Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to endless bands,
belts, tracks, or the like of the type which are used in
caterpillar-type ofvehicles or as conveyor belts.
In particular, the present invention relates to
a construction of this type which is composed of a series of
units which are pivotally connected one to the next so as to
~ form the endless band structure the length of which is deter-
mined by the number of these units which are pivotally connected
one to the next, with this endless band structure having
elongated endless portions which are both stretchable and
non-stretchable.
Although structures of the above general type are
known, the known structures are not always as durable and as
reliable in service as might be desired, under all operating
conditions. In addition, the known structures are not fully
reliable with respect to the transmission of traction or guiding
forces.
Thus, particularly endless tracks of Caterpillar*
type of vehicles are known to suffer from the drawback of
being susceptible to breaking particularly at their central
regions because at the wheels or rollers around which such a
track is guided the track tends to bulge or buckle as the
track tends to deform from the configuration of part of a
cylinder to a configuration bent inwardly from such a cylinder,
primarily as a result of forces of tension which act on the
track. For these reasons conventional tracks receive detrimen-
taldeformations and in addition loud noises are created when
such a track becomes deformed. These drawbacks result from
the fact that the entire tension force in the endless track
structure or in an equivalent conveyor belt is substantially
uniformly distributed over the entire breadth of the endless
structure.
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It is accordingly a primary object of the present
invention to provide an endless structure of the above general
type which is durable and reliable in service under any and all
conditions ! even under highly exacting operating conditions.
It is also an object of the present invention to
provide an endless structure capable of effectively achieving
transmission of traction forces to the endless structure or of
guiding the endless structure with a greater reliability than
is possible with conventional endless structures of the above
type.
A further object of the present invention is to
provide a structure capable not only of avoiding the drawbacks
referred to above but also capable of presenting a rolling
resistance which is less than thàt of known endless structures of
the above general type, while achieving a reduction in energy
losses incurred as a result of deformation of the endless
structure, as compared with previously known endless structures
of the above general type.
While the above objects are applicable both to
- 20 conveyors as well as to vehicle tracks, in connection with
vehicle tracks it is also an object of the present invention
to provide a superior frictional engagement with respect to a
surface on which the track travels, with this superior friction-
al engagement with the travelling surface being achieved by way ~-
of a surface pattern which inherentIy is produced in the struc-
ture of the endless track of the invention.
Furthermore it is an object of the present invention
-to provide an endless structure of the above general type which
requires less material than required by corresponding previous-
ly known endless structures. This particular advantage isspecially important in that manufacturing costs of endless tracks
or conveyor belts are devoted to an extent of approximately
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50% to the costs of the raw materials which are used.
In order to achieve the above objects, among others
which will become apparent, the invention includes an endless
structure which has at least two substantially non-stretchable
continuous endless portions, which extend in the direction of
travel of the endless structure when it forms a vehicle track,
and which may be constituted by reinforcing elements of the end-
less structure or by other equivalent components of units which
are connected together to form the endless structure, with the
endless structure of the invention having at its marginal
regions or at its center an elongated endless resilient sheet
means capable of behaving in a spring-like manner and being
reversibly deformable in the direction of its own plane.
Thus, according to the invention,there is provided an
elongated endless structure adapted to be used for purposes such
as an endless track of a Caterpillar*type of vehicle or as a
belt conveyor, this elongated endless structure including an
elongated endless flexible means for extending around and being
guided by at least a pair of rotary members which have in at
least one position of operation a pair of parallel axes around
which transverse end regions of the endless means are adapted
to curve, with this endless means having when these axes are
parallel a pair of opposed endless side edges respectively
situated in edge planes which are parallel to each other and
normal to the above axes when the latter are parallel. This
endless means includes at least a pair of longitudinally extend-
ing elongated endless portions which are substantially non-
stretchable at least in the longitudinal direction and which
are spaced from each other in the transverse direction with
respect to the end-less means while being symmetrically situated
with respect to the above edge planes. The endless means
includes also an elongated endless resilient sheet means for
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s-tretching and contracting in response to encountering and being
relieved from forces which tend to stretch the sheet means,
and this sheet means of the elongated endless means is also
symmetrically arranged with respect to the above edge planes
when the above axes are parallel to each other.
