IMPROVEMENTS IN THE APPLICATION AND MODE OF WORKING EXCENTRICS ON STEAM ENGINES
Year: 1857

page_text: LETTERS PATENT to Henry Cartwright, of the Dean, Broseley, in the.
County of Shropshire, for the Invention of "IMPROVEMENTS IN THE
PROVISIONAL SPECIFICATION left by the said Henry Cartwright at
the Office of the Commissioners of Patents, with his Petition, on the
9th February 1857.
I, HENRY CARTWRIGHT, of the Dean, Broseley, in the County of Shropshire,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
THE APPLICATION AND MODE OF WORKING EXCENTRICS ON STEAM ENGINES," to be
as follows:-
The improvements are chiefly applicable to engines which require to reverse
their motion and work in either direction; and consist in arrangements for
the purpose of giving."lead" to the steam valves. or cocks of such engines.
To effect this, the excentric, which is losely fitted on the shaft of the engine,
has a radial slot or opening on its prominent side. Two standards or bearers,
one on each side of the excentric, are firmly fixed upon the shaft, so as to :
rotate with it, in or on which a small crank axle has its bearings, its neck
passing through the radial slot in the excentric carries it (the excentric) round''
the shaft. One of the ends of this small axle passes a little beyond the bearer:
or standard, and has a boss fixed firmly upon it, from which radiate two
stout prongs which taper to points at their extremities; the angle between.
the prongs being about fifty degrees, or a little more or less: Outside: the :
standards, and also a little beyond the extremity of the boss and prongs, two..
side plates are fixed, having their faces parallel to the plane of the prongs >

page_text: These plates are conjointly attached to one end of an arm, the other end of
which is fixed to or retained by some convenient part, só as to prevent the
plates from rotating. Extending from one plate to another 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 distance from it.
The action of this arrangement is, that as the shaft rotates the prongs will
be laid down by pressing against the, said stopping bars. This movement
of the prongs is transmitted to the small crank, which again, by means of
the neck acting in the radial slot, turns the excentric a little on the axle
and gives the "lead" to the steam valves; when again the motion of the shaft.
is reversed, the point of the uppermost prong will be caught by the first
stopping bar and the prong will be raised up, the next prong will be caught
by the next 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 move the
excentric round a little way in the leading direction and again give "lead"
to the slide valves.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said, Henry. Cartwright in the Great Seal Patent Office on
the 8th August 1857..
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
CARTWRIGHT, of the Dean, Broseley,' in the County of Shropshire, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Ninth day of February, in the year of our Lord
One thousand eight hundred and fifty-seven, in the twenty-first 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
APPLICATION AND MODE OF WORKING EXCENTRICS ON STEAM ENGINES," upon the
condition (amongst others) that I, the said. Henry Cartwright, my executors.

page_text: 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 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.
NOW KNOW YE, that I, the said Henry Cartwright,. 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:-
The improvements are chiefly applicable to engines which require to reverso
their motion and work in either direction, and consist in arrangements for
the purpose of giving "lead" to the valves or cocks which supply the cylinders
of such engines with steam. The means by which I effect this are as follows:
-The excentric by which the valves or cocks are wrought, and which has
upon its prominent side or larger segment a. radial slot or opening, is loosely
fitted on the main shaft of the engine, so as to be capable of turning on it
when acted upon by a moderate force. On each side of the excentric and
firmly fixed to the shaft, so as to rotate with it, are two standards or bearers,
in or on which a small crank axle has its bearings, its neck passing through.
the radial slot in the excentric. One of the ends of this small axle passes
a little beyond the bearer or standard, and has a boss fixed firmly upon it.
from which boss radiate two stout prongs, which taper to points at their
extremities, the angle between the said prongs being about 50 degrees, or
a little more or less. Outside the standards, and also a little beyond the
extremity of the boss and prongs, two side plates are fixed, having their
faces parallel to the plane of the prongs. These plates, which partly encircle
the main shaft, are at one extremity conjointly attached to one end of an
arm, the other end of which is fixed to or retained by somie, convenient part,
so as to prevent the plates from rotating. Extending from one plate to the
other, near the other 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 distance from it.. The action of this combination of parts is
as follows: When the main shaft rotates the prongs will be laid down by.
passing under the said stopping bars. This movement of the prongs is trans-
mitted to the small crank, which again, by means, of the neck acting against
the side of the slot or opening, turns the excentric a little on, the axle and

