US3667308A

US3667308A - V-belt

Info

Publication number: US3667308A
Application number: US91984A
Authority: US
Inventors: Johann Schwab; Anna Magritsch
Original assignee: Semperit AG Holding
Current assignee: Semperit AG Holding
Priority date: 1969-12-03
Filing date: 1970-11-23
Publication date: 1972-06-06
Anticipated expiration: 1989-06-06
Also published as: CH528687A; FR2072729A5; DE2058764B2; DE2058764A1; CS162626B2; GB1281850A; BE759825A; AT305709B

Abstract

A raw-edged V-belt which is of the type embodying at least a top cover layer, reinforcement insert means, and a substantially trapezoidal-shaped core formed of an elastomer. According to important aspects of the invention, the top cover layer is formed of a fiber fleece or a wide-meshed fabric completely impregnated with an elastomer. If desired, the raw-edged V-belt construction of the invention may further be equipped with a bottom cover layer. The invention further contemplates that one or both cover layers of the V-belt consist of an elastomer of low modulus of elasticity, but higher breaking elongation, than the elastomer of the core.

Description

O United States Patent 1151 3,667,308 Schwab et a1. June 6 1972 54] V-BELT 2,690,985 10/1954 Poole ..74/237 ux m1 Johann schwab, Vienna; Anna Merits, 5123332 3132? 173252; .ffiiifiii Mar'a Enzersdmf bmh Ausma 3,190,137 6/1965 Adams, Jr ..74 233 [73] Assignee: Semperit AG, Vienna, Austria 3,566,706 3/1971 Fix ..74/233 [22] Filed: 235 1970 Primary Examiner-Leonard H. Gerin [211 App] No 91 984 AttorneyWerner W. Kleeman [57] ABSTRACT [30] Foreign Apphcatlon Pnonty Data A raw-edged V-belt which is of the type embodying at least :1

Dec. 3, 1969 Austria ..l 1267 top cover layer, reinforcement insert means, and a substantially trapezoidal-shaped core formed of an elastomer. Ac- 52 us. 01 ..74 233, 74 237 cording to important aspects of the invention, the p cover [51] lnLCL 1 5 1 1 1 22 layer is formed of a fiber fleece or a wide-meshed fabric 58 Field ofSearch ..74 231 R237, 234, 233 completely impregnated with an elaswmaf- If desired, the raw-edged V-belt construction of the invention may further be [56] References Cied equipped with a bottom cover layer. The invention further contemplates that one or both cover layers of the V-belt con- UNITED STATES PATENTS sist of an elastorner of low modulus of elasticity, but higher breaking elongation, than the elastorner of the core. 2,631,463 3/1953 Waugh ....74/233 X 2,526,324 10/1950 Bloomfield ..74/237 X 19 Claims, 2 Drawing Figures PATENTEBJUH 6 m2 3, 667, 308

INVENTOR JOHHNN H h/HB BNNH I? 196R I T2509 BY wsRNe 7% wkle EMQ-NN ATTORNEY V-BELT BACKGROUND OF THE INVENTION The present invention broadly relates to V-type belt constructions and, more specifically, deals with a new and improved construction of raw-edged V-belt which is of the type embodying a top cover layer, reinforcement insert means, a core and, if desired, a bottom cover layer.

It is well-known that the conical sides or flanks of a V-belt are destined to contact the correspondingly shaped surfaces of the V-belt pulley, therefore these sides serve to transmit forces. Since considerable forces come into play due to the prevailing tension, especially at the sides of the V-belt, when the latter is mounted at such belt pulleys, in most instances the prior art resorted to providing the V-belt formed of different elastic materials, typically rubber, and containing reinforcement inserts, with a so-called wrapper or enclosure which extended about the entire cross-section of the V-belt. In other words, the prior art utilized the technique of enclosing or wrapping the V-belt with an enclosure which was generally formed of a rubberized fabric. Typical constructions of such wrapped V-belts can be found in US. Pat. No. 2,621,528, granted Dec. 16, 1952, of Enrique L. Luaces and Melvin A. Crosby, entitled V-BELT HAVING METALLIC NEUTRAL AXIS", US. Pat. No. 2,677,969, of Dale L. Waugh, entitled V-BELT and the further US. Pat. No. 2,71 1,778 ofthe lastmentioned inventor, entitled V-BELTS AND THE METHOD OF MAKING THE SAME.

It should be understood that such wrapped belts are not only expensive to manufacture, but additionally, result in irregularities in the surface of the belt due to the automatically occurring overlapping of the start and terminal portions of the enclosure. In other words, the application of a wrapper or enclosure to a belt causes material to accumulate at certain locations of the belt which tends to generally impair the proper running, longevity and durability of such type belts.

Hence, in order to overcome the drawbacks associated with the wrapped-type V-belt constructions proposals were made towards the fabrication of V-belts without these wrappings or enclosures, so-called raw-edged V-belts wherein the sides or flanks are exposed. Typical constructions of the prior art rawedged belts can be found in US. Pat. Nos. 2,430,024, 2,631,463, 2,642,751, 2,677,969, 2,711,778, 3,051,212 and 3,416,383, by way of example.

