IMPROVEMENTS IN THE CONSTRUCTION OF SEGMENTAL TOOTHED WHEELS
Year: 1870

page_text: LETTERS PATENT to Peter Rothwell Jackson, of Salford, in the County
of Lancaster, Engineer, for the Invention of "IMPROVEMENTS IN THE
CONSTRUCTION OF SEGMENTAL TOOTHED WHEELS."
Sealed the 28th October 1870, and dated the 11th May 1870.
PROVISIONAL SPECIFICATION left by the said Peter Rothwell
Jackson at the Office of the Commissioners of Patents, with his
Petition on the 11th May 1870.
I, PETER ROTHWELL JACKSON, of Salford, in the County of Lancaster,
Engineer, do hereby declare the nature of the said Invention for
“IMPROVEMENTS IN THE CONSTRUCTION OF SEGMENTAL TOOTHED WHEELS," to be
as follows:-
In making large toothed wheels it has heretofore been customary to.
cast the segments in separate pieces, and afterwards to secure them
together to make the complete rim of the wheel; this mode of con-
struction is objectionable as it is impossible to get all the segments of

page_text: the same quality of metal, or when casting of the same temperature,
consequently the contraction of the metal in cooling is irregular, and the
segments are not of uniform hardness.
Now my Invention consists in obviating or reducing these defects by
casting an entire rim of the required diameter, and afterwards cutting or
otherwise dividing the said rim by a slotting tool or other means into
the desired number of segments. Keys or plates may be inserted at the
jointing of the segments to preserve the correct pitch of the teeth.
This improved mode of construction also 'facilitates the fitting of the
segments on to the wheel, or set of arms or internal wheels, or portion of
a wheel for which they are intended, as the rim may be bored out or
turned before it is cut into segments.
1. Topantion is annlicable to internal and external sour and bevel
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Peter Rothwell Jackson in the Great Seal Patent
Office on the 8th November 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PETER
ROTHWELL JACKSON, of Salford, in the County of Lancaster, Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing. date the Eleventh day of May, in the year of
our Lord One thousand eight hundred and seventy, in the thirty-third
year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Peter Rothwell Jackson, Her special
license that I, the said Peter Rothwell Jackson, my exccutors, adminis-
trators, and assigns, or such others as I, the said Peter Rothwell
Jackson, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times there-
after 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 SEGMENTAL TOOTHED WHEELS,"
upon the condition, amongst others, that I, the said Peter Rothwell
Jackson, my executors or administrators, by an instrument. in writing

page_text: 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 Peter Rothwell Jackson, 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 (that is to say) :—
In making large toothed wheels it has heretofore been customary to
cast the segments in separate pieces, and afterwards to secure them
together to make the complete rim of the wheel; this mode of con-
struction is objectionable, as it is impossible to get all the segments of
the same quality of metal, or when casting of the same temperature,
consequently the contraction of the metal in cooling is irregular, and
the segments are not of uniform hardness.
Now my Invention consists in obviating or reducing these defects by
casting an entire rim of the required diameter, and afterwards cutting
or otherwise dividing the said rim by a slotting tool or other means into
the desired number of segments; keys or plates may be inserted at the
jointing of the segments to preserve the correct pitch of the teeth.
This improved mode of construction also facilitates the fitting of the
segments on to the wheel or set of arms or portion of a wheel for which
they are intended, as the rim may be bored out or turned before it is cut
into segments.
My Invention is applicable to all classes of toothed gearing.
And in order that my Invention may be fully understood and readily
carried into operation, I will proceed to describe the accompanying
Sheet of Drawings, reference being had to the figures and letters marked
thereon.
Fig. 1 represents an elevation of a segmental toothed wheel constructed.
according to my improvements, and Fig. 2 is a section through the rim
of the same.
a is the internal rim of the wheel, which may be cast with the arms
and nave as usual or otherwise constructed; and 6 is the toothed rim,
which instead of being cast in separate segments, as now customary, is
část entire, and after it has been turned or fitted internally to fit the

page_text: circumference of the rim a is divided into three or other convenient
number of segments. When the circumference of the rim a has been
turned or fitted to fit the interior of the toothed rim b, the rim 6 is
partly cut through at the joints by a slotting tool or otherwise, or it may
be cast with dividing plates, the remaining metal at the joints is then 5
broken through; to the broken surfaces sulphuric or other suitable acid
is or may be applied to cause corrosion, which removes any slight
particles of iron that would otherwise interfere with the accuracy of the
pitch of the joint. The acid or acids above referred to may be applied
to ordinary split wheels and pulleys. The detached toothed segments 1
are then secured to the rim a by the bolts c, which are provided with
lock nuts fitting in holes cast in the rim a, and the recesses or spaces
between the ends of the segments 6 are filled up by keys d. The keys e
may also be driven into recesses cast or cut in the rims a and b, to assist
the bolts in preventing the rims from sliding on each other. When the 1
internal circumference of the rim 6 fits the entire circumference of the
rim a, as shewn, the noise caused by the vibration of the metal in the
ordinary mode of constructing segment wheels is conderably reduced.
Figs. 3 and 4 represent a segmental toothed wheel constructed
according to a modification of my Invention, in this instance the bolts c 2
pass entirely through the rim a, and the lock nuts are screwed on the
inside of the rim a.
Fig. 5 represents part of a segmental toothed wheel constructed
according to another modification of my Invention, in this instance the
bolts c are dispensed with, and the ends of the toothed segments are cast i
with projections 6¹ fitting in recesses in the rim a, the joint of the
segments is partially cast through by recesses, which are afterwards
filled up by the keys d, and the space from the key d to the inside of
the tooth is eut out in a slotting or other machine, while the remainder
of the space is afterwards broken through, and the broken edges have
sulphuric or other acid applied to them, as before described. The
keys ffare placed diagonally to fit the bevel edges of the projections U¹,
and they serve to secure the rims a and b together.
Fig. 6 is a section through the line A, B, on Fig. 5; and Fig. 7 is a
section through the line C, D, on Fig. 5.
Fig. 8 represents the section of a toothed rim à and the internal rim a,
in this instance the segments are provided with V-shaped recesses, in
which the heads of the bolts c fit, and these bolts secure the internal

page_text: rim a and the external rim 6 together, the bolts c being provided with
lock nuts, as shewn.
Having thus stated the nature of my Invention, and described several
modes of performing the same, I wish it to be understood that I do not
intend to limit myself to the details given, as they may be considerably
varied or modified; but what I claim as my improvements in the
construction of segmental toothed wheels, of whatever class they may
be, is casting an entire toothed rim of the required diameter, and
afterwards cutting or dividing the same into the required number of
segments, which are then secured to the rim of the wheel or other
article, in the manner and for the purposes described.
In witness whereof, I, the said Peter Rothwell Jackson, have here-
to set my hand and seal, this Second day of November One
thousand eight hundred and seventy.