WO1991011357A1

WO1991011357A1 - Belt for track laying vehicles

Info

Publication number: WO1991011357A1
Application number: PCT/AU1991/000029
Authority: WO
Inventors: James Arthur Nagorcka
Original assignee: Warane Pty. Ltd.
Priority date: 1990-01-25
Filing date: 1991-01-24
Publication date: 1991-08-08

Abstract

A drive belt (1) comprising an endless elastomeric main body (3) and reinforcing means (10) which comprises an endless flexible band (20, 30) is disposed effectively within and generally parallel to a longitudinal plane containing a longitudinal axis A-A of the main body, the flexible band including uninterrupted sections including a first group (23, 31) which extend in a direction generally parallel to the longitudinal axis and a second group (24, 32) which extend in a direction laterally of the longitudinal axis. In one form the band (20) comprises a flexible sheet (20) having a plurality of perforations (21) therein which are arranged so as to form the uninterrupted sections therebetween. In another form the band comprises a plurality of flexible interwoven filaments (31, 32) arranged to form the groups of uninterrupted sections.

Description

"IMPROVED BELT OR TRACK FOR TRACK LAYING VEHICLES"

This invention relates generally to track laying vehicles and more particularly, to an improved track therefor. For many years attempts have been made to design a successful endless elastomeric track or belt to replace steel tracks for work and recreational vehicles. Work vehicles that have either a positive drive or a friction drive between the belt or track and the drive wheel need reinforcing filaments to give the belt or track longitudinal and lateral strength and stiffness while maintaining a flexible characteristic.

Many previous proposals have used multi-layered flexible cables moulded into the belt or track structure to achieve this. An example of such an arrangement is described in Australian Patent No. 578,537 in which the first ply portion in the body of the belt consists of cable for sustaining tension loads and is substantially parallel to the longitudinal plane and the interior surface of the belt. A second and third ply portion in the body of the belt are arranged to achieve a positive and negative bias angle and placed substantially parallel to the inner belt surface and adjacent to the first ply. The second and third ply portions are designed to achieve a certain amount of lateral stability. However, multi-layered reinforcing filaments create high shear stress within the body of the elastomeric belt and can lead to temperature increases and belt separation. This problem can be best understood by reference to Figure 8 of the drawings of the specification.

In Figure 8 there is shown an elastomeric belt 50 entrained around an idler or drive wheel 60. The belt or track 50 has a longitudinally extending reinforcing filament 52 substantially parallel to the inner surface 53 of belt 50. The belt or track 50 also has a second longitudinal or inclined reinforcing filament 51 substantially parallel to longitudinal filament 52 and the inner surface 53 and outer surface 54. When the belt or track 50 is laid on a flat surface, the two filaments at any point are in a particular position relative to one another. When entrained around the wheel 60 there is a lateral displacement between the same two points on the two filaments because of the difference in path radius around the wheel. This indicated by dimension Dl. This difference in length dimension Dl creates shear stress within the belt with resultant temperature increase in the belt and possible belt separation. A further problem associated with tracks of belts of this type is schematically shown in figure 9. Belts or tracks are often subjected to side loads L such as, for example, when the vehicle is turning. Such side loads can cause a phenomenon often referred to as "snaking" where the belt will deform as indicated by dimension D2. An object of the present invention » is to provide an improved track suitable for use with a track laying vehicle which alleviates one or more of the above problems.

According to the present invention there is provided a drive belt comprising an elastomeric main body which is adapted to be arranged in an endless configuration having an inner surface, an outer surface and opposed edge portions with a longitudinal axis A-A which extends generally in the direction of travel of the belt when in use and a longitudinal plane which contains the longitudinal axis and is generally parallel to the inner surface of the main body and reinforcing means characterized in that said reinforcing means comprises a flexible band which is adapted to be arranged in an endless configuration and is disposed effectively within and generally parallel to the longitudinal plane of the main body said flexible band including uninterrupted sections including a first group which extend in a direction generally parallel to the longitudinal axis of the main body and a second group which extend in a direction laterally with respect to the longitudinal axis of the main body.

