IMPROVEMENTS IN STEAM AND OTHER FLUID PRESSURE ENGINES
Year: 1886

page_text: Date of Application, 4th Dec., 1886.
Complete Left, 5th Sept., 1887.
Complete Accepted, 7th Oct., 1887
I ARTHUR FORBES SCOTT, of Oak Leigh, Bradford, in the County of York,
Engineer, do hereby declare the nature of this invention for IMPROVEMENTS IN STEAM
AND OTHER FLUID PRESSURE ENGINES to be as follows:-
This invention relates to novel and useful improvements in steam engines, and
other motors, designed to run at a high speed, and worked by fluid pressure; and its
object is to provide an engine capable of working quietly, and economically, at a high
speed, with few working parts.
The said improvements consist in employing a constant pressure at one side of the
piston and so arranging ports in connection with a valve outside the cylinder that the
Huid creating such pressure is at certain periods of the stroke admitted to the other
side of the piston and cut off when desired by such piston.
These improvements are equally applicable to horizontal, and other classes of
engines, but are hereinafter described as applied to steam engines having cylinders of
the inverted vertical type.
To apply my improvements to a simple single cylinder engine the steam is admitted
at the top of the cylinder so as to exert a continuous pressure on the top of the piston.
The cylinder is provided with a port, or passage at or below the middle of the stroke
communicating with a valve box fitted with a valve preferably of the piston type,
operated by a single eccentric, or its equivelant, on the crank shaft. The said valve
box is also provided with ports communicating with the bottom of the cylinder and
with the exhaust; and the valve working therein is so arranged that when the piston
approaches the bottom of its stroke the ports above and below the said piston are put
in communication; thus permitting steam to pass from above to below the piston.
The steam continues to pass in this manner during part of the up stroke until it is cut
off by the piston covering the top port, the exact point of cut off being determined by
the position of such port. Or if it be desired to vary the cut off a circular piece with
inclined edge may be fitted on the top of the piston, capable of being operated by hand,
or connected to a suitable governor. After the steam is cut off below the piston it
continues to expand as the piston rises to the top of the stroke, when the valve is
arranged to connect the port at the bottom of the cylinder with the exhaust, and the
steam from the underside of the piston passes away, or into a condenser. On the
piston again approaching the bottom of its stroke the exhaust is closed, shortly after
which the communication is again opened between the top and underside of the piston,
allowing the steam to pass in the above described manner.
All the. working parts are in constant thrust. On the up stroke the pressure above
the piston relative to that below it increases after cut off. This pressure overcomes the

page_text: momentum of the moving parts and prevents the connecting rod from leaving its crank
at a high speed. A fly wheel secures uniformity of rotation.
When two cylinders are employed the steam which is admitted constantly to the top
side of cach piston. The said cylinders are preferably placed side by side, with the
valve box between them. A piston valve in three parts is preferably employed,
operated by one eccentric on the shaft, the cranks of which are diametrically opposite.
The two cylinders are each constructed and arranged to work similar to the single
cylinder above described. The middle portion of the valve practically dividing the
valve into two the upper half of which is arranged to control the passage of the steam
to and from the underside of one of the pistons, and the lower half similarly
controlling the passage of the steam to and from the underside of the piston in the
other cylinder.
In the above described arrangement the steam is admitted to, and exhausted from,
the underside of the pistons by the same port but a separate exhaust port may be used.
In which case the steam is preferably arranged to pass over the top part of the valve
to the underside of one piston and between the top and middle part of the valve to the
underside of the other piston, the space between the middle and bottom parts of
the valve being arranged to alternately connect the exhaust ports with the exhaust.
To apply my improvements to compound engines when it is desired to have a cut
off in both cylinders, the various parts are preferably arranged as follows.
