IMPROVE- MENTS IN ROTARY ENGINES
Year: 1881

page_text: LETTERS PATENT to Richard Hodson, of Abbey Road, St. John's Wood, in
the County of Middlesex, Civil Engineer, for an Invention of "IMPROVE-
MENTS IN ROTARY ENGINES."
PROVISIONAL SPECIFICATION left by the said Richard Hodson at the
Office of the Commissioners of Patents on the 9th September 1881.
RICHARD HODSON, of Abbey Road, St. John's Wood, in the County of Middlesex,
Civil Engineer.
"IMPROVEMENTS IN ROTARY ENGINES."
.
This Invention relates to improvements on the rotary engines described in the
Specifications of two Patents, granted to me and dated respectively December 22nd,
1875, No. 4458, and August 24th, 1877, No. 3224, the object of the Invention
being to make my improved rotary engines reversible without the assistance of
bevil or other gearing.
To effect this object I introduce into as many of the piston compartments of my
engine as I may think necessary a second clack or abutment valve, the tail end of
which faces in the opposite direction to the original valve, and between these
valves in the circumference of the cylinder I place the exhaust passage. In order
that this passage may take up as little space in the circumference of the cylinder
as possible, and yet there shall be sufficient length of port to insure the steam_
exhausting previous to the piston lifting the clack valve then in operation, I form
in the side next the piston of each valve a wide recess, which is in communication
with the exhaust passage, so that when the piston has passed the valve a certain
distance the steam will commence to escape through the recess in the valve into
the exhaust passage of the cylinder; or instead of the exhaust passage in the
circumference of the cylinder I may, in order to enable me to bring the clack valves
nearer together, exhaust through a port made in the circular or binge portion of
the clack valve, suitable arrangements being made at either end of the cylinder to
carry off the exhaust steam.
At the back of each clack valve or in any other convenient position I provide a
steam casing to contain an oscillating or rotary steam valve, which may be worked

page_text: by an excentric, levers, or wheels; or in each casing I may place an arrangement
of double valve for cutting off at various grades of expansion, such as that described
in the Specification of my Patent, No. 3224, before referred to. Steam is admitted
to the valve casing by means of a suitable slide valve or cock.
It will thus be obvious that if I admit steam into the one casing, and shut it
from the other, the piston will be caused to work continuously in the one direction,
and vice versa.
Instead of providing an independant steam casing and oscillating valve for each
clack, I may use only one casing and one oscillating main steam valve. In this
arrangement I form under the oscillating valve a steam passage for each clack
valve, and I so arrange the port in the oscillating valve that by sliding this valve
forward or backward longitudinally upon its seating in any convenient manner I
am enabled to open either steam passage at will, the valve itself acting as a cover
to one passage while admitting steam to the other. In order that the oscillating
valve should have the lead and cut off suitable to each motion of the piston, I
provide suitable stops.between the excentric and shaft, so that the relative position
of the excentric with either piston may be altered. It will be evident that the
oscillating valve will if desired form a cover over both passages to the cylinder,
thus acting so as to entirely shut off the steam.
Where pistons of large diameter are required I prefer to use stops to prevent the
clack valves from coming quite down on to the smallest diameter of the piston;
thus friction will be reduced by taking off the rubbing pressure of the clack valve
from the piston during a great part of its rotation. In this case a suitable
adjustable packing in the clack valve must be provided to fill up the space between
the face of the clack valve and the piston. Instead of reducing the friction on the
piston as above described; I remove from one or both ends of the piston a circular
portion. The centre of this circular portion will correspond to the centre of the
hole bored for the shaft, and the diameter will be twice the distance from this
centre to the smallest radius of the piston. Into the recess thus formed and
mounted loosely on the shaft is placed a disc, which rotates independently of the
piston. When the clack valve is forced down on to the piston's smallest diameter
it will, instead of rubbing upon the entire surface of the piston's width as hereto-
fore, press only upon the disc, which, being loose on the shaft, leaves the piston
practically free to rotate without friction on its surface; or I make the clack valves
almost equilibrium valves by forming a wing on the hinge portion of each valve at
-a-suitable-angle. This wing is arranged to work steam tight in a recess in the
cylinder and leading to the exhaust passage. A passage controlled by the oscillating-
valve is formed between the recess and the steam casing, so that when steam is
admitted to the clack valve it will also be admitted into the recess, and act on
the wing. I thereby obtain a considerable reduction in the pressure of steam
on the clack valve.