The arrangement is such that the reinforcing means of the invention provides the belt or track with strength in both the longitudinal directions and lateral directions effectively within a single plane and thereby alleviating the problems associated with shear stress within the belt. In one form of the invention the band comprises a flexible sheet having a plurality of perforations therein which are arranged so as to form the uninterrupted sections therebetween including a first group which extend in a direction generally parallel to the longitudinal axis of the main body and a second group which extend in a direction laterally with respect to the longitudinal axis of the main body. Most advantageously, the uninterrupted sections in the second group are inclined at an angle between the longitudinal axis and an axis which is at right angles to the longitudinal axis.

The sheet may advantageously be formed from metal. Preferably the sheet is disposed internally of the main body between the inner and outer surface thereof. The elastomeric main body may be formed from two layers one each side of the sheet and bonded th » ereto with the assistance of the perforations.

Preferably the perforations are in the form of holes arranged in a series of groups, the perforations in each group being spaced apart from one another and extending in a direction generally parallel to the longitudinal axis of the main body, the groups of perforations being spaced apart so as to form the sections of uninterrupted sheet in the direction of the longitudinal axis. Preferably the perforations in adjacent groups are off-set from one another in the longitudinal direction so that the sections of uninterrupted sheet in the lateral direction are inclined to an axis which is at right angles to the longitudinal axis.

In another form of the invention, the flexible band comprises a plurality of interwoven reinforcing filaments arranged to form said groups of the uninterrupted sections including a first series of filaments forming the first group in the direction of the longitudinal axis of the main body and a second series of filaments forming the second group in a direction laterally of the longitudinal axis, said interwoven filaments being effectively disposed in said longitudinal plane. Advantageously, the lateral series of filaments are interwoven with the longitudinal series of filaments such that each lateral Filament passes over one of the longitudinal filaments and then under the next adjacent longitudinal filament and so on so as to form a mat which is effectively disposed within the longitudinal plane. As mentioned earlier, in a most advantageous form, the uninterrupted sections in the second group are inclined at an angle between the longitudinal axis and an axis which is at right angles to the longitudinal axis. For both forms of the invention, the second group of uninterrupted sections may include two sub-groups including a first sub-group inclined in one direction with respect to the aforementioned axes and a second group which is inclined in another direction with respect to the aforementioned axes. That is the two sub-groups provide a positive and negative bias ply. It will be appreciated that insofar as the second series of filaments are concerned they could be made up of a continuous length which is interwoven across and back with respect to the first series in crisscross fashion. Preferably the flexible woven reinforcing filaments are formed from wire rope or cable. The woven reinforcing filaments may be disposed internally of the main body between the inner and outer surface thereof. Preferably the main body is formed from two layers one each side of the filaments and bonded thereto with the assistance of the open area between the sections.

Preferably the filaments are arranged in a group of longitudinal filaments which are arranged so as to be spaced apart from one another and extending in a direction generally parallel to the longitudinal axis of the main body so as to form uninterrupted sections in the direction of the longitudinal axis and a group of filaments arranged in spaced apart relation and extending at an inclined angle to the longitudinal axis and an axis which is at right angles to the longitudinal axis.

Preferably each of the lateral filaments comprises at least two filament elements wound together said filaments interweaving with the longitudinal filaments.

