CERTAIN IMPROVEMENTS IN MACHINERY FOR A NEW ROTATORY OR ENDLESS LEVER ACTION
Year: 1825

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
BURNETT, of Arundel Street, in the County of Middlesex, Gentleman, send
greeting.
WHEREAS His present Majesty King George the Fourth, by His Letters
Patent under the Great Seal of Great Britain, bearing date at Westminster,
the Nineteenth day of February, in the sixth year of His reign, did, for
Himself, His heirs and successors, give and grant unto me, the said Henry
Burnett, His especial licence, that I, the said Henry Burnett, my exors,
adiiors, and assigns, or such others as I, the said Henry Burnett, my exors,
adñiors, or assigns, should at any time agree with, and no others, from time
to time and at all times during the term of years therein expressed, should
and lawfully might make, use, exercise, and vend, within England, Wales,
and the Town of Berwick-upon-Tweed, and also in all His said Majesty's
Colonies and Plantations abroad, my Invention of "CERTAIN IMPROVEMENTS
IN MACHINERY FOR A NEW ROTATORY OR ENDLESS LEVER ACTION;" in which said
Letters Patent there is contained a proviso obliging me, the said Henry
Burnett, by an instrument in writing under my hand and scal, particularly to
describe and ascertain the nature of my said Invention, and in what manner
the same is to be performed, and cause the same to be enrolled in His
Majesty's High Court of Chancery within six calendar months next and
immediately after the date of the said recited Letters Patent, as in and by
the same, reference being thereunto had, will more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Henry Burnett, do hereby declare that the nature of my said Invention, and
the manner in which the same is to be produced, applied, and carried into
effect, is herein-after particularly described and set forth, that is to say:-
My Invention consists in a new arrangement and combination of mechanical
principles applicable to all purposes where rotatory motion has been or is to
bo produced by cogged or toothed wheels and pinions, or what in large machi-
nery is technically called gears, either for the purpose of gaining mechanical
power and diminishing velocity of motion, or vice versa, for multiplying small
quantities of motion and gaining increase of speed; and in this way it is
applicable either to the most complex and elaborate train of wheel-work or
gearing, or to the most simple form in which it can be constructed. One of
the most essential features in my said improvement is, that however numerous
the wheels may be in any piece of machinery constructed upon my principles,
as herein-after described, still a uniformity of action will be obtained through-
out the whole, far surpassing that which can be obtained by any of the
ordinary modes of constructing gears or wheel-work, and that with increased
strength and greatly diminished friction, since that which is usually a rubbing
is converted into a rolling action, and only simple points are called into action
at once, and these are constantly operating upon the line which joins the
centers of any pair of revolving axles or pivots. The change in the velocity
of motion is likewise much increased, so that effects which before required
large wheels with very considerable numbers of teeth, may by my improve-
ment be brought about with much smaller wheels and lower numbers of
teeth, whereby the expence of constructing machinery on my principle will be
considerably reduced. The manner in which I bring about the several beneficial
effects above enumerated is as follows:-Instead of using wheels and pinions
of the form and construction generally adopted, I use wheels with bevil or
oblique teeth, such as are shewn at a, c, in Fig. 1 of the annexed illustrativo
Drawing, and instead of permitting tho teeth or cogs of such wheels to act
into or be acted upon by pinions or other wheels, I cause them to act into
or be acted upon by spiral groves in the nature of endless screws, which
groves are cut and formed on the arbors, spindles or axles, which come into
contact or greaving with such wheels, as seen at b, d, in the said Figure.
Now, it is evident, that if the wheel a be a driving wheel, or one which has
power applied to it to turn it round, it will by its motion communicate a
rotatory or revolving motion to the arbor or spindle 6, which carries the
wheel a fixed upon it, and this wheel c will in like manner give rotatory
motion to the spindle d; or, if instead of imagining the moving power to bo

