that the extent of frictional or
rubbing surface which has heretofore caused great wear and prevented
'

page_text: these engines from being kept steam-tight, is not found in engines of my
improved construction, but that such surface is therein reduced to a
minimum, and that in addition the steam is to a great extent used
expansively.
By reference to the Drawings accompanying this Provisional Specifica-
tion the nature of my Invention and the manner in which it is accom-
plished will be readily understood.
In these Drawings, Figure 1 is a front view with cover removed, and
Figure 2 a transverse section of my rotary engine.
It will be seen therefrom and from the following description that my
Invention consists in a scroll disc rotary steam engine, applicable also
as a pump, the scroll disc working inside a cylinder, the outer diameter
of scroll disc and inner diameter of the cylinder forming the working
port for steam, a cod piece being fitted in the full or enlarged part of
the scroll to keep the piston tight, thus forming the piston. The
valve is a hollow equilibrium valve with the steam passing through it.
It is kept close and perfectly steam-tight throughout the whole revolu-
tion of the disc by a small pressure of steam on its end, the pressure
being regulated by a small cock, so that any required degree of pressure
can easily be put on to it when working.
There are really only two working parts in the whole engine; and from
the shape or construction of the piston and valve, as shewn in the
Drawing, a high piston speed and expansion of steam is attained, thus
preventing the great defect of rotary engines as hitherto constructed,
which exhaust the steam at the same pressure at which it enters, unless
extra valves and cocks have been fitted for that express purpose, which
adds naturally to the cost, and much complicates rotary steam engines.
This engine can also be made single or compound, or have as many
valves around the one disc, or as many discs around the same shaft as
may be required or found desirable. The valve may be fitted below,
as shown in Drawing, or in any part of the circumference of the
cylinder as required.
A compound engine can also be made upon this principle by exhausting
the steam from a smaller to a larger engine, or one of a very cheap and
simple kind made by having a larger cylinder with a division plate one
side deeper than the outer, and two discs fitted on the same shaft, set at a

page_text: position to suit the pressures on each other, so that the full pressure
would be at the greatest on one when at least on the other, exhausting
the steam from the smaller to the greater cylinder, and then to the
condenser.
The working of the engine is effected by the steam entering at A
through the valve B at the outlet C into the space D, the cod piece E
keeping the piston F steam-tight, which is driven round halfway when
the inclined plane of the scroll disc begins to close the valve B which
forms the thrust as well as the steam valve. When the scroll has
travelled round to the point G the valve port is closed, and steam from
that point is an expansive force until the face of piston H has passed
the exhaust port I, which is then full open, until the next revolution,
thus giving a free exhaust the whole length of the circumference of the
cylinder. The piston still going round passes the valve B, which instantly
glides down the curve of the face of piston H (this curve prevents the
valve from going up the face too quickly and thus striking hard on the
disc when going at high velocities), it opens the steam port and fills
again with steam the space between the face of piston H and the
valve B. The space behind the valve and piston being open to the
exhaust nearly the whole revolution, thus preventing back pressure and
giving a free exhaust. The valve is in a small casing cast on the
cylinder, and the steam pressing equally on all sides when shut makes
it an equilibrium valve.
The end and side is fitted with plates set up by
screws in case of wear, but this from experience is very trifling, almost
nothing, so that in small engines the plates would not be needed. The
valve is entirely independent of any mechanical arrangement, being kept
up to its place by steam alone, which pressure can be adjusted by a cock
on a small drain pipe, thus reducing the whole working parts to two in
number, namely, the scroll disc piston and the valve.
The advantages of the scroll shape are the ease with which it shuts and
opens the valve thrust and cutting the steam off at any part of the stroke
required. In addition from the valve always being pressed on the disc
throughout the whole circumference it keeps a constant and steady
motion, and from the difference of the radius of the disc steam constantly
lubricates the face of valve, which may be steel faced in brass or
iron.
As a pump the scroll disc, Figure 3, is worked in all parts the same as

page_text: top of the cylinder, and the valve being made with a large port. The foot
of it is fitted with lignum vitæ, the cod piece in piston being made of the
same material or of metal if required, but I prefer lignum vitæ ; for
pumps in salt water, the bearings could also be lined up with the same
material.
The advantages of this pump over the centrifugal pump, are,-
Firstly. Requiring a much less speed to drive up the same quantity of
water, thus reducing the heavy friction attendant upon high speeds.
Secondly. One of the great defects in a centrifugal pump when fitted
as a circulating pump for marine engines is stopping the circulation
immediately the engines are used, thus getting the condenser hot and
losing the vacuum, whilst the scroll disc throws water every revolution,
no matter how slow it is worked, and the forcing of water is almost
continuous. It would from this cause be of great value in India and
Egypt, and all flat countries for irregation, where the engine and pump
could be worked and fitted on the same shaft, at about half the cost of
fitting a reciprocating engine and centrifugal pump.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Cooper in the Great Seal Patent Office on
the 6th March 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
COOPER, of Clarendon House, Bridge Road, Southampton, in the County
of Hants, Chief Engineer, Peninsular and Oriental Steam Navigation
Company, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighth day of September, in the
year of our Lord One thousand eight hundred and seventy-four, in the
thirty-seventh year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto the said William Cooper, Her special
licence that I, the said William Cooper, my executors, administrators,
and assigns, or such others as I, the said William Cooper, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term

