Improvements in Variable Speed-driving Mechanism.
Year: 1895

page_text: Date of Application, 29th Oct., 1895-Accepted, 18th Jan., 1896
COMPLETE SPECIFICATION.
Improvements in Variable Speed-driving Mechanism.
We, WALTER AMES, of 24 Mutual Street, Machinist, and EDUARD
WAKEFIELD BLACKHALL, of No. 93 Wood Street, Bookbinder, both in the City
of Toronto, County of York and Province of Ontario, in the Dominion of Canada,
do hereby declare the nature of this invention and in what manuer the same is
to be performed, to be particularly described and ascertained in and by the following
statement :-
This invention relates to variable-speed-driving mechanism, the object being to
furnish an improved driving mechanism, especially adapted for use in connection
with machine-tools and other machines, in which the machine-spindle requires to
have a variable velocity, and whereby the driving-spindle and element may have
its velocity of rotation changed during the rotation of the same, and relatively to
the driving wheel or member; also, whereby this relative change of velocity may
be effected by means of variable-speed apparatus connected and operating as a
retaining apparatus for one portion of the principal driven-gearing.
By means of our present improvements, a variability in the speed-driving
member is effected through the combined operation of a positively-acting driving
apparatus with a negatively-acting driving apparatus, having therein a variable-
speed device.
In the drawings, accompanying and forming part of this Specification,
Figure
is a perspective view of a variable driving mechanism embodying
our present improvements.
Fig. 2 is a vertical longitudinal view through the center of the mechanism.
Fig. 3 is a transverse, sectional elevation in line a-a, Fig. 4, showing the parts
at the left hand of said line, as seen from a point at the right hand thereof. In this
view, which especially illustrates the variable-speed device of the negatively-acting
driving apparatus, the frictional driving-wheel Q is shown in one position at 10 in
solid lines, and at another position at 20 in dotted lines.
Fig. 4 is a sectional, plan view of the machine, for more fully illustrating certain
normal feature of the mechanism shown in the preceding views.
Similar characters designate like parts in all the figures of the drawings.
Our improved driving mechanism, in the preferred organization thereof shown in
the drawings, comprises two principal portions or apparatus, one of which we
designate as the "positive or "forwardly-driving" mechanism, and the other of
which we designate as the "negatively-driving " apparatus.
"
Said member, or forwardly-driving apparatus, may properly consist, as herein
illustrated and described, of a driving member or wheel and a driven-member or
shaft and gearing connecting said driving and driven members; whereby, on the
rotation of the driving-member, the driven-member will be correspondingly
rotated. This operation of the driven-member from the driving-member is effected
through an independently rotatable member with which the intermediate gearing
referred to is connected.
In the mechanism, which we have illustrated in the drawings, the driven-member
consists of a shaft A, which shaft is shown provided with a driven-gear K, fixed on
said shaft by means of a key or other holding device k. The principal driving-
member consists of the gear-wheel J, which is shown fixed by means of the key
or other suitable fastening device j on a tubular shaft or sleeve, (herein designated
by the character F, and shown rotatably supported on the continuation of the
driven member or shaft A).

page_text: In practice, however, said shaft A, may not be continued as shown, but may be
divided at a point between the driven-wheel K and the driving-wheel J, in which
case, that portion of the shaft A at the left hand in Figs. 1 and 2 would constitute
a driven-member, while that portion of the shaft A at the right hand on said
division would constitute merely a support for the shaft F.
This operation in the mode of fitting up the mechanism, we deem to be within
the ordinary skill of the mechanic, and, therefore, does not require further
elucidation.
For the purpose of applying power to the principal driven-member J and its
shaft F, we provide the shaft F with a driving-wheel E, adapted to receive a
driven-band for rotating the same. The band-wheel E is shown fixed on the shaft F
by means of a set-screw e. Said band-wheel E is also shown provided with a
driving-wheel or gear E¹, whereby, as hereinafter more fully described, the
negatively-acting driving apparatus is operated.
As a means for transmitting power from the principal driving-member J to the
principal driven-wheel K, the forwardly-operating portion of our improved driving
mechanism is provided with an independently rotatable member suitably supported,
relatively to the other members of the mechanism, and adapted for carrying
connecting gearing for connecting the driving-wheel J with the driven-wheel K.
