IMPROVEMENTS IN STEAM ENGINES, PART OF WHICH INVENTION IS ALSO APPLICABLE TO FIXING EXCENTRICS, CAMS, OR PULLEYS ON TO THE SHAFTS OF OTHER MACHINERY."
Year: 1866

page_text: LETTERS PATENT to John Cole Chapman, of No. 2; Stamp End, in the
City of Lincoln, for the Invention of "IMPROVEMENTS IN STEAM ENGINES,
PART OF WHICH INVENTION IS ALSO APPLICABLE TO FIXING EXCENTRICS, CAMS,
OR PULLEYS ON TO THE SHAFTS OF OTHER MACHINERY."
PROVISIONAL SPECIFICATION left by the said John Colo Chapman at
the Office of the Commissioners of Patents, with his Petition, on the
5th October 1866.
I, JOHN COLE CHAPMAN, of No. 2, Stamp End, in the City of Lincoln,,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
STEAM ENGINES, PART OF WHICH INVENTION IS ALSO APPLICABLE TO FIXING
EXCENTRICS, CAMS, OR PULLEYS ON TO THE SHAFTS OF OTHER MACHINERY," to be as
follows:-
This Invention is designed principally as a substitute for the "link" motion
or other equivalent device in locomotive and other double cylinder steam
engines, the object of the said Invention being to enable the position of the
excentrics upon the crank shaft to be reversed or otherwise changed at any
time, whilst the engine is running or stationary, without in any way preventing
or interfering with the expansive working of the steam.
In carrying out this Invention the excentrics are made in the form of
rings, the inner diameter of which is considerably larger than that of the crank

page_text: shaft, so that these rings can be moved into various positions over the said shaft,
either concentric with the shaft or excentric or out of the centre more or less
on either side, and at the same time be thrown forwards or backwards on the
shaft so as to cut off sooner or later, and thus work the steam expansively.
These excentric rings are connected to the crank shaft and to each other in the
following manner:-To each crank on the inner side (or that next to the
excentrics) is bolted a circular plate or disc, and each excentric ring has fixed
to it (and projecting at right angles from its inner face) a twisted cam plate or
scroll, the ends of the said cam plates being pivoted into holes in the circular
plates or dises above mentioned. These two twisted cam plates or scrolls (being
thus carried between the two discs and themselves carrying the excentric
rings,) pass through openings in a collar or clip which is mounted on the crank
shaft between the two excentrics and is capable of sliding longitudinally on
the said shaft, but is at the same time caused to revolve therewith by means
of keys or feathers. It will be evident that if this collar or clip be caused to
slide in a longitudinal direction from one excentric to the other, the sides of
the openings in the clips acting upon the twisted cam plates or scrolls (as a
nut acts upon a screw) will cause the latter to turn partially on their axes in
the circular plates or disos, and thus throw the excentric rings to which they
are connected either forwards or backwards over the shaft, according to the
direction in which the collar or clip is moved. When the collar or clip is
exactly midway between the two excentrics the latter will be concentric with
the crank shaft, and the further that it is removed from this point in either
direction the greater will be the throw of the excentrics, and consequently
the steam may be worked to any desired amount of expansion.
peculiar form of the cam plates or
shifted over the centre, but are also
I
may here remark that owing to the
scrolls the excentric rings are not only
thrown forward or backward round the crank shaft at the same time. The
sliding of the collar or clip upon the shaft between the excentrics may bo
effected in a variety of ways, one of the simplest ways, and which I have
found effectual, being to cut or form a V groove round the circumference and
to place a gab, or ring thereon, the said ring or gab being acted upon by
means of a lever, screw, inclined plane, or other mechanical equivalent.
The way in which I mount or fix the collar or clip upon the shaft, and
which is also applicable to fixing excentrics, cams, or pulleys on to the shafts
of other machinery (especially when it is desired to do so without dismounting
the shaft) is as follows:-The collar or clip is made in two parts; thus I take
two rings, and I cut out, or remove from one side of each a portion thereof of
the width of the eye or inner circle, so that instead of now being a ring, each