If desired, a further reinforcing means may be provided in spaced relation to the longitudinal plane having uninterrupted sections which extend generally at right angles to the longitudinal axis. It will be appreciated that with a belt of the type according to the invention the longitudinally uninterrupted sections are capable of sustaining tension in the longitudinal direction and the lateral uninterrupted sections are capable of maintaining substantial lateral stiffness without distortion due to imposed lateral loads in a single plane thereby avoiding the problem of shear stress discussed earlier. Preferred embodiments of the invention will hereinafter be described with reference to the accompanying drawings in which:

Figure 1 is a schematic plan view of a section of reinforcing member according to a first embodiment of the present invention;

Figure 2 is a partial sectional view of a belt or track according to the present invention incorporating the reinfo » rcing member shown in Figure 1;

Figure 3 is a schematic plan view of a section of reinforcing member according to a second embodiment of the present invention;

Figure 4 is a partial sectional view of a belt according to the present invention incorporating the reinforcing member shown in Figure 3; Figures 5 and 6 are sectional views taken along A-A in Figure 3 showing the reinforcing member in a flat configuration and in a configuration when entrained around a wheel;

Figure 7 is a schematic side elevation of the belt according to the present invention entrained around a wheel; Figure 8 is a schematic view of a belt showing the effect of entrainment around a wheel; and

Figure 9 is a schematic view of a belt illustrating the effect of side forces on a belt.

Referring to the drawings and in particular to Figures 1 to 4 where like parts have been identified with like reference numerals for both embodiments there is shown a belt generally indicated at 1 comprising a main body 3 having an inner surface 4 and an outer surface 5. The main body 3 is formed of elastomeric material and comprises two layers 3A and 3B. A longitudinal axis A-A extends in the longitudinal direction of the belt and a longitudinal plane contains the axis A-A and extends between the sides 8 and 9 of the belt and parallel to the inner surface 4. The belt is provided with reinforcing means 10 in the form of a flexible band which is disposed within the longitudinal plane of the belt.

With reference to Figures 1 and 2 of the drawings in this embodiment, reinforcing means 10 comprises a flexible band in the form of a substantially non-extensible endless yet flexible steel sheet 20 placed in the endless elastomeric main body substantially parallel to the longitudinal plane and the interior surface 4 of the main body.

The flexible yet inextensible steel sheet 20 has perforations 21 therein which in the form shown are round holes .which form uninterrupted longitudinal sections 23 and uninterrupted lateral sections 24.

The lateral spacings Y between the perforations 21 of the sheet 20 give the elastomeric belt or track the necessary longitudinal strength to sustain high tension and drive loads D as well as giving the belt or track an inextensible characteristic. This is necessary for a highly tensioned frictional drive belt and for a positively driven elastomeric track. The longitudinal spacings Z between the perforations 21 of the filament give the elastomeric belt or track the necessary lateral stiffness to resist the lateral side loads L and stops "snaking" of the belt or track when the vehicle is turning. These lateral spacings Z also act as a positive and negative bias ply with angle α . The perforations 21 of the sheet allow bonding of the two elastomeric layers 3A and 3B to form a single body of the belt or track.

With reference to Figures 3 and 4 in this embodiment, the reinforcing band comprises substantially non-extensible yet flexible band of wire cables 30 making up a mat placed in the endless main body 3 of an endless elastomeric drive belt or track- substantially parallel to the longitudinal plane and the interior surface 4. The flexible yet inextensible woven cables 30 form longitudinal filaments 31 and inclined lateral filaments 32. Preferably the cables used to form the longitudinal filaments are heavier than the cables used to form the inclined lateral sections. The longitudinal filaments of the woven reinforcing mat give the elastomeric belt or track the necessary longitudinal strength to sustain high - 7 - tension and drive loads as well as giving the belt or track an unextensible characteristic. This is necessary for a highly tensioned frictional drive belt and for a positively driven elastomeric track. The woven lateral sections or cables of the filament give the elastomeric belt or track the necessary lateral stiffness to resist lateral side loads and prevent deformation or "snaking" of the belt or track when the vehicle is turning.

The woven lateral sections or cables of the band also act as a positive and negative bias ply with diagonal angle α . The open areas of the band allow bonding of the two elastomeric layers 3A and 3B to form a single body of the belt or track.

Shear stresses do not occur in the woven flexible band as the lateral diagonal filaments woven around the longitudinal filaments maintain generally equal length along the filament centre line whether the filament centre line is on a flat plane or entrained around a radius such as a drive wheel or idler wheel.

