IMPROVEMENTS IN ROTARY ENGINES
Year: 1870

page_text: LETTERS PATENT to Richard Dudgeon, of the City of New York,
United States of America, for the Invention of "IMPROVEMENTS IN
ROTARY ENGINES.”
Sealed the 6th September 1870, and dated the 15th July 1870.
COMPLETE SPECIFICATION filed by the said Richard Dudgeon at the
Office of the Commissioners of Patents, with his Petition and
Declaration, on the 15th July 1870, pursuant to the 9th Section of
the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, RICHARD
DUDGEON, of the City of New York, United States of America, send
greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS IN
ROTARY ENGINES," and have petitioned Her most Gracious Majesty Queen
Victoria to grant unto me, my executors, administrators, and assigns,
Her Royal Letters Patent for the same, and have made solemn
Declaration that I am the first and true Inventor thereof.

page_text: NOW KNOW YE, that I, the said Richard Dudgeon, do hereby
declare the nature of the said Invention to be as follows:-
The Invention consists of an engine which is a combination of the
following instrumentalities, viz., two cog wheels geared together, cheek
pieces to close the ends of the spaces between the cog teeth and an
entry port so arranged as to admit steam into the spaces between the
cog teeth at one side of the line connecting the axes of the two cog
wheels. In this combination the aggregate surface of the cog teeth,
upon which the steam can act at the side of the steam port which is
nearer the line drawn through the axes of the wheels, is less than the
aggregate surfaces of the teeth upon which the steam can act at the
side of the steam port which is further from said line, hence the pre-
ponderating pressure of the steam will cause the wheels to turn. As
the wheels turn each pair of cog teeth pass over the steam port in
succession, and act as a valve to close the supply of the steam to the
space between them and the preceding pair of teeth, and to admit steam
to the space between them and the succeeding pair of teeth; moreover,
as the teeth gradually draw out of engagement during their recession from
the steam port the space between the teeth is enlarged and the steam
enclosed in that space is permitted to expand progressively, the expan-
sion being continued until the teeth recede sufficiently to form an
opening, whereupon the steam exhausts.
The Invention consists further of the combination of the said cog
wheels, cheek pieces, and entry port with a second port, the two ports
being arranged at opposite sides of the line drawn through the axes of
the wheels, so that one port may be used to supply steam when the
wheels are run in one direction, and the other port may be used when
the direction of the motion is to be reversed. This combination is
advantageous, because it permits the engine to be readily reversed by
simply shutting off the supply of steam to one steam port, and admitting
the supply to the other port.
The Invention consists, further, of the combination of the said cog
wheels, cheek pieces, and steam port with an external casing to receive
the exhaust steam, so that the said steam may be conducted to an
exhaust pipe, and be thereby discharged in any desired direction.
The Invention may be embodied in various forms, a few of which
are represented. in the accompanying Drawings as illustrations of the

page_text: diversity of form which the Invention may assume without a change
in its principle.
Figure 1 represents a side elevation of one form of rotary engine
embodying the Invention; Figure 2 represents a vertical longitudinal
section of the same; Figure 3 represents a plan of the engine with
certain portions removed. The two cog wheels A, A¹, are secured to
shafts B, B', which are constructed to turn in boxes c, c, formed in the
casing D, one of the shafts B extending sufficiently beyond the casing
to receive a pulley wheel E to which a belt may be applied for the
purpose of transmitting the power. The teeth of the two cog wheels
should be carefully scraped, so as to engage accurately throughout their
whole length, and prevent the passage of steam between their contiguous
faces. The sides of the wheels, as far as the ends of the teeth and the
rims, should be carefully faced off, so that these sides may move steam-
tight against the adjacent faces of the check pieces F, F, which close
the ends of the spaces between the teeth of the wheels. These cheek
pieces F, F, are fitted into sockets formed for the purpose in the
casing D, and are constructed to be pressed against and held in contact
with the adjacent sides of the cog wheels by means of set screws which
are not shewn in the Drawing. One of the cheek pieces is perforated
to form the steam port e, by means of which steam is admitted into the
adjacent space between the teeth of the two cog wheels, the steam being
supplied to this port by means of a steam pipe which leads from the
boiler is connected with the rear side of the port, and is provided with
a throttle valve. The steam port e is arranged to admit the steam into
the said space when it is at one side of the dotted line B, B¹, drawn
through the axes of the two cog wheels, so that the aggregate of the
portions of the surfaces of the cog teeth m, m, upon which the steam
can act at one side of the said space is greater than the aggregate of the
portions of the surfaces of the cog teeth n, n, upon which the steam can
act at the other side of that space. Hence when steam is admitted
into the space between the cog teeth the preponderating pressure upon
the teeth m, m, will cause the wheels to turn in the direction of the
arrow f. As the wheels turn, the space is gradually enlarged by the
recession of the teeth from their engagement, so that the quantity of
steam admitted increases until one of the succeeding set of teeth n passes
over the steam port, and closes it for the first space. The steam which
is now within that space is permitted to expand by the continued
enlargement of the space produced by the turning of the wheels and