page_text: piece is almost in the form of a crescent. I then remove half the thickness
of each piece, fitting the sides of the cut in a V form, so that when these two
pieces are placed with their cusps or points opposite to each other they can be
made to slide together till their centres coincide, and they then form one solid
ring or collar; when this collar has been thus placed on the shaft (one half
from each side) a pin or screw is driven through the parts which overlap each
other, and the whole is completely fixed as though it were one solid piece.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Cole Chapman in the Great Seal Patent Office on
the 22nd March 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
COLE CHAPMAN, of No. 2, Stamp End, in the City of Lincoln, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifth day of October, in the year of our Lord
One thousand eight hundred and sixty-six, in the thirtieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Cole Chapman, Her special licence that I, the said John
Cole Chapman, my executors, administrators, and assigns, or such others
as I, the said John Cole Chapman, 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 STEAM ENGINES, PART OF WHICH INVENTION IS ALSO APPLICABLE
TO FIXING EXCENTRICS, CAMS, OR PULLEYS ON TO THE SHAFTS OF OTHER MACHINERY,"
upon the condition (amongst others) that I, the said John Cole Chapman,
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 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 John Cole Chapman, do hereby declare
the nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following

page_text: statement in writing, and on reference to the accompanying Sheets of
Drawings, that is to say :-
This Invention is designed principally as a substitute for the "link" motion
or other equivalent device in locomotive and other double cylinder steam
engines, the object of the said Invention being to enable the position of the
excentrics upon the crank shaft to be reversed or otherwise changed at any
time, whilst the engine is running or stationary, without in any way preventing
or interfering with the expansive working of the steam.
In carrying out this Invention the excentrics are made in the form of rings,
the inner diameter of which is considerably larger than that of the crank shaft,
so that these rings can be moved into various positions over the said shaft,
either concentric with the shaft or excentric (or out of the centre) more or
less on either side, and at the same time be thrown forwards or backwards on
the shaft, so as to cut off sooner or later and thus work the steam expansively.
These excentrix rings are connected to the crank shaft and to each other in
the following manner:-To each crank on the inner side (or that next the
excentrics) is bolted a circular plate or disc, and each excentric ring has fixed
to it (and projecting at right angles from its inner face) a twisted cam plate
or scroll, the ends of. the said cam plates being pivoted into holes in the
circular plates or discs above mentioned. These two twisted cam plates or
scrolls (being thus carried between the two discs and themselves carrying the
excentric rings) pass through openings in a collar or clip which is mounted on
the crank shaft between the two excentrics and is capable of sliding longitu-
dinally on the said shaft, but is at the same time caused to revolve therewith
by means of the twisted cam plates, which act as keys or feathers. It will be
evident that if this collar or clip be caused to slide in a longitudinal direction
from one excentre to the other, the sides of the openings in the clips acting
upon the twisted cam plates or scrolls (as a nut acts upon a screw) will cause
the latter to turn partially on their axes in the circular plates or discs, and
thus throw the excentric rings to which they are connected either forwards or
backwards over the shaft, according to the direction in which the collar or
clip is moved. When the collar or clip is exactly midway between the two
excentrics the latter will be concentric with the crank shaft, and the further
that it is removed from this point in either direction the greater will be the
throw of the excentrics, and consequently the steam may be worked to any
desired amount of expansion. I may here remark that owing to the peculiar
form of the cam plates or scrolls the excentric rings are not only shifted over
the centre, but are also thrown forward or backward round the crank shaft at
the same time. The sliding of the collar or clip upon the shaft between the

