Improvements in Speed Varying Mechanism.
Year: 1898

page_text: Date of Application, 26th Apr., 1898-Accepted, 17th Sept., 1898
COMPLETE SPECIFICATION.
Improvements in Speed Varying Mechanism.
I, MILTON OTHELLO REEVES, of 1225, E. 7th Street, City of Columbus, County
of Bartholomew, and State of Indiana, United States of America, Mechanical
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:-
The object of my invention is to provide a countershaft in which the speed of
a machine belted thereto may be varied, while the speed of the line shaft remains
constant; to provide a countershaft in which said variation can be accomplished
without stopping the shaft, or the machine to be operated, and to provide means
for maintaining a uniform tension upon the belt in the mechanism hereinafter
described, and, further, to provide a compact and efficient device.
The elementary construction of the device to which the present invention apper-
tains, consisting of two parallel shafts mounted in a frame, and each carrying
a pair of cone shaped driving elements, splined thereto, and having their cone
surfaces facing each other, per se, forms no part of the present invention. The
driving elements are provided with projecting hubs, each of which bears against
a ball-bearing thrust collar. Corresponding collars of each pair are connected
by levers, pivoted half way between the shafts, and adapted to oscillate on said
pivots, and to move one pair of driving elements toward each other, and simul-
taneously therewith move the other pair apart. A bevelled edged driving belt
of any desired construction, but having edges as shown in Fig. 5 of the drawings.
is stretched between the driving elements, and as one pair move together the belt
assumes a greater driving diameter, while the other pair moves apart and the belt
assumes a lesser driving diameter, thus varying the speed of one shaft relatively
to the other.
It is a well known principle that more belt is required to connect a large and
small pulley than is required to connect two pulleys of the same diameter, the
mean between the large and small, both pairs being spaced the same distance
between centers. This difference in length can be mathematically calculated,
and can also be found by geometrical construction.
A number of devices have been devised to obviate the effect of this variation in
the length of belt, so as to make the speed varying mechanism. of the class above
described practical, but each method has heretofore possessed inherent defects,
which prevented highly efficient results. One of the methods was to mount one
pair of driving elements in such manner as to be held together by resilient means,
but this was found ineffective as soon as any power was transmitted.
The present invention is designed to provide a method equally applicable to
all sizes of machines, and, primarily, consists in constructing the levers with their
center pivots out of line with the points of contact of the levers upon their thrust
collars and the invention further consists in the arrangement of parts hereinafter
described and claimed.
In the drawings,
T
1 plan of my device

page_text: device.
Fig. 5 a section of the belt.
Fig. 6 a diagrammatic view of the lever with the pivot in line with the points
of contact of the lever upon thrust collars.
Fig. 7a diagrammatic view of the lever with the pivot out of line with the
points of contact of the lever upon the thrust collars.
In order to make the action of these levers clear, I will first describe the diagram-
matic view. In Fig. 6, A represents the pivot half way between the points of
contact of the lever upon the thrust collars B and C. If the collar represented
by B were moved to the position D, collar represented by C would be moved to
position E. The lever would assume the position indicated in dotted lines, and
distance B D would equal C E. The position shown in dot and dash lines is the
reverse to that shown in dotted lines, and B D' equal C E'.
The action of this principle in a speed varying mechanism of the class described
is to move one pair of driving elements apart exactly the same distance as the
other pair are moved together, or, in other words, paying out just as much belt
from one as the other is supposed to take up; but, as above stated, it is a well
known principle that more belt is required for the large and small diameter
than for the mean diameter, and that if the belt is very loose upon the mean
diameters it will gradually tighten as the elements move until it is extremely
tight at the limit of movement of the driving elements.
In a speed varying mechanism of the class described, this tightening action
takes place in both directions from the mean driving diameter.
By the hereinafter described lever construction the belt is kept at any desired
tension or any desired variation of same.