In our improved mechanism, which we have illustrated in the drawings, said
independently rotatable member is designated in a general way by G, and is shown
in the form of a sleeve or tubular shaft rotatably supported on the tubular shaft F,
and constructed for carrying intermediate gearing for operatively connecting said
wheels J and K.
9,
. In the present instance, said member G is furnished with a stud
and adapted for carrying an intermediate driving device comprising, in practice,
fixed thereon,
two intermediate wheels; the driven intermediate I, meshing with the driving-
wheel J, and the driving intermediate H, meshing with the driven-wheel K.
The two wheels H and I may be formed integrally in a well-known manner; but
the wheel H, may, as herein shown, have a tubular hub-extension, on which, the
other intermediate I, may be secured by means of some suitable key or fastening
device i.
As a convenient means for holding the intermediate gearing on the stud g, the
said stud is shown provided with a flange or collar h', held in place by means of a
screw h².
The foregoing description of an intermediate driving-gearing is made in
connection with the upper portions of Figs. 1 and 2.
In practice, however, said intermediate gearing may be used in multiple, as also
shown in said figures, especially when great power is required and a larger amount
of wearing surface is deemed desirable.
The relative velocities of the driving and driven members, of course, depend on
the relative proportions of the driving-wheels J and K, and of the interinediate
wheels I and H.
In the drawings, these proportions are so related, that one revolution of the
wheel J, provided the member G remains stationary, will operate through the
intermediate wheels, to rotate the wheel K through one-half of one revolution.
It will be evident, however, that other ratios of rotation of said driving and
driven members may be obtained by suitable proportioning relative diameters of
said several wheels, or gears constituting the driving-train of the mechanism.
It will be evident, that if the rotation of the member G be relatively smaller in
amount, the reduction of the speed-member K will be correspondingly small; and
that if the rotation of the member G be relatively rapid, this will reduce the
resultant movement of the member K by a correspondingly-large amount.
It is, therefore, one of the objects of our present invention to furnish for use, in
connection with the other portions of our improved driving mechanisin, a variable
speed device or apparatus in operative connection with said principal driving-
member and with said in epe milently rotatable member; whereby the rotation

page_text: of the latter member relatively to the former member may be varied for
regulating at will, within a given range of movement, the velocity of the shaft A,
relatively to the principal driving member or wheel J.
Said variable-speed device consists of two portions: first, a controlling apparatus
in direct operative connection with said independently rotatable member G ; and
second, a variable-speed device proper.
Said controlling apparatus consists in some suitable gearing, whereby the proper
rotation and control of said member G may be secured; and it is one of the objects
of our present invention to provide for this purpose a controlling-gearing of
an approximately-neutral character, whereby, on the operation of the entire
mechanism, said controlling-gearing may be operated with a relatively-small
amount of power; so that, with a driving mechanism of relatively-large size and
great power, the variable-speed device may be of relatively-small size aud power,
while retaining a high degree of efficiency and reliability. Accordingly, we
provide the member G with a worm-wheel, which is designated by L, and which
is shown fixed on the member G by means of a key or like fastening device l.
It will, of course, be understood, that the gear L may be formed integrally
with the member G, or otherwise, as may be found preferable in any particular
instance. The gear-wheel L, meshes with a worm M, which is shown mounted on
the shaft m that is supported in the bearings xx of a bracket D', that is suitably
fixed on the bed D, and constitutes a portion of the frame-work of the mechanism.
The inclination of the teeth L and of the worm-thread of the worm M, should
be such, as to substantially coincide with the normal angle of repose, so as to be,
as herein stated, approximately neutral, so as to require a relatively-small amount
of power, either for holding the member G against rotation, or for causing the
same to rotate at any required speed (within the given limits) during the operation
of the entire mechanism.
For the purpose of actuating the worm M to give the variable speed required,
we provide a driving-disk O, which is mounted on the shaft N, that is supported
in some suitable bearings D³, and has a relatively-small gear N¹, fixed thereon,
meshing with the aforesaid driving-wheel or gear E on the band-wheel.
On the extended end of the shaft m, is mounted a frictional-wheel Q, which
is adapted to slide on said shaft--it being splined thereto-and whose rim is
adapted to frictionally engage the face of said driving-disk O.