page_text: applied to the wheel a, we suppose it applied to the axis d, then a rotatory
motion will be communicated to the wheel c and its axis b, which will in
like manner give a much slower motion to the wheel a, and thus an increase
of power will be obtained proportionate to the respective velocities of d and a,
and so of any additional wheels and spirals which might be introduced into
the machine.
The foregoing short account contains a description of the
general principles of my aforesaid Invention, by which it may at first sight
appear, that it contains nothing more than wheels having oblique or bevil
teeth, and common endless screws to act into the same, neither of which are
in themselves new, or capable of being appropriated in their ordinary state by
any Patentee; and accordingly, in their separate and ordinary state, I make no
claim to them under or by virtue of my herein-before in part recited Letters
Patent;
but in their joint and combined state, and in the manner in which
I use them, it will be found, not only that the mode of using and combining
them is essentially different from that commonly practiced, but that they are
attended with beneficial results not heretofore contemplated; and I shall
therefore now proceed to point out how they differ from the ordinary modes
of construction, and how I therefore ground my claim to the novelty of
my Invention of their use and application when combined and used as
herein-before described. The wheel with bevil or oblique teeth has hereto-
fore been used either to act into other wheels or pinions having their teeth
similarly disposed, and thus producing the same relative velocity of motion
as in other wheels with common teeth or cogs, or else to act into an endless
screw in the ordinary way. Now the common application of the endless
screw is in the direction of a tangent line (or very nearly so) to the wheel to
which it is applied, and whether it be the driver or is driven, the direction of
the force exerted by or upon it is constantly in a direction coincident with
its longitudinal axis, and never in that of its radius, while a perfect rubding
action always takes place between the threads of the screw and the teeth
with which they are engaged, thus producing an excessive friction, not only on
this point of contact, but likewise on the resisting pivot of the screw; and
thus, tho' the common endless screw is a convenient and steady driver, it can
seldom be driven to advantage unless the rake of its thread be very great, or
it is assisted by the momentum of a fly wheel. In my application of the
spiral or endless screw its axis is not a tangent to the wheel with which it
is engaged, but it is placed at right angles to the plane of the wheel or
parallel to its axis in every case, except that of bevil geer, or where the two
axes of motion make an angle of each other, and then it is only so far
removed out of its parallelism as to accomodate it to the necessary angle in

page_text: which the motion requires to be communicated. The consequence of my
arrangement is, that the power of the screw or spiral, as I apply it, whether it
be driver or driven, is no longer exerted in the direction of its length or axis,
but in that of its radius; consequently it can be driven by the wheel with tho
same facility that it will drive the wheel, (difference of leverage, according to
their respectivo radii, only excepted), and thus it becomes changed from its
character of the endless screw to that of a pinion of a single leaf, but which
leaf being extended quite round the arbor never becomes disengaged from the
tooth or cog with which it is acting until the arbor has made an entire revo-
lution, and by that time another tooth or cog is ready to engage with it, by
which the most steady and equable continuous motion is produced. Independent
of the last-mentioned advantage, from the circumstance of the wheel and screw
having their axes parrallel or nearly parallel to each other, and from there
being but one point of bearing in action at once, and that uniformly on the
line of centers, and that action passing over equal spaces in equal times, and.
in the same direction, all the sliding action which would take place between
a wheel and an endless screw is converted into a complete rolling action,
whereby nearly the whole of the friction that would otherwise occur is
destroyed, so that the mere external appearance of an endless screw is
maintained without any of its detrimental properties; and as all the points of
contact must be in the line of centers, joining one axle to another without tho
possibility of change, so it follows that this new mode of constructing geers
resembles most closely an endless or perpetual series of levers, and that its
action is more equable and regular than any gearing heretofore constructed.
As the tooth of the wheel may be admitted into and made to bear almost close
to the center of the arbor, or at any rate much closer than when a pinion is
used, a great difference of relative motion may thereby be given from one
wheel to another, or from a wheel to any arbor, as is required in many parts
of clock and watch work, and many other machines. And further, by this
arrangement a great comparative increase of power or velocity may be gained;
consequently this gearing is equally applicable and valuable when a quick or
powerful motion is required; and it possesses one perfectly original and valuable
feature, that any required strength may be given to the arbor without affecting
either its power or velocity. This will be rendered evident by an inspection of
Fig. 3, in which the black lines e, e, and f,f, represent the sections of two
arbors of very different sizes, and consequently strength, while their mechanical
action is exactly similar. The section is taken transversely through that part
of the arbor on which tho spiral groove in which the tooth is to act is formed, as
at g, in both the sections; but it will be seen, notwithstanding the difference in
:

