IMPROVEMENTS IN ROTARY ENGINES
Year: 1875

page_text: LETTERS PATENT to Joseph Monteith, of Carstairs, North Britain,
Gentleman, for the Invention of
"IMPROVEMENTS
IN
ROTARY
ENGINES."
Sealed the 26th April 1876, and dated the 28th October 1875.
PROVISIONAL SPECIFICATION left by the said Joseph Monteith at
the Office of the Commissioners of Patents, with his Petition, on
the 28th October, 1875.
I, JOSEPH MONTEITH, of Carstairs, North Britain, Gentleman, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
ROTARY ENGINES," to be as follows :-
My improved rotary engine consists of two or more short curved
cylinders attached transversely to radial arms connected to bosses
which are keyed on to a main central shaft.
The curved cylinders are provided with pistons, the rods of which are
bent to the same curve as the cylinders, and are firmly attached to other

page_text: radial arms connected to bosses mounted loosely on the main shaft.
The ends of the piston arms are bevilled off in order that they may be
enabled to pass spring stops mounted in a framing which surrounds the
working parts. These stops are intended as abutments against which
the piston arms are intended to press during the working of the engines.
The ends of the cylinders are made steam tight, and steam is admitted
into the cylinders in any convenient manner through the arms and
bosses which are made hollow for that purpose.
The working of the engine is as follows:-Let it be supposed that
two cylinders only are used, mounted one in advance of the other on
the main shaft, with piston arms between them, and the engine is being
driven forward. The piston head being at the head of the cylinder, and
the piston arms being pressed back against the stops. Steam is admitted
into one cylinder between the piston head and the head of the cylinder,
the cylinder is thus driven forward a quarter of a circle, and being
keyed on the main shaft causes the same to move round the same
distance. Steam is then admitted in the same manner to the 2nd
cylinder, which drives the chain shaft another quarter circle, at the
same time bringing with it No. 1 cylinder, which carries its piston
round with it one quarter circle. It will now be seen that No. 1
cylinder has made a half circle, but its piston only a quarter circle,
and it is therefore necessary for the piston to overtake the cylinder so as
to be ready for the next stroke. This is effected by admitting a little
steam behind the piston head which drives it forward to the head of
the cylinder and brings the piston arm past the stop ready for the
next stroke of No. 1 cylinder. Thus each cylinder alternately drives
and is driven by the other a quarter of a circle, and a good balance is
obtained.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Joseph Monteith in the Great Scal Patent Office
on the 28th April 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
MONTEITH, of Carstairs, North Britain, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-eighth day of October, in the
year of our Lord One thousand eight hundred and seventy-five, in tho
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Joseph Monteith, Her special
licence that I, the said Joseph Monteith, my executors, administrators,
and assigns, or such others as I, the said Joseph Monteith, my exe-
cutors, administrators, and 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 "IMPROVEMENTS IN
ROTARY ENGINES," upon the condition (amongst others) that I, the said
Joseph Monteith, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, 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 Joseph Monteith, 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 Drawing hereunto
annexed and to the letters and figures marked thereon (that is to
say) :—
-

