IMPROVED MACHINERY FOR FINISHING THE TEETH OF SPUR AND OTHER GEARING
Year: 1859

page_text: LETTERS PATENT to Peter Fairbairn, of Leeds, in the County of York,
Knight, for the Invention of "IMPROVED MACHINERY FOR FINISHING THE
TEETH OF SPUR AND OTHER GEARING."
Sealed the 4th November 1859, and dated the 19th September 1859.
PROVISIONAL SPECIFICATION left by the said Peter Fairbairn at
the Office of the Commissioners of Patents, with his Petition, on the
19th September 1859.
I, PETER FAIRBAIRN, of Leeds, in the County of York, Knight, do hereby
declare the nature of the said Invention for "IMPROVED MACHINERY FOR
FINISHING THE TEETH OF SPUR AND OTHER GEARING," to be as follows:-
The object of this Invention is to facilitate the finishing of spur and other
gearing of a large size, whether consisting of wheels, segments, or racks. For
the finishing of wheels and segments I propose to employ a modified form of
lathe which will not only operate upon the faces of such wheels or segments,
but will trim and finish the teeth. On the mandril or shaft which carries the
face plate for receiving the work to be operated upon, a worm wheel is
mounted, into which gears a worm that is capable of being thrown out of gear
and leaving the parts free to turn, as in an ordinary lathe, the mandril being
in that case driven by the ordinary spur or other gearing. For regulating the

page_text: axial motion of the face plate and retaining it in a fixed position while the
trimming of the teeth is proceeding, I employ a dividing wheel, into the
divisions of which a stop enters for determining the amount of intermittent
axial motion to be given to the work at certain periods of the operation. A
slide rest of the ordinary construction is provided in front of the face plate to
receive the cutter which is to act on the face of the work, and at right angles
thereto is another slide rest which carries a rose cutter, the axis of which will
be on a level with the axis of the work. This cutter is intended to finish the
teeth of the wheel or segments carried by the face plate, and for this purpose
is made the counterpart in profile of the finished tooth required. Rotary
motion is imparted to this cutter when brought into action, and at the same
time it receives a slow lateral motion. As, therefore, the work to be operated
upon is brought up and fixed by means of the dividing wheel in a position to
allow of the rose cutter entering a space between the cog teeth, the cutter will
pass through that space and trim the sides of the two adjacent teeth to the
required shape with the greatest accuracy. The face plate has then to be
turned a distance equal to the breadth of one tooth, and the operation is
repeated.
It will be readily understood that this arrangement admits of modification
to suit the finishing of bevil, worm, and of other kinds of gearing wheels.
Thus, for finishing the teeth of worm wheels the rose cutter would be mounted
in a radial arm, or the rest would be made to turn on its centre pin, and for
finishing diagonal or skew teeth the traverse of the cutter would be in the
direction of an inclined plane or across the plane of the axis of the work,
instead of horizontally or at right angles to the face plate. The teeth of bevil
wheels may also be trimmed by the combined use of the rose cutter and
dividing wheel, by setting the face of the rest which carries the cutter at the
proper angle, and making the cutter (whose diameter must not exceed the
width of the narrowest portion of the space between the teeth) operate on the
side of one tooth only at a time.
For trimming the teeth of straight racks I propose to clamp the rack to be
operated upon to a bed or table, to which an intermittent progressive motion is
to be given through the medium of a dividing screw or its equivalent to bring the
work into the proper position for the rose cutter to act, and the cutter I mount
vertically in a slide carried by a cross-head. This slide may be made adjustable
so as to travel in a line at right angles to the work or at any degree of incli-
nation thereto, and carry the cutter between the teeth. Rotary motion being
given at the same time to the cutter it will trim the near sides of two adjacent
teeth at every traverse which it makes across the rack to be trimmed; or, if

page_text: desired, two or more tools fitted to the same slide may be used, the first to
rough out and the other to finish the work. The like remark applies to the
finishing of the teeth of wheels and segments.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Sir Peter Fairbairn in the Great Seal Patent Office on the
19th March 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, Sir PETER
FAIRBAIRN, of Leeds, in the County of York, Knight, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Nineteenth day of September, in the year of our
Lord One thousand eight hundred and fifty-nine, in the twenty-third year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Sir Peter Fairbairn, Her special license that I, the said
Sir Peter Fairbairn, my executors, administrators, and assigns, or such
others as I, the said Sir Peter Fairbairn, 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 MANCHINERY FOR FINISHING THE TEETH OF SPUR AND OTHER GEARING,"
upon the condition (amongst others) that I, the said Sir Peter Fairbairn, by
an instrument 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 Sir Peter Fairbairn, 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 Drawings hereunto annexed,
and to the letters and figures marked thereon (that is to say):-
The chief object of this Invention is to facilitate the finishing of spur and
other gearing of large size, whether consisting of wheels, segments, or racks.
For the finishing of wheels and segments, I propose to employ a modified form
of lathe, which will not only surface such wheels or segments, but will, by a
continuous operation, trim and finish the teeth.

