IMPROVEMENTS IN MACHINERY OR APPARATUS FOR CUTTING THE TEETH OF WHEELS, RACKS, OR SEGMENTS
Year: 1862

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, and of 166, Buchanan Street, in the City of
Glasgow, North Britain, Gentleman, for the Invention of "IMPROVEMENTS
IN MACHINERY OR APPARATUS FOR CUTTING THE TEETH OF WHEELS, RACKS,
OR SEGMENTS." -A communication from abroad by Ludwig Philipp Schultz,
Carl Schultz, and Adolf Schultz, all of Mayence, in the Kingdom of
Sealed the 10th October 1862, and dated the 16th April 1862.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on the
16th April 1862.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, and of 166, Buchanan Street, in the City of Glasgow, North
Britain, Gentleman, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN MACHINERY OR APPARATUS FOR CUTTING THE TEETH OF WHEELS,
RACKS, OR SEGMENTS," a communication from abroad by Ludwig Philipp Schultz,
Carl Schultz, and Adolf Schultz, all of Mayence, in the Kingdom of Prussia,
Engineers, to be as follows:-
This Invention relates to a peculiar construction, arrangement, and
combination of mechanism for cutting or forming the teeth of wheels, racks,
or segments, and consists in the employment for that purpose of a cutter of
the form of an endless screw made of hardened steel, and having it's surfaces
roughened or file cut, so as to be capable of cutting or reducing metals:
The pitch of this screw must coincide with that of the teeth to be cut, and
the shape of the threads must correspond to the desired outline of the teeth

page_text: This cutting screw is keyed on to an axle which rotates in bearings in a plate
having a vertical or up-and-down motion imparted thereto by a screw spindle
or otherwise, such plate being also capable of adjustment angularly, or made
to turn upon an imaginary axis or centre of its own, so as to cause the axis
of the cutting screw to be inclined more or less from a horizontal position.
The wheel to be operated upon is carried upon a fixed stud passing through
its centre, and secured to a slide rest supported by the bed plate of the
machine, so as to be capable of being set up to the cutter as the work
proceeds.
In cutting large teeth it is found advantageous to notch out the rim roughly
into the desired number of teeth before placing it in the machine, as a con-
siderably saving of time in the cutting operation will thereby be effected. If
the axis of the cutting screw were perfectly horizontal and at right angles to
that of the wheel, the teeth which would be cut in the rim of the latter by
the cutter would of course be inclined to the axis of the wheel in place of
being parallel thereto, such inclination being due to the angle or pitch of the
threads of the screw itself, and therefore when ordinary spur gearing is to be
cut, the axis of the cutting screw is adjusted to a proper angle by turning the
supporting plate on its bed until the desired angle is obtained, when the plate
is fixed in its position by suitable set screws. By this angular adjustment of
the cutting screw it is obvious that the teeth may be cut in the wheel either
parallel or at an angle to the axis of the wheel. In commencing to cut, the
plate carrying the cutter is elevated until the centre line of the screw coincides
with the upper edge of the rim of the wheel so as to commence the cut at the
upper sides of the teeth. The rotation of the cutting screw turns the wheel,
and equally divides the teeth, so that all the teeth are cut consecutively with-
out any special mechanism being required for rotating the wheel, or for
dividing the same. After the wheel has made one revolution it is set up to
the cutter to take a fresh cut, and the operation is continued until the proper
depth of tooth is attained. The slide carrying the wheel is then fixed in its
place, and the self-acting mechanism for causing the descent of the cutting
screw is thrown into action when the cutting is allowed to proceed until the
teeth are formed, and the cutting screw has arrived at the lower edge of the
rim. It is obvious that in lieu of adjusting the cutting screw to an angle the
wheel to be operated upon may be placed at an angle, and made to rise in
lieu of having a descending motion imparted to the cutter, without altering
the nature of the said Invention.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Henry Johnson in the Great Seal Patent Office on the
16th October 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex, and
of 166, Buchanan Street, in the City of Glasgow, North Britain, Gentleman,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixteenth day of April, in the year of our Lord One
thousand eight hundred and sixty-two, in the twenty-fifth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
John Henry Johnson, Her special license, that I, the said John Henry
Johnson, my executors, administrators, and assigns, or such others as I, the
said John Henry Johnson, my executors, administrators, or 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 "IMPROVE-
MENTS IN MACHINERY OR APPARATUS FOR CUTTING THE TEETH OF WHEELS, RACKS,
OR SEGMENTS," a communication from abroad by Ludwig Philipp Schultz, Carl
Schultz, and Adolf Schultz, all of Mayence, in the Kingdom of Prussia,
Engineers, upon the condition (amongst others) that I, the said John Henry
Johnson, my executors or administrators, by an instrument in writing, under
my hand and seal, or under the hand and seal of one of them, 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 imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Henry Johnson, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the fol-
Jowing statement, reference being had to the accompanying Drawings, and to
the letters and figures marked thereon, that is to say :—
The said Invention relates to a peculiar construction, arrangement, and
combination of mechanism for cutting or forming the teeth of wheels, racks,
or segments, and consists in the employment for that purpose of a cutter of
the form of an endless screw made adjustable to any desired angle, and com-
posed of hardened steel, and having its surfaces file-cut or formed with cutting