I do not confine myself to any given number of pistons placed upon a shaft in
one engine, nor to their being set at any given angle, nor do I confine myself
to the cylinders or compartments in one engine being of the same diameter
throughout.
For high and low pressure engines where one compartment or cylinder exhausts
into another I prefer that the low pressure cylinder should be of the largest
dismotan

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Richard Hodson in the Great Seal Patent Office on the 9th March
1882.
RICHARD HODSON, of Abbey Road, St. John's Wood, in the County of Middlesex,
Civil Engineer. "IMPROVEMENTS IN ROTARY ENGINES."
The object of this Invention is to produce a reversible rotary engine especially
suitable for use in steam ships, where reversal of the direction of rotation is
frequently required for backing and manoeuvring the vessel, and which is also well
adapted for locomotives.
In carrying out this object I adopt the construction of engine patented by me
August Twenty fourth, One thousand eight hundred and seventy seven, No. 3224,
having the cylinder divided up into two compartments by a transverse partition
wall, and fitted in each compartment with a rotating piston, such pistons being
secured to one common shaft and working against a hinged abutment valve.
In this engine an oscillating valve is provided for closing the steam supply ports,
and thereby regulating the supply of steam to the cylinder.
I now propose to make this valve control additional steam ports by giving it an
endway motion, so as to admit steam by the additional ports to the front of the
pistons, and thereby reverse their direction of rotation. For this purpose I provide
also additional abutment valves acting in an opposite direction to the original
valves, such additional valves coming into action when the others are thrown out
of action.
I also propose, by the use of a second oscillating valve acting in conjunction
with the reversing valve, to cut the steam at any desired point of the stroke, and
thus, besides converting the rotary engine into a reversing engine, to make it work
expansively.
In Sheets I. and II. of the accompanying Drawings I have shewn in several
views the simplest form of my improved reversing rotary engine. Fig. 1, Sheet I.,
is a side elevation of the engine, the cover of the steam chest being removed to
show the steam valve therein; Fig. 2 is a longitudinal central section of the engine.
In Sheet II. Fig. 3 is a transverse section of the engine taken in the line 1, 2, of
Figures 1 and 2; Fig. 4 is a transverse section taken in the line 3, 4, of the same
Figures; and Fig. 5 is a transverse section taken in the line 5, (i, of the same
Figures; Fig. 6 is a view of the steam chest, representing four ports, which lead
two to one compartment and two to another compartment of the cylinder, the
engine in this example being provided only with two compartments, and conse-
quently two pistons; and Fig. 7 is a similar view of the valve chest, its valve being.
in place.
.
A is the steam cylinder divided with two chambers or compartments 1, 2, by a
diaphragm or partition B. C, C, are two cam pistons feather-keyed on the shaft D,
one on each side of the wall or partition B. B1, B2, are covers which form the
ends of the chambers and in which the shaft D rotates in phosphor bronze bearings.
The ends of the pistons C and C¹ work steam tight against the covers and the
partition wall, their tightness being maintained by suitable metallic surfaces kept
in contact by the steam pressure, and similar provision is made for maintaining
steam tight contact between the pistons and the inner periphery of the cylinder.
In recesses slotted in the respective chambers 1, 2, lie the hinged abutment valves
E and E* one pair in each chamber, which are recessed on their face for the
purpose to be hereafter explained, and are packed at their ends like the pistons to
make them steam tight.

page_text: When the valves E are open to the pressure of the steam, which occurs while
the engine is rotating in the direction of the arrows, the valves E* are closed, there
being no steam admitted to them; but when it is desired to reverse the engine the
steam is cut off from the valves E and admitted to the valves E*, which being
thereby opened will cause a reversal of the direction of rotation of the engine.