In Fig. 7, this lever construction is diagrammed, and consists of a lever A²
having a projection 132 extending at right angles thereto, and half way between
the points of contact C and 13 upon the thrust collars. The pivot for the lever
is located in extension B³. I have shown in full lines the position of the lever
when the belt is upon the mean driving diameter of each pair of driving elements,
one member of each pair being indicated in dotted lines. Now if the lever is moved
to the position shown in dotted lines, it will be noticed C² has moved forward less
than D2 has moved backward. This is because the thrust collars slip along the
straight line F2 (the shaft), while the lever rocks unon a pivot and the collar
approaching a perpendicular drawn from the shaft through the pivot, moves at
a gradually decreasing speed, and at the same time that this end of the lever is
moving towards this perpendicular at a gradually decreasing speed, the opposite
end is moving away from the perpendicular at a gradually increasing speed. To
augment this as a further explanation suppose the lever should be moved into a
position nearly parallel with the shaft, an infinitesimal movement of the lever
would slip the collar on the shaft an infinite distance. In this construction
the lever proper instead of swinging upon a pivot swings tangentially around a
circle having a radius equal to extension 132.
If the lever were moved in the opposite direction as indicated in dot and dash
lines, exactly the reverse would take place, the end receding fastest would approach
the perpendicular slowest, and the end approaching slowest would recede fastest.
In Fig. 1, I have shown a device embodying this principle. Mounted in a
frame 1 are two parallel shafts 2 and 3. Splined on shaft 2 is a pair of cone shaped
discs or driving elements 4. having their conical surfaces facing each other. Said
discs are provided with hubs 5 which bear against the Ball-bearing thrust collars 6,
consisting of a circular cupped part 7 adapted to slide upon the shaft, and contain-
ing a hardened track 8, a ball carrying plate 9, and a hardened track 10. The
ball plate is supported between the hardened tracks, and the hub of the disc takes
against track 10, thereby relieving the discs from undue friction upon the
thrust collars. Integral with the cupped part 7 are two lugs 11, diametrically
opposite each other, the purpose of which will be hereinafter more fully described.
Splined to shaft 3 is a second pair of driving elements similar to those on shaft 2,

page_text: and having hubs taking against similar thrust collars. Mounted adjacent to the
corresponding thrust collars of each pair of driving elements is a pair of levers 12,
provided with slotted openings 13, through which lugs 11, pass, the levers resting
upon shoulders 14 formed upon collars 6. The collars are held from any circum-
ferential movement by washer 13 secured to lugs 11, by means of cap screw 15.
Levers 12 are provided with an inwardly projecting tit or boss 16 which pivots
upon adjustable nut 17. In the form shown levers 12 are extended to a point
in the rear of shaft 2, and are provided with slotted openings 18 taking over nuts 19,
working upon a right and left hand screw shaft 20. By manipulating the screw
shaft, the levers are moved upon their pivots. The slots 13 and 18 in levers 12
prevent the nuts and thrust collars from cramping upon the levers while the
latter are being operated.
Secured transversely across the frame, and outside of levers 12, are two parallel
bars 21, one above and one below the frame which take against the nuts 19.
This is an important feature of the construction, as the bars hold the nuts from
rotating, but leave them free to move longitudinally along the shaft, and also
hold levers 12 upon nuts 19. This same construction is adopted with nuts 17,
but two pairs of bars are used instead of 1, thus serving the same function as
bars 21.
As an, illustration of the action of the levers shown in Fig. 1 suppose the driving
elements were moved to the position just the reverse to that shown.
It will be seen that the approaching discs slide towards each other faster than
the receding discs slide apart, and this continues until the levers are parallel with
each other. Now, at this moment, the discs are theoretically sliding at exactly
the same rate of speed; but, by a continued movement of the levers, the approaching
discs slide towards each other slower than the receding discs slide apart; or, in
other words, the rate of movement of the discs passes each other.
In a device where very high speed is required, the belt should be somewhat
tighter at the extreme diameters than at intermediate diameters, and this can be
accomplished by varying the length of the off sets for the pivot.
I have shown a preferred form of frame, consisting of shaft boxes 28 provided
with ears 29, and screw shaft supports 30 provided with ears 31. These boxes
are lined up and bolted together by means of coupling bolts 32 passing through
bars 33 on each side of the boxing, and through ears 29 and 31. Two partial
frames of this construction are made and secured together by the transverse bars 21,
and the bars supporting nuts 17. This construction makes a very light and strong
frame.