The invention is illustrated by way of example in
the accompanying drawings which form part of this application
and in which:
FIG. 1 schematically illustrates in a fragmentary
side elevation one possible embodiment of an endless structure
of the invention shown in FIG. 1 guided around a pair of end
rolls which respectively have horizontal axes while being
incapable of turning about axes, such as vertical axes, which
are perpendicular to these horizontal axes;
FIG. 2 is a fragmentary schematic plan view of part
of the endless structure of FIG. 1 taken along line II-II of
FIG. 1 in the direction of the arrows;
FIG. 3 is a schematic side elevation of another em-
bodiment of an endless structure according to the invention also
shown on end rolls which cannot turn about upright axes;
FIG. 4 is a fragmentary schematic plan view of
part of the endless structure of FIG. 3 taken along line IV-IV
of FIG. 3 in the direction of the arrows;
FIG. 5 is a schematic fragmentary plan view of a -
further embodiment of an endless structure of the invention;
FIG. 6 is a fragmentary schematic plan view of a
further, highly preferred embodiment of the invention;
FIG. 7 shows part of the structure of the embodiments
of FIGS. 4-6 taken along line VII-VII in FIGS. 4-6, in the
direction of the arrows;
FIG. 8 also shows part of the structure of FIG~. 4-6,
taken along line VIII-VIII of FIGS. 4-6, in the direction of
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the arrows; and
FlG. 9 is a sectional view of part of the structure
of FIG. 5 taken along line IX-IX of FIG. 5 in the direction of
the arrows.
Referring now to FIG. 1, there is illustrated therein
an endless track structure 10 of the invention shown in FIG. 1
- extending around a pair of rotary members 20 and 21 which in
the illustrated example may be considered as forming part of a
snowmobile, for example, so that in the example of FIG. 1 the
endless structure 10 forms part of a caterpillar-type of vehicle.
In this example it is assumed that the snowmobile is provided
with rotary members 20 and 21 which while capable of turning
about their own horizontal axes are incapable of turning about
upright axes so that they cannot steer the vehicle. Instead
such a vehicle is provided with one or more separate steering
skis.
The endless structure 10 is made up of a series of
identical transverse units 11 each having opposed transverse
edge regions each of which is provided with a means for pivotally
connecting the opposed edge regions of each unit 11 to the ad-
joining edge regions of adjoining units 11 in such a way that
these units 11 can pivot one with respect to the next about an
axis which is parallel to the axes of the rotary members 20 and
21. Thus, FIGS. 1 and 2 schematically illustrate adjoining
edge regions 19 of adjoining units 11, these edge regions 19
carrying the means for pivotally connecting the units one to the
next, as described in greater detail below. Thus, the pivotally
interconnected units 11 form the elongated flexible endless
structure 10 in the form of an elongated endless flexible means
capable of extending around and being guided by the pair of
rotary members 20 and 21 the axes of which are parallel to each
other in the illustrated example at all times.
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Thus, as is shown in FIG. 2, the endless means 10
terminates in a pair of outer side edges which are respectively
situated in vertical edge planes which are parallel to each other
and which are normal to the axes of the rotary members 20 and 21.
Situated symmetrically with respect to these edge
planes, inwardly therefrom, are a pair of elongated endless
substantially non-stretchable portions 15 and 16 of the endless
means 10. ~s is apparent from FIG. 1, the substantially non-
stretchable endless portions 15 and 16 which are identical are
thicker than the remainder of the endless means 10, extending
inwardly beyond the remainder of the endless means 10, with the
rotary members 20 and 21 being provided, for example, with annular
grooves for receiving these thicker substantially non-stretchable
portions 15 and 16. Thus, each unit 11 has a pair of portions 11a
and 11b respectively forming part of the substantially non-
stretchable endless portions 15 and 16. These portions 11a and ~ -
11b of each unit 11 may be suitably reinforced so as to have the
required rigidity. Each unit 11 may have in a known way at its
thicker portions 11a and 11b substantially no capability of
stretching whereas outwardly beyond these portions 11a and 11b
each unit has thinner substantially wavy sheet portions which ~ --
are capable of resiliently stretching and contracting. Thus
the endless portions 15 and 16 are substantially non-stretchable.
The above-referred to outer portions 12 and 13 are however capable
of stretching and contracting, forming an elongated endless
resilient sheet means for the endless means 10, with these
portions 12 and 13 being capable of stretching in response to
encountering forces which tend to stretch the portions 12 and 13
while these portions are also capable of contracting when relieved
of these forces which tend to stretch the same~ Thus the portions
12 and 13 of the endless means 10 form an endless sheet means
which in a springy manner is capable of stretching in the
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direction oE the plane of the track, while also being contract-
able, as required. These portions 12 and 13 can have a wavy,
corrugated or accordion-like configuration.
In the example shown in FIG. 2, between the sub-
stantially non-stretchable endless portions 15 and 16 the end-
less means 10 has an endless portion 14 which also is substan-
tially non-stretchable. Thus the part of each unit 11 which
forms the central portion 14 of the endless means can also be
made of a material thicker than the wavy portions 12 and 13 and
being substantially non-stretchable. If desired, however, the
portion 14 may be stretchable and may have a construction conform-
ing to the wavy structure of the parts 12 and 13. In this latter
event it is possible to provide a third endless substantially
non-stretchable portion 17 as shown in dotted lines in FIG. 2,
this portion 17 in this case having the same structure as the
portions 15 and 16. Thus, with these different possible construc-
; tiOI15 the stretchable and non-stretchable portions are symmetric-ally arranged with respect to the edge planes in which the
opposed side edges of the endless means 10 are located.
