Improvements in Speed Varying Mechanism.
Year: 1899

page_text: Date of Application, 8th Aug., 1899-Accepted, 2nd Dec.,
1899
COMPLETE SPECIFICATION.
Improvements in Speed Varying Mechanism.
I, MILTON OTHELLO REEVES, of Columbus, Bartholomew County, State of
Indianna, United States, 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 mechanism wherein a variation
of speeds, from maximum to minimum, can be obtained, without varying the
initial driving speed, and more especially to provide means for maintaining a
uniform tension upon the belt, in the machine hereinafter described and claimed,
and also to provide a compact and efficient device.
My invention consists in the combination and arrangement of parts, herein-
after described and claimed.
The device primarily consists of two parallel shafts mounted on a suitable
frame, and each carrying a pair of cone-shaped driving elements splined to its
shaft, the members of each pair have their cone surfaces facing each other.
Each driving element is provided with a projecting hub, bearing against a ball
thrust bearing. The corresponding bearings of each pair are connected by means
of levers pivoted half way between the shafts, which, when oscillated, move one
pair of driving elements together, and move the other pair apart simultaneously
therewith.
A beveled edge driving belt of suitable construction is stretched between the
pairs of driving elements, and as one pair move apart, the belt assumes a small
driving diameter, and simultaneously therewith, the other pair move together,
and the belt assumes a large driving diameter, thus varying the speed of one
shaft relatively to the other.
As is well known among mechanics, more belt is required to pass around and
connect a large and small pulley than is required to pass around and connect
two pulleys of the same diameter, the mean between the large and the small
one, the pulley, of course, spaced the same distance between centers.
It will be noticed that this fundamental principle is met in a speed varying
mechanism of the class described, and to construct a suitable mechanism for
transmitting power, the variation in belt must be taken care of.
If the driving elements are actuated along their respective shafts by levers
pivoted half way between the shafts, it will be noted that the approaching and
receding elements slide exactly the same distance, but in opposite directions,
thus increasing the driving diameter upon the approaching pair exactly the same
amount as the driving diameter upon the receding pair is decreased. But as
heretofore stated, more belt is required for this latter position of the driving
elements than is required in the intermediate position.
A part of my present invention consists in making the belt long enough to
assume a driving diameter upon each pair slightly greater than the mean
diameter, when the levers are parallel, and then providing means for moving the
pairs of driving elements in a differential ratio whereby the belt is kept at
uniform tension upon all driving diameters.

