IMPROVEMENTS IN ROTARY STEAM ENGINES
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by William Bancroft Espeut at the Office
of the Commissioners of Patents on the 25th August 1882.
WILLIAM BANCROFT ESPEUT of Jamaica West Indies but at present residing at
Cambridge Street Hyde Park in the County of Middlesex "IMPROVEMENTS IN
ROTARY STEAM ENGINES"
My Invention has reference both to the single acting and compound form of
engine
My said Invention consists, first of a circular plate fixed upon the shaft of the
engine and formed with two three or more pockets (in which balls are placed) and
faced against a plane surface of a fixed head or casting formed with a short circular
channel into which the balls are adapted to drop for successively constituting the
piston heads of the engine-the principle of both the single acting and compound
form of the engine
My invention consists further of certain valve mechanism whereby the steam
may be used expansively also of a compound arrangement of the engine, and also
of the construction, arrangement and combination of the parts of the engine, all as
hereinafter more fully described
I will describe the application of my Invention to a compound engine from which
its other applications will be readily understood
There is a high pressure circular plate and a low pressure circular plate-Each
plate is formed with two three or more pockets and in each of these pockets, balls
are placed which fit the said pockets the plates are fixed upon the shaft and are
faced against the opposite plane faces or sides of the fixed hollow casting between
them through which the shaft passes
The low pressure plate is of larger diameter than the high pressure plate and the
pockets therein are larger than the pockets in the high pressure plate, and the balls
are correspondingly larger to fit the pockets and to present a greater area to the
action of the low pressure steam
In the side of the casting between the plates below the passage for the shaft and
the same distance therefrom that the pockets are from the shaft, a curved channel
or channels is or are formed which is or are of a width centrally equal in width to
the diameter of the balls and of a depth in the centre about equal to one half of

page_text: the diameter of the balls, so that as the plate revolves, the channel (or each channel)
will successively receive the balls-For convenience of description I will proceed
with the description of the arrangement as being provided but with one channel
but it will be understood that two or more channels may be used as aforesaid
From the centre, or part of greatest depth, the channel grows gradually shallower
to the ends thereof, so that the balls will pass into, and out of the channel gradually
and without jarring
The steam enters and exhausts from this channel through steam ports and acts
upon the balls as upon piston heads, and causes the plate and shaft to revolve
The side of the casting on the low pressure side is formed with a curved channel
(or channels as aforesaid) which is in all respects similar to the channel on the
other side except that it is larger, to receive the larger balls and is farther from the
shaft
The said channel receives and exhausts steam (by ports as on the other side)
which it receives from the exhaust of the channel on the high pressure side
The steam inlet pipes and the final exhaust pipes and the communicating pipes
or passages from side to side are connected with a valve seat or sleeve in which is
placed a multiple way cock which is operated by a lever for starting stopping and
reversing the Engine
In the steam inlet pipes is fitted a cock which is provided with an operating arm
which reaches over the edge of the high pressure plate and is provided at its outer
end with a weight or with a spring attachment which normally holds the cock
closed-Upon the high pressure plate at its edges between the pockets are secured
plates which are adapted to come successively in contact with the said arm as the
plate revolves for opening the cock at the proper time and permitting the weight
to close it at the proper time so that the steam may be used expansively in the
channel of the high pressure side
The plates for acting upon the said arm are by preference made adjustable by
means of slots and bolts by which they are secured to the high pressure plate so
that they may be set to admit and cut off the steam just at the proper time
or point
Instead of using a six way cock operated by a single lever for admitting, cutting
off and reversing the steam in the Engine, the steam pipes and ports might be
arranged so that two four way cocks could be used for this purpose
In this case
the Engine when made in compound form might be used either as a single or double
acting engine as desired-When used as a single acting Engine, the one side would
act entirely independent of the other side and it will be understood that when my
improved Engine is built as a single acting Engine a single solid upright plate will
take the place of the hollow casting.
The plates may be held against the plane faces of the casting to form a steam
tight joint by nuts screwed upon the shaft
The pockets are so formed in the plates that their outer walls will be slightly
inclined outwardly toward the edges of the plates so that both the gravity of the
balls and the centrifugal action will tend to cause them to readily drop into and
follow the channels when the Engine is in action.
In action when each of the balls pass the inlet port for the steam the steam will
fill the pocket at the back of the ball then in the channel and forces it outwardly
from the pocket forming a practically steam tight joint between it and the walls of
the channel so that it serves the purpose of a piston while the channel serves the
purpose of a steam chest for imparting rotary motion to the plate.
It will be understood that at the time the ball in question passes the inlet port
the preceding ball passes the exhaust port and that at the time the ball in question
passes the exhaust port the succeeding ball will come into action so that the
motion of the plate is continuous.
In the compound form of the engine the exhaust from the channel of the high
pressure side will be into the channel of the low pressure side either through one or
other of two sets of pipes or ways as the case may be. According to the direction of

page_text: movement of the engine in which channel it will act upon the balls of the low
pressure side to cause the plate of the low pressure side to revolve in the same
manner as that in which it acted upon the balls in channel of the high pressure
side-The steam after acting on the low pressure side will exhaust into the final
exhaust pipe
It will of course be readily understood that Engines of the type described may be
driven by water pressure, compressed air or the explosion of gas as well as by
steam. It will be adapted for use as a pump if the plate or plates be driven by
power and the inlets and outlets to and from the channels be made the suction and
delivery of a pump.,