The valves E, E*, it will be seen are placed near together and back to back, and
between these valves is situate the eduction or exhaust port F, which leads to the
exhaust pipe G. The eduction passages from the two compartments 1 and 2 meet
in a cross passage F*, in communication with which is the pipe G. H is the steam
chest in which is bored perfectly true a semi-circular seating to receive the oscil-
lating valve I, which serves to control four steam inlet passages L, L', and M, M³,
which supply steam to the cylinder A, the passages L, L', being open to the valve
chest H when the direction of rotation required is that of the arrows, and the
passages M, M', being open to the valve chest H when the reverse direction takes
place. This oscillating valve I is carried by a squared rod I, and is free to slide
endwise thereon. This valve rod receives a rocking motion through its arm. I², to
which is connected the rod K¹ of an excentric strap surrounding the excentric K
on the shaft D. Into a recess in the back of the oscillating valve projects a clip N
carried by a slide N¹ which moves in guides formed in the cover H¹ of the
steam chest. From the slide outside the steam chest projects a pin N³, to which
is connected the slotted end of a hand lever O pivotted to a bracket standing up
from the cover of the steam chest.
Keyed to the pivot pin of the rock lever O is a bevil wheel O', into which gears
a bevil pinion O2 for the purpose of transmitting an axial motion to a four way
plug cock P, which cocks serves, when it is desired to reverse the direction of
motion of the engine to put either the steam passages L, L', or M, M', into com-
munication with the exhaust passage F. The pinion O2 is keyed on a short shaft,
which carries a slotted arm 0³, furnished with an adjustable pin. The pin of this
arm enters a slot in an arm P¹ fixed to the plug cock P. When therefore the hand
lever is moved to traverse the valve I through the slide and clip before
mentioned for the reversal of the engine, the cock P will be simultaneously turned
to bring the now closed ports into communication with the exhaust passages F,
and thereby to relieve the closed abutment valves E, E, as the case may be, of
the back pressure of steam. On referring to Fig. 6 the disposition of the four
ports L, L, and M, M', of the steam chest will be clearly seen.
The ports--Lenter-directly_one_into_each_chamber behind their respective
abutment valves E, and the two ports M, M', after extending around nearly one
third of the cylinder, open one into each chamber behind their respective abutment
valves E. In the oscillating valve I are two ports i, i, (see Fig. 7) set so as to
correspond with either the ports L, L', or the ports M, M. By sliding therefore
this valve end wise on its rod I, it will admit steam to the cylinder either through
L, L', or M, M¹, as desired, or if shifted to a central position it will admit no steam
through either set of ports.
These ports connect by the passages P2 with the seat of the plug cock P, and
by means of passages P³ this scat is brought into connection with the exhaust
passage F*.
The action of the engine is as follows:--
When going ahead, as indicated by the arrows, steam is admitted to the
passage L, L, and so soon as the largest radius of the piston of each compartment
has passed over the abutment valve E, steam will enter the chamber and drive
round the piston, but before the piston opens to-the-exhaust, the steam will be cut
off by the valve I actuated by the excentric K as already explained. The recess c
cast in the abutment valves provides an escape for the steam (when the piston is
at, say, y), which passing the piston escapes by the port F and thence through the
pipe G. The pressure of the entering steam on the back of the abutment valve E
keeps it tight up to the piston, while the valve E lies back in the recess, as shewn,
and for the time being forms part of the cylinder. To reverse the engine, the

page_text: oscillating valve I is slidden along by means of the hand lever O from the position
shewn in Fig. 1, to the position shewn in Fig. 7, so that the steam is admitted
through the ports M, M, the ports L, L', being now closed. The abutment
valves E now come into action, the steam pressure keeping them tightly up to
their pistons, while the valves E being relieved from pressure fall back into their
recesses and form part of the cylinder. At the moment of reversing the engine a
communication is opened between the ports L, L', and the exhaust ports F, as
already explained, for the purpose of relieving the abutment valves E from back
pressure.
The diagrams in Sheet II. are each drawn to correspond with the positions of
the engine in their adjacent Figures, and illustrate more clearly the action of the
oscillating sliding valve I in respect to the movements of the rotating piston.