page_text: In the drawings:
Fig. 1 is a plan of the device embodying my invention.
Fig. 2, a cross section on line 2-2 of Fig. 1.
Fig. 3, a diagrammatic sketch showing the principle of operation of the
device.
Fig. 4, a section on line 6-6, Fig. 1, and
Fig. 5, a detached plan of one of the levers.
1, represents the frame, having mounted therein two parallel shafts 2, 3, each
carrying a pair of driving elements 4, splined to their respective shafts to rotate
therewith, but free to slide longitudinally thereon. Each driving element bears
against a ball thrust bearing, 5, supported between pairs of levers, 6. These thrust
bearings are provided with diametrically opposite trunions, 7, which are adapted
to work in slots, 8, the purpose of which will be hereinafter described.
4
The corresponding members of each pair of driving elements are connected by
a separate pair of levers, 6, which are prolonged at one end and provided with
slotted openings, 9. Mounted adjacent to these extended ends is a screw shaft
provided with a left-hand threaded part and a right-hand threaded part, each
carrying a nut, 10, engaging with its corresponding pair of levers, by means of
trunions, 11, working in slots, 9.
Levers 6, are provided with an inwardly projecting teat or part, 12, having
the pivot for the lever formed therein. Each pair of levers, pivot upon corre-
sponding pivots. 13, which are free to slide laterally relatively to the frame.
Links 14 are pivoted to suitable supports, 15, have their free ends pivotally
secured to their corresponding lever at 16..
Now the movement of these levers may be noted: Starting from the position
shown in Fig. 1, if the screw shaft is actuated the extended ends of the levers
are caused to approach each other. This, as will be readily seen, causes the pair
of driving levers closest the screw shaft to approach each other, and simultaneously
therewith causes the other pair to recede, but as this is taking place, it will be
noted that levers 6 are swinging about their pivots, 13. but since points 16 must
swing about pivots 15, on account of link 14, the pivots 13 are forced longi-
tudinally towards each other. This movement continues until point 16 comes in
line with pivots 13 and 15. Now, by further movement of the screw shaft, 30,
the pivots 13 begin to recede from each other, on account of links 14 having
passed to the other side of the line through the pivots. The slots in lever 6
allow of the necessary sliding movement upon thrust collars 5. The result of
this action is as follows:
Now as the levers move from the position shown in Fig. 1, the approaching
pair move apart, because the pivots 13 are being forced toward each other, at the
same time that the levers are swinging on their pivots and moving the driving
elements, and the belt is caused to ride on the approaching driving elements upon
a slightly larger diameter than it would occupy if the approaching elements were
moved exactly the same distance as the receding elements. This relative move-
ment of the driving elements continues until the pairs of levers are parallel. Now,
upon investigation it will be found that the belt is upon equal diameters of each
pair, but these diameters are slightly above the mean. If movement in the same
direction is continued, the links 14 swing to the other side of the center line
drawn through the pivots, and the pivots 13 recede, thereby causing the approach-
ing pair to move gradually slower and the receding pair. gradually faster.
It will thus be seen that the driving elements are moved in a differential ratio,
the approaching faster than the receding, until the levers are parallel, and from
thence on vice versa. The same action takes place, no matter in what direction
the driving elements are moved.
For adjusting the driving elements so as to produce any desired initial tension
upon the belt. I provide means for moving pivots 15 simultaneously in opposite
directions. The arrangement consists of a right and left-hand threaded screw
shaft, carrying nuts 17, which carry the pivots 15. By simply turning shaft 18,

page_text: the pivots are forced a little closer together, thereby forcing both pairs of
elements together, and any losseness caused by stretching is taken up.
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 speed varying mechanism, the combination of a frame, two parallel
shafts mounted thereon, a pair of cone shaped driving elements carried by each
shaft; a belt connecting the pairs: levers pivoted between the shafts and adapted
to oscillate and simultaneously move one pair of driving elements together and
the other pair apart, and means for concurrently advancing or receding the lever
pivots towards or from each other, said means controlled by levers 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 carried by each
shaft, a belt connecting the pairs, levers pivoted between the shafts, and adapted
to oscillate and simultaneously move one pair of driving elements together and
the other pair apart; and means controlled by the levers for advancing the pivots
towards each other through a part of the oscillating of the levers and recede the
pivots through each other through the remainder of their movement, substantially
as and for the purpose set forth.
(3) In a speed varying mechanism, the combination of a frame and two parallel
shafts mounted therein, a pair of cone-shaped driving elements carried by each
shaft; a belt connecting the pairs; thrust bearings taking against the driving
elements; levers connecting the corresponding thrust bearings; an inwardly
projecting teat formed on each lever, pivots formed in said teats, free to move
laterally relatively to the frame. A link pivotally secured to a suitable support
in rear of lever, and pivotally secured to the levers, and means for oscillating,
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 carried by each
shaft, a belt connecting the pairs; thrust bearings taking against the driving
elements; levers connecting the corresponding thrust bearing; an inwardly pro-
jecting teat formed on each lever, pivots formed in said teat, free to move laterally
relatively to the frame, links pivotally secured to adjustable support in the rear of
the levers and pivotally secured to the levers, and means for oscillating the levers,
substantially as and for the purpose set forth.
Dated this 5th day of tout 1800
CHEESBROUGH & ROYSTON,
Applicant's Patent Agents, 15, Water Street, Liverpool