IMPROVEMENTS IN ROTATORY ENGINES
Year: 1863

page_text: PROVISIONAL SPECIFICATION left by John Henry Johnson at the
Office of the Commissioners of Patents, with his Petition, on tho
9th May 1863. A communication from abroad by Enrico Fava, of
Gênes, in the Kingdom of Italy.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
of Middlesex, Gentleman, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN ROTATORY ENGINES," a communication from
Enrico Fava, of Gênes, in the Kingdom of Italy, to be as follows:-
This Invention relates to a peculiar construction and arrangement of
rotatory engine, and consists in the employment of two pistons each filling
about one quarter of the annular steam space surrounding the main shaft
inside the cylinder. These pistons work loose upon the main shaft, but
are cach connected by a long collar or boss with a disc outside the cylinder,
on the periphery of which are formed two ratchet teeth or notches on
diametrically opposito sides of the disc which take into a fixed detent
or stop, the object of this detent being to prevent the rotation of the
disc and its corresponding piston in other than one direction. The steam
is admitted into the cylinder between the contiguous faces of the two
pistons (which are always at the completion of each stroke nearly close
together) by means of two distinct ports or passages made longitudinally in
the shaft, each communicating with a transverse passage passing diametrically
through the shaft from side to side. At the steam inlet extremity of the
main shaft there is a disc which answers as an oxpansion valve, being provided
with an opening which exposes only one of the two longitudinal passages at
a time, but, as the shaft rotates, it follows that each passage is open alternately.

page_text: In front of this disc there is a steam chest, into which the steam is conducted
by a steam pipe from the boiler; close to cach of the notched discs herein-
before referred to there is keyed on to the main shaft another notched disc,
and into this latter engages a pall carried by each of the notched discs first
referred to, which are connected direct to the loose pistons. The steam enters
the cylinder between the faces of the two pistons, and tends to separate them
in opposite directions, but as one of them is prevented from rotating in a
backward direction by the detent or stop above referred to, the other alone is
free to rotate, and describes a half revolution. During its semi-revolution it
carries round with it through the disc and connecting pall the main shaft,
whereupon the second steam passage is opened and steam again enters, but by
the second of the transverse ports between the contiguous faces of the pistons
and forces round the piston, which was previously hold stationary, whilst that
which has last operated is held in turn by its detent, and prevented from
rotating backwards. The shaft is thus carried round continuously by a series
of half revolutions of the two pistons acting alternately upon it in one and the
same direction. The exhaust takes place through ports in the cylinder, which
are uncovered at the proper times by the rotation of the pistons. By making
the disc or valvo which regulates the supply of steam to the cylinder, so as to
open or close the parts sooner or later in the revolution of the shaft the engine
may be worked expansively.