Thus at Fig. 3a, where the piston is at its dead point, that is, over the exhaust port,
the valve I has cut off the supply of steam, and will require a considerable back
inovement before the supply of steam is renewed. At this time the piston in the
adjoining compartment is moving forward under the full action of the steam.
In diagram, Fig. 4a, the piston has moved forward one quarter of a circle and
steam is again acting upon it, the valve having partially opened the steam supply
port.
In diagram, Fig. 5ª, the piston has moved forward three quarters of a circle, and
the valve I has commenced to close the steam supply port. These diagrams
illustrate the action of the engine, whether working in the direction of the arrows
or the reverse, the endway motion of the valve to bring into use the second set of
steam ports making no change in the character of the diagram.
Where pistons of large diameter are required, I prefer to use stops to prevent the
abutment valves from coming quite down on to the smallest diameter of the piston,
thus friction will be reduced by taking off the rubbing pressure of the abutment
valve from the piston during a great part of its rotation. In this case a suitable
adjustable packing in the abutinent valve must be provided to fill up the space
between the face of the abutment valve and the piston.
Sheets III. and IV illustrate an arrangement of expansion engine whereby the
steam can be cut off at any part of the rotation between wand y of Figures 3, 4,
and 5; Fig. 8, Sheet III., shews the reversing expansion engine in side elevation,
the cover of the steam chest being removed to show the arrangement of cut-off
valves therein; Figures 9 to 15, inclusive, Sheet III., illustrate the working of the
valves in the steam chest, and Figures 16, 17, and 18, Sheet IV., show in face view
the arrangement of the ports in the valve chest and of the ports in the oscillating
valves, the relative positions longitudinally of the valves varying in each Figure to
correspond with Figures 13, 14, and 15. The cutting off of the steam at any part
of the rotation of the piston is effected by having the ports in the valve seating
cut on the incline, as shewn in Sheet IV.
At Fig. 18, Sheet IV., the valve seat is shewn in face view and in transverse
section. The valve chest is fitted with two separate oscillating valves I and I*,
working one over the other. These two valves are carried by a divided spindle I¹,
to the two parts of which independent rocking motions are given from a pair of
excentrics K, K*, on the piston shaft D. The valve I is in this instance made fast
to its spindle, and the valve I* while rocked by its spindle is free to slide endwise
thereon as in the preceding arrangement. The mode of connecting the ends of the
divided valve spindle with their respective excentrics is precisely similar to that
described above.
In the valve I (shewn detached at Figures 18b, Sheet IV.) are cut four ports 1, 1,
m, m¹, inclining two to the right and two to the left, corresponding to those on the
valve seating, but these ports, it will be seen, are not all in line, and thus contrast
with the ports in the valve seating, which ports all range in a line. In the
reversing valve I*, shewn detached at Figures 18°, and which is also capable of
acting as a stop valve, are cut two elongated ports i*, i*, inclining towards cach
other at an angle corresponding to the angle of the ports in the valve I.

page_text: I have said that the valve I has simply a rocking motion, but that the valve I*
has the rocking and longitudinal motions imparted to the valve in the first
described arrangement. The different positions of this valve determine whether
the steam shall enter the ports M, M, or L, L, and afford a means of stopping
the engine or of working the engine either ahead or astern with any grade of
expansion.
These functions of the valve I will be clearly understood by reference to the
Figures in Sheets III. and IV. Fig. 9 shews the piston at its dead point, and the
steam cut off from the cylinder by the action of both valves I and I*; Fig. 10
shews the piston to have rotated one quarter, and the valve I as admitting steam
to the cylinder, the advance of the valve I* having been accelerated to gain the
position for acting expansively.
Fig. 11 shews the piston to have completed one half a rotation, and the valve I*
to have just closed the port in the valve I, thereby leaving the steam in the
cylinder to act expansively; Fig. 12 shows the piston to have completed three
quarters of a rotation, and the valve I to be closing the steam inlet to the cylinder,
the valve I having followed up the movements of the valve I to prevent the
passage of steam from the steam chest.
