IMPROVEMENTS IN THE CONSTRUCTION OF EXCENTRICS, AND IN THE MODE OF WORKING THEM WHEN APPLIED TO STEAM ENGINES
Year: 1858

page_text: LETTERS PATENT to Henry Cartwright, of the Dean Broseley, in the
County of Shropshire, Farmer, for the Invention of "IMPROVEMENTS IN THE
CONSTRUCTION OF EXCENTRICS, AND IN THE MODE OF WORKING THEM WHEN
APPLIED TO STEAM ENGINES."
Scaled the 30th September 1858, and dated the 3rd April 1858.
PROVISIONAL SPECIFICATION left by the said Henry Cartwright at
the Office of the Commissioners of Patents, with his Petition, on the
3rd April 1858.
I, HENRY CARTWRIGHT, of the Dean Broseley, in the County of Shropshire,
Farmer, do hereby declare the nature of the said Invention for "IMPROVEMENTS:
IN THE CONSTRUCTION OF EXCENTRICS, AND IN THE MODE OF WORKING THEM WHEN
APPLIED TO STEAM ENGINES," to be as follows:-
In a grant of Letters Patent which I obtained, dated Ninth of February, in.
the
year Eighteen hundred and fifty-seven, for a similar Invention, being.for.
"Improvements in the Application and Mode of Working Excentrics on Steam.
Engines," in the Specification whereof it was stated, that "two side plates are
fixed, having their faces parallel to a pair of prongs which radiate from a boss
on the end of a small crank axle, the neck of which passes through a radial slot
"in the excentric," and that "extending from one of these plates to the other
"near their extremity are two stopping bars, preferably of triangular section; .
"these bars are about the same distance from each other as the points of the.
prongs are from each other, but nearer to the main shaft than the points of.
the prongs are when the motion of the excentric throws them to their greatest.

page_text: " distance from it." Instead of having the said prongs fixed on the boss at
the end of the small crank axle and outside the standards which support it,
I find they act better when made to rotate from the axle itself and inside the
standards close to the excentrics, also that the said bars should be round in
section instead of triangular, and that they should move freely up and down
in slots or guides about their extremities, and instead of being placed at the
ends of the said side plates they (the bars) with the guides in which they are
supported and move, should be placed vertically over the excentrics, and sup-
ported by a block or seat placed on the said side plates, or by a pillar or pillars
rising from the bed plate of the engine, in which last-mentioned case the side
plates may be omitted altogether.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Henry Cartwright in the Great Seal Patent Office on the
2nd October 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
CARTWRIGHT, of the Dean Broseley, in the County of Shropshire, Farmer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Third day of April, in the year of our Lord One
thousand eight hundred and fifty-eight, in the twenty-second year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Henry Cartwright, Her special licence that I, the said Henry Cartwright,
my executors, administrators, and assigns, or such others as I, the said
Henry Cartwright, my 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
THE CONSTRUCTION OF EXCENTRICS, AND IN THE MODE OF WORKING THEM WHEN
APPLIED TO STEAM ENGINES," upon the condition (amongst others) that I,
the said Henry Cartwright, my executors or administrators, by an instru-
ment in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said Inven-
tion, and in what manner the same was to be performed, 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 Henry Cartwright, do hereby declare
the nature of iny said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, that is to say:-
The object I wish to obtain by this my said Invention of improvements in the
construction of excentrics is to enable me to give to the steam cocks or steam
valves which supply the cylinder with steam, what is technically called "lead,"
in whichever direction they are moving, that is to say, the combination is to
enable the valves to have "lead" while working either way, an object which is
not attained by the ordinary form of excentric.
In a grant of Letters Patent which I obtained, dated the Ninth day of
February, Eighteen hundred and fifty-seven, for an Invention for a similar
purpose, being for "Improvements in the Application and Mode of Working
Excentrics on Steam Engines," in the Specification of the same I therein
describe a construction for effecting the same object as the present, but ou
testing the same practically, I found that it either effected the intended pur-
pose very imperfectedly or not at all; I therefore propose to substitute for it
the arrangement now. described.
In order more fully to illustrate the form and action of the various parts,
the following Drawings are appended, the various parts being indicated by
similar letters in each figure.
DESCRIPTION OF THE DRAWINGS.
Figures 1, 2, and 8 are intended to illustrate and shew the form of the
various parts of the excentric; Figures 4, 5, and 6, to shew its action, being
views of it at different moments during its rotation. Figure 1 is a plan of the
excentric mounted on part of the main axle. Figure 2 is a sectional elevation
of the excentric on the line x, x¹, being the part marked with the star to the
right of the sectional line shewing the side plate. Figure 3 is a view of the
corresponding section on the other side.
a, a, is the main shaft; b is the excentric with its rod b¹ formed in the usual
manner, but having within its larger segment a radial slot d, and a sunk
segmental portion e; within the former there works the neck of a small
cranked axle f, the crank of the same turning within the hollow or sunk
portion; this axle has its bearings upon the standards c, c, one on each side
of the excentric, which are firmly fixed to the shaft, and rotate with it. Near.
the end of the small axle, but within the standard, is fixed a boss, from which
radiate two stout prongs g, g, which taper to points at their. extremities, tho