page_text: a,
In the accompanying Drawing, Figure 1 shews in plan view, Figure 2 in
side elevation, and Figure 3 in end elevation, an arrangement of machinery
for facing up and trimming and finishing the teeth of spur wheels according to
this Invention. A, A, is a framing of cast iron in standards, A¹, A¹, of which
a hollow mandril or shaft B is mounted; this mandril B carries at one end a
face plate C for receiving the work to be operated upon, and to its other end is
keyed a worm wheel D, for communicating an intermittent axial motion to the
work. Mounted loosely on the boss of the worm wheel D is a worm wheel E
of smaller diameter, which wheel is intended to impart a continuous axial
motion to the work for the facing up or turning operation. The two worm
wheels are for this purpose temporarily connected together by a lock bolt
attachment but while the trimming and finishing of the teeth is proceeding
the lock bolt a is thrown out, leaving the worm wheel E to move freely on the
boss of the worm wheel D. F is an axle passed through the hollow shaft or
mandril B, and resting in a bearing 6; this axle is intended to receive and
assist in supporting the wheel to be operated upon, and to prevent all tendency
to vibration in the axle; it is coned to fit the mandril B, and slotted at its rear
end to receive a cotter c, which will key it fast to the mandril. G shews the
position of the wheel to be operated upon when mounted in the machine.
Besides being supported by the axle F it is clamped to the face plate C. The
tools employed for finishing the wheel are carried by slide rests of the ordinary
construction, which when applied to the slide H may be moved up to their
work over a pair of parallel "ways" or guides I, between which the wheel G
is mounted. To prevent the vibration of large heavy wheels while under the
action of the cutters, I provide adjustable stop pins c¹, c¹, which project
laterally from the guides or "ways," and bear against the opposite sides of the
work to resist the lateral pressure of the cutters; or the stop pins may be
inserted in standards carried by the slide H. For driving the worm wheel E,
and thereby imparting rotary motion to the work, the following arrangement is
adopted: K is a series of driving pullies, mounted on the shaft K', and
receiving motion from a driving band from any first mover applied to one or
other of the pullies, according to the surface speed required to be given to the
work. On the axle of these pullies is a bevil pinion d, which gears into a
similar pinion d¹ on a horizontal shaft d³. To this shaft is keyed a worm d³,
which gears into and drives the worm wheel E; when, therefore, the driving
strap is thrown off the pulleys K, the work will be brought to rest. This
rotary motion of the work is required for the facing up or turning of wheels;
and for this purpose the slide rest shewn at L is applied to the slide H. By
employing two cutters in this slide rest both sides of the wheel may be

page_text: simultaneously operated upon. This is the first operation to which the wheel
is subjected in the machine, and the cutters used for this purpose will be of
the ordinary construction. In order, however, to effect the trimming and
finishing of the teeth, I use one or more rose cutters, the peculiar adaptation
of which to the present purpose forms the main feature of this Invention,
and in conjunction therewith, when applied to machinery for finishing spur
wheels and segments, I employ suitable mechanism for giving a regulated
intermittent axial motion to the face plate, to which the wheel or segment is
attached, and retaining it in a fixed position while the trimming of the
teeth is proceeding. To this end I provide a dividing plate e, into the
notches of which a spring stop forming part of a hand lever e¹ takes. This
hand lever is keyed to a stud axle, which carries a spur pinion ² in
gear with an intermediate change wheel e carried by a swinging frame.
This change wheel takes into and drives a spur wheel e on a horizontal
shaft e that lies immediately below the worm wheel D. This shaft is fitted
with a feather along its whole length to receive a worm e, which turns in
bearings in a sliding bracket piece M, pendent from the under side of the
main framing, and gears into and drives the worm wheel D. The object of
making this bracket piece to slide is to enable it to carry the worm out of
gear with the wheel D when a continuous axial motion is required to be given
to the work. When the worm e is brought into use, the bracket piece M is
secured in position by means of clamping screws f,f. It will now be under-
stood that for the purpose of shifting the work on its axis to bring the teeth
in succession under the action of the rose cutters, it will only be necessary to
turn the spring lever, and the train of gearing e³, es, and e', will transmit the
required motion through the worm wheel D to the face plate c carrying the
work.
I have stated that the rose cutters I mount in a slide rest which is adjustable
on parallel ways to suit the diameter of work in hand. To admit of this
movement, it will be necessary to transmit the rotary motion to the cutters
and the lateral motion to the slide rest from driving pullies mounted in a
sliding frame. This arrangement is shewn at Figures 2 and 3, where g, g, is
the sliding frame, suspended in guides h, h, and fitted with pendent swinging
arms g', 9', jointed to which are weighted arms, in which the axle of the belt
pullies i,,, has its bearings. The pulley i receives a strap or belt from the
fixed shafting, whereby all the pullies are driven. A belt from the pulley i,
communicates motion through a pulley k on the axle of a worm k to a worm
wheel, with which the worm is in gear, and thus through a screw shaft which
forms the axle of the worm wheel l, communicates the required lateral motion

