IMPROVEMENTS IN STEAM ENGIN ES.
Year: 1862

page_text: LETTERS PATENT to Thomas Scott, of Nelson Square, in the County of
Surrey, Engineer, for the Invention of "IMPROVEMENTS IN STEAM ENGIN ES.
PROVISIONAL SPECIFICATION left by the said Thomas Scott at the Office
of the Commissioners of Patents, with his Petition, on the 11th January
1862.
I, THOMAS SCOTT, of Nelson Square, in the County of Surrey, Engineer, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN STEAM
ENGINES," to be as follows:-
My Invention consists of new arrangements hereafter described of combined
or high and low pressure cylinder engines, also of a new parallel motion to
be used in steam engines.
I place my cylinders one over the other, that is, the small or high-pressure
cylinder over the large cylinder, or I place them side by side according to the
work the engines are intended to perform, that is, whether they are to be
horizontal or vertical. The large cylinder is furnished with two piston rods,
united by a cross head, and this cross head, by links, to one end of an oscillating
beam. The high-pressure cylinder has one piston rod only, and this, through a
connecting rod and parallel motion to be hereafter described, is connected to
the opposite end of the oscillating beam. The ports or passages for the steani
are from top to top or from bottom to bottom of the cylinders, and while the

page_text: piston rod of the high-pressure cylinder is proceeding in one direction, the
piston rods of the large cylinder move in the opposite direction, and cause: the
beam to oscillate. The main connecting rod to the crank shaft is attached at
one end to the cross head, and the power from the high-pressure cylinder is
transmitted through the oscillating beam and links, and through the cross head
to the main connecting rod.
My parallel motion for maintaining the parallelism of the piston rod of the
high-pressure cylinder, applicable to other similar cases in steam engines is as
follows: The piston rod head is connected by a connecting rod to the end of
the oscillating beam, then to the lower end of the piston rod head. I secure a
guide bar connected at its opposite end to the top of a curved slide, the lower
end of which works on a quadrant bed fixed between the two cheeks of.the
oscillating beam.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Scott in the Great Seal Patent Office on the 11th
July 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
SCOTT, of Nelson Square, in the County of Surrey, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day of January, in the year of our Lord
One thousand eight hundred and sixty-two, in the twenty-fifth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Thomas Scott, Her special licence that I, the said Thomas Scott, my
executors, administrators, and assigns, or such others as I, 'the said Thomas
Scott, 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 STEAM ENGINES,"
upon the condition (amongst others) that I, the said Thomas Scott, my
executors or administrators, by an instrument in writing under my, or their,
or one of their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be per-
formed, 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.

page_text: NOW KNOW YE, that I, the said Thomas Scott, 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
thereof, reference being had to the Drawings hereunto annexed, that is to
say:-
My Invention consists of new arrangements hereafter described of eombined
or high and low pressure cylinder engines...
I place my. cylinders one over the other, that is, the small or high-pressure
cylinder over the large cylinder,.or I place them side by side, according to the
work the engines are intended to perform, that is, whether they are to be
horizontal or vertical. The large cylinder is furnished with two piston rods
united by a cross head, and this cross head by links to one end of an oscillating
beam. The high-pressure cylinder has one piston rod only, and this through
a connecting rod and parallel motion is connected to the opposite end of the
oscillating beam. The ports or passages for the steam are from top to top or
from bottom to bottom of the cylinders, and while the piston rod of the high-
pressure cylinder is proceeding in one direction, the piston rods of the large
cylinder move in the opposite direction, and cause the beam to vibrate or
oscillate. The main connecting rod to the crank shaft is attached to the centre
of the cross head, and the power from the high-pressure cylinder is transmitted
through the oscillating beam and links, and through the cross head. to the
main connecting rod.
In horizontal engines I, by preference, place the high-pressure or smaller
cylinder over the low-pressure or larger cylinder.
In engines where the cylinders are vertical they stand side by side. In
constructing horizontal engines, according to-my Invention, the two cylinders
are placed adjacent to each other, with their axes parallel, and the high-pressure
cylinder on the top of the low pressure. The piston of the lower, or low-
pressure cylinder, is furnished with two piston rods,, connected together. by a
cross head, and the piston of the upper cylinder with one piston rod. The
cross head of the lower cylinder and the piston rod of the upper are coupled by
links, or connecting rods to the opposite ends of a beam or lever, which has its
fulcrum between its two ends. The main connecting rod that transmits the
power from the pistons to the crank, takes hold of the cross head above
named of the lower cylinder and connects it with the crank shaft,. which
may be placed either between the cross head and the cylinder, as in. steeple.
engines or beyond the cross head, as in ordinary horizontal engines..
The valves, ports,. passages,. pistons, and other parts of my engines are
constructed in the ordinary manner, steam jackets to. the cylinders. and

