Improvements in and relating to Motion Transmitting and Speed Changing Mechanism.
Year: 1898

page_text: Improvements in and relating to Motion Transmitting and Speed
Changing Mechanism.
I, EDWARD WILLIAM SERRELL, Junior, of Chabeuil, Department of Drôme in
the Republic of France, Engineer, do hereby declare the nature of this invention
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 an improved apparatus for the transmission of motion
by means of which the speed, and if desired the direction, of the relative move-
ments of the driving and the driven parts may be caused to vary.
The different speeds are obtained by the displacement of belts upon adjacent
cones having equal angles of inclination, and an essential feature of the invention
consists in the special means employed for ensuring efficient working of the belts.
As is well known, the method of transmitting power by means of cone pulleys
and belts, as hitherto carried out, are very defective owing to the fact that adhesion
between the belt and the pulleys is uncertain.
This adhesion being due to the tendencies of the belt to mount towards the base
of each of the cones when these latter are rotating; it follows that, with the
methods hitherto adopted, the belt remains in position only when the speed of
rotation of the driven cone is sufficiently rapid to prevent slipping. If, however,
slipping is once set up owing to any resistance or retardation experienced by the
driven cone, the adhesion of the belt becomes lessened, from this cause itself, and
the usual result is that, the driven cone being acted upon to a less extent, its
speed becomes still further retarded and the belt having less tendency to mount
towards the base of the cone, all adhesion ceases and as a consequence no power
is transmitted, whilst the belt falls towards the top of the driven cone.
I have found that this defect is entirely obviated, and that efficient working of
the belt is obtained, when this belt, instead of operating the driven cone, serves
on the contrary to moderate the speed of this cone, which latter is caused to rotate
by parts other than the belt, with a tendency to exceed the speed of the belt.
Seeing that a slight amount of slip usually exists with all transmission by
means of belts, it is obvious that if this slip is occasioned owing to an acceleration
of the driven cone, its effect will be to increase the tendency of the belt to mount
towards the base of the cone, and that there will consequently exist a large increase
of adhesion at the desired moments.

page_text: This tendency to acceleration of the cones, and the resulting efficient operation
of the apparatus is obtained in accordance with this invention in a manner which
may be described generally as follows;
The transmission is effected by means of a train of gearing so combined as t
obtain (at any point) equilibrium between a portion of the power which is trans-
mitted directly to the driven parts of the apparatus, and another portion of the
power which, by means of the cones and the belt which connects them, serves
in the first place for effecting changes of speed by the displacement of the said
belt. The portion of the power which is so transmitted by the cones is then
recovered, so to speak, and utilized for the transmission by causing one of the
cones to participate in the initial motion of transmission.
The essential features of the invention having been set forth, a form of applica
tion will now be described by way of example with reference to the accompanying
drawing, in which;
Figure 1 represents an end elevation of the improved transmission device.
Figure 2 is a plan view, partly in section, upon the line 1-2 of Figure 1.
By means of this device, motion may be transmitted either by the shaft A,
the shaft B, or by the disc C.
For the sake of clearness in the description of the operation, we will assume
the driving part to be represented by the shaft A and the driven part by the
shaft B.
This being the case, the shaft A is connected with the disc C by means of gear
wheels and E, or by means of belts or their equivalents, in such a manner
that the disc C is caused to rotate around the driven shaft B with a speed pro-
portional to that of the shaft A.
This disc is provided with a series of axes F, which may be of any desired
number (three being shown in the drawing) upon each of which axes are mounted
two gear wheels G and H which are rigidly connected one with the other. The
pinions G gear with a gear wheel I common to them all which is rigidly mounted
upon the shaft B, and the gear wheels H mesh with a toothed crown K which
is rigidly connected with the cone L. This cone L is connected by means of the
belt M to the cone N, this latter being rigidly fixed upon the shaft A.
When a movement of rotation is imparted to the shaft A, and consequently to
the disc C, the pinions G tend to turn around the gear wheel I without driving
it, but this tendency is opposed by the gear wheels H which mesh with the crown K
so that the gear-wheel I is driven and with it the shaft B, if the angular velocity
of the crown K is not sufficient to enable the pinions G to rotate freely. If the
angular velocity of the crown K is the same as that of the disc C, the pinions G
are no longer able to rotate upon their axes, and the gear wheel I (and consequently
the shaft B) is driven with an angular velocity equal to that of the disc C. If,
on the other hand, the crown K has sufficient angular velocity to enable the pin-
ions G to turn freely, and if resistance is opposed to the rotation of the shaft B, this
latter will not rotate. From this it follows that there exists a velocity ratio
between the crown K and the disc C causing immobility of the shaft B, and that if
this ratio is modified, by the acceleration of the speed of the crown K, the shaft B
will rotate in the opposite direction. Now the relative angular velocity of the
crown K being regulated by the position of the belt M upon the cones L and N,
the desired speed of rotation of the shaft B may be obtained by displacing this
belt, whatever the speed of the shaft A may be.
As long as the shafts A and B continue to rotate in the same direction, any
resistance opposing the rotation of the shaft B will tend to accelerate the rotation
of the cone L and consequently to increase the adhesion of the belt M.
The portion of the power which is transmitted by the belt M is recovered,
because the cone N is rigidly connected with the shaft A and tends to cause it to
rotate in the same direction as that produced by the initial force.
It is obvious that the gear wheels and the like may be arranged in various
ways, upon condition that they fulfil their purpose of opposing resistance to the

page_text: rotation of the shaft B in equilibrium with the tension created upon the belt M
which connects the cones; it is also obvious, that the relative dimensions and
the arrangement of the gear wheels may be modified, that bevel gearing may be
employed, and that finally, by inverting the arrangement illustrated in the draw-
ing, the shaft B may be connected with the crown K and the cone L with the
central gear wheel, without thereby in any way departing from the nature of my
invention.
It follows from this that the degree of acceleration or retardation of the angular
velocity of the cone L which will correspond with a given acceleration or reduction
of speed of the shaft B, may be either increased or decreased at will, assuming
the velocity of the shaft A to be constant.
These features are of great importance as regards practical applications, owing
to the fact that, for a given effect of rotation upon the shaft B, the tension upon
the belt M diminishes in the ratio of the amplification of the differences of relative
angular velocities for the belt M and, consequently, very large efforts upon the
shaft B may be balanced by means of a relatively small belt, upon condition
that considerable variations are effected in the speed of such belt. On the other
hand, when a relatively greater tension upon the belt is permissible, it becomes
possible to effect great variations of the speed of the driven shaft by means of
very small displacements of the belt upon the cones.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is;-
1. The combination herein before described as a whole, consisting essentially
of a belt capable of lateral displacement upon cones rotated by accessory means,
in such a manner as to cause the adhesion of the belt to be maintained owing to
the tendency to acceleration which is imparted to one of the cones, by the said
accessory means, the whole substantially as described and illustrated.
2. In an appliance for transmitting mechanical motion, the combination of a
cone rotated in equilibrium with the rotation of the driven shaft, of a belt for
retarding the velocity of the said cone, of a cone rigidly connected with the trans-
mission shaft and of the accessory means necessary for the operation of the
apparatus substantially as and for the purpose specified.
Dated this 21st day of June 1898.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.