The
cylinders are placed side by side working on oposite cranks. A valve in three parts
works between them and the high pressure cylinder which is similar to the ones
already described exhausts into the low pressure cylinder at its upper end through
the top and middle parts of the valve. The steam passes from here by a port through
the middle and bottom parts of the valve to the underside of the piston, until the
piston rising closes this port. The steam below the piston expands to the top of the
stroke, and is then exhausted by the lower part of the valve, while the steam above is
compressed into a receiver and forces the piston down on the return stroke.
In a compound engine in which a cut off is only required in the high pressure
cylinder, I arrange the cylinders as last described, and the valve is similarly traversed
by a single eccentric on a double crank shaft, the cranks of which are opposite. A
piston valve in two parts is preferably used and the steam is exhausted froin below the
high pressure cylinder between the two parts of the valve onto both sides of the low
pressure piston during a certain part of the up stroke of such piston, until the piston
rising above the port in the side of the cylinder the admission of steam above the
piston is prevented. Steam continues to pass into the low pressure cylinder below
such piston until near the top of the stroke, and when at the top the steam below
it is exhausted through the two parts of the valve and the steam above having been
meanwhile compressed into a receiver or space above the piston, now forces the piston
down again.
A high and low pressure cylinder may be arranged on the "tandem" principle, with
a cut off in either one, or both, cylinders. The valves and steam passages being
arranged in a somewhat similar manner to the compound engines last described.
More than two cylinders may also be employed together, either independently
supplied with steam, or the steam expanded from one to the other, on the principles
already described.
It is obvious that various modifications of the above described arrangements may
be employed without departing from the principle of my invention, and that
other types of valves may be used, and if necessary connected with reversing
mechanism.
Piston valves are preferably employed, to enable a downward pressure to be exerted
upon them.
DRACUP & NOWELL,
Bradford, Agents.

page_text: COMPLETE SPECIFICATION.
Improvements in Steam and other Fluid Pressure Engines.
I, ARTHUR FORBES SCOTT, of 27, Welbury Drive, Bradford, in the County of
York, Engineer, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and by
the following statement:-
This invention relates to novel and useful improvements in steam engines and other
motors designed to run at a high speed and worked by fluid pressure. And the
object of the said invention is to provide an engine capable of working quietly and
economically at a high speed with few working parts.
The said improvements consist in employing a constant pressure at one side of the
piston and so arranging ports in connection with a valve outside the cylinder that the
fluid creating such pressure is at certain periods of the stroke admitted to the other
side of the piston and cut off when desired by such piston.
My improvements are equally applicable to horizontal and other classes of engines
but are herein after described as applied to steam engines having cylinders of the
inverted vertical type.
In order to fully describe my invention reference is to be had to the accompanying
drawings forming a part of this specification, in which similar letters of reference
indicate corresponding parts in all the figures.
Figure 1 represents a vertical section of a single cylinder engine constructed in
accordance with my invention. Figures 2 and 3 are similar sections illustrating two
methods of applying my invention to compound engines. And Figures 4 and 5
represent vertical sections of "tandem" engines with my improvements applied
thereto.
In figure 1 the steam is admitted by the passage A at the top of the cylinder B so
as to maintain a continuous pressure upon the top of the piston C. port or
passage D is formed at or about the middle of the cylinder communicating with the
interior of the valve box E which is fitted with a piston valve F connected to the
eccentric G on the crank shaft H by the rod I. The valve box E is also provided
with a port J communicating with the bottom of the cylinder and also with an
exhaust port K.
The ring 2 on the valve F when the engine is in the position represented in figure 1,
is rising and uncovering the port J thereby placing the underside of the piston in
communication with the exhaust K until the piston approaches the bottom of the
stroke, when the exhaust is closed and the ring 2 having descended below J steami
passes from the top to below the piston by means of the ports D and J. The steam
continues to pass in this manner during part of the up stroke until it is cut off by the
piston rising above the point at which the port D enters the cylinder side. After the
steam is cut off by the piston it expands below until the top of the stroke is reached
when the underside of the piston is again placed in communication with the exhaust.