page_text: to the slide rest in the manner common to slide rest lathes. In like manner,
a belt from the pulley drives a pulley m on a stud axle, which carries a spur
pinion m¹ in gear with spur pinions on the axles of a pair of rose cutters, one
of which is made a counterpart in profile of the finished tooth required, and
the other is an approximation thereto, and of rather smaller diameter than
the finishing tool, it being intended to prepare or rough out the work for the
finishing tool. These cutters, one of which is shewn in full size at Figure 4,
are so mounted, that the plane of their axes will be on a level with the plane
of the axis of the wheel under operation.
It will now be understood that as the work is brought round and fixed by
means of the dividing plate in a position to present a space formed by adjacent
cog teeth to the rose cutters, the slide rest is to be set in motion and the
cutters will then pass through the space (the finishing tool being preceded by
the roughing or preparing tool), and trim the sides of the two adjacent teeth
with the greatest accuracy. This operation will be repeated until all the
teeth of the wheels have been brought in succession under the action of the
cutters.
I may here remark that when thought desirable, a similar arrangement of
slide and cutter may be introduced on the opposite side of the work, thereby
doubling the working capacity of the machine. It should be remarked that
the above described arrangement requires some modification to adapt it to
the finishing of bevil, worm, and other kinds of gearing wheels. Thus, for
finishing teeth of worm wheels, the rose cutter should be mounted in a radial
arm, or the rest should be made to turn on its centre pin, and for getting the
requisite rake or inclination for the teeth, the traverse of the cutter should be
in the direction of an inclined plane or across the plane of the axis of the work
instead of horizontally, or in the plane of the axis of the face plate. I also
propose to trim the teeth of bevil wheels by the combined use of a rose
cutter or cutters and dividing wheel by setting the face of the rest which
carries the cutter at the proper angle, and making the cutter (whose
diameter must not exceed the width of the narrowest portion of the space
between the teeth) operate on the side of one tooth only at a time.
The mode of applying the Invention to the trimming of the teeth of straight
racks, I have not thought it necessary to illustrate by a Drawing, as the
following explanation will enable any competent mechanic to apply the rose
cutter to straight in contradistinction to circular work. The rack to be
operated upon I clamp to a bed or table, to which an intermittent progressive
motion is to be given through the medium of a dividing plate or its equivalent
to bring the work into the proper position for the rose cutter to act; and the

page_text: cutter I mount vertically in a slide carried by a cross head. This slide may
be made adjustable, so as to travel in a line at right angles to the work, or at
any degree of inclination thereto, and carry the cutter between the teeth.
Rotary motion being given at the same time to the cutter, it will trim the
near sides of two adjacent teeth at every traverse which it makes across the
rack to be trimmed, or if desired, in this as in the former examples, two or
more tools fitted to the same slide may be used, the first to rough out, and
the other to finish the work.
Having now set forth the nature of my Invention of improved machinery
for finishing the teeth of spur and other gearing, 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 adaptation of the rose cutter to
the finishing of spur and other gearing in the manner above described.
In witness whereof, I, the said Peter Fairbairn, have hereunto set my
hand and seal, the Seventeenth day of March, in the year One thousand
eight hundred and sixty.
Signed and sealed by the said Peter
Fairbairn in the presence of
JA. W. HAMILTON RICHARDSON,
Solicitor,
Leeds.
P. FAIRBAIRN. (L.B.)