IMPROVED MACHINERY TRIMMING THE TEETH OF WHEELS
Year: 1856

page_text: LETTERS PATENT to Thomas Greenwood, of Leeds, in the County of
York, Machinist, for the Invention of "IMPROVED MACHINERY
TRIMMING THE TEETH OF WHEELS."
FOR
Sealed the 13th February 1857, and dated the 18th September 1856.
PROVISIONAL SPECIFICATION left by the said Thomas Greenwood at the
Office of the Commissioners of Patents, with his Petition, on the
18th September 1856.
I, THOMAS GREENWOOD, of Leeds, in the County of York, Machinist, do
hereby declare the nature of the said Invention for "IMPROVED MACHINERY FOR
TRIMMING THE TEETH OF WHEELS," to be as follows:-
The object of this Invention is to trim the teeth of wheels by mechanical
means, and thus greatly to economise labor and facilitate the operation. In
order to trim a bevilled wheel I provide a bed frame to receive four sliding
frames, arranged at right angles to each other, and capable of adjustment to
suit various sizes of work. Upon a shaft mounted in suitable bearings on one
of these sliding frames, and capable of receiving a rotary motion from a worm
and worm wheel, or other analogous contrivance, I key the cast wheel which
is intended to be trimmed. In a line with the shaft that carries this wheel is
a sliding frame, to which two adjustable guides are connected. These guides

page_text: carry the traversing frames on which the cutting tools are mounted, and they
are so connected to a common centre that they are capable of both lateral and
vertical adjustment; the first for the purpose of varying the angle of traverse
of the cutters to suit the work in hand, and the other movement to enable the
tools to give the curved figure to the side of the tooth. The cutters act
alternately and at opposite sides of the wheel, and of the teeth of the wheel.
A reciprocating motion is given to them by a crank and crank rods. A
rotating cam acting upon crank levers gives motion through click rods, clicks,
and ratchet wheels to screw stops carried by the guide frames, and these
screws being slowly protruded against a fixed stop, the guide frames will be
moved inwards, and thereby cause the cutters to advance to the bottom of the
tooth. Simultaneously with this inward movement, a vertical motion will be
imparted to the guide frames by reason of their outer end resting upon a
former or pattern, which will give the cutters an undulating movement corre-
sponding to the form of tooth desired to be cut. These formers or patterns
(and also the fixed stops) are carried by sliding frames to suit different sizes of
work, and they may be readily replaced by other patterns according to the
varied forms of tooth required.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Greenwood in the Great Seal Patent Office on the
18th March 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
GREENWOOD, of Leeds, in the County of York, Machinist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of September, in the year of our Lord
One thousand eight hundred and fifty-six, in the twentieth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the
said Thomas Greenwood, Her special license that I, the said Thomas Green-
wood, my executors, administrators, and assigns, or such others as I, the
said Thomas Greenwood, 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
IMPROVED MACHINERY FOR TRIMMING THE TEETH OF WHEELS," upon the

page_text: condition (amongst others) that I, the said Thomas Greenwood, by an instru-
ment in writing under my hand and seal, 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 Thomas Greenwood, 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, reference being had to the Drawing hereunto annexed, and to the
letters and figures marked thereon (that is to say):
The object of this Invention is to trim the teeth of wheels by mechanical
means, and thus greatly to economise labour, and facilitate what has hitherto
been considered a tedious operation. In order to trim, for example, a bevilled
wheel, I provide a bed plate or frame to receive four sliding beds or frames
arranged at right angles to each other, and capable of adjustment to suit
various sizes of work. Upon a shaft mounted in suitable bearings on one of
these sliding beds, and capable of receiving a slow axial motion from a worm
and worm wheel, or other analogous contrivance, I key the cast wheel which
is intended to be trimmed. In a line with the shaft that carries the cast
wheel is a sliding bed, to which two adjustable slide frames are connected. On
these slide frames work the slides which carry the cutting tools. They are so
connected to a common centre that (besides the primary adjustment before
starting the machine) they are capable of receiving both a lateral and a
vertical movement during the progress of the work; the first for the purpose
of constantly varying the angle of traverse of the cutters to suit the work
in hand, and the other movement being to enable the tools to give the curved
figure to the sides of the teeth. The cutters act alternately and at opposite
sides of the wheel, and of the teeth of the wheel, a reciprocating motion
being given to them through crank rods by a central crank, which receives
rotary motion through suitable gearing from the main driving shaft or axle.
Having now explained the general character of my improved machinery, I
will proceed to point out in detail the peculiarities of its construction.
In the accompanying Drawing, Fig. 1 represents, in side elevation, my
improved machine for trimming the teeth of wheels; Fig. 2 is a plan view of
the same; and Fig. 3 is an end elevation. A, A, A, are two strong cast-iron
bed plates, forming the foundation of the machine. Upon one of these bed
plates is placed the beadstock B, B, which carries the dividing wheel C, C,

