IMPROVEMENTS IN THE CONSTRUCTION OF ROTARY ENGINES AND PUMPS
Year: 1878

page_text: LETTERS PATENT to John Cooke, of Langley Old Hall, in the County of
Durham, for the Invention of "IMPROVEMENTS IN THE CONSTRUCTION OF
ROTARY ENGINES AND PUMPS."
Sealed the 19th July 1878, and dated the 22nd January 1878.
PROVISIONAL SPECIFICATION left by the said John Cooke at the Office
of the Commissioners of Patents on the 22nd January 1878.
JOHN COOKE, of Langley Old Hall, in the County of Durham.
IN THE CONSTRUCTION OF ROTARY ENGINES AND PUMPS."
"IMPROVEMENTS
This Invention consists in certain improvements relating to such rotary engines
and pumps as are described in the Specifications of Inventions of "Improvements
in the Construction of Rotary Engines and Pumps," for which Letters Patent were
duly granted to me, bearing date respectively the 20th day of April 1868,
numbered 1279, andthe 15th day of March 1875, and numbered 950, especially to
that last mentioned.
The present Invention has for its object the obtaining of an equable or nearly
equable flow of the fluid or gas without duplicating either the drum or the shutter,
and so as to obviate any necessity for partitions, such as are described in the
Specification of an Invention of "Improvements in the Construction of Rotary
Engines and Pumps," for which Letters Patent were duly granted to me, bearing
date the 6th day of March 1875, and numbered 839.
The object of the present Invention is effected by using a platform, piston, or
diaphragm of any suitable shape connected on one side to the passage, where an
equable flow of the fluid or gas is required, whilst the other side thereof is open;
or the respective passages may be connected to the respective sides of the platform,
piston, or diaphragm.
The said piston is not necessarily formed in one piece, but it will be more con-
venient to arrange it on and with the box or chamber surrounding its edges.
The arrangements may be termed a "differentiator," its area and position and
mode of actuating the same being so arranged as to withdraw about half the

page_text: capacity per revolution of the rotary engine or pump during the semi-revolution
when the same is closing, closed, and opening, and to return the same during the
semi-revolution when the rotary engine or pump developes most of its capacity.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Cooke in the Great Seal Patent Office on the 22nd July
1878.
JOHN COOKE, of Langley Old Hall, in the County of Durham.
IN THE CONSTRUCTION OF ROTARY ENGINES AND PUMPS."
T
"IMPROVEMENTS
My said Invention consists of a novel construction and arrangement of such
rotary engines and pumps as have a cylindrical piston rotating eccentrically in a
cylindrical casing, and which have also a shutter constantly kept near to, or in
some cases touching, the same, and passing in and out through a suitable port in
the circumference of the cylinder, of the same length as the piston, in such a
manner as to divide the inlet from the outlet of the rotary engine or pump, and
also in such a manner as to prevent leakage while the piston is passing the
port.
The object of the present Invention is to obtain an equable or nearly equable
flow of the fluid or gas without duplicating either the drum or the shutter, and so
as to obviate any necessity for partitions for that purpose, although admitting of
their use, when the length of either drum or shutter requires dividing to avoid too
great a distance between supports.
The object of the present Invention is effected by using a platform, piston, or
diaphragm of any suitable shape, connected on one side to the passage, where
equable flow is required, while its other side is open; or the respective passages
may be connected to its respective sides. This piston is not necessarily in one
piece, and may be a hinged flap or flaps of sufficient dimensions and sweep, but it
will be found more convenient to arrange it in one piece, reciprocating rectilineally
a minimum distance, forming with the box or chamber surrounding its edges what
may be called a differentiator, its area and position and mode of actuation being
so arranged as to withdraw about half the capacity per revolution of the rotary
engine or pump during the semi-revolution when the shutter is closing, closed, and
reopening, and to return the same during the semi-revolution when the rotary
engine or pump developes most of its capacity.
The arrangements may be classed under five heads.
1. When the line of the edge of the shutter, or the line of the centre of the
shutter arc at the edge of the shutter are connected to the centre line of the
eccentric, piston, or drum, as described in a former Patent, the shutter may be a
plane, or a plane with an arc, whose versed sine is part of its edge next the drum.
In such a case, to apply the present Invention, the plane shutter is suspended
below or above the cylindrical casing, while the differentiator is formed by a flap
swinging to and fro in pendulum fashion, and so as to effect the withdrawal and