page_text: magnitude of the two sections, that they have but one common pitch line marked
,, in both the Figures, and as these pitch line circles are of equal diameter, it
follows that the two arbors may work into the same wheel, and that their power
and velocity must be equal, notwithstanding their disparity in strength, which
gives my arrangement a decided superiority; for even when the tooth of the
wheel is brought almost close to the centre of the arbor, (which is next to
impossible either in common or oblique toothed wheels and pinions), I can,
upon this principle, always command as much strength in the arbor as may be
requisite for the work it has to perform, all that is necessary being to so cut or file
away the external circular part of the arbor, shewn by a dotted line at h, to
such an extent as to clear the next two adjacent teeth before they come into
action, as will be seen in Fig. 4, which represents part of a wheel with
bevelled teeth acting into a grooved arbor, also shewn in section, as in Fig. 3.
The point or line of the arbor on which the tooth of the wheel bears must be
calculated as follows:-Having ascertained what power or velocity we are in
pursuit of, and the means of getting at the same, the arbor must be made of
sufficient thickness to insure strength enough to resist what it has to bear; next
the distance of the bearing point or pitch line from the centre of the arbor
must be determined, and this may be taken at pleasure, except only that the
tooth to act into it should not be made so long as to weaken it, but where
greater length than ordinary is necessary the teeth may be round-bottomed, or
else shaped as in Fig. 4. The angle which the teeth of the wheel make with
its axis should be rather obtuse, when the wheel is to be driven, and rather
acute when it is to be the driver, which variation in angle will not affect the
power of the gears, since this must always be in proportion to the diameters of
the respective pitch lines acting together, and the number of teeth will not be
affected. To determine the size of the wheel it must be noticed that the
arbor with its spiral grove, as above described, will make one complete revolu-
tion for each tooth of the wheel with which it is connected, consequently the
wheel must have as many teeth as it is intended the arbor shall make revolu-
tions for one turn of the wheel; and the distance between one tooth and
another upon the wheel must be equal to three times the diameter of the
pitch line or circle of the arbor; therefore, if this last-mentioned pitch line
has been first determined, as aforesaid, it will determine the size of a wheel
to work into it with any assigned velocity, because we have only to multiply
the diameter of such pitch line by three, and its product by the number of teeth
or revolutions required, to obtain the length or circumference of the pitch line
of the wheel as sought; or, on the contrary, if the size and number of teeth of
the large wheel be given, the pitch line of the arbor must be one third of the

page_text: distance between its two teeth from center to center. In the construction of
'my aforesaid wheels it is evident that the angle which the teeth make with
the axis of the wheel may be varied without varying the number of teeth in
such wheel; but in this case the breadth of the face or periphery of the wheel
must be altered, because in every case the inclination of the teeth must be so
set out that lines drawn parallel to the axis of the wheel and to each other
may touch or connect the center lines of two contiguous teeth at their
opposite ends, in the manner shewn at the line k, l, in Fig. 1, such line being
parallel to the axis of the wheel a, and at the same time touching the lower
end of the tooth m, and the higher end of the tooth n, the intention of this
being that so soon as any one tooth has passed the spiral groove in the arbor,
and is just about to be withdrawn from it, the next succeeding tooth may be
ready to enter and engage with it. The spiral groove on the arbor must
in every case be of a length corresponding with the breadth of the wheel with
which it has to engage; and if the arbor is required to make one revolution
for each tooth of the wheel, this groove must in its length traverse exactly
once round the arbor; on the contrary, if two or more revolutions of the arbor
are required to be made for each tooth of the wheel, then the spiral groove
must extend twice or more round the arbor; but this is a construction I do
not recommend, since, to obtain additional velocity, it is always better to
increase the size and number of teeth in the driving wheel; but where a
slower motion is required in the arbor, it may be very well brought about by
forming two or more spiral grooves, each extending half or a quantity in pro-
portion to their number round the arbor, and thero letting them engage with
two or more successive teeth to produce one revolution of the arbor. The
curve of the spiral groove upon the arbor may be found by covering the edge
of the wheel with a strip of thin paper, and marking the bevil of one tooth
upon it, when the extension of that tooth 'may be cut off and wrapped round
the arbor, which will give the form of spiral, which may be marked and cut;
but this is only a proximate method, and I recommend that the groove should
be cut in a regular and proper engine for cutting screws or spiral grooves of
this description. But as the process of cutting the spiral groove forms no
part of my aforesaid Invention, and is well known and understood by every
competent workman, I shall not describe it, but will merely state, that the
smoothness and perfect working of my aforesaid improved gearing depends,
like all other wheel-work, on the perfect workmanship of the teeth and
grooves, and their being well finished and fitted to each other.
I may
also notice generally that as this gearing tends to produce a lateral bearing on
the several arbors or axles employed in it, the friction of the pivots may be

page_text: very greatly diminished, particularly in small and light work, by making them
revolve on central points instead of using pivots with shoulders working in
holes, because in this way much smaller moving surfaces are brought into
contact.
So far I have only described the manner in which my machinery or gearing
is to be constructed and applied when the axis of motion of the different
wheels and arbors are parallel to each other; but it will be evident that my
aforesaid improvement applies equally when this is not the case, or to the
construction of what aro techninally called bevil gears. The only difference in
the construction in this case is, that instead of making the wheels and arbors
true cylinders, which they should always be when used for parallel axes
or arbors, that both the wheels and arbors must be conical to the same extent
and in the same proportion as is used for common bevil gear with cogs, the rules
for which are well understood by mechanics. What has been said respecting
the formation of my bevil or oblique teeth upon cylindrical wheels, equally
applies to them when they are formed upon conical wheels, and the spiral
groove in the arbor must be cut upon the conical part of it; but motion
of right angles may be also communicated by means of contrate or face wheel,
with bevil teeth, acting into an arbor lying in the same place of the wheel, in
which case its conical form will be determined by two radii of the wheel into
which it is to act, to the intent that the smallest diameter of the part of the
arbor where the spiral groove is cut may be in the same proportion to the
diameter of the circle formed by the inside of the teeth as the largest diameter
of the pivot is to the diameter of the outside of the teeth.
One of the great advantages of my aforesaid improved combination of gears
is the simplicity which is thereby introduced into machinery, and the consequent
diminution of friction, for since each tooth on the wheel will produce or be
equivalent to an entire revolution of the arbor, a great saving in wheels may
be effected; thus, for instance, if a common wheel has one hundred teeth, and
this works into a pinion of ten leaves, the same power or velocity may be
obtained in my improved gearing by using a wheel with ten teeth, working
into one spiral groove upon the arbor; as an example of which, Fig. 1 is a side,
and Fig. 2 elevation, of a regulator clock drawn to the real size, and which is
capable of shewing hours, minutes, and seconds, and will go for a whole year
with once winding up by a weight of only a few pounds; indeed, such is the
variation in power and velocity which my aforesaid gearing admits of, that
although the wheels may be large, and made to contain many teeth, yet they
may be diminished in size and number of teeth to a single tooth; and if this
is made to bevil or traverse once round the cylindrical or other wheel in the

page_text: manner of a screw, it will work into the spiral groove of another cylinder or
.conical arbor, as the case may be, and each of them will perform their revolu-
tion in the same time.
The objects which I claim as my particular Invention and property are
therefore not the wheel with bevilled or oblique teeth, or the endless screw in
their separate and detached state, but the combination of them in the form
herein-before described, in which the power of the screw is exerted in the
direction of its radius instead of that of its axis, whereby I am enabled to apply
my power much nearer to the center of the arbor that in any other modifica-
tion of wheel-work, and thereby to obtain greater power or velocity than
has hitherto been effected, and with much less friction, on account of the
rolling motion that is induced instead of the rubbing one, and having only one
point on the wheel or arbor in action at once, and that always in the line of
centers, which, together with the power that I possess of giving strength
to my arbor, constitutes an entirely new system of geer work requiring less
space, less materials and consequent weight, less labour for its construction, and
less friction when completed, than any other geer work hitherto constructed.
In witness whereof, I, the said Henry Burnett, have hereunto set my
hand and seal, the Eighteenth day of August, in the year of our Lord