IMPROVEMENTS IN STEAM ENGINES
Year: 1872

page_text: PROVISIONAL SPECIFICATION left by Richard Henry Cotter at the
Office of the Commissioners of Patents, with his Petition, on the
18th December 1872.
I, RICHARD HENRY COTTER, of Trieste, in the Empire of Austria, do
3 hereby declare the nature of the said Invention for "IMPROVEMENTS IN
STEAM ENGINES," to be as follows:-
This Invention relates to certain improvements in the construction
and working of steam engines, a continuous rotary motion being pro-
duced by the presentation of a surface directly connected with an axle
or prime shaft to the continuous action of steam or other pressure, the
reversing movement being obtained by simply shifting a valve.
The surface or "fan" is provided with a boss which is made fast to
the axle, and is surrounded by a cylindrical or spherical casing (which
to obtain strength and lightness may be constructed of ribbed metal)
provided with two main steam ports and passages, through either one of
which (depending upon the required direction of the motion) live steam
is admitted (to one of two circular chambers in the boss, whencé it
passes through one of two ports in the fan) into the interior of the
casing.

page_text: The fan is provided with suitable packing, which presses against
sides of the casing and makes it steam tight.
The boss of the fan is cut away at opposite sides thereof, forming the
above-named circular chambers (two circular rings on the axle forming
the outer walls or sides thereof) and is also cut away or grooved at the
circumferential part thereof, and provided with ports situated so that
when steam enters one of the main passages and through its boss
chamber and port in fan into the casing, the opposite one acts as the
exhaust, and when it enters the other main passage it reverses the
motion of the axle, whilst the first steam port in the fan then acts as
the exhaust; the admission of the steam to either main passage being
regulated by an external valve.
The action of the engine depends mainly upon the working of two
pairs of slides (placed within the casing) which are operated by the
rotation of the axle in such a manner as to open and close alternately;
this may be accomplished by the employment of two excentrics fixed
on the axle at opposite sides of the casing, and which by the pressure of
steam on the fan are caused to revolve therewith and act upon levers
attached to the slides so as to open and close them at the proper intervals,
the slides being if necessary perforated so as to admit steam at their
backs to counteract adverse pressure of steam, or the advance and with-
drawal of the slides may be accomplished by the employment of other
suitable means, or by the action of steam.
The action of the improved engine may be described as follows:-
Steam passes through one of the main ports and passages into its boss
chamber, and enters the casing through its port in the fan, and at the
side thereof, which would cause it to receive a motion (say) from left to
right. Now suppose the casing to be divided vertically and represent a
half circle divided into degrees; also suppose that the upper slides at 0°
are full open, and that the fan is also at 0°, and passing them whilst the
lower slides are at 180° and closed steam tight. When the fan has been
driven about 20° by the steam entering the casing between it and
the lower slides, and is free of the upper slides, the revolution of the
excentrics (or the action of the other means) causes the upper slides to
begin to close in the steam which is propelling the fan, but as the cir-
cumferential part of the boss of the fan now under the slides as above-
mentioned is cut away or grooved the steam passes thereunder (and
through the above-mentioned perforations in the slides) and still has

page_text: access to and acts against the lower slides, whilst the upper ones are
closing, and indeed until the fan has traversed to about 75° or 80°, but
as the fan goes on from about 80° to about 90° or 95°, as the grooved
part emerges at the fan side of the now closed upper slides, and the
ungrooved part or full circumference of the boss presents itself, the
upper slides are thus gradually brought to bear the whole pressure of
steam, and so allows of the further propulsion of the fan.
At about 95° to about 105° the grooved part or aperture of the boss
at the atmosphere side of the fan, and now acting as the exhaust begins
to come under the lower slides, and the enclosed or cut off portion of the
steam rushes out gradually from between the upper and lower slides at
the other side of the half circle and now in communication into the
exhaust aperture and port in the fan and boss, thus causing the lower
slides, to have atmospheric pressure at each side previous to their being
opened to allow of the passage of the fan, and as the said aperture
comes more fully under or upon them it removes the friction of the full
or ungrooved circumference of the boss upon them.
From about 105° to about 110° the lower slides are caused to begin to
open (by the means employed) the steam pressure being entirely off them
and borne by the fan side of the upper slides.
At about 160° the lower slides are completely open and keep so till
the fan has been driven by the pressure of the steam between it and the.
upper slides to about 20° of the other half circle, when the lower slides
begin to close, the action being exactly similar and continuous to that
above described, there being no intermittent motion and no
* dead
points" to overcome.
When employing steam to move the slides in one modification I
enlarge the backs thereof and fit them in steam-tight cylinders or
chambers so as to afford sufficient pressure surface for the steam to act
thereon, and effect the advance or withdrawal thereof at the proper
intervals by admitting the steam to alternate sides of the backs through
ports correspondingly situated in the rings above-mentioned, and which
are provided mainly for counteracting all lateral pressure caused by the
steam entering only one of the circular chambers at a time.
The similar chambers of the opposite slides are placed in communica-

page_text: Or in another modification I effect the same by attaching small
pistons and cylinders to the sides of the slides conveying steam to them
by pipes in the usual way. One of cach pair of slides may be provided
with spring facings in order to make a perfect steam tight joint when
they meet.
It may here be stated that the circular chambers instead of being in
the boss of the fan as above described, may be placed at cither side
thereof, and suitably secured to or form part of the casing, still being
however in communication with the main steam passages with which
the latter is provided. The boss in this case is merely provided with its :
two ports which communicate with the said chambers, and with the
circumferential parts cut away as above described.
It may also be stated that two single slides at opposite sides of the
axle may be employed and actuated by one eccentric precisely as above
instead of their both being in duplicate.
The action of the engine in either case is precisely aliko.
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