page_text: return of about half the contents of the engine or pump each revolution. This
mode of effecting the object of the Invention with plane shutter requires for the
shutter the full stroke of the eccentric, piston, or drum, and a very large sweep for
the flap, and port leakage being to provide against, does not admit of large enough
clear openings at low pressures for the inward and outward flow of the fluid.
2. Or the shutter may describe an arc of a circle, being suspended so as to swing
pendulum fashion, the differentiator platform having a vertical rectilineal motion
minimised where the machine is large, by using a short stroke crank as well for
the reciprocating steam engine (when one is used) as for the platform, the crank
at the other end of the drum developing the correct movement of the shutter by
means of the lever and connecting rod arranged as described in a former Patent.
By these means an even flow is obtained at less cost than by duplicating such
machines, it being desirable to balance the eccentric piston or drum accurately,
whether there is duplication or not.
3. When the application secondly described is very large, the deflection of the
shutter and lever, and the great weight and stroke of the connecting rod and lever
impair the exactness and efficiency of the machine, thus requiring something more
than modification, as follows:-'
:-The angles developed in such a rotary engine, by a
drum or piston having the same proportion of stroke to the distance of the shutter,
and its length centre of axis to centre of arc are the same for a given angular move-
ment of the shutter, on whatever scale the construction may be. The converse is
also true. The shutter is at the same angle for a given angular movement of the
piston, whatever the scale may be. Hence, by applying on one machine a secondary
lever, longer or shorter than the centre shutter axis, to centre of shutter arc, and
altering its distance and the length of connecting rod and crank in the same propor-
tion, a similar and corresponding series of angles is produced. The axis of this lever
may be placed in a line parallel to the chord of the are described by any part of the
shutter, and the crank brought round through the same angle and in the same
direction as the axis of the secondary lever makes with the line joining the centre
of the casing and the axis of the shutter.
The line joining the part of the shutter selected, and the shutter axis, and the
parallel line joining the shutter axis, and the axis of the secondary lever, form two
sides of a parallelogram, which must be completed, and a pin placed at the intersec-
tion nearest the end of the secondary lever, carried rigidly attached to the secondary
lever in any suitable manner.
A connecting rod, which may be called the parallel rod, joins this to the part of the
shutter selected, or its equivalent outside the frame, and the angular movements of the
shutter being parallel to those of the secondary lever are correct. Such a parallelo-
gram, as described, having one of its axes in a line parallel to the chord of arc,
described by point of attachment to shutter, moves symmetrically, i.e., varies as much
from a rectangle at one extremity of its oscillation as at the other, and therefore
presents the simplest strains, and the least variation from wear of the parts.
When this method of construction is adapted, the platform is suspended from each
end of the piston, the cranks both being of such scale as is approved, whatever the
size of the machine, much as is shewn in the Drawings, and the shutter is firmly
laid hold of at each end in such wise as to minimise deflection and greatly reduce
the weight of the parts. An instance of reduction only is here given. And the
differentiator may be precisely the same as in the arrangement fourthly described,
having regard to the angle at which the crank may have been placed. The separate
pin near the end of secondary lever rigidly attached thereto, and the comparative
uncertainty of the angle of crank and lever axis, and of the distances of the sides of
the parallelogram render this method of construction less simple and suitable for the
workshop than is desirable.
4. On reference to the diagrams, four in number, four right angled triangles are
seen with horizontal base, and corresponding perpendicular and hypothenuse, which
may be called the angle of construction. Each of them has a thick black base, and
perpendicular to the same hypothenuse being co-sine and sine respectively to an angle,

