CA1087656A

CA1087656A - Endless structure for a conveyor or vehicle track

Info

Publication number: CA1087656A
Application number: CA293,476A
Authority: CA
Inventors: Jorma T. T. Pohjola
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-12-20
Filing date: 1977-12-20
Publication date: 1980-10-14
Also published as: SE7714324L; FI55155B; SE440740B; JPS5396132A; JPS6128545B2; FI55155C; DE2756620A1; FI763658A

Abstract

ABSTRACT OF THE DISCLOSURE:

An elongated endless structure which is adapted to form an endless track of a vehicle or a belt conveyor includes an elongated endless flexible band 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 band are adapted to curve, with this endless band having when these axes are parallel a pair of opposed endless side edges which are respectively situated in edge planes which are parallel to each other and normal to the above axes when they are parallel to each other. This endless band includes at least a pair of longitu-dinally extending elongated endless portions which are sub-stantially non stretchable at least in the longitudinal direc-tion and which are spaced from each other in the transverse direction with respect to the endless band while being symme-trically situated with respect to the above edge planes. Also, the endless band includes an elongated endless resilient sheet structure for stretching and contracting in response to en-countering and being relieved from forces which tend to stretch this resilient sheet structure, and the resilient sheet structure is also situated symmetrically with respect to the above edge planes when the above axes are parallel to each other.

Description

10~656 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.
* Trademark -- 1 -- .

.

~0~656 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 ~ ' ~0876$6 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 * Trademark -10~76S6 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 .

~' `'"~ .

- - . - . . .
. ~. . . .. ~ . , : :

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.

"~
~ ~ :
- : : . . . :
.: . ~ : . : . , :
- ' -' ' '-: . - . ~ ' , ' :... . . .

~ !37656 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 .,. " ~ .

' ' ' . - ' ' ' ' .: . .. : . ~ ' . .

1~7~56 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-,' - .

:- . . . ~ . - .
,.: . . : ~ . . . . ~

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 : :~
, j .

- : :
~ ' 1~7656 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.

_ g _ '', , , '. ' 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 ' ,, , "'' ~

,, .
, ~7656 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 .~ :
- -- : ,: ~ -.

. . :

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 , ~ :, ~' ' : :~- .

1~76~6 , 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.

' - 13 -~ ~ ' , . : .,

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An elongated endless structure adapted to be used as a vehicle track or as a belt conveyor, comprising 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 said endless means are adapted to curve, with said endless means having when said axes are parallel a pair of opposed endless side edges respectively situated in edge planes which are parallel to each other and normal to said axes when the latter are parallel, said endless means including at least a pair of longitudinally extending elongated endless portions which are substantially non-stretchable at least in the longitudinal direction and are spaced from each other in the transverse direction with respect to said endless means while being symmetrically situated with respect to said edge planes, and said endless means including an elongated endless resilient sheet means for stretching and contracting in response to encountering and being relieved from forces which tend to stretch said sheet means, and said sheet means of said elongated endless means also being symmetrically arranged with respect to said edge planes when said axes are parallel to each other.

2. An elongated endless structure as claimed in claim 1, wherein said elongated substantially non-stretchable portions of said endless means are situated on opposite sides of and are equidistant from a central plane which is situated midway between and parallel to said edge planes.

3. An elongated endless structure as claimed in claim 1, wherein said pair of elongated substantially non-stretchable portions of said endless means are situated inwardly between and respectively at equal distances from said edge planes, said resilient sheet means being situated between said edge planes and said pair of substantially non-stretchable portions while between the latter non-stretchable portions said endless means is also substantially non-stretchable.

4. An elongated endless structure as claimed in claim 1, wherein except for said non-stretchable portions, the remainder of said endless means is formed by said resilient sheet means.

5. An elongated endless structure as claimed in claim 1, wherein said substantially non-stretchable portions of said endless means have inner regions conforming with driving or guiding components.

6. An elongated endless structure as claimed in claim 5, wherein said inner regions of said substantially non-stretchable portions are formed with recesses for receiving driving or guiding components.

7. An elongated endless structure as claimed in claim 1, wherein said elongated substantially non-stretchable portions of said endless means are respectively situated adjacent said edge planes while at least the part of said endless means situated between said pair of substantially non-stretchable portions thereof is formed by said endless resilient sheet means.

8. An elongated endless structure as claimed in claim 7, wherein said pair of substantially non-stretchable portions are situated directly next to said edge planes, respectively.

9. An elongated endless structure as claimed in claim 7, wherein between said edge planes and said substantially non-stretchable portions said endless means includes a pair of elongated relatively narrow marginal endless portions forming part of said resilient sheet means.

10. An elongated endless structure as claimed in claim 7, wherein between edge planes and said pair of non-stretchable portions of said endless means the latter has a pair of elongated relatively narrow endless marginal portions which also are substantially non-stretchable.

11. An elongated endless structure as claimed in claim l, wherein said elongated endless resilient sheet means has a wavy, substantially corrugated or zig-zag construction.

12. An elongated endless structure as claimed in claim 1, wherein said endless means is made up of a series of transversely extending units each having opposed transversely extending edge regions respectively carrying means for pivotally connecting said edge regions to adjoining edge regions of adjoining units for providing between adjoining units the capability of turning one with respect to the other about an axis parallel to said pair of axes when the latter are parallel to each other.

13. An elongated endless structure as claimed in claim 1, wherein said pair of non-stretchable portions of said endless means are integral with said endless resilient sheet means and defined by reinforced portions greater in thickness than the endless sheet means.