As is indicated in FIG. 2, the substantially non-
stretchable endless portions 15 and 16 formed by the series of
parts 11a and 11b of each unit 11 have inner regions of a
configuration adapted to conform with structure for providing
traction or guiding for the endless means 10. In the illustrated
example this structure takes the form of inner regions of the
portions 11a and 11b which are formed with recesses 18 adapted
to receive teeth projecting from the rotary members 20 and 21
in the grooves thcrcof which receive the substantially non-stretch-
able portions 15 and 16. Thus these portio-ns form the equivalent
of chain-like tooth portions which operate in cooperation with
teeth of the rotary members 20 and 21 for bracing the endless
means against the rotary members of the vehicle. This construc-
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tion is particularly useful when the rotary member is capable of
turning about an upright axis for the purpose of steering as
well as for the purpose of providing traction and guiding. Thus
through this construction it is possible to transmit the traction
or steering force to the endless means in at least a pair of
vertical planes in which the non-stretchable portions 15 and 16
- are situated, so as to achieve in this way a significant
advantage in practice.
Referring now to FIG. 3, there is also illustrated
therein, by way of example, an endless means 10 forming a track
of a snowmobile provided with non-swivelling rotary members 24
and 25 around which the endless means 10 is guided in the manner
illustrated, this snowmobile having one or more steering skis.
The rotary members 24 and 25 can take the form of suitable rolls
or wheels. The endless means of FIG. 3 is also made up of a
series of transversely extending identical units 11 pivotally
joined to each other at their transversely extending end edge
regions in the manner described above, these end edge regions 19
; also being indicated in FIG. 3. As is apparent from FIG. 4,
this endless means 10 also has a pair of elongated endless sub-
stantially non-stretchable portions 15a and 16a disposed sub-
stantially symmetrically between while being spaced inwardly
from the edge planes which contain the opposed side edges of the
endless means 10. Thus the pair of substantially non-stretch-
able endless portions 15a and 16a are situated equidistantly
from a central vertical plane situated midway between the edge ~-
planes and extending in the general direction of travel of the
vehicle. Thus each unit of this embodiment of FIGS. 3 and 4
also has the stlff portions 11a and 11b respectively situated
in end-to-end relation at the several units 11 so as to form
substantially non-stretchable endless portions 15a and 16a.
Although the particular endless means 10 of FIG. 3
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is shown partially in a plan view :in FIG. 4, FIGS. 5 and 6
illustrate also partially in a plan view possible other embodi-
ments of the endless means 10 of the invention. Thusin each
of the embodiments of EIGS. 4-6 there is situated between the pair
of endless non-stretchable portions 15a, 16a of FIGS. 4 and
5 and 1Sb, 16b of FIG. 6 a central endless region 14 which is
in the form of at least part of an endless resilient sheet means
of the endless means 10, this elastic central portion 14 having
a wavy-corrugated, or equivalent zig-zag or accordion-shaped
construction and possessing a relatively high degree of elastici-
ty. I-lowever, in the embodiments of FIGS. 4-6, these substantial-
ly non-stretchable portions 15a, 16a, and 1Sb, 16b are formed
with openings 21' passing therethrough instead of recesses 18
as shown in FIG.2, the latter recesses extending only part of
the way through the non-stretchable substantially rigid portions
11a and 11b of each unit 11 of FIG. 2. Thus, as may be seen
from FIG. 8, the openings 21' pass completely through the sub-
stantially rigid portions 11a and 11b made of a relatively thick
plastic composition, which may include a suitable rubber or the
like, if desired, which has very little if any capability of
stretching and contracting. These openings 21' receive the
sprockets 26 whiGh are fixed and project from the rotary
members 24 and 25.
In the embodiment of FIG. 4, the non-stretchable
portions 15a and 16a are situated adjacent the edge planes while
between the latter and these portions 15a and 16a the illustrated
endless means 10 has the relatively narrow marginal portions 12a
and 13a which are endless and which also are part of the resilient
sheet means being stretchable and contractable and having the
same wavy configuration as the portion 14 of FIG. 4. Thus, with
the embodiment of FIG. 4, except for the endless portions 15a
and 16a, the remainder of the means 10 is stretchable.
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I~owever, with the embodiment of FIG. 5, the outer
marginal portions 12b and 13b are non-stretchable. Thus the
marginal portions 12a and 13a of FIG. 4 have the construction
shown in FIG. 7 while the marginal portions 12b and 13b of
- FIG. 5 have the construction shown in FIG. 9. These portions
12b and 13b of FIG. 5 can be in the form of plate-like elements
- which while being sufficiently flexible to conform to the
curvature of the members 24 and 25 nevertheless cannot stretch.
