IMPROVEMENTS IN ROTARY ENGINES
Year: 1870

page_text: LETTERS PATENT to Thomas Graham, of Green Mount Street,
Beeston Hill, Leeds, in the County of York, Mechanical Engineer,
and Thomas Dixon, of Leek Terrace, Hunslet, near Leeds, afore-
said, Blacksmith, for the Invention of "IMPROVEMENTS IN ROTARY
ENGINES."
PROVISIONAL SPECIFICATION left by the said Thomas Graham and
Thomas Dixon at the Office of the Commissioners of Patents,
with their Petition, on the 22nd June 1870.
We, THOMAS GRAHAM, of Green Mount Street, Beeston Hill, Leeds,
in the County of York, Mechanical Engineer, and THOMAS DIXON,
of Leek Terrace, Hunslet, near Leeds, aforesaid, Blacksmith, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN ROTARY
ENGINES," to be as follows:
-:
In constructing a rotary engine according to our Invention we
employ a steam cylinder fitted with a piston and piston rod as in an
ordinary reciprocating steam engine. The cylinder is mounted at one

page_text: end on axes supported in suitable bearings, and the cross head of the
piston works in guides carried by this end of the cylinder. On the cross
head are carried rollers which bear against a continuous cam surface
fixed to the framing of the engine around the axis which carries the
cylinder. The cam surface forms a continuous incline to and from
the axis which carries the cylinder for the rollers to bear against, and as
the rollers are drawn or pressed against this incline they cause the
cylinder to turn round with its axis. The cam surface is by preference
so made that as the rollers carried by the cross head approach the axis,
and consequently as the leverage decreases, the incline of the cam
surface shall increase; this produces a cam somewhat of a heart shape.
Two rollers may be employed to bear against two opposite points of such
a cam, or the cam may have corresponding external and internal surfaces,
and one roller be caused to bear against the interior whilst the other bears
against the exterior surface. One of the axes which carry the cylinder
forms the driving or main axis of the engine, the other has ports formed
in it and passages leading to the two ends of the cylinder and forms a
rotary valve by which steam can be alternately admitted to and allowed
to escape from the two opposite ends of the cylinder. In place of the
cross head carrying rollers to bear against a continuous cam surface it
might carry two toothed racks to come on two opposite sides of a fixed
wheel which has teeth around one-half of its circumference, so that as
the piston together with racks carried by it moves endwise to and fro
the racks roll around the partially toothed wheel, each one in turn
gearing with the teeth, and so the cylinder is similarly caused to revolve
continuously.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Graham and Thomas Dixon in the
Great Seal Patent Office on the 22nd December 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, THOMAS 30
GRAHAM, of Green Mount Street, Beeston Hill, Leeds, in the County.
of York, Mechanical Engineer, and THOMAS DIXON, of Leek Terrace,
Hunslet, near Leeds, aforesaid, Blacksmith, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-second day of June, in the 31

page_text: year of our Lord One thousand eight hundred and seventy, in the
thirty-fourth year of Her reign, did, for Herself, Her heirs and suc-
'cessors, give and grant unto us, the said Thomas Graham and Thomas
Dixon, Her special license that we, the said Thomas Graham and
Thomas Dixon, our executors, administrators, and assigns, or such others
as we, the said Thomas Graham and Thomas Dixon, our 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
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 we, the said
Thomas Graham and Thomas Dixon, our executors, or administrators,
by an instrument in writing under our or their hands and seals, or
under the hand and seal of one of us or them, 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 we, the said Thomas Graham and Thomas
Dixon, do hereby declare the nature of the said Invention, and in
what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement thereof, that is to
say:-
In constructing a rotary engine according to our Invention we employ
a steam cylinder fitted with a piston and piston rod, as in an ordinary
reciprocating steam engine. The cylinder is mounted at one end ou
axes supported in suitable bearings, and the cross head of the piston
works in guides carried by this end of the cylinder. On the cross head-
are carried rollers which bear against a continuous cam surface fixed to
the framing of the engine around the axis which carries the cylinder:.
The cam surface forms a continuous incline to and from the axis.
which carries the cylinder for the rollers to bear against, and as the
rollers are drawn or pressed against this incline they cause the cylinder:
to turn round with its axis. The cam surface is by preference approxi-
mately so made that as the rollers carried by the eross head approach,
the axis, and consequently as the leverage decreases, the incline of the
cam surface shall increase; this produces a cam somewhat of a heart-

page_text: shape. Two rollers may be employed to bear against the two opposite
points of such a cam or the cam may have corresponding external and
internal surfaces, and one roller be caused to bear against the interior
whilst the other bears against the exterior surface. One of the axes
which carry the cylinder forms the driving or main axis of the engine;
the other has ports formed in it and passages leading to the two ends of
the cylinder, and forms a rotary valve by which steam can be alternately
admitted to and allowed to escape from the two opposite ends of the
cylinder. In place of the cross head carrying rollers to bear against a
continuous cam surface it might carry two toothed racks to come on two
opposite sides of a fixed wheel which has teeth around one-half of its
circumference, so that as the piston together with racks carried by it
moves endwise to and fro the racks roll around the partially toothed
wheel, each one in turn gearing with the teeth, and so the cylinder is
similarly caused to revolve continuously.

page_text: forms a rotary valve for putting each port alternately in communication
with the steam supply and exhaust. If the engine is required to work
in one direction only we prefer to form the valve in the manner shewn
on an enlarged scale at Figures 3; if the engine is required to work in
either direction then we prefer to adapt to the rotary valve a reversing
slide valve in the manner shewn at Figure 4. The manner in which
these valves are constructed is clearly shewn by the Drawing, so that it
is unnecessary to describe them in detail. In place of a single wheel at
each end of the cross head being received between an inner and outer
cam surface, as shewn by the Drawings, each end of the cross head may,
as before stated, carry two rollers to work against the interior and
exterior surfaces of one cam.
At Figure 5 we have shewn a diagram view of a rotary engine similar
to that above described, except that the cross head in place of carrying
rollers to work against cam surfaces carries at each of its ends, as
herein-before described, two toothed racks H, H, to come on two
opposite sides of a fixed wheel K which has teeth around one-half of its
circumference, so that the racks shall ultimately come into gear with
the teeth of the wheel and roll around its circumference as the piston
moves in and out of the cylinder.
Having thus described the nature of our Invention, and the manner
of performing the same, we would have it understood that what we
claim is,―
1. The construction of rotary engines substantially as herein described
and illustrated at Figures 1 and 2 of the Drawings hereunto annexed.
2. The construction of rotary engines substantially as herein described
and illustrated at Figure 4 of the Drawings hereunto annexed.
In witness whereof, we, the said Thomas Graham and Thomas
Dixon, have hereunto set our hands and seals, this 19th day of
December, in the year of our Lord One thousand eight hundred
and seventy.
THOMAS GRAHAM. (L.S.)
THOMAS DIXON.
(L.S.)