Even though shifting of the design of a V-belt from the wrapped type to the raw-edged type tended to at least overcome the difficulties experienced with wrapped belt constructions, still the raw-edged V-belt had to cope with the drawbacks that adherence of the individual layers of the V-belt (baseand reinforcement insert, cover layer, etc.) to one another had to be particularly good, since in the presence of the tension forces to which the V-belt was subjected by the V- belt pulleys, the individual layers had the tendency of detaching from one another. Moreover, the locations of cutting the reinforcement insert and the cover layer were subjected to increased attack, since generally they could not be bonded by a sufficient impregnation or by the rubber.

Therefore, prior art raw-edged V-belts generally consist of an impregnated fabric insert at the base of the V-belt possessing good adherence properties, a core formed of a rubber mixture of, for instance, 80 to 85 Shore, a reinforcement insert formed of polyester cord wound in the peripheral direction or with a slight inclination, and a cover layer formed of an impregnated fabric likewise possessing good adhering properties and composed of three to four fabric layers. As a general rule, the fabric layers consist of cotton since the adherence problems can be most easily overcome because of the large number of individual fibers, in that, for instance, at the calender machine there can be frictionally applied to the cotton fabric the desired rubber mixture or composition.

However, the prior an raw-edged V-belts of this type generally possess two basic drawbacks. The fabric material located at the base of the V-belt reduces the elasticity of the belt at that location. Should the fabric layer at the base of the V-belt become damaged even if such damage is slight because of the repeated bending and rolling movements of the belt which occur during continuous operation, then such damage can eventually lead to a tearing or rupture of the fabric inasmuch as from the moment of time where the base layer has become damaged a considerable portion of the deformation energy tends to concentrate at this location. Consequently, the tendency towards the formation of fissures or tears at the core of the V-belt can increase.

On the other hand, the fabric layers of the raw-edged V-belt at the top thereof, notwithstanding their treatment tending to impart thereto good adherence'properties, nonetheless still have the tendency of disconnecting from one another and from the reinforcement inserts, owing to the previously mentioned pronounced loads which are applied to the sides of the raw-edged V-belt which, in turn, can lead to premature wear of such V-belts.

Accordingly, the raw-edged belt constructions of the prior art, including those using rubberized fabric layers as the top and/or bottom layer, have not been able to successfully cope with the aforementioned difiiculties existant in such rawedged V-belts during use thereof.

SUMMARY OF THE INVENTION Accordingly, a real need still exists in the art for a rawedged V-belt construction which is not associated with the aforementioned drawbacks of the prior art. A primary object of the present invention, therefore, relates to an improved construction of raw-edged V-belts which effectively fulfills this need and overcomes or at least minimizes the difficulties associated with the prior art belt constructions of this type.

Still a further significant object of the present invention relates to an improved construction of raw-edged V-belt which is economical to manufacture, provides for increased durability and adherence of the various layers and components of the belt to one another during operation, therefore affording increased belt longevity, and generally, tends to provide a belt construction of the type mentioned which is superior to the prior art constructions.

Now, in order to implement these and still further objects of the present invention, which will become more readily apparent as the description proceeds, it has been surprisingly found that significant advantages can be obtained if, contrary to the prior art teachings using simply a rubberized fabric as the top and/or bottom layer, there is used at least for the top layer of the belt either a fiber fleece or a wide meshed fabric which is completely embedded with an elastomer. The use of a fiber fleece or a wide-meshed fabric as opposed to the conventional fabric layers of the prior art allows for positive imbuing of such with the elastomer. As the fiber fleece there can be used a non-woven fabric or web, the fibers of which are randomly oriented or, at best, only slightly oriented, and specifically preferably transversely with respect to the direction of travel of the belt. While a wide-meshed fabric can be employed in the practice of the invention, it is here mentioned that the use of a randomly oriented or only slightly oriented fiber fleece is most preferred, with random-orientation being considered the most desirable. In this regard, there is preferably used a fiber fleece or wide-meshed fabric formed most preferably of polyamide fibers, although other materials such as polyester fibers, steelwool, glass fibers, by way of example, may conceivably also be used in the practice of the invention.

Considering then the invention in its most basic concepts, there is provided a raw-edged V-belt embodying a top cover layer formed of a fiber fleece or a wide-meshed fabric completely imbued with an elastomer, reinforcement insert means, and a substantially trapezoidal-shaped core formed of elastomeric material. If desired, a further cover layer may be provided at the base of the V-belt which likewise contains or is imbued with an elastomer.

According to a further aspect of the invention, at least one of both cover layers consists of an elastomer of lower modulus of elasticity but higher breaking elongation than the elastomer of the core.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawing wherein:

FIG. 1 is a schematic cross-sectional view of a first embodiment of inventive raw-edged V-belt designed according to the teachings of the present invention; and

FIG. 2 is a similar cross-sectional view of a modified form of a raw-edged V-belt construction of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now the drawings, there is shown in FIGS. 1 and 2 two exemplary embodiments of inventive raw-edged V-belt constructions. More specifically, in FIG. 1 there is shown in cross-sectional view a raw-edged V-belt possessing the top cover layer 1, reinforcement insert means 2 and a core 3, whereas the modified form of V-belt construction of FIG. 2 additionally possesses two adhering layers 4 as well as a bottom cover layer 5 provided at the base of the V-belt.

