Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to composite gears or
sprocket wheels. More particularly, the invention relates to such
gears or wheels where the outer teeth or sprocket members, ~or
engaging other gears or chains, are formed independently on a gear
blank or center portion and are mounted on the rim of the blank to
complete the gear or sprocket.
The invention provides a transmission member comprising
the combination of an inner blank having a circular outer rim, a
strip of molded flexible plastics material substantially equal in
length to the circumference of said blank rim and cut from an
indeterminate length of the plastics material and fastened around
said blank and having radially directed teeth for engagement with
cooperating teeth on an interconnected transmission member, said
strip of plastics material having longitudinal cord means embedded
therein, and said blank having a slot in its rim and said strip of
plastics material having radially inwardly projecting locking means
locked in said slot.
This invention makes use of known techniques for forming
a variety of strips, belts or chains of differing shapes by a
continuous plastic extrusion and molding process. Such belts
include teeth or sprocket engaging members formed of a plastic
body which is reinforced with embedded non-stretchable cable or
cording. These belts or chains, with their integral teeth or chain
engaging members, provide an inexpensive and effective outer work-
ing surface for the gears or sprocket wheels. The central blank
is easily molded or otherwise formed of plastic or metal with a
smooth or grooved rim to which a section of the belt material is
attached. These blanks are rapidly and inexpensivel~ manufactured
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since they require no precision molding or machining of the
critical tooth or sprocket portions. The strips for forming the
teeth or sprockets, on the other hand, are easily and inexpensively
manufactured by known continuous extrusion molding processes,
wherein a plastic body portion including precisely ~ormed teeth or
sprockets are molded around embedded strengthening members such as
metal or fiber reinforcing cords.
Thus, each gear or sprocket in accordance with the
invention includes the central gear blank or disc surrounded by an
outer working portion comprising a circular section formed of end-
less strip, belt or chain cu-t to length and cemented, screwed,
snapped or otherwise attached to the blank. The term gear as used
herein is meant to designate such generally similar items as years,
or sprocket wheels or toothed wheels or the like.
other features of the present invention will become
apparent upon an understanding of the illustrative embodiments
about to be described or will be indicated in the appended claims,
and various advantages not referred to herein will occur to one
skilled in the art upon employment of the invention in practice.
BRIEF DESCRIPTION OF T~IE DRAWINGS
A preferred embodiment of the invention has been chosen
for purposes of illustration and description and is shown in the
accompanying drawings, forming a part of the specification, wherein:
Figure 1 is a side elevational view of a continuously
molded belt-like member for forming the outer portions of gears or
sprocket wheels in accordance with the present invention.
Figure 2 is a vertical sectional view of the member of
Figure 1 mounted on a gear blank forming a sprocket wheel.
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Figure 3 is a side elevational view illustrating a sprocket wheel as
illustrated in Figure 2 in engagement with an endless chain.
Figure 4 is a fragmentary perspective view of a continuously molded
flexible gear belt for use in the gears of the invention.
Figure 5 is a perspective view of a preferred embodiment of a composite
gear in accordance with the invention.
Figure 6 is a Eragmen-tary side elevational end view of t}le gear of
Figure 5 partially in section.
Figure 7 is a fragmentary perspective view of another embodiment of a
continuously molded belt for use with the composite gears of the invention.
Figure 8 is a side elevational view of another embodiment of a con-
tinuously molded belt-like member for use in the gear or sprocket wheels of the
invention.
Figure 9 is a vertical sectional view of a sprocket wheel having an
outer chain engaging member as illustrated in Pigure 8.
Figure lO is a perspective view of a gear in accordance with the
invention illustrating a composite gear having an outer toothed belt member
attached by a plurality of screws to an inner gear blank or disc.