page_text: The angle of construction with one of these variations of the proportion of driving
parts applied may be moved round altogether, either to the right or to the left,
rather than employ radius rods to change the direction and length of the stroke of
the differentiator platform, or rather than employ one or more extra cranks or
eccentrics for this purpose, thus still preserving the vertical stroke of the differen-
tiator platform; but on the other hand, the employment of radius rods renders
the adjustment of the platform stroke to the semi-revolution of the rotary engine
easy.
5. The use of such angles of construction, as described in the fourthly described
method of application, is new and useful, even in cases where the even flow of the
fluid is preserved without the use of the differentiator.
I will now proceed to refer to the accompanying Drawings, from which the nature
of my said Invention will be more clearly understood.
Fig. 1 shews the arrangement of a rotary engine or pump constructed according
to this Invention, for the purpose of mine ventilation, in the method fourthly
described, the angle of the axis of the secondary lever having been determined to
be that shewn in the first diagram for the proportion of parts, and is partly in
section through the line C, D, of Fig. 2, the masonry at engine end being removed
for the sake of clearness. The angle of the axis of the secondary lever is shewn
midway between that of the hypothenuse of angle of construction, and the vertical
line passing through the centre of the casing and the crank E; the connecting rod F
and distance to the axis of secondary lever from the centre of the casing G are one-
half respectively of the distances given by the notes for the first diagram for e, d,
and hypothenuse.
Fig. 2 shews the same arrangement, partly in section, through the line A, B, of
Figure 1, the cranks, connecting rods, and secondary levers being seen at each end
in corresponding positions, duplicate engine H, if any, also placed at the other
side.
Similar letters refer to similar parts in the 2 Figures.
I is the parallel rod connecting L to J, the part of the shutter describing the arc
in a line parallel to whose chord is the axis of the secondary lever. When a bar
passes through in one line between J and J at each side, it may be called a through
bar, and is shown dotted through in Figure 2, although not necessarily used.
J is connected rigidly to the shutter in any suitable way and passes beyond the
edge of the shutter so as to come opposite L, the parallel rod I then connecting
them.
The motion of the shutter M will now be continually as near as required to that
of the drum or piston N, shewn dotted through the side of casing, and the shutter
is shewn to have a wide cover to prevent leakage at the curved slot through which
J projects; but there are 2 or 3 obvious ways of meeting this requirement; and
leakage, while passing the port, is prevented by the shutter being closed on the
shutter face O, while the drum or piston is passing the port.
The upper arrow shews the exit of the air from the rotary engine, and the lower
arrow shews the air, half of it to be entering the rotary engine from the mine P
and half of it to be given out through the passage Q from the differentiator R at
this position of the machine, having been previously drawn into the same when the
machine was on the opposite semi-revolution.
The differentiator is seen to consist of platform S dipping into water T so as to
make water joint and thus avoid all leakage, the outward atinospheric air reaching
its under side through the passages U which may be left of brickwork or woodwork
at each end of the differentiator. Vare tubes for stays for the platform which are
placed in sufficient number; W is the masonry on which the machine rests; X, the
radius rods so adjusted as to make the movements of S harmonise with those of the
rotary engine; and Y, the connecting rod from S to X. Finally Z connects X to E,
the crank which developes the other motion and receives the engine power.
As will be noted, S is constructed of sheets bent to radius except the sides and
supports, which are also sheets, or at least very light; steel is preferred.

page_text: The fluid is not necessary water, and is preferred to be suited to the material of
the platform.
Having thus declared and ascertained the nature of my said Invention and in
what manner the same is to be performed, I would observe in conclusion that I do
not claim the several and distinct parts of the said apparatus separate and apart
from each other as being of my Invention, but what I do claim as constituting the
Invention secured to me by the said herein-before in part recited Letters Patent are,
the several combinations and arrangements of parts and mechanism herein-before
described, substantially as and for the purposes set forth or any mere modifications
thereof.
In witness whereof, I, the said John Cooke, have hereunto set my hand and
seal, this Twentieth day of July, in the year of our Lord One thousand
eight hundred and seventy-eight.
JOHN COOKE. (L.S.)