page_text: expansion will continue until the teeth at the advancing side of the
space recede sufficiently to form an opening, and permit the steam to
exhaust. Meanwhile the tooth which closed the steam port to the first
space has passed by it sufficiently to open it to the succeeding space
between the teeth; and this space in turn receives a supply of steam
to act in the same manner as the supply to the preceding space. The
steam operating in succession upon all the spaces between the teeth of
the two wheels produces a continuous rotary motion without jar, and
this motion may be transmitted directly to the machinery to be driven
by the belt pulley E and a belt, or by other transmitting mechanism.
In order that the direction of motion of the engine may be reversed a
second steam port e¹ is provided at the side of the line B, B², opposite
that at which the first steam port e is situated. The second port is
supplied with steam by means of a steam pipe connected with it, and
fitted with a throttle valve, hence when the engine is to be reversed the 1
throttle valve of the first steam port is closed, and that of the other is
opened, whereupon motion commences in the direction indicated by the
arrow g in Figure 2.
The form of the engine and the shape of the cog teeth may be varied
to a great extent without changing the principle of the Invention.
Thus, for example, the cog wheels of the engine thus far described are
plain spur wheels with the teeth of both wheels of the ordinary form.
Teeth of different forms are represented in profile in Figure 4, in which
Figure the letters indicate the same parts as the corresponding letters in
the previous Figures.
In the form of engine represented at Figures 5, 6, and 7 the cog
wheels A, A', have conical faces similar to those of the bevilled wheels.
The cheek pieces F, F¹, are of spherical form, the one F convex and the
other F¹ concave, and the teeth are of different dimensions, the teeth /
of one wheel having concave sides and being very broad while the 's
teeth of the other wheel are very narrow. Wheels of this construction
should not have less than eight teeth on each wheel; four only are
represented upon the wheels in the Drawing in order that their forms
may be more clearly seen.
Figure 8 represents a transverse section of another form of engine, a
and Figure 9 represents the arrangement of the teeth in profile. In
this form the two toothed wheels A, A', have bevilled faces and are both
constructed with broad teeth similar to those h of one of the wheels of

page_text: the last preceding engine. As the teeth do not engage with each other
a separate piece H is provided to engage simultaneously in the opposite
cavities between the teeth of the two wheels. This piece H consists of
two wings r, r, which are secured to a bolt 8, so as to change their
relative positions, like the two parts of a hinge. The bolts connects
the piece H with the spherical casing F¹, which forms the cheek piece at
the outer ends of the cog teeth. The steam is supplied in this case by a
steam port e formed in a stationary hub T that surrounds one of the
wheel hubs, and the exhaust takes place through a similar port a formed
in a stationary hub T" surrounding the hub of the other wheel A. The
space between each set of teeth is connected with the steam port by
means of a passage u and with the exhaust port by means of a passage v.
In this case the spherical check piece F revolves with the wheels. The
Drawing, Figure 8, represents a section of the engine taken in a plane
which is at right angles to the plane in which the axes of the two
wheels diverge. In practice it is proposed to use a slide valve operating
against the back face of the cheek piece to reverse the engine, the valve
being so arranged that when it is moved to the greatest extent in either
direction it will open a port at one side of the line joining the
centres of the wheels and close the port at the opposite side of that
line, and when the valve is in its central position both ports will be
closed.
The engine may be used as a condensing engine as well as a high
pressure engine. In the former case the exterior casing may be con-
nected with the condenser or the condenser may be connected by a
pipe with a port formed in one of the cheek pieces at the side of the line
joining the centres of the wheels opposite the side at which the steam
port is arranged.
I also propose to employ the engine as a pump by connecting one or
more of the steam ports in the cheek pieces with the source from which
the water is to be taken.
Having thus described several modes in which the principle of the
Invention may be embodied I declare that I am aware that cog wheels
have been employed in the construction of many rotary engines long
previous to my Invention, and therefore I do not claim them soparately
from the other members which are required to constitute my new com-
binations; but what I claim as the Invention to be secured by Letters.
Patent is, the combination substantially as before set forth of two cog

page_text: wheels, the cheek pieces, and the entry port arranged to admit steam as
described.
I also claim the combination, substantially as before set forth, of
the two cog wheels, the cheek pieces, and two ports arranged as
described.
I also claim the combination, substantially as before set forth, of the
two cog wheels, the cheek pieces, the entry port, and the exterior casing.
In witness whereof, I, the said Richard Dudgeon, have hereunto
set
my hand and seal this 24th day of June, in the year of our
Lord One thousand eight hundred and seventy.