page_text: angle between them being about fifty degrees or more or less. Outside the
standards two side plates i, i, are fixed, having their faces parallel to the
excentric; these plates, which are constructed so as partly to encircle the axle,
are held together at each end by the bolts m, m, so that the axle turns in them.
The side plates are intended to carry the two blocks or seats 'h, h, which have
eyes or slots .k, k, formed in them, which retain the ends of the small
cylindrical bars n,.n, in such a way, that the bars are free to rise and fall
easily within the slots. The plan, Figure 1, shews the general arrangement
of the parts when put together; Figure 2 shews the side plates i, with the
block h, and the eyes or slots k; Figure 3, the view of the other part in
section, shews the standard c, and the mode of forming it; the sunk portion of
the excentric; the slot with the neck of the crank; the prongs 9, 9, and the
bars n, n, in the slots together with the mode of fixing the side plates through
the excentric rod by the bolt m.
The action of this combination of parts is as follows:-When the main
shaft rotates the prongs which revolve with it are caught by the bars n, n, and
forced down until they will pass under them; this movement of the prongs is
transmitted to the small crank (they being firmly fixed on the boss), on the end
of it, which by means of the neck acting against the side of the slot or opening
turns the excentric a little on the axle, and thus gives "lead" to the valves
or cocks, which, by means of levers, are connected with the excentric rods..
When, again, the motion of the shaft is reversed, the point of the uppermost
prong will be caught by the first stopping bar and raised up, the next prong
will be caught by the second stopping bar, and laid down in a backward
direction, causing the neck of the small crank to act against the side of the
slot, and again move the excentric round a little way in the leading direction,
and thus give "lead" to the valves or cocks as before.
This action will be better understood by referring to the Figures 4, 5, and
6, which shew the position of the prongs, the small crank and the excentric at
different points in its rotation, and also when rotating in different directions.
In Figure 4 the excentric, which has been previously travelling in the
opposite direction, is there just beginning to turn in the direction of the arrows;
the dotted prong escapes the bar n, but the next one is caught by it and
gradually turned back in the opposite way to the motion of the excentric,
until it is brought into the position shewn in Figure 5, which is the extreme
limit it can be laid down, and so long as the motion of the excentric continues
in the same direction it will remain, passing under the bars each revolution.
By this action of the prong it will be seen that the neck of the crank will

page_text: press against the side of the slot in the excentric, and urge it a little round
on the shaft in the direction of the motion, and thus give "lead"
"lead" to the valves
or cocks.
The prongs will now remain in this position as long as the engine continues
to work in that direction; but whenever its motion is reversed by acting on
the reversing gear, then the excentric will move in an opposite direction to
the arrows, and the upper prong in Figure 5 will be caught by the bar n and
raised up; which motion will at the same time act upon the neck of the crank,
which will press against the slot in the excentric, until the whole is brought
into the position shewn in Figure 6, when the motion of the excentric will be
in the direction of the arrows over that Figure. It will be observed that the
actual amount of "throw" is easily regulated, and is equal to and measured by
the horizontal distance between the excentric centres as shewn at a, a, a, in
the different Figures. The length of the "lead" is also shewn in the eye or
slide in the excentric rod, through which the bar m passes, the red line to the
right and left of the bar m shewing the length of the throw, and the excess of
the one over the other from the centre of the bar being equal to the "lead"
given by the before described action of the excentric.
Having now particularly described and ascertained the nature of the said
Invention, and how the same is to be carried into effect, I now state, that
what I claim as new and wish secured by the before in part recited Letters
Patent, is, the construction of excentrics of the form and to act substantially
as shewn in the Drawings and described in the Specification, and for the
purpose of being applied to work the slide valves or steam cocks of steam
engines, so as to give "lead" to such said valves or cocks when working in
either direction.
In witness whereof, I, the said Henry Cartwright, have hereunto set
my hand and scal, this 25th day of September, in the year of our
Lord One thousand eight hundred and fifty-eight.
HENRY CARTWRIGHT. (L.S.)