There are a number of ways in which the levers could be constructed in order
to accomplish the result of this differential movement of the driving elements,
such as angular slots through which the lugs on the thrust collars pass. and I do
not wish to limit myself to the exact construction shown.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim is :-
1. In a speed varying mechanism, the combination of a frame, two parallel
shafts mounted therein; a pair of cone shaped driving elements splined to each
shaft, the individual members of each pair adapted to slide toward or from each
other upon their respective shafts; means for simultaneously sliding the approach-
ing pair of discs at a gradually decreasing speed, and the receding discs at a
gradually increasing speed, and a belt connecting the pairs of discs; substantially
as and for the purpose set forth.
2. In a speed varying mechanism, the combination of a frame; two parallel
shafts mounted therein; a pair of cone shaped driving elements splined to each
shaft, the individual members of each pair adapted to slide towards or away from
each other upon their respective shafts; levers pivoted between the shafts, and
connected with the driving elements, so as to simultaneously slide the approaching
discs at a gradually decreasing speed and the receding discs at a gradually increas-

page_text: ing speed; a belt connecting the pair of driving elements, and means for actuating
the levers; substantially as and for the purpose set forth.
3. In a speed varying mechanism, the combination of a frame, two parallel
shafts mounted therein; a pair of cone shaped driving elements splined to each
shaft, the individual members of each pair adapted to elide towards or from each
other upon their respective shafts; means for simultaneously sliding the approach-
ing pair of driving elements at a gradually decreasing speed and the receding
elements at a gradually increasing speed, and arranged so as to slide the receding
pair slower than the approaching pair through a part of their movement and
slide the receding pair faster than the approaching pair through the remainder
of the movement, and a belt connecting the discs, substantially as and for the
purpose set forth.
4. In a speed varying mechanism, the combination of a frame; two parallel
shafts mounted therein; a pair of cone shaped driving elements splined to each
shaft a belt connecting the pairs; levers pivoted between the shafts; and con-
necting thrust collars taking against the corresponding elements of each pair;
said lever pivots being out of line with the points of contact of the lever upon
the thrust collars in the direction of the driving elements; substantially as and
for the purpose set forth.
5. In a speed varying mechanism, the combination of a frame; two. parallel
shafts mounted therein; a pair of cone shaped driving elements splined to each
shaft; a belt connecting the pairs; thrust collars mounted on the shafts taking
against the driving elements and provided with diametrically protecting lugs:
levers provided with slotted openings taking over said lugs and having an inwardly
projecting tit or boss between the shafts adapted to pivot upon the frame; sub-
stantially as and for the purpose set forth.
6. In a speed varying mechanism, the combination of a frame: two parallel
shafts mounted therein; a pair of cone shaped driving elements splined to cach
shaft a belt connecting the pairs; thrust collars mounted on the shafts taking
against the driving elements, and provided with diametrically projecting lugs;
shoulders upon said thrust collars and adjacent said lugs; levers provided with
slotted openings taking over said lugs and resting upon said shoulders; caps
secured to said lugs and taking over the levers; an inwardly projecting tit or
boss between the shafts, adapted to pivot upon the frame; substantially as and
for the purpose set forth.
7. In a machine of the class described, a thrust collar consisting of a cupped
portion provided with diametrically projecting lugs, a hardened track supported
within said cupped portion, a second hardened track adapted to take against a
driving element and balls supported between said tracks and within the cupped
portion; substantially as and for the purpose set forth.
8. In a speed varving mechanism, the combination of two parallel shafts: boxes
supporting said shafts; side rails connecting said boxes: bars parallel with the
shafts, and connecting the side rails: a pair of cone shaped driving elements
mounted on said shafts: levers pivoted between the shafts, and adapted to actuate
the pairs of driving elements; extensions upon said levers taking over nuts 19.
supported upon a right and left hand threaded screw 20, and bars 21, taking over
said levers and against said nuts: substantially as and for the purpose set forth.
Dated this 25th day of April 1898