In the embodiment of FIG. 6, the non-stretchable end-
less portions 15b and 16b are situated directly at the edge
planes forming the outer margins of the endless means 10 of
this embodiment so that the embodiment of FIG. 6 does not have
any structure conforming to the marginal portions 12a, 13a of
FIG. 4 or the marginal portions 12b, 13b of FIG. 5.
The endless means oE FIGS.3-9 derive its strength,
particularly in the direction of travel, from the non-stretch-
able portions 15a, 16a and 15b, 16b. The remainder of the
structure is substantially freely deformable. When the endless
track 10 or an equivalent conveyor belt is provided with the
construction of FIG. 6 where the non-stretchable portions are
situated at the outer side regions, then there is the further
advantage that these marginal portions, which otherwise might
be susceptible to rupture, can be made as durable as possible.
Thus, the greater thickness and/or different composition of the
substantially non-stretchable portions 15a, 16a and 15b, 16b, as
compared to the thinner corrugated configuration of the stretch-
able portions provide the endless means 10 with considerable
strength while at its stretchable portions the endless means
10 is free to stretch and contract as required.
~s is apparent from FIGS. 7-9, when the endless
means 10 is to be used as a track~for a vehicle, it is provided
at each unit 11 with exterior transversely extending ribs 23
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which extend completely across each unit 11, being situated at
the lower crests of the corrugations of the stretchable portion
14, as indicated in FIG. 7. Thus these outer transverse ribs
23 provide for an endless track of a vehicle the capability of
affording a relatively great friction with respect to a surface
on which the track travels.
- As is shown in FIG. 7, the upper crests of the
corrugations are also provided with transverse ribs 22 which
provide the endless means 10 with a relatively large surface
area at its interior capable of contacting the rotary members
24 and 25. Thus in this way there is provided for the endless
means of the invention, whether it is in the form of a track
or a conveyor belt, a large supporting surface for engaging the
rotary members around which the endless means is guided.
As indicated above, the tension forces to which the
endless means 10 is subjected, whether it be a track or conveyor
belt, are concentrated at the substantially non-stretchable end-
less portions 15, 16 of FIG. 2, 15a, 16a of FIGS. 4 and 5, and -
15b, 16b of FIG. 6. In addition, the wavy elastic portions
forming the resilient sheet means of the endless means 10 afford
a considerable saving of material as a result of the fact that
this resilient sheet material means is relatively thin. The
elastic central region 14 is made elastic to the required
degree, in the direction of its own plane and the plane of
travel of the track, so that the track is capable of deforming
at the rotary members around which it is guided, in such a
manner that there will be no buckling and no loud reports or
noises. In addition, this central region of the endless means
is made elastic to the required degree with a view to adapting
it to the particular terrain on which the track will be required
to travel, so that it will not be subjected to excessively
localized loads when encountering objects such as tree stumps
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and stones, for example. Wlth a particular embodiment of an
enclless track according to the invention, the track forms an
endless track for a snowmobile and has a width of about 600mm,
while its tension force is about 2500 N, and this force is
predominantly distributed between the pair of substantially
non-stretchable endless portions 15, 16 of FIG. 2, 15a, 16a,
- of FIGS . 4 and 5, and 15b, 16b of FIG. 6 . It will be noted
tl1at it is through these substantially non-stretchable portions
that the transmission of the driving force to the track 10 is
provided.
Referring to FIGS. 7-9, it will be seen that the
transverse edge regions 19 of each unit 11 is formed with a
bore 20' passing therethrough. These edge regions 19 are of
a castellated step configuration, with each unit 11 having
along its left edge 19 as viewed in FIGS. 7-9 a series of
notches and along its right edge as viewed in FIGS. 7-9 a
series of notches which are out of line with the notches at
the left edge so that there are formed along one edge of each
unit 11 a series of projections which are aligned with notches
at the opposite edge. In this way when a pair of units 11 are
placed next to each other they can be interdigitated at their
adjoining edges, so that the bores 20' of the pair of units
will become aligned, and a suitable rod is passed through
these aligned bores of the interdigitated pair of units to
provide the means which pivotally interconnects each pair of
units 11 for turning movement one with respect to the next
about an axis which is parallel to the axis of a rotary member
such as the members 20, 21, 24, and 25.
As is apparent from the above, the structure of
the invention may also be used as a conveyor belt, achieving
many of the advantages referred to above in connection with a
track. However when used as a conveyor belt the elasticity of
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the central area or other details of the design may be determined
by the particular material which is to be conveyed. With the
track of the invention a dense surface pattern is inherently
obtained, resulting, for example, in a multitude of projec-
tions 23 which provide a better grip than has previously been
achieved for the travelling surface. For example these ribs
23 afford an excellent friction with respect to snow.
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