IMPROVEMENTS IN ROTARY ENGINES
Year: 1875

page_text: LETTERS PATENT to John Fraser, of Bombay, British India, but at
present residing at Glasgow, in the County of Lanark, North
Britain, Engineer, for the Invention of "IMPROVEMENTS IN ROTARY
ENGINES."
Sealed the 5th November 1875, and dated the 26th August 1875..
PROVISIONAL SPECIFICATION left by the said John Fraser at the
Office of the Commissioners of Patents, with his Petition, on the
26th August 1875.
I, JOHN FRASER, of Bombay, British India, but at present residing
at Glasgow, in the County of Lanark, North Britain, Engineer, do
hereby declare the nature of the said Invention of "IMPROVEMENTS IN
ROTARY ENGINES," to be as follows, that is to say:
This Invention, which relates to improvements in rotary engines,
consists, under one arrangement, in the employment of one or more
abutment plates of rectangular, circular, or other section sliding from
end to end of the cylinder. On a shaft placed through the interior of

page_text: the cylinder a piston plate is situated extending from the shaft to the
circumference of the cylinder, and by the action of the steam against
which the shaft is caused to revolve and transmit power from the
engine. The abutments are so arranged that when the piston passes a
certain point one abutment slides in immediately behind it and closes a
space at the back of the piston, the said abutment being withdrawn
again through one end of the cylinder when the piston in its revolution
comes up to or near its opposite face. The abutments are operated
backwards and forwards out of and into the cylinder by cams or other
equivalent mechanism, and steam is or may be employed in assisting the
cams to force the abutments into the cylinder immediately after the
piston has passed. The shock of the abutments on arriving at the ends
of their inward strokes is lessened or prevented by cushioning the blow
with compressed air or other suitable means, the requisite mechanism
being provided for that purpose.
The steam for actuating the piston may be admitted to the cylinder
through a valve placed in the piston rod by valves placed in or in
connexion with the abutments, or the said valves may be situated in any
other convenient situation.
Under another modification of the Invention, in lieu of employing
sliding abutments, one or more rotatory abutments are used, and which
are preferably of a circular shape. According to this arrangement the
piston is curved to correspond with the contour of the abutment, and a
slot or slots is or are made in each abutment to allow the piston to pass,
the mechanism being so arranged that accordingly as the piston
approaches or recedes from the position occupied by the abutment so
does the abutment open or close the space through which the piston
passes. A steam tight packing is provided between the abutment and
the piston rod in both of the arrangements set forth.
Any suitable form of abutments other than those herein-before
dèscribed may be employed, it being understood that the Inventor does
not restrict himself to such arrangements.
In order to render the engines constructed in accordance with this
Invention reversible clutch mechanism is provided in connexion with
the main or cam shaft which operates the abutments, and by actuating

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Fraser in the Great Seal Patent Office
on the 24th February 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
FRASER, of Bombay, India, but at present residing at Glasgow, in the
County of Lanark, North Britain, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-sixth day of August, in the
year of our Lord One thousand eight hundred and seventy-five, in the
39th year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Fraser, Her special license
that I, the said John Fraser, my executors, administrators, and
assigns, or such others as I, the said John Fraser, my executors,
administrators, or assigns, should at any time agree with, and
no others, from time to time and at all times thereafter during the
term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVE-
MENTS IN ROTARY ENGINES," upon the condition (amongst others)
that I, the said John Fraser, by an instrument in writing under
my hand and seal, should particularly describe and ascertain the
nature of the said Invention, 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 John Fraser, 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, reference being had to the accompanying Drawings
and to the letters and figures marked thereon, that is to say :-
My said Invention relates to improvements in rotary engines, which
engines can be actuated by either water, steam, compressed air, or other

page_text: elastic fluid. My said Invention is specially adapted for engines in
which the motive power is derived from an elastic fluid, but is also
applicable to water engines.
My said Invention is especially applicable where a large amount of
motive power is wanted, such as in the driving of mills, propelling
steam ships, and other analogous purposes. It can also be applied to
locomotive engines on either tramways, railroads, or common roads, or
to any other purpose where motive power is required. It can also be
used in conjunction with other rotary or reciprocating steam engines,
high pressure, condensing or compound, or it may be worked either
single or coupled high pressure or condensing, as the case may be.
In the ordinary reciprocating engine the piston comes to a dead stop
at each end of its stroke, the motive power being transmitted from the
piston to the shaft through the connecting rod and crank, the greatest
useful duty being done when the crank or piston is on the half centre
or stroke and little or no duty at or near the ends.
Under this Invention, as in some other forms of rotary engines the
cylinder is continuous, a shaft passing through the centre, on which
shaft the piston or pistons is or are so arranged that they transmit the
motive power from themselves to the shaft direct. The cylinder is fitted
with one or more abutments, and these are so arranged as to move
across the path of the piston at the required time. To allow of this
continuous motion of the piston the abutments are withdrawn to let
the piston pass, and immediately after it has done so they are replaced
and the steam or other elastic fluid is admitted to act thereon.
It is evident that with the same piston area the greatest amount of
useful duty done by the reciprocating engine, at or about half stroke,
is done under this arrangement of engine from the commencement to
the end of stroke. The distance travelled by the piston during a
revolution of the crank in the reciprocating engine is two diameters of
the crank's path, while by this Invention a circumference is travelled
by the piston during the same period, or the ratio of distance travelled
is as 1 to 1/2, or nearly so. There are no dead centres to cause shocks
at admission of steam, and therefore a very high initial pressure can
be employed for more expansively working than has hitherto been
used.