page_text: with the requisite worm shafts, change pinions, and handle box, as usually
employed in ordinary wheel-cutting machines. Bolted firmly to the two
bed plates A, A, A, are two transverse beds D, D, which carry the longitudinal
and transverse slides E, E, and F, F. On the bed plate A, A, opposite
the headstock, is placed the bed G, G, which carries a slide H, H. On the
bed G, G, is mounted a stud axle which carries the driving pulley a, a, and
on the same axle is a pinion 6 that takes into a spur wheel c on the end
of a shaft d. This shaft turns in bearings carried by the bed G, and it is
grooved to receive a feather on the inner face of the boss of a bevil
pinion e, through which it passes for the purpose of communicating rotary
motion thereto. This pinion e gears into a bevil pinion f keyed on the lower
end of an upright shaft g, which shaft works in a socket forming part of the
slide H, H. On the upper end of the shaft g is mounted a face plate h, having
a dovetail slot cut on its upper side to receive a sliding crank pin i. To
this crank pin are hinged two connecting rods j, j, the other ends of which
are attached to slides k, k, by means of stud pins. These slides carry vertical
and transverse slides, and suitable tool holders, for the purpose to be presently
explained. On the upper end of the socket H are mounted two joint pieces
I, I, (see Figs. 4 and 5,) so as to move freely round the upper end of the
socket H. To these joint pieces are respectively hinged two slide frames J, J,
which have their other ends resting upon the slides F, F, before mentioned.
On the periphery of the horizontal face plate h are two projections or cams for
actuating the friction bowls of a pair of bell cranks 1, 1. To the shorter arms
of these bell cranks are attached connecting rods m, m, which are jointed at
their other ends to levers n, n, that carry suitable pawles for working the
ratchet wheels o, o. These ratchet wheels are keyed upon adjusting screws
p, p, mounted near the ends of the slide frames J, J, which frames carry each
a nut and suitable bearings for supporting the screws. One end of these
screws is placed in contact with adjustable stationary stop pieces q, q, which
are fastened to the slides F, F. On the upper side of these slides F, F, are
placed two steel templates r, r, which are counterparts of each other, and
have their faces shaped to correspond respectively to the form of the opposite
sides of the tooth required to be cut. Two pieces of steel s, s, shaped with a
blunt edge, are attached to the under side of the slide frames J, J, and rest
upon the templates r, r. t, t, are screws for moving the longitudinal slides
E, E; and u, u, is a shaft provided with bevil wheels for moving the screws
t, t, simultaneously; vis an adjusting screw for the slide H, H. Mounted on
the headstock B is the shaft K, which carries at one end the dividing worm

page_text: wheel C, C, and at the opposite end the bevil wheel to be operated upon;
w, w, are adjusting screws for the slides F, F.
When the wheel to be operated upon is fixed upon the end of the shaft K,
the dividing apparatas must be properly arranged in the well-known manner
to suit the number of teeth in the wheel, and the slide frames J, J, must be
placed at the angle corresponding to the angle of the bevil wheel, their
adjusting screws p being still in contact with the fixed stops q, and the blunt
steel edges s, s, being brought to the ends of the templates r, r. The cutting
tools having been properly adjusted to their work, motion is applied to the
driving pulleys a, a, when the slides k, k, with their cutting tools, will, by reason
of the throw of the crank pin i in the grooved plate h, traverse the length of
the tooth, and thus a cut will be effected alternately on the upper side of one
tooth at one side of the wheel, and on the under side of another tooth at the
opposite side of the wheel. As the plate h revolves, the cams on its periphery
will actuate the cranks 1, 1, thereby giving motion to the levers n, n, the pawles
upon which, taking into the teeth of the ratchet wheels o, o, will drive them
round tooth by tooth, and thereby give an axial motion to the screws p, p,
which as they move, will push the slide frames J, J, from the stops q, q, and
over the irregular face of the templates r, r.
As one side of each tooth is completed, the slide frames J, J, must be
moved back to the starting point, and the handle of the dividing apparatus
turned to bring the next succeeding tooth in position, and so on until the
wheel is completed. Instead of stopping the operation of the machine by
hand on completing the trimming of the side of each tooth, the advance of the
slide frames may be caused to set in action an ordinary stop motion, which will
slip the belt from the driving pulley to the loose pulley, as will be well under-
stood by all persons acquainted with the construction of machinery used in
cutting metals. I would also remark that the rodsj, j, should be made in two
parts, so as to admit of their being lengthened or shortened to reduce or
increase the throw of the crank pin i to suit the length of motion required
by the cutting tools, which motion will vary according to the work desired to
be performed.
Having now set forth the nature of my Invention of "Improved Machinery
for Trimming the Teeth of Wheels," and explained the manner of carrying the
same into effect, I wish it to be understood that under the above in part
recited Letters Patent I claim the general arrangement of parts, as described
with reference to the Drawing, for trimming the teeth of wheels. And
particularly I claim operating the adjustable slide frames as described, whereby

page_text: the cutters will be caused to follow the curve designed to be imparted to the
teeth.
In witness whereof, I, the said Thomas Greenwood, have hereunt set
my hand and seal, the Seventeenth day of March, in the year of our
Lord One thousand eight hundred and fifty-seven.
THOMAS GREENWOOD. (L.S.)