Note: Descriptions are shown in the official language in which they were submitted.
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The present invention generally relates to a power
, transmission element incorporating a positive drive connection
between a rotatable wheel and a flexible drive or driven member
in the form of a rope in which the periphery of the wheel in-
cludes a pair of divergent surfaces thus having a plurality of
circumferentially spaced and arranged impressions or grooves
therein which are substantially frustoconical in shape with
the tapering portions of the frustoconical shape extending along
the circumference of the wheel rather than radially thereof to
;~ 10 provide a positive drive connection between the wheel and rope.
Transmission of power by using a flexible power trans-
mitting element engaged with a pulley rotatable about an axle
has been used for many years and has included pulleys with flat
surfaces for engaging flat drive belts, pulleys with a V-shaped
groove for engaging V belts and similar types of structures in
which friction between the pulley and flexible element serves
to transmit power and to perform work. Various efforts have
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~ been made to modify rope pulleys to increase the frictional
; engagement between the rope and pulley but such devices usually
employ radial converging surfaces, such as ribs or lugs, on
the radially converging surfaces of the pulley groove which
increase friction but even so~ slippage will occur between the
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~ rope and pulley when a sufficient load iB encountered when the
,~ compressed diameter of the rope or cable i8 insertable in the
; narrowest construction of the walls of the pulley or sheave.
~; An ob;ect of the invention is to provlde a positive
drive element for the transmission of power between a com-
pressible filament such as a rope and a wheel having a uniquely
; constructed peripheral groove in which slippage is eliminated
by compression of the filament or rope.
A still further object of the invention is to provide
a positive drive transmission element which is quite simple in
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construction, easy to utilize in various power transmission
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: arrangements and efficient in positive transfer of driving
force.
; The present invention provides a positive drive power
transmission element comprising a generally circular wheel ~ .
adapted to be rigidly connected to an axle for rotational ::
: movement about an axle, the wheel including a peripheral groo~e .~ -
receiving a flexible, compressible filament and means incor- .
porated into the groove to provide a positive driving connection ..
between the wheel and filament, the means including a plurality ~ --
of equally spaced circumferentially extending semi-frustoconical
. impressions in each wall of the groove, the impressions being
:: arranged in pairs including a minor constriction area having .
: wall portions spaced apart a minimum distance and a major
constriction area having a pair of opposed curved walls spaced
apart a major dimension with the area between the major con-
: striction and the minor constriction being smooth, curved
. tapering wall surfaces tapering i.nwardly in the line of
:,. . .
- circumference of the wheel for compressing the filament to in-
;. crease the density thereof adjacent the minor constriction for
~ 20 locking the filament and wheel in relation to each other when
. the load is transmitted therebetween.
.. Figure 1 is a side elevational vi.ew, with portions
broken away, illustrating the present invention.
Figure 2 is an edge view of the positive drive wheel.
Figure 3 is a sectional view, on an enlarged scale, ;
:; taken substantially upon a plane passing along section line
3-3 of Figure 1.
Figure 4 is a sectional view, on an enlarged scale,
taken substanti.ally upon a plane passing along section line 4-4
of Figure 1, .
. Figure 5 is a developed section of the wall surface
. of one cycle of the periphery of the positive drive element
~ .
: illustrating the tapering construction of the semi-frustoconical
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grooves or impressions.
The positive drive power transmission element of the
present invention is in the form of a generally circular wheel
~: designated by reference numeral 10 and including a central
aperture 12 for mounting on a shaft or axle with the aperture
12 including a keyway 14 communicated therewith to receive a
; key for locking the wheel 10 to a shaft or axle for rotation
therewith so that power may be transmitted from the wheel to
the axle or from the axle to the wheel in a positive manner.
Engaged with the wheel 10 is a flexible compressible filament
-; 16 which, for the purposes of description, will be considered
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a rope although other equivalent types of flexible co~pressible filaments may
be employed. As illustrated, the wheel 10 is constructed of two plates 18 and
20 which are secured rigidly together in face to face relationship by a plural~
ity of screw threaded fasteners 22 which may be conveniently countersunk into
one plate and screw threaded into the other and terminating flush therewith
thus providing flat surfaces on the wheel 10.
As illustrated in the drawings, the peripheral edge of the plate 18
is provided with an inclined bevel 24 and the peripheral edge of the plate 20 is
provided with a similar inclined bevel 26 around the periphery thereof so that
the beveled surfaces or inclined surfaces 24 and 26 coact with each other when
the plates 18 and 20 are secured together to form a generally V-shaped peripheral
groove or recess in the wheel which may be considered similar to a V-shaped
groove in the periphery of the sheave of a V-belt drive pulley.