page_text: edges so as to be capable of cutting or reducing metals. The pitch of this
screw must coincide with that of the teeth to be cut, and the shape of the
threads must correspond to the desired outline of the teeth. This cutting
screw is keyed on to an axle, which rotates in bearings in a plate having a
vertical or up-and-down motion imparted thereto by a screw spindle or other-
wise, such plate being also capable of adjustment angularly, or made to turn
upon an imaginary axis or centre of its own, so as to cause the axis of the
cutting screw to be inclined more or less from a horizontal position. The
wheel to be operated upon is carried upon a fixed stud passing through its
centre, and secured to a slide rest supported by the bed plate of the machine,
so as to be capable of being set up to the cutter as the works proceeds. In
cutting large teeth it is found advantageous to notch out the rim roughly into
the desired number of teeth before placing it in the machine, as a considerable
saving of time in the cutting operation will thereby be effected. If the axis
of the cutting screw were perfectly horizontal, and at right angles to that of
the wheel, the teeth which would be cut in the rim of the latter by the
cutter would of course be inclined to the axis of the wheel in place of being
parallel thereunto, such inclination being due to the angle or pitch of the
threads of the screw itself, and therefore when ordinary spur gearing is to be
cut, the axis of the cutting screw is adjusted to a proper angle by turning the
supporting plate on its bed until the desired angle is obtained, when the plate
is fixed in its position by suitable set screws. By this angular adjustment of
the cutting screw it is obvious that the teeth may be cut in the wheel either
parallel or at an angle to the axis of the wheel. In commencing to cut, the
plate carrying the cutter is elevated until the centre line of the screw coincides
with the upper edge of the rim of the wheel, so as to commence the cut at
the upper sides of the teeth. The rotation of the cutting screw turns the
wheel, and equally divides the teeth, so that all the teeth are cut consecutively
without any special mechanism being required for rotating the wheel, or for
dividing the same. After the wheel has made one revolution it is set up to
the cutter to take a fresh cut, and the operation is continued until the proper
depth of tooth is attained. The slide carrying the wheel is then fixed in its
place, and the self-acting mechanism for causing the descent of the cutting
screw is thrown into action, when the cutting is allowed to proceed until the
teeth are formed, and the cutting screw has arrived at the lower edge of the
rim. It is obvious that in lieu of adjusting the cutting screw to an angle,
the wheel to be operated upon may be placed at an angle, and made to rise in
lieu of having a descending motion imparted to the cutter without altering
the nature of the said Invention,

page_text: And in order that the said Invention may be fully understood, I shall now
proceed more particularly to describe the same, and for that purpose I shall
refer to the several Figures on the Sheet of Drawings hereunto annexed, the
same letters of reference indicating corresponding parts throughout all the
corresponding Figures. The object of this machine is the cutting of wheel
teeth, either parallel to the axis of the shaft, or at an angle thereto as shewn
respectively in Figures 1 and 2. It also produces a stronger form of tooth
shewn at Figure 3, the thickness a, b, of the tooth being equal to the width
of the space b, c, the bottom of the space being rounded so as to avoid all
angles. By this machine also spur wheels of all sizes may be cut, the teeth
being shaped relatively to the diameter of the wheel, so that a train of various
sized wheels will gear together in a perfect manner (see Figures 4 and 5).
The method of causing an endless screw or worm to gear with a worm wheel,
is well-known to engineers. A worm or screw of hardened steel, and having
its surfaces file cut, or made with cutting edges, is used in cutting the teeth of
the worm wheel, the wheel blank being mounted upon a vertical spindle and
the cutter or screw on a horizontal shaft (see Figure 6). On a rotary motion
being imparted to the tool, the wheel is brought up to it and the cut com-
menced. By this means a well-made toothed wheel is produced, but which
is only suitable for gearing with a screw or worm. The tool in the improved
machine is similar to that above referred to, but by its peculiar arrangement
and mounting a very different result is obtained, enabling prismatic teeth
either parallel with the axis of the wheel, or at a greater or less angle thereto;
as desired by a simple adjustment of the same cutter or tool. The same
machine is also suitable for cutting the teeth of straight or curved racks, and
of internal toothed wheels. Figure 7 is a front elevation of the improved
machine; Figure 8 is a side elevation and partial section of the same, and
Figure 9 is a plan corresponding to Figure 8. E is an endless screw of
hardened steel, having its surface roughened or file cut and keyed upon a
shaft D, working in the bearing c¹, c²; these bearings are cast on the plate
C, which is capable of receiving a rectilinear movement by means of the
screw spindle c. B is a strong frame or standard, the base b, b, of which is
curved so as to form a portion of a cylinder, and rests within or upon a
correspondingly concave curved table or bed plate A, so as to be free to turn
on an imaginary axis x, x, (Figure 8). The bed plate A is firmly secured to
a suitable standard or lathe bed O, resting on any convenient support R, R;
G', G³, are fast and loose driving pullies fitted on to the shaft I, and actuating
the machine by means of a driving strap. The movement is transmitted from
the pulley G to the tool E in the following manner:-The plate C receives