Figures 13 and 14 shew different relative positions of the valves I and I* at
their starting point to suit different degrees of expansion from that provided for
by Fig. 9, and Fig. 15 shews the valve I* as set in a position to reverse the
direction of rotation of the engine. This is more clearly illustrated in the face
view, Fig. 18. The relative endway positions of the valves in Figures 13 and 14
are similarly better illustrated in the face view, Figures 16 and 17, which shew
the amount of endway motion that has been imparted to the sliding valve I*. I
would remark that as it is necessary to give the excentric of the valve I* a start in
advance of the excentric K in whichever direction the engine is working, the
excentric Kis mounted loosely on the shaft and is worked by means of a recessed
driver keyed upon the shaft, and receiving in its recess a stud projecting from the
side of the excentric.
A. modification of my improved reversing engine is shewn in Sheet V., where
instead of giving the oscillating valve an endway motion for reversing, two oscil-
lating valves, nounted each on a separate steam chest, but having no endway motion,
are used, the advantage being that the passages from the steam chest for the
steam used in backing the engine are materially contracted in length. Fig. 19 is
-a-longitudinal-elevation_of_this_engine, and Fig. 20 is a transverse section of the
same. I, I, are the oscillating valves, as in the first arrangement, but now working
in steam chests H at opposite sides of the cylinder A. Leading to these steam
chests are the steam passages H2 which are controlled by a valve H3 which is used
for cutting off steam from one or other of the passages H according to the direction
in which it is desired to drive the engine. This valve is rocked to reverse its
position by means of a handle attached to the spindle of the valve. The valves I
are each actuated by an excentric K on the shaft D, but although oscillating during
the whole time that the engine is at work, their movements will only be efficient
when steam is allowed to pass by the valve H³ to their respective steam chests.
The valves I, it will be understood on reference to Fig. 19, instead of having ports
cut therein are recessed at their opposite edges to open and close alternately the
ports which they control, which ports are so arranged that steam will be admitted
at different times to the two compartments to suit the varied positions on the
shaft D of the pistons contained therein. The valve H³ serves only to direct the
course of the steam to the right or left hand steam chest, but also to regulate the
supply of steain thereto and to cut off steam from the engine.
It will be obvious that some provision is required for releasing the back pressure
of steam when reversing the engine. If thought desirable an expansion valve may
be adapted to the cut off valve I, which is used when the engine is going ahead.
I would remark that I do not confine myself to any given number of compart-
ments in the cylinder of my engine, nor consequently to a pair of pistons placed

page_text: upon a shaft in one engine, or the angle at which they may be set on the
shaft, nor do I confine myself to the cylinders or compartments in one engine,
being of the same diameter throughout.
For compound or high and low pressure engines where one compartment or
cylinder exhausts into another, I prefer that the low pressure cylinder should be
of the largest diameter.
Having now set forth the nature of my Invention and explained the manner of
carrying the same into effect, I wish it to be understood that under the above in
part recited Letters Patent I claim,―
First. The arrangement of parts above described with reference to Sheets I.
and II. of the Drawings for reversing the direction of motion of the rotary engine,
such arrangement consisting in providing each compartment of the cylinder with
a pair of abutment valves and a double set of steam induction passages, which
passages are controlled by an oscillating valve capable of receiving an endway
motion on its seat, and are when the reversing takes place brought alternately into
communication with the exhaust passage by means of a plug cock actuated by the
reversing gear.
Secondly. In combination with the reversing valve which has an oscillating
and is capable of receiving an endway motion, a second oscillating valve forming
the seat for the reversing valve and controlling the steam ports for the purpose of
cutting off the steam at any required part of the stroke, as described with reference
to Sheets III, and IV. of the Drawings.
Thirdly. The modification above described with reference to Sheet V. of the
Drawings, in which the reversing of the engine is effected by the aid of a pair of
oscillating valves working in separate steam chests, and controlled as above set
forth.
In witness whereof, I, the said Richard Hodson, have hereunto set my hand
and seal, the Seventh day of March, in the year of our Lord One thousand
eight hundred and eighty two.
R. HODSON. (L.S.)