page_text: I now proceed more particularly to set forth the system, mode, or
manner in or under which the same is or may be used or practically
carried into effect, reference being had to the annexed Sheet of
Drawings, and to the letters and figures marked thereon, that is to
say:-
On the Sheet of Drawings hereunto appended Figure 1 is an elevation
of one end of the engine, showing the cylinder cover and steam pipe;
Figure 2 is a front elevation, showing one general arrangement of the
engine; Figure 3 is an elevation of the end of the engine opposite to
that shown at Figure 1; Figure 4 is a section of the cylinder showing
the internal steam valve abutments and piston; Figure 5 is a section
on the lines a, b, and c, d, Figures 1 and 4, showing the piston and
cylinder in section, also the cylinder cover and steam valve, together
with the shaft and position and arrangements of the abutments;
Figure 6 shows one half of the cam for actuating the abutments indi-
cating the position of the cam when the bottom abutment is about to be
pulled out; Figure 7 shows the other half or side of the cam indicating
its position when the top abutment is about to be inserted; Figure 8 is
another view of the cam, herein-after more particularly referred to;
Figure 9 is a part general plan showing the piston and abutment in
section; Figure 10 is a side elevation of part of an engine with a
cylinder of circular section, the upper part shows the piston and shaft
in section; and Figure 11 is a sectional elevation of an engine with
three abutments and two pistons, or an engine of same size' as that
shown at Figure 5, but of double the power with the same average
pressure of steam with double the piston area, and with the same
centre of effort as in the other engines.
In Figures 1, 2, and 3 the cylinder is marked A, the boxes B con-
taining the sliding abutments which are operated from the cam C. The
cam C is shown in detail at Figures 6 and 7, and the profile or form
of its groove b is shown projected on the flat or plane at Figure 8.
Steam is admitted to the engine through the steam pipe D at the centre,
and by the internal steam vale X driven by a feather key on the
driving shaft L, as more particularly shown at the sections, Figures
4 and 5. The steam escapes into the cylinder A so as to act upon the
revolving piston E through the ports F in the abutments G, as indicated
by the arrows. The abutments G are provided at each side with abut-
ment rods I, these being by preference formed of square section, as

page_text: shown, so that they may fill and slide in the groove in which the
abutments slide. One rod is provided for each abutment, and to it
the abutment driving links J are coupled, as shown more particularly
at Figures 2 and 3, the other ends of these links being centred on the
brackets Kformed on or attached to the framing or bed plate L'. On
the abutment driving links J stud rollers or slide blocks a are carried
which in working are situated in the groove b in the cam C, shown at
Figures 6, 7, and 8, the inclined portion of the cam gradually pulling
one of the abutments open as the piston is being driven towards it by
the action of the steam between the piston and the other abutment.
The cam also allows each abutment to close with all the rapidity
possible so soon as the piston has passed it, and to permit of this the
cam C is so arranged on the shaft L that immediately the piston passes
the point at other times occupied by the abutments, the straight part
of the cam groove, or that part c where the groove runs parallel to the
longitudinal axis of the shaft L, comes opposite to the stud roller or
slide block a on the driving link J of the abutment which had been last
drawn to allow of the passage of the piston E.
The return of the abutments may be effected either by constituting
the rearward part of the abutment box B a steam cylinder, and making
the corresponding end of the abutments fit the same and be acted upon
with a forward motion by the steam admitted into the abutment box
by a suitable slide or other valve, or a separate steam cylinder connected
to the abutment, or through which the rod of the abutment passes, may
be employed for that purpose. A separate cam with a short travel may
also be used in conjunction with the cam C, and with or without a
steam cylinder; or other equivalent means may be employed to effect
such return of the abutments. After the piston has passed an abutment,
and after that abutment has been returned into the cylinder A, the
steam in that part of the cylinder from which the piston has just passed
is exhausted through a port M in such abutment, and passes into the
exhaust pipe N provided in connection with such port, as shewn at
Figure 9 of the Drawings.
It is preferred to cut off the steam by means of the valve X when the
piston has performed about one half of its stroke between the two
abutments, from which point, and until the piston comes up to the
abutment whose turn it is next to be drawn out, the said piston is
operated by expansion of the steam behind it,