DESCRIPTION OF TIIE PREFERRED EMBODIMENT
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Figures 1 through 3 illustrate one embodiment of a composite sprocket
wheel 1 in accordance with the invention and formed by the method of the inven-
tion. The composite sprocket wheel 1 includes a central blank or disc 2 having
a central hub 3 with the usual shaft mounting hole 4. The rim 5 of the blank
2 is provided with an inwardly directed circular slot 6 for engaging the spaced
locking projections 7 formed of the molded belt-like me~ber 8 as illustrated in
Figure 1. The belt-like member 8 is formed by known extrusion methods whereby a
surrounding plastic body portion 9 is extruded and molded surrounding an embedded
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reinforclng cable 10 which ls Eiber or s-teel or a combination thereof. The
plastic portion may te nylon or polyurethane or other suitable plastics. The
belt-like member 8 includes rounded sprockets or teeth 11 shaped for engaging
a particular sprocket chain or belt 12 of the general type illustrated in Figure
2. The bottom portion of the belt-like member body 9 has the identical spaced
locklng projectlons 7 for engaging the slok 6 in the blank 2. The projections 7
have a generally truncated pyramidal shape as lllustrated in ~igures 1 and 2 wi-th
a central slot 13 providing flexibility for blank mounting and having spaced
locking flange portions 14 -for engaging the Eacing circular flanges 15 of the
gear blallk slot 6. The composite sprocket wheel 1 is assembled by cutting a
length of the belt-like member 8 to the exact length required to encircle the
blank 2. Thereafter, this cut portion is snapped into place in the above des-
cribed groove 6 with the locking projectlons 7 holding the short section of the
belt-like member 8 in position. ~hile the section of belt 8 may require no
additional fastening, it is also possible that the facing ends may be either
welded or cemented or otherwise fastened together and to the gear blank 2.
Figures 4, 5 and 6 illustrate another embodiment more particularly
useful as a gear 20 for engaging other gears or appropriately toothed belts or
chains. This embodiment employs a generally similar central gear blank or disc
21 having a hub 22 and a mounting hole 23. Figure 4 lllustrates a portion of
a continuously extruded and molded flexible gear belt 24 having molded teeth 25.
The belt 24 is also formed by kno~n continuous molding processes and includes
a molded plastic body portion 26 reinforced by a pair of cords 27 of fiber or
steel or a combination fiber and steel. The gear 2Q is also assembled by cutting
an appropriate length from the belt 2~ which will encircle the outer generally
cylindrical rim 28 of the gear blank 21 in the manner illustrated in Figures 5
and 6. In this case, the portion of the belt 24 is cemented or otherwise
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fastened to the outer rim 28 Oe the gear blank 21 to form the completed compos-
ite gear 20.
Figure 7 illustrates another embodiment of an extruded belt 30 for
use as the outer portion of a composite gear. This also is a flexible molded
belt with teeth 31 similar to a timing belt or other belt and having a molded
plastic body 32 with embedded flexible cords 33. This embodiment has spaced
apertures 3~ for use with mounting screws or pins Eor attaching it to a gear
blank. It also illustrates another form o:E tooth having spaced projecting side
flanges 35 which are useful in certain applications for acting as side guides
for a timing belt or other belt.
Figure 8 illustrates another embodiment of a belt ~0 which has the
general form of spur gear stock. The belt 40 has the usual plastic molded body
41 with reinforcing embedded cords~ 42 (Figure 91- Spaced spur teeth or sprockets
43 extend from ~he body 41 of the belt 40. Figure 9 illustrates the belt 40
cut to encircle a spur gear blank 44 where the outer ~ortion of the belt 40 is
cemented into an appropriate circular groove 45 at the rim of the blank 44.
Figure 10 illustrates a composite gear 50 employing screw fastenings
51 for holding the outer toothed belt portion 52 in place on a gear blank 53.
It will be seen that an improved composite gear or sprocket wheel has
been described ~hich is formed from a novel combination of an extruded belt-like
plastic member with a gear blank. This novel combination is particularly advan-
tageous as it permits the inexpensive manufacture of gearing and also permits
gears or sprocket wheels to be manufactured with a wide variety of differing
si~es, shapes, and specifications as needed and in either large or small numbers
as required at a given time for use with other transmission memberssuch as gears
or belts of chains and the like.
As various changes may be made in the -form, construction and arrange-
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ment of the parts herein without sacrificing any o~ its advantages, it is to be
understood that all matter herein is to be interpreted as illustrative and not
in a limiting sense.
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