IMPROVEMENTS IN ROTARY ENGINES
Year: 1875

page_text: LETTERS PATENT to Richard Hodson, of the Thames Iron Works
Company, Limited, Blackwall, in the County of Middlesex, Civil
Engineer,
for the Invention
ነሰ
IMPROVEMENTS IN
ROTARY ENGINES.
Sealed the 20th June 1876, and dated the 22nd December 1875.
PROVISIONAL SPECIFICATION left by the said Richard Hodson at the
Office of the Commissioners of Patents, with his Petition, on the
22nd December 1875.
I, RICHARD HODSON, of the Thames Iron Works Company, Limited,
Blackwall, in the County of Middlesex, Civil Engineer, do hereby
déclare the nature of the said Invention for "IMPROVEMENTS IN ROTARY
ENGINES," to be as follows:-
The object of my Invention is to construct a rotary engine in a cheap
and simple manner, which may be driven at a high rate of speed by
means of steam, compressed air, or water, and in which the working
parts are so few that the friction, which is the great cause of failure in
so many rotary engines, is greatly reduced.

page_text: In carrying out my Invention I cast the steam cylinder and steam
chest in one, coreing out the inlet and exhaust passages. The ends of
the cylinder are closed by caps, which form the bearings for the main
shaft, on which are keyed two cam-shaped pistons. The steam cylinder
is bored perfectly true from end to end of the castings, and to enable it to
receive the two pistons it is divided transversely by a central partition.
Before inserting this partition I slot out a recess in the casting from end
to end thereof to receive two clack valves, which form abutments to the
two pistons. The admission of steam into the two compartments thus
formed is regulated by an oscillating valve placed in the steam chest,
mounted on a rod having its bearings in the ends of the steam chest ;
this valve alternately opens and closes the inlet passages to the two
compartments.
The required amount of oscillation is given to the valve by means of
an excentric on the main shaft, and connected with the valve rod by a
strap and arm; or the required oscillation may be given to the valve in
any other convenient manner.
The pistons are mounted on the main shaft in such a manner that
before the exhaust passage of one piston is opened the other piston is
brought in action. By this means the dead point is overcome.
Broad grooves are cut in the backs of the pistons to serve as auxiliary
exhaust passages, whereby the steam is allowed to escape to the front
side of the piston, and thus equalize the pressure.
:
1
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Richard Hodson in the Great Seal Patent Office on 2
the 22nd June 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, RICHARD
HODSON, of the Thames Iron Works Company, Limited, Blackwall, in
the County of Middlesex, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her 3
Letters Patent, bearing date the Twenty-second day of December, in the
year of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-

page_text: cessors, give and grant unto me, the said Richard Hodson, Her special
licence that J, the said Richard Hodson, my executors, administrators,
and assigns, or such others as I, the said Richard Hodson, my 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 I, the said
Richard Hodson, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should par-
ticularly 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 Richard Hodson, 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)
The object of my Invention is to construct in a cheap and simple
manner a rotary engine, which may be driven at a high rate of speed by
means of steam, compressed air, or water, and in which the working
parts are so few that the friction (usually the great cause of failure in so
many rotary engines) is greatly reduced.
In carrying out my Invention I cast the steam cylinder and steam
chest in one piece, the inlet and exhaust passages being made in the
casting by means of suitable cores. The ends of the cylinder are closed
by caps or covers, which form the bearings for the main shaft, on which
are keyed two cam-shaped pistons. The steam cylinder is bored perfectly
true from end to end of the casting, and to enable it to receive the two
pistons it is divided transversely by a central partition. Before inserting
this partition I form a recess in the casting from end to end thereof
in order to receive two clack valves, which form abutments to the two
pistons. The admission of steam into the two compartments thus formed
is regulated by an oscillating valve placed in the steam chest, and