page_text: When the piston is at the position shewn at Figure 4, and the top
abutment G in place, the bottom abutment is not immediately with-
drawn, but is allowed to remain during about one-eighth of a revolution
of the piston E in order to allow of the steam in the space O from
which the piston has just passed to be exhausted, as herein-before set
forth, and so prevent or diminish back pressure on the piston when the
bottom abutment is withdrawn. By so arranging the parts of rotary
engines the steam is caused to act on the piston from the period of its
admission at the beginning of the stroke up to the time that the exhaust
ports M in closing the abutments begin to open from the end of the
trunks or boxes P in which the abutments slide, that is to say, during
nearly one half of a revolution of the engine.
In lieu of making the cylinder rectangular in section, as in the
modification of my said Invention herein-before described, the said
cylinder may be made circular, as shewn at Figure 10, or of other
convenient form in section; and instead of employing two sliding
abutments as herein-before set forth and shewn more particularly at
Figure 4 of the Drawings, three such abutments and one or two pistons
may be used, as illustrated at Figure 11 of the Drawings, or any other
suitable number of such abutments operating either singly, from one
end of the cylinder, or in pairs, from both ends towards the centre of
the cylinder, may be used together with as many revolving pistons as
may be deemed necessary or expedient.
When three abutments are used it is preferred that the action of the
cam C in withdrawing and returning the abutments be assisted by steam
power brought to bear upon such abutments by suitable means.
Instead of employing sliding abutments as herein-before set forth and
shown on the Drawings, abutments arranged either to move through
an arc or to completely rotate may be used to perform the functions
required.
Figure 12 of the Drawings represents one form of abutment arranged
to move through an arc, and which abutment A is situate on a shaft or
axis B placed at right angles or nearly so to the driving shaft C, that is
to say, to the axis of the piston. Under this arrangement, whent it is
necessary to withdraw the abutment in order to allow the piston to pass,
the shaft B is partially rotated, so as to bring the abutment into the
position shown in dotted lines at Figure 12, and the piston having so

page_text: passed the abutment is again moved inwards by partially rotating the
shaft B in the opposite direction, such movement of the said shaft
being effected by any arrangement of. apparatus suitable for that
purpose.
Under another arrangement shown in vertical section at Figure 13
rotating abutments are employed at the upper and under side of the
cylinder A. In these abutments B, holes C are formed, which when it
is required that the piston should pass the space occupied by the
abutment are moved round by the shafts D, so as to come within the
cylinder, and so effect a passage for the piston. The abutments now
under reference may also be arranged to move through an arc only
instead of performing a complete revolution.
The pistons are packed in the cylinders steam-tight by means of
packing rings held in position by springs, steam, set pins, or equivalent
means, and to avoid or lessen the shock consequent upon the sudden
return of the abutments into the cylinder A by the means herein-before
referred to such shock is cushioned by compressed air or by other
equivalent means.
In lieu of supplying steam to the engine through ports in the
abutments, and by a rotating valve, as at X, the ports may be made in
the piston itself, and the steam supplied therethrough; or it may be
supplied by other suitable means, it being understood that I do not
confine myself to arrange the rotary engine precisely in the manner
herein before described, as such engine may with regard to its details be
considerably modified without departing from the essential features of
my said Invention.
In order to render the engine constructed in accordance with my my
said Invention reversible, and thereby adapt it for employment as a
marine engine or for locomotive or other purposes, wherein reversible
engines are used, the cam C, steam valve X, and exhaust M are made
changeable by suitable reversing gear.
.
Having now described and particularly ascertained the nature of my
said Invention, and the system, mode, or manner in or under which
the same is or may be used or practically carried into effect, I would
observe in conclusion that I am aware that both sliding and rotating
abutments have heretofore been used in rotary engines; I do not
therefore claim the employment of such abutments constructed and

page_text: operated otherwise than in the manner set forth, but what I consider to
be novel and original and therefore claim as the Invention secured to
me by the herein-before in part recited Letters Patent is,-
First. The arrangement and construction of rotary engine herein-
before described and shewn on the Sheet of Drawings hereunto appended,
wherein sliding abutments operating as described are employed as and
for the purpose set forth.
Second. The arrangement and construction of rotary engine illustrated
at Figure 11 of the appended Drawings wherein by the employment of
three sliding abutments and two pistons an engine of double the power
with the same average pressure of steam is obtained in equal space as
compared with the engine wherein two sliding abutments and one piston
are used, substantially as herein-before set forth.
Third. The arrangement and construction of rotary engines wherein
abutments moving inwards and outwards to and from the cylinder,
either through an arc or by performing a complete revolution are used,
substantially as and for the purposes herein-before described and shown
at Figures 12 and 13 of the Drawings.
In witness whereof, I, the said John Fraser, have hereunto set
my hand and seal, this Twenty-second day of January, One
thousand eight hundred and seventy-six.
TATTA
TD
243
JOHN FRASER. (L.S.)