page_text: during the working of the machine a descending movement. Concentrically
with the fixed boss H³, which forms part of the standard B, and in which the
shaft I works, is mounted a lever H, and on the movable boss K', formed
in one piece with the bearing c¹, is mounted another leaver K. These two
leavers, Hand K, are united by a bolt at I, I, which forms a joint pin. Now
it is obvious that on gearing the shafts I and D, through the intervention of
the
spur wheels m', m, and n, a rotary motion may be transmitted to the shaft
D, whether such shaft with its supporting bearings be in a higher or lower
position, consequently the rotatory motion of the tool E will be unaffected in
whatever position it may be placed. The sliding plate C may be moved by
hand, but a small driving strap d is also used for transmitting the rotatory
motion of the shaft I to a small screw spindle c; this is accomplished by
micans of the small pulley d², driven by the strap d, and driving in its turn
a spur pinion d¹, gearing into a pinion du fast on the spindle d. This
spindle has keyed on to it an endless screw or worm which gears into a worm
wheel d', d, fixed on the upper squared end of the screw spindle c, thereby
imparting a slow rotatory movement to the spindle and lowering the plate C
correspondingly. On the bed O is placed a sliding bed plate M, carrying a
stud or bolt N, the plate M sliding in a direction towards or from the cutting
tool E, and carries the wheel blank S, which is mounted so as to turn freely
round the bolt N as a centre. Supposing it be required to cut a wheel of
100 teeth with a pitch of one inch, the spaces between the teeth being half
an inch in width; for this purpose a steel cutting screw of 1 inch pitch is
prepared, the threads being of a section to produce the desired shaft of tooth.
This cutter is keyed on to the shaft D and a wheel blank of a circumference
of 100 inches, and having a corresponding number of equidistant notches
made or cast in its periphery (see Figure 10) is adjusted on to the stud N,
and in order to support it more steadily under the action of the cutter, a piece
of timber is fitted beneath that portion of its circumference under the
immediate action of the cutter. The inclination of the cutter shaft D is now
determined. In order to cut the teeth parallel to the axis of the wheel, it is
requisite that the tangent of the screw be parallel to the axis of the bolt N,
and this adjustment is readily obtained by turning the standard B, and then
fixing it in its proper position by means of the set screws b', 6'. The sliding
plate C is now raised by means of the handle 1, so that the centre of D shall
coincide exactly with the upper edge of the wheel. The plate M and bolt N,
with the wheel blank upon it, are now brought up to the cutting screw E, the
threads of which are entered into the notches in the wheel blank. On the
machine being set in motion the screw cutter will shape out the forms of teeth.

page_text: and rotate the wheel simultaneously. One rotation of the wheel blank having
been thus completed, it is brought nearer to the cutter, and this is repeated
at each revolution of the wheel blank until the proper depth of the tooth is
obtained, whereupon the plate M is allowed to remain stationary, and the
small strap d is brought into action, causing the cutter to work its way down
the teeth at the same time turning the wheel until the entire length of the
teeth have been cut, the cutter finishing at the lower edge of the rim of the
wheel. In Figure 8 the cutter is represented as having arrived at the middle
of its descent, its axis coinciding with the longitudinal centre of the teeth on
the wheel. When inclined teeth are required the angle of the cutter shaft
D is adjusted accordingly. If desired the wheel may be inclined and the
cutter left unaltered, and in lieu of the cutter descending the wheel blank
may be made to rise and fall vertically. When small teeth are to be cut
the notches in the wheel blank may be dispensed with.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried
into effect, I would observe in conclusion that what I consider to be novel and
original, and therefore claim as the Invention secured to me by the herein-
before in part recited Letters Patent is,-
First, the general construction, arrangement, and combination of machinery
or apparatus for cutting the teeth of wheels or racks substantially as herein-
before described.
Second, the adjustment of the angle of the cutter shaft as herein-before
described.
Third, the peculiar arrangement of machinery for cutting wheel teeth
whereby no intermediate gearing is required between the cutting tool and the
wheel to be cut as herein-before described. .
In witnesss whereof, I, the said John Henry Johnson, have hereunto
set my hand and seal, this Sixteenth day of October, in the year of our
Lord One thousand eight hundred and sixty-two.
J. HENRY JOHNSON.
(L.S.)