page_text: ་
mounted on a rod having its bearing in the ends of the steam chest.;
this valve alternately opens and closes the inlet passages to the two
compartments of the cylinder.
The required amount of oscillation is given to the valve by means of
an excentric on the main shaft, and connected with the valve rod by a
strap and arm; or the required oscillation may be given to the valve in
any other convenient manner.
In the accompanying Drawing Fig. 1 is a transverse section of my
improved rotary engine taken in the line 1, 2, of Fig. 2, which is a
longitudinal section of the engine; Fig. 3 is a plan view of the same;
Fig. 4 is an end elevation, and Figures 5, 6, and 7 are respectively a
plan view, front edge view, and section of the clack valves.
A is the steam cylinder; B, the steam chest, these two parts being
cast in one piece; C and D are the inlet and exhaust passages respec-
tively, which are produced by coreing out the casting; E, E, are the
caps or covers which close the ends of the steam cylinder and form
bearings for the main shaft F, as shewn best in Fig. 2; on this shaft are
mounted two cam-shaped pistons G. The steam cylinder is bored
`perfectly true from end to end of the casting, and it is divided trans-
versely by the partition H so as to form two compartments or chambers, a
one for each piston. Before inserting this partition I bore a hole tho
whole length of the casting to serve as a socket to receive the cylindrical
part 6 of the clack valves I; I then cut out or form the recess a, also from
end to end of the casting, to form a valve chamber to receive the two
. clack valves I, which form abutments to the two pistons G; the central
partition H is then inserted in the cylinder, and the clack valves I are
then slipped into their separate chambers a, and the end caps or
covers E, E, are bolted or otherwise secured to the main casting.
Steam is admitted into the steam chest B through an opening in the
cover E, Fig. 2, and passes thence through the inlet passages C into the
steam cylinders. The admission of steam to the steam cylinders is regu-
lated by the oscillating valve K, placed in the steam chest B, and
mounted on the valve rod c, which has its bearings in the ends of the
steam chest; this valve as it oscillates alternately opens and closes the
inlet passages to the two compartments, and may be so arranged that
the steam may be cut off at any portion of the stroke, so that the engine
may be made to work expansively.
:

page_text: The requisite amount of oscillation is given to the valve K by means
of an excentric d, Figures 2 and 4, mounted on the main shaft F, and
connected by a strap and arm f (see Fig. 4) to a short lever e, which is
slotted for the purpose of regulating or adjusting the cut off, and is
keyed on to the end of the valve rod c; or the required oscillation may
be given to the valve K in any other convenient manner.
'
The requisite amount of oscillation is given to the valve K by means
of an excentric d, Figures 2 and 4, mounted on the main shaft F, and
connected by a strap and arm ƒ (see Fig. 4) to a short lever e, which is
slotted for the purpose of regulating or adjusting the cut off, and is
keyed on to the end of the valve rod c; or the required oscillation may
be given to the valve Ķ in any other convenient manner.
The exhaust passages D are so arranged that before the exhaust
passage of one piston is opened the other piston is brought into action.
By this means the dead point is overcome.
The clack valve which I prefer to use is that shown at Figures 5, 6,
and 7, and is formed in three parts, the centre part being bevilled off on
both sides, as shewn, to fit against the bevilled inner edges of the two
outside parts. By constructing the valve in this manner the centre part
will act as a wedge to force the outside parts outward against the sides
of the valve chambers; thus I am enabled to dispense with all packing,
as all the edges of the pieces soon wear true, and form a thoroughly
steam-tight valve.
In order to prevent the clack valves from rattling, and also to keep
them always bearing against the surface of the pistons, I employ a small
piston h of any convenient form, which bears against the upper side of
the central part of the valve I. This piston' projects into the steam
chest B, and as there is always a pressure of steam in this chamber, the
pistons are always kept forcibly pressed against the steam pistons G in
the cylinder A.
h
In order to lubricate the various parts of the engine I place in the
steam chest a short tube i, into which oil or other lubricant is introduced
through an opening in the cap or cover E¹. This tube is pierced at two
or more places, so that the lubricant can run through on to the parts
that require lubricating.
The operation of the several parts is as follows:-Steam being
admitted into the steam chest B, passes from thence through one of the
inlet passages C into the cylinder, and forces one of the pistons G round
in the direction of the arrows into the dotted position shown at Fig. 1.
By this time the second piston will be coming into action, and its inlet
passage C will be opened by the oscillation of the valve K, while at the
same time the inlet passage of the first piston will be closed, and the