page_text: bis loosely fitted; cis the radial slot or opening in the largest segment,
through which passes the neck d of the small crank. The dotted lines sliew
the excentric turned slightly round on the crank axle or main shaft:
Figure 2 is a similar section, shewing in addition to the former Figure-the
standards e, on which the small crank d has its bearings, and the boss f, from
which radiate the prongs g, g, h, h, being the sections of the triangular
stopping bars.
pre-
Figure 3 is a similar section, shewing in addition to the before-named
parts the arrangement of the arın k, which supports the side plates-l,
venting them from turning with the shaft by its end being attached to the
cross piece r, the ends of the side plates being curved to the outline of tho
shaft and turned up on their edges to increase the wearing surface. The ends
of the stopping bars are shewn ath, h¹.
Figure 3 is a plan of the forked arm or bar k, for supporting the side
plates, Figure 3b is an elevation of one side plate l.. The mode of fixing
or joining the two plates will be apparent from the Figures.
Figure 3° is a plan (on a smaller scale) of the excentric rods and the arm
k, shewing the mode of attachment' to the cross piece r; through which the
excentric rods work while the arm or bar holding the plate is fixed. The
side plates may, however, be fixed in several other modes and positions.
When from a reversal of the motion of the shaft the prongs on the boss
fixed to the end of the small crank have been laid down, by pressing against
the stopping. bars, which we shall suppose they have passed under; then the
neck of small crank will stand forward a little beyond a tangential position,
the slot being long enough to allow it to do so, and while it (the neck) is
pushing a little obliquely outwards as well as forward against. the side and

page_text: end of the slot, urging the excentric round, it will consequently have a
tendancy to keep in this position; but when the motion of the shaft is reversed.
then the opposite side of the slot of the excentric will resist the pull or
pressure of the neck, and will force it into a tangential position, and the prongs
will then stand out so far that they will be caught by the stopping bars, and
be laid down or forced back in the opposite direction by the retrograde motion
of the shaft, and the excentric will now receive "lead" in the new direction
of the shaft's rotation. When the shaft with the excentric is travelling in
the direction of the arrow 1, Figure 2, the prongs g, g', will pass under the
stopping bars h, h¹; the neck of the crank standing forward and propelling
the excentric with lead; but when the motion of the shaft is reversed, the
crank is brought into a tangential position, occasioned by the resistance of
the left-band side of the slot to the pull of the crank, and the prongs are
thrown outwards into the position shewn by the dotted lines; but when the
shaft commences to rotate in the direction of arrow 2, same Figure, the prongs
being now raised, when the prong g arrives at the bar h, as in Figure 4, it
is arrested by that bar and raised, while by the further rotation of the shaft
in the same direction the prong g' is arrested and laid down by the stop h¹,
and shewn in this position in Figure 5, the neck of the crank being likewise
shewn as having acted against the side of the slot in the excentric, and caused
it (the excentric) to take the "lead" in the same direction in which the
shaft rotates.
Having now fully described the nature of my Invention, and how the same
is to be effected, what I claim, and desire secured by the Letters Patent, are,
the combination of parts and arrangement above described for giving the
"lead" to the valves or cocks which supply the steam to the cylinders of
engines which require to work in either and both directions.
In witness whereof, I, the said Henry Cartwright, have hereunto set my
hand and seal, this Fifth day of August, in the year of our Lord One
thousand eight hundred and fifty-seven.
Witness,
WN PERRIN, Draper,
Broseley.
HENRY CARTWRIGHT. (L.S.)