page_text: excentrics may be effected in a variety of ways, one of the simplest ways, and
which I have found effectual, being to cut or form a V groove round the
circumference, and to place a gab or ring thereon, the said ring or gab being
acted upon by means of a lever, screw, inclined plane, or other mechanical
equivalent.
As a modification of the above arrangement I propose in some instances
(instead of using the twisted cam plates or scrolls) to provide the interior of
the sliding collar or clip with two or more teeth or projections acting in
inclined or scroll-shaped slots formed in the boss of the circular plate or disc
which carries the excentric ring, so that as the collar or clip slides between
the excentric rings it imparts a corresponding motion to the latter round the
crank shaft. The way in which I mount or fix the collar or clip upon the
shaft, and which is also applicable to fixing excentrics, cams, or pulleys on to
the shafts of other machinery (especially when it is desired to do so without
dismounting the shaft), is as follows:-The collar or clip is made in two parts;
thus I take two rings, and I cut out or remove from one side of each a portion
thereof of the width of the eye or inner circle, so that instead of now being a
ring each piece is almost in the form of a crescent; I then remove half the
thickness of each piece, fitting the sides of the cut in a V form, so that when
these two pieces are placed with their cusps or points opposite to each other
they can be made to slide together till their centres coincide, and they then
form one solid ring or collar. When this collar has been thus placed on the
shaft (one half from each side) a pin or screw is driven through the parts
which overlap each other, and the whole is completely fixed as though it wero
one solid piece.
Such being the nature and object of my said Invention for " Improve-
ments in Steam Engines, Part of which Invention is also applicable to Fixing
Excentrics, Cams, or Pulleys on to the Shafts of other Machinery," I will
now proceed to describe more in detail the manner in which the same is to
be or may be performed or carried into practical effect, and in order that the
same may be distinctly understood I have annexed hereunto two Sheets of
Drawings illustrative thereof, and have marked the same with figures and
letters of reference corresponding with those in the following explanation
thereof, that is to say :-
In Sheet 1 of the annexed Drawings Figure 1 represents a side elevation
of a horizontal stationary steam engine with double. cylinders, part of the
same being drawn in section, and Figure 2 is a plan view of the same as
seen from above; Figure 3 shows an enlarged side elevation and edge
view of my improved excentric with its twisted cam plate or scroll;

page_text: Figure 4, similar views of the sliding collar or clip; Figures 5, 6, and 7
illustrate the application of part of my Invention to an ordinary grooved driving
pulley.
In Figures 1 and 2, a, a, is the bed plate of the engine; b, b, the steam
cylinders; c, c, the piston rods; d, d, the connecting rods; e, e, the cranks;
ff, the crank shaft; and 9, 9, the fly wheel. To the inner side of each
crank is bolted or otherwise fixed a circular plate or disc h, h, between which
plates or discs the excentric rings i, i, are carried in the following manner :-
Each excentric (see detached views, Figure 3) has fixed to it and projecting
from the inner face thereof a twisted cam plate or scroll j, j, somewhat in the
form of a quick-threaded screw, the ends k, k, of the said cam plates being
pivoted into both plates or discs h, h, and thus each cam plate forms the
centre of motion of its respective excentric ring i, i; 1, 1, represents the
ordinary excentric rods and clips, one excentric only being required for each
slide valve; these cam plates j, j, are embraced by and pass through openings
1*, *, in a sliding collar or clip m, m, (see also detached views, Figure 4); this
collar or clip is capable of sliding on the crank shaft f,f, between the two ex-
centrics i, i, and it is evident that as it is moved from one to the other the action of
the sides of the openings *, *, against the cam plates j,j, will impart a partial
revolving motion to the latter, and hence the position of the excentrics i, i,
with regard to the cranks will be reversed, as shown by the dotted circle n, n,
in Figure 3, and consequently the crank shaft would be caused to revolve in
the opposite direction to the arrow. It will also be evident that the excentrics
can be caused to assume any intermediate position, and therefore to give any
required amount of expansion by moving the collar or clip m, m, a portion of
the distance only. The dotted circle o, o, in Figure 3 shows that at the time
of the clip passing the central point between the two excentrics both the
latter are for the moment concentric with the crank shaft. The sliding of
the collar or clip m, m, on the crank shaft f, f, may (as previously mentioned)
be effected in various ways, one of which is shown at Figure 1 in the Drawing.
p, p, is a ring or clip embracing the collar m, m, and connected to a slide q, q,
working in V grooves in the bed plate a, a. From the under side of the
slide, q, projects a pin r, which fits in a groove in the twisted cam plate or
scroll 8, s, keyed upon a transverse shaft t, t, upon one end of which (see
Figure 2) is also keyed or fixed a crank or lever u, u, connected to a lever u, v,
by a. link w, w; this lever v, v, is provided with a bolt x, x, working in
notches y, y, of a quadrant z, z, and by means of this lever the position of the
excentrics and consequently the direction in which the engine revolves (and
the amount of expansion at which the steam is worked) are controlled. The