For normally holding and adjusting the driving-disk in contact with said
frictional-wheel Q with a steady pressure, some suitable device as, for instance,
the spring P-is provided for bearing against the rearward end of the shaft N
for sliding said shaft in its bearing, to carry the disk O forcibly against the
frictional-wheel Q.
As a means for adjusting the position of the wheel Q, relatively to the axis of
the disk O, a guide device R is mounted to slide on the guide-rod d, fixed in the
bracket Di; the arm on said guide engaging in the groove formed in the hub of
said friction-wheel, whereby, this may be mounted radially on the disk O.
By means of this wheel-sliding device, the variable-speed device may be
regulated for varying the rotation of the worm M, and through this and the
gear L, the rotation of the member G for reducing by a greater or lesser amount
the movement of the shaft A, relatively to the movement of the driving-
member J.
When the driving-member Q is set, as shown by dotted lines at 20, Fig. 3,
immediately adjacent to the axis of the disk O, it is evident that the disk O will
only rotate the wheel Q with a relatively-small velocity, so as to rotate the
M relatively slow, and impart a correspondingly-slow rotation to the
member G, thereby subtracting but a small increment from the amount of
movement normally transmitted from the wheel J through the intermediate
wheels I and H to the driving-wheel K, when the member G is stationary.
worm
If, however, the wheel Q be slid outward on the shaft m, to a point more distant
from the axis of the disk O-as shown, for instance, by the solid lines at 10,

page_text: Fig. 3-it is evident that said disk will now impart a greater velocity to the
wheel Q, and force the worm M and the wheel L to give a correspondingly-greater
velocity to the member G, thereby subtracting a relatively-greater amount of
movement from the amount which would otherwise be transmitted from the
wheel J through said intermediate wheels to the driven-wheel K and the shaft or
spindle A.
By means of the described organization of my improved mechanism, whereby
the variability in the resultant movement-that is, the movement in the shaft A-
is effected by subtraction from a given resultant movement, and this subtraction
effected through a normal and approximately-neutral controlling device for the
member G, we are able to obtain a relatively-wide range of speed for the shaft A
by means of a relatively-small but efficient and reliable frictional driving device.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is:
1. In a driving mechanism, the combination with a driven-member carrying a
gear; of a tubular driving-member rotatably disposed on said driven-member, and
carrying a gear parallel with, and adjacent to the driven-member gear, and also
carrying a driving-wheel gear remotely disposed relatively to its other gear and
adapted to receive power; an independently-rotatable member comprising a
tubular sleeve supported on said driving-member, and carrying pinions meshing
with the parallel gears on the driving and driven-members, respectively, and
adapted to transmit power from the driving-member to the driven-member, and
also carrying a worm-wheel intermediate of its pinions and the driving-wheel
gear of the driving-member; a worm-shaft carrying a worm in mesh with the
worm-wheel; a friction-wheel adjustably supported on the worm-shaft and adapted
to control the speed of said worm, and whereby the velocity of the driven-member
relatively to the driving-member can be varied independently of the speed of said
driving-member; a disk-shaft extending parallel with the driving-member, and
carrying a rotating disk in engagement with the friction-wheel and adapted to
transmit power thereto; a gear on said disk-shaft in mesh with the driving-wheel
gear of the driving-member; and means for holding said disk in frictional
engagement with the friction-wheel, substantially as described.
2. In a driving mechanism, the combination with a driven-member having a
gear thereon; of a driving-member rotatably supported on said driven-member
and carrying a gear, and also having a driving-wheel gear thereon adapted to
receive power; an independently-rotatable member comprising a tubular sleeve
supported on said driving-member and carrying mechanism for transmitting power
from the driving-member to the driven-member, whereby said driven-member will
be rotated at a given speed from said driving-member independently of the speed
of the independently-rotatable member, and also carrying a worm-wheel; a worm-
shaft carrying a worm in mesh with said worm-wheel; an adjustable friction-
wheel supported on the worm-shaft and adapted to control the speed of said worm ;
and whereby the velocity of the driven-member relatively to the driving-member
can be varied independently of the speed of said driving-member; a disk-shaft
carrying a disk rotatable therewith and in frictional engagement with the friction-
wheel, and also carrying a gear in mesh with the driving-wheel gear ou the
driving-member, whereby power is transmitted to the adjustable friction-wheel
to vary the speed of rotation of the worm and thereby the driven-member,
substantially as described.
Dated this ol 1
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicants.