Improvements in Variable Transmitting Friction Gearing.
Year: 1892

page_text: Date of Application, 31st Oct., 1892-Accepted, 14th Jan., 1893
COMPLETE SPECIFICATION.
Improvements in Variable Transmitting Friction Gearing.
I, CHARLES ARTHUR ALLISON, of 52 Chancery Lane, London, in the County
of Middlesex, Patent Agent, do hereby declare the nature of this invention (which
has been communicated to me from abroad by Hans Charles Behr, of the City
and County of San Francisco, State of California, United States of America,
Engineer) and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
This invention relates to that class of gearing employed to produce a differential
or varying rate of movement between two shafts, or rotating parts of a machine,
by, adjustment, or as may be determined by a variable force, and is applicable to
instruments for indicating or recording the difference of movement between two
shafts, or of producing such difference of movement, as in the case of instruments
for measuring or recording power, also variably feeding machine tools, wood-
working, or other machines.
This invention consists of frictional discs, or wheels, bearing upon their sides
and in the plane of rotation, so mounted that the path of rotation of both the
driving and driven elements are, at the point of contact, as nearly coincident as
possible and therefore rotate together by virtue of nearly perfect rolling friction
between the driving surfaces; also in providing the driving discs, or wheels, with
annular bearings surrounding the axis of the driven disc, or wheel, so the axis of
both may be approximately in the same line or will deviate as little as possible
therefrom, in the range of adjustment for which the gearing is adapted.
The object of this invention is to attain as nearly as possible a coinciding
movement of the driving frictional surfaces of such gearing, at the point of
contact, and thus avoid the wear of such surfaces caused by excessive sliding of
one upon the other.
In the drawings employed to illustrate this invention, Figures 1, 2, 3 and 4 are
diagrams employed to show the manner of its operation.
Fig. 5 is a side view of an apparatus for transmitting motion differentially,
according to this invention.
Fig. 6 is a plan view of the same, partially in section, and
Fig. 7 is an end view of the same apparatus.
Similar letters of reference are employed on the different figures to indicate
corresponding parts thereof.
Referring first to Fig. 1, which is an exaggerated illustration of this invention
to better explain the mode of its operation, A, A, are the driving elements, and
B is the driven one.
a, a, is the line of the axis of the driven element B, and
lines e, e, the axes of the driving clements A, A, the divergence of these lines
being exaggerated in the present case to more clearly show the nature of this
invention.
The driving elements A, A, are mounted in and revolve in the supports or
bearings C, C, the journals D, D, being hollow and large enough to permit within
them a lateral adjustment of the wheel B and its axis a, a, as shown in Figs. 2, 3
and 4, in which the circles m and o represent the outer and inner edges of the
driving element A, A, and the circles n, the driven, or adjustable element B.
In Fig. 2 the driven element n is adjusted so the point of frictional contact at E,
corresponding to G in Fig. 1, is on the outer periphery m of the driving element
and so the movement on the circles m and n will be in proportion to their circum-
ference, or as their diameters relatively.
In Fig. 3 the driving and driven elements are concentric, both moving at the
same rate of rotation.

page_text: In Fig. 4 the element represented by the circle n, is removed to the other
extreme, so the point of frictional contact at F is brought upon the inner circle o,
and the relative rate of rotation between the circles o and n, or the elements A, A,
and B will be in the proportion that the circle o bears to the one n.
It will be understood, that the extreme of variation between the driving and
driven elements depends upon the proportion of the various parts, and is as the
variation between the points E and F; also, that the terms driving_and_driven
employed here for convenience, can be changed, the member B, Fig. 1,
'driving A, A, instead of the reverse, as has been described.
Referring now to Figures 5, 6 and 7, these represent a practical application of
my invention for varying the speed between two machines, or shafts, connected to
the apparatus by the belts H and I, respectively.
The discs or wheels A, A, are both driven uniformly by tooth gearing, a belt H,
or in any other suitable manner. These discs are provided with hollow annular
bearings D, supported loosely in the standards, or brackets C, C, but with their
axes forming a slight angle with each other, as shown by the different spaces s, s,
between the rims in Fig. 6, or in a more exaggerated way in Fig. 1. This
angular position is only enough to insure pressure at E on the rim of the wheel B,
and to avoid contact at J on its opposite side.
The brackets or standards C are pivotally supported at K, K, and are pressed
inward by adjustable coil springs L, L, so as to cause the discs A to bear at E
upon the driven disc B with such force as the amount of power transmitted may
require.
The bearings or journals D, D, of the discs A are made hollow as shown, with
their internal diameter large enough to permit a lateral adjustment of the axis M
of the disc B to such extent as the variations of relative speed may require.
The shaft or spindle M, has bearings N, N, connected to the adjustable plate O,
so the whole can be adjusted forward or back by means of a screw P and hand-
wheel Q, and thus shift the disc B to the positions shown in the diagrams,
Figs. 2, 3 and 4, or any intermediate position between these points.
The plate O moves on the slots and screws R, and can be fixed at any point by
means of these screws.
The discs A, A, can be driven by a belt, as shown, or by means of gear-teeth
formed on their periphery, or the disc B may become the driving one, and the
. two A, A, be the driven.
Having now particularly described and ascertained the nature of this inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
:-
1. In a differential transmitting gearing, as herein described, consisting of
driving and driven discs, operating by frictional contact, their centers of rotation
arranged in one plane, and coincident, when all the discs are revolving at one rate,
and variable in the degree of the excentricity of the driving and driven discs,
substantially in the manner described.
2. In a differential transmitting gearing, as herein described, a pair of driving
or driven discs mounted on hollow axes, within which the axis of another disc may
pass and be adjusted laterally so as to produce variable rates of rotation, the paths
of the driven and driving elements being coincident and moving in the same
direction, in the manner and for the purposes substantially as described.
3. In a differential transmitting gearing, as herein described, two outer or
clamping discs driven at an uniform speed, a frictionally-driven disc between,
clamped at one side by the driving discs, and having its axis nearly parallel with
those of the latter; the driving discs mounted in adjustable bearings, so as to
- permit varying degrees of pressure between the frictional driving surfaces; springs
to maintain such pressure and render it uniform, in the manner and for the purposes
substantially as described.
4. In a differential transmitting gearing, driving and driven discs as described,

page_text: connected and driven by frictional contact on their sides; the axis or the
embracing discs set at a slight angle to each other so the frictional contact and
driving power will act at one side, and the other be free; the contact surfaces
moving in one direction, and with a minimum amount of sliding action due to
rotation, in the manner substantially and for the purposes specified.
Dated this 29th day of October 1892.
ALLISON BROS.,
Agents for the Applicant.