page_text: surface condensers are easily applicable to my engines, and by preference I
use them.
The accompanying Drawings illustrate the manner in which the Invention
may be carried into effect. Figure 1 is an end elevation; Figure 2 is a side
elevation, and Figure 3 is a plan. A is the small or high-pressure cylinder;
B is the large or low-pressure cylinder; C is the slide jacket common to both
cylinders; D is the steam pipe; E is the exhaust passage; F is the condenser ;
G is the connecting rod of small or high-pressure cylinder; H is the beam or
lever; I, I, are the connecting rods or links; K is the main connecting rod;
L, L, are the piston rods of large cylinders; M is the piston rod guide of small
cylinders; N is the framing for crank shaft and vibrating beam; O is the
stay to small cylinders; P is the cross head for piston rods. Figure 4 is a
section of the slide valve I prefer to employ in constructing my engines, the
action is as follows:-On steam being admitted into the slide jacket C, and
the slide valve being in the position to admit the steam behind the piston of
small or upper cylinder A, the piston impelling with it the beam or lever H,
in the direction indicated by the arrow, thereby causes the piston of the lower
cylinder to move in the opposite direction, as indicated by the arrow S, at the
same time the main connecting rod K communicating motion to the crank
shaft; when the piston of the upper cylinder A has reached the termination of
its stroke, the exhaust port is opened and the stream that actuated the motion
of the piston A, is now allowed to expand into the lower cylinder B, and the
pressure upon its piston causes it to move in the direction of the arrow r, fresh
steam at the same time entering the upper cylinder A, and urging the piston
back again towards the arrow S. When the piston of the cylinder B reaches
the termination of its stroke at the arrow r, the exhaust valve opens and allows
the steam to escape into the condenser, at the same time the steam that was
urging the piston A, is allowed to get on the other side of the piston of the.
cylinder B, and fresh steam is admitted to reverse the motion of the piston in
cylinder, thus the effect both of the high-pressure steam in cylinder A, and
the low pressure expanding steam in cylinder B, is made to give motion
through the medium of the lever H, and through the connecting rod to the
crank shaft, the pistons of the respective cylinders moving at the same time in
opposite directions. An advantage gained by this arrangement is that the
steam passages between the high and low pressure cylinders are made very
short as compared with those of high and low pressure engines constructed
in the usual manner, for in them the pistons move in the same direction, and
consequently the steam from one end of the high-pressure cylinder has to be
conveyed to the opposite end of the low-pressure cylinder, for example in a

page_text: vertical engine the steam acting on the top of the high-pressure piston, has to
be conveyed to the bottom of the low-pressure cylinder to act underneath its
piston, long passages being thus required which involve great loss of useful
effect, by the condensation of the steam and otherwise. Thus engines
constructed according to my Invention produce greater power from a given
quantity of steam than engines constructed in the ordinary manner by obviating
the loss in the long passages from one cylinder to the other. I also obtain a
compact and strong arrangement, at the same time permitting a ready access
to the working parts of the engine; and in horizontal engines applied to
driving screw propellers, I obtain a more easy motion than usual, when the
whole energy
of the steam at one time acts in one direction.
And having now described the nature of my said Invention, and in what
manner the same is to be performed, I declare that I do not limit myself to the
precise arrangement of parts herein-before described, as such must be varied
to suit the particular description of engine to which my Invention is applied,
and I lay no claim to the employment of high and low pressure cylinders,
placed underneath and connected to the main lever of a beam engine, even on
the opposite side of the centre, neither do I claim the employment of pistons
moving in opposite directions, by connecting their piston rods to opposite
cranks on the same shaft; but I claim as my "Improvements in Steam
Engines."
First, connecting the piston rods of high and low pressure engines to the
opposite ends of a vibrating beam or lever, whereby the said rods are caused
to move in opposite directions, at one and the same time, substantially in
manner herein-before described and illustrated in the accompanying Drawings.
Second, the employment of a beam in high or low pressure engines, where
the cylinders stand close to each other, to produce the opposite motion in the
piston, but not the medium of communicating power between the cylinders
and crank shaft, whereby the length of the passages between the high and
low pressure cylinders is considerably reduced, all substantially in manner
herein-before described and illustrated in the accompanying Drawings.
In witness whereof, I, the said Thomas Scott, have hereunto set my hand
and seal, this Eleventh day of July, One thousand eight hundred
and sixty-two.
THOMAS SCOTT. (L.S.)