page_text: As a constant pressure of steam is maintained at the top of the piston, while beneath
the pressure is reduced by expansion during a certain part of the up stroke all the
working parts are in constant thrust and so knocking" is prevented when running
at a high speed. The fly wheel L insures uniform rotation.
When two cylinders are employed the steam is admitted constantly to the top side
of each piston.
The said cylinders are preferably placed side by side with the valve
box between them. A piston valve with three rings is preferable employed operated
by one eccentric or its equivalent on the crank shaft the cranks of which are
diametrically opposite. The two cylinders are each constructed and arranged to work
in a similar manner to the single cylinder above described.
In the compound engine illustrated by figure 2. The high pressure cylinder B is
similar to the simple cylinder above described. It has not been deemed necessary to
show the means of actuating the valve or the crank shaft, the cranks of which are
opposite.
J
The valve F has three rings respectively numbered 1, 2, 3, and the steam exhausts
from beneath the high pressure cylinder B into the receiver O above the low pressure
cylinder P. In the position shown the valve F is rising and ring 1 is uncovering the
port and connecting it with R so that steam is at liberty to pass from beneath the
high pressure cylinder into the receiver O. At the same time ring 2 uncovers
the port S and puts it in communication with port T which allows steam to pass from
the upper to the lower side of the low pressure piston U until such piston cuts off the
supply by passing above S. And during the remainder of the up stroke the steam
beneath the piston U expands while the steam from below the high pressure piston C
continues to exhaust into the receiver O. At the top of the stroke of the piston U the
steam beneath it is exhausted by the ring 3 of the valve F descending and connecting
the port T with the exhaust K. Ring 1 on the valve is at the same time connecting
the ports D and J and steam again passes from the upper to the lower side of the
piston C. The port R being closed the steam in the receiver O forces down the
piston U, and the high pressure piston rises above 1 and cuts off the supply of
steam to the underside.
Figure 3 illustrates a modification of figure 2 in which the steam is distributed to
the high pressure cylinder B in a similar manner and to the low pressure cylinder as
now described. In the position shown ring 1 of the valve F is uncovering J and
connecting it with both S and T, thus allowing steam to pass from beneath the
piston C to both sides of the low pressuro piston U until such piston rises above S.
The steam above U is then compressed to some extent in the receiver O while below
it continues to enter from the high pressure cylinder until near the top of the stroke,
there is therefore a continuous downward thrust to prevent "knocking "when running
at high speeds. At the top of the stroke of the piston U the valve descends and
ring 2 connects the port T with the exhaust K whilst the pressure in the receiver O
forces the said piston down.
At
Referring to the "tanden" engine illustrated by figure 4. Ring 1 of the valve F
controls the supply of steam to the high pressure cylinder B, and in the position
shown is uncovering the port J so that the steam from beneath the piston C can pass
through J and R to the top of the low pressure piston U. At the bottom of the
stroke the ring 2 descends below the port S and the steam above U passes below by the
ports R and S during the up stroke and remains at about the terminal pressure.
the top of the stroke ring 2 connects S with the exhaust K so that during the down
stroke the steam is exhausted from beneath U. By this means the temperature of the
upper side of the piston U is not reduced to the temperature of the exhaust or
condenser and so waste by condensation is prevented. The steam may however be
exhausted direct from the upper side of the low pressure piston during the up stroke
or it may be passed to the underside of the piston, in which case the underside is in
permanent connection with the exhaust.
Figure 5 illustrates a modification of the engine last described in which a space is
provided at the top of the low pressure cylinder for the reception of the exhaust steam
from beneath the high pressure piston arranged somewhat similarly to the receiver

page_text: described in connection with figure 2. As in the engines above described steam is
admitted constantly at A. The pistons are shown at the top of the stroke and the
valve ring 1 is uncovering the port J and allowing steam to pass to the receiver
above the piston U by means of the ports J and R. The underside of the piston U
is at the same time connected with the exhaust K by the valve ring 3 uncovering the
port T.