page_text: The curved cylinders are provided with pistons, the rods of which are
bent to the same curve as the cylinders, and are firmly attached to radial
arms connected to bosses and mounted loosely on the main shaft.
In the accompanying Drawings Fig. 1 is a sectional elevation or front
view of my improved rotary engines; Fig. 2 is a vertical section of the
same. Fig. 3 is a detached view of the curved cylinders with the boss.
Fig. 4 is a plan view of some of the working parts partly in section
and taken in the line 1, 2, of Fig. 1, and Fig. 5 is an end view of the
steam box, showing the inlet and exhaust ports.
A, A', are the curved cylinders connected transversely to the boss B,
which is keyed on to a main central shaft C having its bearings in the
standards D.
a, a', are the pistons, the rods a³, a³, of which are firmly secured to
radial arms b, b', cast on the bosses c, c', which are mounted loosely on
the main shaft C.
The ends of the radial arms b, b', are provided with spring pawls d,
which catch into ratchet teeth or notches e formed in the framing E,
which surrounds the working parts, and which is firmly secured to the
bed plate of the engine. These ratchet teeth or notches e arc intended
to act as abutments, against which the radial arms b, b', through their
pawls d, abut during the working of the engine.
The ends of the cylinders are made steam tight, and steam is admitted
to and released from the cylinders through the boss B, which is provided
with steam ports b², 6, for that purpose.
The working of the engine is as follows:-Let it be supposed that
only two cylinders are used. The piston of one of the cylinders, say A,
see Fig. 1, is at the head of its cylinder, and its radial arm b abuts
against one of the ratchet teeth or notches e, and the engine is thus
ready for the admission of steam. Steam is admitted from the boiler
into the annular space f in the steam box F (see Fig. 2), whence it
passes through openings f¹ into the port in the boss B, and thence
into the cylinder A at g, Fig. 1, between the piston a and the head of
cylinder. As the radial arm b abuts against one of the notches e the
piston a cannot be driven back, and the cylinder A must therefore go
forward say one-sixth of a circle, driving with it the main shaft C the
same distance. Steam is then cut off from cylinder A and admitted to

page_text: cylinder A' with the same effect, each cylinder alternately being driven
by and driving the other and its piston and radial arm one-sixth of a
circle. It will thus be seen that cylinder A will have proceeded a
distance equal to one-third of a circle, but its piston a and the radial
arm 6 will have been driven only a sixth, it will therefore be necessary
to provide means for driving forward the piston a so that it will
overtake the cylinder A. This may be effected by admitting steam
behind the piston a, but the means which I prefer to employ consists of
On the boss c of
an arrangement of gearing shown detached in Fig. 4.
the radial arm b is mouuted a spur wheel 1, which gears into a pinion 2
carried by a stud secured to the boss B. This pinion 2 gears into a
second pinion 3 carried by a second stud, also secured to the boss B, and
into this pinion gears a spur wheel 4 mounted on the boss c¹ of the
radial arm . Thus it will be seen that the forward motion of the
cylinder A one-sixth of a circle will, through the gearing, cause the
radial arm of the piston a' in connection with the cylinder A¹ to
travel one-third or double the distance, thus returning the piston a' to
the head of the cylinder A' ready for the next stroke, the same move-
ment being repeated in regard to the piston a and its adjuncts of the
cylinder A. The exhaust of the steam from the cylinder A is effected
by the movement of the cylinder bringing the steam port & opposite
one of the openings f in the steam box F. If preferred, friction
clutches may be used in place of the spring pawles d, in which case the
ratchet teeth or notches e would be dispensed with.
The steam box F is supported on the main shaft C which rotates
therein, and is provided with means for adjusting the rubbing surface to
the boss B. Any convenient means of effecting this object may be
employed, but I prefer the plan shown in Fig. 2, in which the steam
box F is forced forward by means of the tightening screws h, h, which
pass through a flange keyed on to the main shaft, the outer ends of tho
screws being made to bear against the plate i, i, which revolves in
contact with the back of the steam box F.
Having now described the nature of the said Invention of “ Improve-
ments in Rotary Engines," and having explained the manner of
5 carrying the same into effect, I wish it to be understood that under the
above in part recited Letters Patent, I claim, the mode herein set forth
of constructing rotary engines, the main feature of which consists in

page_text: securing to the central shaft to be driven two or more curved cylinders
provided with suitable pistons having curved rods connected with radial
arms mounted loosely on the main shaft, the several parts being so
arranged that on steam being admitted between the cylinder heads and
the pistons the cylinders will be driven forward a portion of a revolution
while the pistons remain stationary, the said pistons being afterwards
moved forward by gearing, or in any other convenient manner.
In witness whereof, I, the said Joseph Monteith, have hereunto
set my hand and seal this Twenty-seventh day of April, in the
year of our Lord One thousand eight hundred and seventy-
six.