The wheel 10 has a unique and novel peripheral structure disposed at
the inner edge of the beveled or inclined surfaces 24 and 26 with the peripheral
surface having a peripheral groove defined therein by an offset shoulder 28 on
one of the plates, as illustrated in Figures 3 and 4. The groove has two walls
.,
; which are opposed to each other outwsrdly of the peripheral shoulder 28 in which
each groove wall is of identical construction and includes six depressions or im-
20 pressions along the line of circumference of the walls. Each impression or de-
? pression is generally designated by numeral 30 and include a ms~or width area 32
and a minor width area 34 with the impression 30 including semi-frustoconical
tapering surface areas 36 in each wall. As illustrated, ~ix cycles or impres-
sions are provided in the periphery of the wheel 10 with each cycle including a
continuous bottom wall defined by the shoulder 28 and the two walls of the groove
tapering along the line of circumference of the wheel from a ma~or spaced rela-
tion to a minor spaced relation in which the ma~or spaced relation is designated
by numeral 32 and the minor spaced relation 34 is spaced therefrom with the
walls between the ma~or and minor spaced relationships tapering inwardly as
~ 30 indicated by numeral 36 to generally form a semi-frustoconical configuration
i with the walls at the minor dimension 34 being substantially parallel and op-
posed as illustrated in Figure 3 and the wall~ at other places being curved as
indicated in Figure 4. This tapering construction of the walls of the impres-
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sions 30 provides for compression of the rope 16 30 that the density of the
rope engaging the tapering surfaces 36 opposed to the application of the load
to the rope will sec~rely lock the rope to the wheel 10 in a manner that will
prevent slippage.
In one practical embodiment of the invention which has been succes~-
fully tes~ed, a 9-inch diameter wheel was provided with the two plates being
~oined together with the width of the shoulder 28 being 1/8 inch so that the
minor transverse dimension or constriction 34 is 1/8 inch wide and the major
` dimension at 32 is 3/8 inch wide and the developed linear distance between
point 32 and point 34 in Figure 5 is two inches. The dimensional character-
istics may vary insofar as the diameter of the wheel and thickness of the wheel
i6 concerned but the ratio of the minor dimension or constriction and the major
dimension or constriction should remain approximately a one to two or three ratio
for compression of common rope with the taper from the maximum constriction at
point 32 to the minor constriction at point 34 being smooth and straight with
the walls being curved to approximate a semi-frustoconical shape although the
,
wall surfaces will define a cycloidal transition from the walls at point 34 to
; the curved walls at a point approaching point 32.
The construction of the wheel will transmit power between the wheel
and rope, round belt, cable or the like without slippage with the compression
of the rope preventing slippage rather than friction which occurs in most pulley
and rope drives. The compression locking flction is the function of the semi-
frustoconical impressions 30 in each wall of the tapered groove. The equally
spaced semi-frustoconlcal impressions mesh with the round belt, rope or cable
with the tapering construction of the opposed pairs of impressions compressing
the round belt, rope or cable and increasing the density thereof thus positively
connecting the round belt, rope or cable to the wheel. In the test model of the
invention dimensioned as set forth above, a 5/16 inch diameter solid braided
nylon rope was employed with the rope or cord positioned onto the wheel with a
tail length of the cord hanging toward the floor and the other end of the cord
was connected to a losd of 1000 pounds and torque exerted on the wheel in a
direction to lift the load. When the nylon cord had been stretched to near
breaking point, the apparatus was stopped and it was noted that the cord had
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not and did not slip even though tangentially held by only one tapered groove
in the periphery of the wheel and the tail length of the nylon cord was hanging
free and completely slack while the portion of the cord running through the
load is stretched out to near its breaking point.
Even though the walls of the semi-frustoconical impressions are smooth
surfaces and do not provide any substantial coefficient of friction, slippage
- was eliminated by virtue of compression of the rope with the compression of the
rope increasing the density thereof with the rope being locked with a resistance
equal to an infinite load as the load is applied. Thus, the wheel of this
invention does not reduce or retard slippage through friction since it does not
incorporate friction in the working principle. The substantially semi-frusto-
conical impressions in which the taper is in the direction or line of circum-
ference provides the mechanical function of locking the rope to the wheel in a
pobitive relationship for transferring driving force therebetween.
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