At the bottom of the stroke the valve descends and ring 1 connects D and J.
Thus the pistons and U have respectively their upper and lower sides connected and
in both cases such connections are cut off by the pistons rising above the ports D
and S. The steam beneath the two pistons then expands until the top of the stroke
when the exhaust takes place as described.
In figure Lan arrangement is illustrated for regulating the point at which the steam
to the underside of the piston is cut off by closing the port D.
The attachment a is secured to the top of the piston in such a manner that it is
capable of being rotated by the square bar which passes through a square central
hole in the cross piece attached to a into an axial hole in the piston rod formed for
its reception. The end of the rod is round at the part passing through the stuffing
box c on the cylinder cover and the outer end is provided with a lever d for the
purpose of rotating the said rod and attachment. One side of the attachment a is
arranged to fit closely against the cylinder side and its upper edge e is inclined, thus
by turning the said attachment the part of the incline e coming opposite the port Dis
changed therefore such port is closed sooner or later according to the direction the
attachment is turned. This arrangement, though only shown in figure 1, may be
fitted to any of the engines herein described.
It is obvious that various modifications of the above described arrangements may be
employed without departing from the nature of my invention, and that more than two
cylinders may be employed together and the steam expanded from one to the other in
a somewhat similar manner to the compound engines above described. And also that
other forms of valves may be used, but piston valves are preferably employed in order
that a downward pressure may be maintained upon them and so prevent knocking.”
Having now particularly described and ascertained the nature of my said Invention,
and in what manner the same is to be performed, 1 declare what I claim is:
::
a constant
1. In a steam or other fluid pressure engine, the construction and arrangement of
a cylinder provided with an admission passage at one end permitting
pressure to be maintained at that side of the piston, in combination with suitable ports
and a valve outside the cylinder adapted to allow the steam or other fluid to pass
during the first part of one stroke to the other side of said piston and be cut off by
such piston and at the return stroke to place that side of the same in communication
with the exhaust, substantially as herein shown and described.
2. In a compound engine, the combination with a high pressure cylinder constructed
and arranged substantially the same as the one represented in figure 1, of a low
pressure cylinder provided with a receiver at one side of the piston adapted for the
reception of the exhaust fluid from the high pressure cylinder and to permit the full
pressure in such receiver to be constantly maintained at that side of the piston and
having ports in connection with a valve outside the cylinder arranged to allow the
steam or other fluid to pass from the receiver to the other side of the piston during
the first part of one stroke and be cut off by such piston and at the return stroke to
place that side of such piston in communication with the exhaust, substantially as
herein described and illustrated in figures 2 and 5.
3. In a compound engine, the combination with a high pressure cylinder constructed
and arranged substantially the same as the one represented in figure 1, of a low
pressure cylinder with a receiver at one end the pressure in which is permanently
maintained at that side of the piston, and provided with ports in connection with a
valve outside such cylinder adapted to pass the exhaust fluid during the first part of
one stroke from the high pressure cylinder into the said receiver and also during the
said stroke to the other side of the piston and during the return stroke to place such

page_text: side of the piston in communication with the exhaust substantially as herein
described and illustrated in figure 2.
4. In a compound engine of the "tandem" type, the combination with a high
pressure cylinder constructed and arranged substantially as the one illustrated in
figure 1, of a low pressure cylinder provided with ports in connection with a valve
outside the cylinder adapted to convey the exhaust fluid from the high pressure
cylinder to one side of the low pressure piston and during the return stroke to pass
such fluid into the exhaust or to the other side of the piston which is either
permanently or intermittently in communication with the exhaust, substantially as
herein described and illustrated in figure 4.
5. In a steam or other fluid pressure engine having a port or ports controlled by
the piston and by a valve outside the cylinder, of an inclined attachment to said
piston capable of being operated from the outside and adapted to regulate the point at
which the said port or ports are covered by the piston, substantially as herein shown
and described.