Finally, various alterations, modifications and or additions may be incorporated into the various constructions and arrangements of parts without departing form the spirit and ambit of the invention.

Claims

1. A drive belt (1) comprising an elastomeric main body (3) which is adapted to be arranged in an endless configuration having an inner surface (4), an outer surface (5) and opposed edge portions (8, 9) with a longitudinal axis A-A which extends generally in the direction of travel of the belt when in use and a longitudinal plane which contains the longitudinal axis and is generally parallel to the inner surface (4) of the main body (3); and reinforcing means (10) characterized in that said reinforcing means (10) comprises a flexible band (20, 30) which is adapted to be arranged in an endless configuration and is disposed effectively within and generally parallel to the longitudinal plane of the main body said flexible band including uninterrupted sections including a first group (23, 31) which extend in a direction generally parallel to the longitudinal axis of the main body and a second group (24, 32) which extend in a direction laterally with respect to the longitudinal axis of the main body.

2. A drive belt according to claim 1 wherein said band (20) comprises a flexible sheet (20) having a plurality of perforations (21) therein which are arranged so as to form said uninterrupted sections therebetween including a first group (23) which extend in a direction generally parallel to the longitudinal axis of the main body and a second group (24) which extend in a direction laterally with respect to the longitudinal axis of the main body.

3. A drive belt according to claim 2 wherein said sheets formed from metal sheet.

4. A drive belt according to claim 2 or claim 3 wherein sheet is disposed internally of said main body between the inner and outer surface thereof.

5. A drive belt according to any one of claims 2 to 4 wherein said main body (3) is formed from two layers (3A, 3B) one each side of said sheet and bonded thereto with the assistance of said perforations (21).

6. A drive belt according to any one of claims 2 to 5 wherein said perforations (21) are in the form of holes arranged in a series of lines, the perforations in each group being spaced apart from one another and extending in a direction generally parallel to the longitudinal axis of the main body, said lines of perforations being spaced apart so as to form said sections of uninterrupted sheet in the direction of the longitudinal axis.

7. A drive belt according to claim 6 wh »erein said perforations in adjacent lines are off-set from one another in the longitudinal direction so that the sections of uninterrupted sheet in the lateral direction are inclined α.to an axis which is at right angles to the longitudinal axis.

8. A drive belt according to claim 1 wherein said flexible band (30) comprises a plurality of flexible interwoven filaments (31, 32) arranged to form said groups of uninterrupted sections including a first series of filaments forming the first group (31) in the direction of the longitudinal axis of the main body (3) and a second series of filaments forming the second group (32) in a direction laterally of the longitudinal axis said interwoven filaments being effectively disposed in said longitudinal plane.

9. A drive belt according to claim 8 wherein said first series of filaments are disposed generally parallel to one another in side by side relation and said second series of filaments extend laterally winding over one of the first series and then under an adjacent filament across the series.

10. A drive belt according to claim 8 or 9 wherein said flexible woven reinforcing filaments are formed from wire rope or cable.

11. A drive belt according to claim 8, 9 or 10 wherein said woven reinforcing filaments are disposed internally of the main body between the inner and outer surfaces thereof.

12. A drive belt according to claim 11 wherein said main body is formed from two layers one each side of the filaments and bonded thereto with the assistance of the open area between the sections.

13. A drive belt according to claim 8, 9,10, 11 or 12 wherein said filaments are arranged in a group of longitudinal filaments (31) which are arranged so as to be spaced apart from one another and extending in a direction generally parallel to the longitudinal axis of the main body so as to form uninterrupted sections in the direction of the longitudinal axis and a group of filaments arranged in spaced apart relation and extending at an inclined angle α to the longitudinal axis and an axis which is at right angles to the longitudinal axis.

14. A drive belt according to claim 13 wherein each of the lateral filaments comprises at least two filament elements wound together said filaments interweaving with the longitudinal filaments.