page_text: method of fixing the collar m, m, over the crank shaft or of fixing any other
collar, excentric, cam, or pulley on to a shaft without dismounting the latter
is illustrated at Figures 5, 6, and 7. I take two rings of equal dimensions,
and I firstly cut out or remove from opposite sides of each a portion about
equal in width to the diameter of the eye or inner circle, as shewn at 1, 1,
(Figures 5 and 6). I then remove half the thickness of each ring, as shewn
at 2, 2, fitting the sides of the cut together in a v form, as seen at 3, 3. The
two parts are then made to slide together till their centres coincide, and they
form one solid ring, as shown at Figure 7, and they are then fixed in this
position by the insertion of pins or screws 4, 4.
The modification of my Invention herein-before alluded to, wherein the
twisted cam plates or scrolls are dispensed with is illustrated on Sheet 2 of
the Drawings, Figure 8 being an elevation of the crank shaft and excentric
gear. e, e, are the cranks; f, f, the crank shaft; h, h, the circular plates or
discs connected to the cranks; i, i, the excentric rings; and m, m, the
sliding collar or clip, as previously described with reference to Sheet 1.
Figure 9 is a transverse section taken vertically through the line A, B, in
Figure 8. In this modification each excentric ring i, i, is carried between
two discs h, h, j, j. Back and face views of the outer discs h, h, are shown
at Figure 10, and similar views of the inner discs j, j, at Figure 11. The
outer discs h, h, which are bolted to the cranks, are provided with slightly
curved horizontal slots g, g, so arranged that a constant lead is maintained,
and the inner discs j, j, with radial slots k, k. The pin l, l, which supports
the excentric ring, passes through the slides n, n, which work in these slots.
The excentric ring i, i, is also provided with a guide pin o, o, which works in
a similar slide moving in a radial slot in the disc h, h. The modification
shewn at Figure 10 may also be used as a fixed excentrix to be set at any
degree of expansion, and fastened with the nut without the shifting gear.
A section of one of the outer discs h, h, and an elevation of the other is
shewn at Figure 12, and similar views of the inner discs j, j, at Figure 13.
It will be seen on referring to this latter Figure and also to Figures 8 and 11
that the inner discs j,j, are provided with a boss p, p, fitting loosely on the
crank shaft, and that an inclined or scroll-shaped slot q, q, is cut or framed in
each side of this boss for a purpose described hereafter, and a straight slot r, r,
is formed in each side of the crank shaft. The sliding collar or clip m, m,
(detached views of which are shown at Figure 14) slides on the boss p, p,
and is provided internally with two teeth or projections s, s, which take
through the slots q, q, and into the slots r, 1. The parts of these teeth which
work in the slots r, r, are straight, whilst the parts of the same which pass

page_text: through the slots q, q, are formed at a corresponding angle to the inclination
of the slots. The consequence of this arrangement is that the clip can only
slide longitudinally on the crank shaft, but, in doing so it causes the boss p, p,
to partially revolve in either direction, and thus set the excentric rings in
advance of or behind the cranks, according to the direction in which the
sliding collar or clip m, m, is moved. The collar or clip m, m, is embraced
by a strap 8, 8, (shown detached at Figure 15) actuated by two levers t, t, on
a shaft u, u, which is caused to oscillate in either direction by an ordinary
reversing lever or otherwise. It will be seen on referring to Figure 9 that
this strap is formed elliptical to allow for oscillation and also for the wearing
of the brasses or bearings of the crank shaft.
Having now described the nature and object of my said Invention for
Improvements in Steam Engines, Part of which Invention is also applicable
to Fixing Excentrics, Cams, or Pulleys on to the Shafts of other Machinery,"
together with the manner in which the same is to be or may be performed or
carried into practical effect, I would remark in conclusion that I claim as my
Invention the novel method of and apparatus for reversing or otherwise
changing the position of the excentrics upon the crank shafts of steam
engines, substantially as herein-before described and shown in the annexed
Drawings.
And, secondly, I claim the method shown and described of fixing a collar,
excentric, cam, or pulley upon a shaft without dismounting the same as
applied to machinery in general..
In witness whereof, I, the said John Cole Chapman, have hereunto set
my hand and seal, this Fourteenth day of March, in the year of our
Lord One thousand eight hundred and sixty-seven.
JOHN COLE CILA DAN
JOHN COLE CHAPMAN. (L.C.)