page_text: therein expressed, should and lawfully might make, use, excrcise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "AN IMPROVED
ROTARY STEAM ENGINE AND PUMP," upon the condition (amongst others) ·
that I, the said William Cooper, my executors or administrators, by an in-
strument in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said Inven-
tion, and in what manner the same was to be performed, and cause
the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said William Cooper, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement, that is to say :-
The object of my Invention is the construction of a rotary steam
engine and pump, which shall be to a great extent free from the defects
of machinery of this class, namely, that therein there shall be a
reduction or absence of complicated working parts, and the speciality
of my Invention is in the form and construction of the cylinder piston
and slide valve.
This engine or pump can be made single or double, and have as many
valves around the same disc or as many discs around the same shaft as
may be required or found desirable or effective, and the valve or valves
may
be fitted in any part of the circumference of the cylinder as cir-
cumstances may require or may be deemed necessary.
In order that the nature of my Invention, and the manner in which
the same is effected. may be clearly described and understood, this
Specification is accompanied by two Sheets of Drawings marked I. and
II., having figures and letters of reference marked thereupon, the like
letter being used to denote a similar or corresponding part in each
Figure.
A compound engine may be made on the principle of my Invention
(as is shown in the dotted lines in Sheet I. of the Drawings) by exhaust-
ing the steam from a smaller or narrower piston or disc to a larger or
broader one, or the alteration of proportions made in the area of pistons
or the discs, the discs fitted on the same shaft as a double engine,

page_text: with the exception that the discs are to be set so that a free exhaust is
open from the high-pressure disc to the steam side of the low-pressure
disc, as will be seen by reference to the dotted line in Drawings.
The Drawings accompanying this Specification show the nature of my
Invention, the construction and manner of working.
In the Drawings Figure 1 is a view in section of the inside of
cylinder, the piston, and the slide valve thrust; Figure 2 is a longitu-
dinal view of a cylinder with two discs or pistons to show a double,
single, or compound engine; Figures 3 and 4 are external views of the
engine.
It will be seen from these Drawings and from the following description
that my Invention consists in a scroll disc rotary steam engine and pump
with self-acting slides, which form the valve and thrust in both cases,
the scroll discs working inside the cylinder, the inner diameter of
cylinder and outer diameter of scroll disc piston forming the length and
area of the working port for steam, or really the working cylinder in the
engine and the pump.
The working of the engine is effected by the steam entering at A
through the valve B at the outlet C into the space D, the cod piece E,
assisted by the spring c, keeping the piston F steam-tight, the piston
thus being driven round by the force of the steam acting against the
face of piston on the curve H, and the point of thrust being formed
by the face of valve from the outlet C to where it impinges on the
face of the disc, and the valve forming also a steam-tight block from
the face of piston to the exhaust port. When the piston has travelled
round as far as the point G the increased diameter of piston has closed
the port of the valve, and from this point to the end of the revolution
the steam acts expansively. (This point of cut-off can be altered at any
part of the revolution that is found to suit the makers the best, or give
the greatest effect for the least steam). The steam acts expansively until
the face of the piston H has passed the exhaust port I, which is then
full open until the next revolution, thus giving a free exhaust nearly the
whole length of the revolution. The piston still going round passes the
valve B, which instantly glides down the face of piston H. (The face
of the piston is to be made slightly curved, but at such an angle as will
prevent the slide valve moving down the face without getting off it, as
this incline will require to be slightly altered to suit slower or higher

page_text: velocities, as may be found by experience in working to be the best.)
The piston opens the steam again, and fills with steam the space between
the piston H and the valve thrust, and commences again with another
revolution, whilst the space behind the valve thrust and the piston is
open to the exhaust port nearly the whole revolution, thus giving a free
exhaust and preventing any back pressure. The valve or thrust is in a
casing fitted or cast on the cylinder, and the steam pressing equally on
all sides when shut makes it an equilibrium valve, and it is entirely
independent of any mechanical arrangement to work it, being kept up to
its work by steam alone passing through the hole K (see dotted lines in
Drawing) into the space L, which forces the valve up to the face of the
disc throughout the whole revolution of the engine, and the form of the
scroll disc forcing it in again as it revolves round, thus causing the face M
of valve to keep steam-tight to the face of piston, and cutting steam off
at any part of the stroke, as required, as in the ordinary slide of a
reciprocating engine.
The advantages of the scroll-shaped disc are the case with which it
shuts and opens the valve thrust, and giving the maker the privilege of
cutting off the steam at any part he may think more effective or
economical. In addition, from the valve being always pressed on the
disc throughout the whole circumference, it keeps up a constant steady
motion; and if fitted well, quite steam-tight.
As a pump, the scroll disc and self-acting slide is worked in all parts
the same as the engine, with the exception of the inlet and outlet valves
and ports being at the top of the cylinder, and the valve being made
with larger ports (see Figures 5 and 6, Sheet No. II. in the Drawings).
The foot of the valve is made so that a piece of lignum vitæ or any
other material that is found to work well can be fitted, but I prefer to
use lignum vitæ if for pumping salt water, and the cod piece to be made
of the same material.
The working and arrangement will be readily understood by reference
to the Drawings of pumps in section, and after reading the description of
engine.
The great advantages claimed for both pump and engine are, the few
working parts required to complete the internal working of either
engine or pump, single or double, and the speciality is in the form
and construction of the working parts, as already described, from which

page_text: I shall call it the scroll disc rotary steam engine and pump, with self-
acting slide valve thrust.
In witness whereof, I, the said William Cooper, have hereunto set
hand and seal, this Fifteenth day of January,
in the year of
our Lord One thousand eight hundred and seventy-five.
my