IMPROVE- MENTS IN ROTATORY ENGINES
Year: 1863

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, Gentleman, for the Invention of "IMPROVE-
MENTS IN ROTATORY ENGINES." -A communication from abroad by Enrico
Fava, of Gênes, in the Kingdom of Italy.
COMPLETE SPECIFICATION filed by the said John Henry Johnson at the
Office of the Commissioners of Patents, with his Petition and Declaration,
on the 18th November 1863, pursuant to the 9th Section of the Patent
Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS IN
ROTATORY ENGINES," and have petitioned Her Majesty to grant unto me, my
executors, administrators, and assigns, Her Royal Letters Patent for the
same, and have made solemn Declaration that the said Invention is communi-
cated to me from abroad by Enrico Fava, of Gênes, in the Kingdom of
Italy.
NOW KNOW YE, that I, the said John Henry Johnson, do hereby declare
that the following Complete Specification under my hand and seal fully
describes and ascertains the nature of the said Invention, and in what manner
the same is to be performed, in and by the following statement:-
The said Invention consists of a peculiar construction and arrangement of

page_text: rotatory expansion engine, which is illustrated by the accompanying Sheet of
Drawings.
Figures 1 and 2 represent respectively a side and end elevation of the
improved rotatory expansion engine; Figure 3 is a longitudinal vertical
section of the same taken through the centre of the main shaft; Figure 4 is
a sectional detail of the driving shaft, pistons, and steam passages; Figure 5
is a transverse section of the cylinder and working pistons; Figure 6 is an
elevation of the arrangement of apparatus for transmitting the rotatory motion
of the pistons to the main shaft; and Figure 7 is an elevation of the valve or
diaphragm employed in the distribution of the steam. The same letters of
reference indicate corresponding parts throughout all these Figures.
A is the cylinder, and B, b, the two pistons working therein, but loose upon
the main shaft G; m is the main driving shaft, along the interior of which the
distribution of the steam in the cylinder is accomplished, as herein-after more
fully explained; D, D', are two ratchet wheels connected with the pistons B, b,
respectively, which transmit alternately the motion of the pistons to the main
shaft through the notched discs H, H', which are keyed on to that shaft; F is
the inlet for the steam; X, the valve chamber; S, the outlet for the exhaust;
and g, a metal diaphragm or disc having an eccentric opening c, c, made
therein. The steam first enters at F into the chamber X; into the front part
or end of this chamber is fitted the diaphragm or disc g, the aperture c, c, of
which serves for the passage of the steam, air, or other medium employed into
the main shaft G, m. In the interior of this shaft are made two longitudinal
passages or steamways h and i, which correspond with four other openings or
passages 1, 1, 0, 0, made through the sides of the main shaft transversely at
right angles to each other. The extremity m of the shaft is in contact with
the diaphragm or disc g, and by reason of the coincidence of the opening c, c,
with the passage h, as shown in the Drawing, the steam enters that passage
and issues through the corresponding openings 0, 0, in the side of the shaft,
and enters the interior of the cylinder A between the adjoining faces of the
two pistons B, b. The pressure of the steam tends to cause both the pistons
to revolve in opposite directions, but the piston B being held stationary by
means of the stop or detent y acting against a notch y' in the ratchet wheel D
to which that piston is fixed, cannot turn in a backward direction, and conse-
quently the pressure of the steam exerted against the opposite piston b causes
that piston to rotate in the direction of the arrow in Figure 5, and to carry
round with it the main shaft G, m. The piston and shaft describe a semi-
revolution, and turn both together by reason of the pall q', which is fixed to
the ratchet wheel D₁ engaging into a notch in the disc II', which is keyed on

page_text: to the main shaft itself. Each piston is connected with or made in one piece,
with one of these ratchet wheels D and D', and each ratchet wheel is provided
with palls q, q', which act upon notches in a separate dise H, II', keyed on to
the main shaft, motion being transmitted to such shaft through each ratchet
wheel and disc alternately. After having described a semi-revolution the
piston assumes the position indicated by the dotted lines in Figure 5, being
again brought nearly into contact with the face of the piston B. The steam
then enters between the two pistons, the exhaust taking place through the
port S during the semi-revolution of the piston b. By reason of the moving
together of the piston 6 and the shaft G, m, it follows that the passage h in
the shaft becomes closed by the diaphragm or disc g, whilst on the contrary
the passage i in the same shaft is brought by the revolution of that shaft
opposite to the opening c, c, of the diaphragm or dise, and allows of the free
passage of the steam along the passage or port i, and out by the cross ports
1, 1, into the cylinder A. The action of the piston b already described is now
followed by the piston B, whilst the piston is in its turn held stationary by
the stop or detent y, as herein-before described. The entrance of the steam
into the passages or steam-ways h and i alternately produces, as is shown, an
alternate rotatory motion of the two pistons and a continuous rotatory motion
of the main shaft. By suitably adjusting the position of the eccentric opening
c, c, in the disc or diaphragm g by means of the handle g¹ on the spindle of
the diaphragm, any degree of expansion may obviously be obtained, or if
preferred, the expansion may be fixed at any given point.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried
into effect, I would observe in conclusion, that 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, the peculiar construction and
arrangement of rotatory expansion engine, as herein-before described and
illustrated by the Figures on the annexed Sheet of Drawings.
In witness whereof, I, the said John Henry Johnson, have hereunto set
my hand and seal, this Eighteenth day of November, One thousand
eight hundred and sixty-three.
J. HENRY JOHNSON. (L.S.)