There is advantageously employed as the top cover layer a rubber impregnated randomly oriented fiber fleece and instead of the previously used prior art fiber layer at the base of the V-belt there is employed a rubber cover layer possessing a modulus of elasticity which is less than a third, preferably about one-sixth, of that of the core mixture. The breaking elongation of the base mixture should be more than twice, preferably about four times, that of the core mixture. The Shore hardness is advantageously less by about to about 30, preferably about 20, than that of the core mixture. If desired, the same relationship noted above may be provided for the top cover layer and the core.

Due to these measures the forces acting upon the open sides of the V-belt are considerably absorbed. The rubber layer at the base of the V-belt, which possess a lower modulus of elasticity, however a higher breaking elongation than the core mixture and/or the use of an elastomer imbued-randomly oriented fiber fleece, bring about a comparative distribution of the kinkand rolling loads at the base of the V-belt.

Pressing of a soft rubber layer onto the base of a V-belt equipped with an enclosure prior to vulcanization is known and in such instance functions as a dust protective device. Such a rubber layer, however, is inserted in the mold and thus must amount to at least one to 2 millimeters, and, on the other hand, does not prevent rupture of the enclosure, since during use such is loaded to the same extent as in the absence of the soft rubber layer.

Furthennore, not only is there considerably improved by the inventive teachings anchoring of the cover layer upon the reinforcement layer, by means of the fiber fleece or wide meshed fabric which is completely imbued by the rubber mixture, but furthermore due to the embuing of this fiber material with the rubber mixture, at the cut open sides of the belt there no longer occur any damaging effects due to the tension forces acting upon the freely exposed cut ends of the fibers of the sides of the V-belt subjected to tension.

According to a preferred manifestation of the present in- .vention the optionally employed softer rubber mixture used for the base of the V-belt simultaneously is used as the imbuing-or embedding mixture for the material of the top cover layer and/or as the adhering agent between the reinforcement inserts and-the cover layer and core respectively. In order to provide an oil-resistant V-belt it is possible, for instance, to

* use the following exemplary formulation:

Furthermore, an alternative imbuing mixture in which chloroprene and SBR (styrene butadiene rubber) are mixed with one another and compatible, consistsof the following composition:

50 parts Chloroprene (W-Type neoprene of Dupont) 50 parts SBR 35 parts SFR-gas black 5 parts Zinc oxide 4 parts Magnesium oxide 3 parts aromatic plasticizer 1 part N-Cyclohexyl-2-benzothiazolsulfenamide l part sulphur 0.5 parts Tetramethylthiuram monosulfide The last-enumerated formulation for the imbuing mixture should not be used for the core since it possesses insufficient oil resistance.

As top cover layer there can be employed a non-compacted polyamide randomly-oriented fiber fleece of a thickness 1.5 to 2 mm with a surface weight of 200 g/m, which preferably is prepared with a resorcinol fonnaldehyde resin-vinylpyridine latex-mixture. The fleece is then imbued with a 25 percent solution or dispersion of the imbuing mixture in toluol, squeezed between two rolls and dried in a hot air channel at 70 C. to C. In this manner it is possible to apply in a single working operation, 400 g/m rubber, whereby the fleece already compacted to a thickness of one millimeter possesses a surface weight of 600 g/rn.

In comparison, when imbuing a conventional fabric of the prior art as discussed above, in one work operation there could only be applied at most 40 g/m rubber, because suchis more compact. Therefore, there was more of a tendency to frictionally apply the rubber mixture to the fabric, to which end there was, however, required at least two working operations. In addition, it was oftentimes necessary to initially imbue it with a thin solution. Furthermore, the fabric can only be cut diagionally, the fleece on the other hand can be applied in the direction of travel.

In order to further elucidate the invention, the following examples are now given:

EXAMPLE I In order to fabricate V-belts 9.5 X 900 there is wound upon a suitable winding drum a glass clear polyester foil of a thickness 0.1 to 0.2 mm as the separation agent, and which is fixedly retained by an adhesive foil or clamped into the drum segment. Upon this foil there is applied over the entire width the base plate in a thickness of 0.4 mm. which has been drawn at the calender, and at the joint overlaps by about 2 to 3 mm. Now the core mixture drawn at the calender to a plate thickness of 1.2 mm is wound-up fourfold, so that there results a core height of about 4.8 mm. Possibly appearing joints are distributed or displaced, respectively, towards the overlapping of the base plate over the periphery of the winding drum. The same holds true for the subsequent adhering layer at which there is now applied a layer of a 0.4 mm thick base plate. Now an appropriately prepared polyester cord 1000/3 X 2 of a den sity of 85 threads/100 mm is wound up, and again thereover a base plate. The cover forms two layers of the just-mentioned preprepared fleece imbued with the rubber solution.

The pre-preparation solution is prepared as follows: A solution of 3 parts of a 37 percent formaldehyde solution, 5.5 parts resorcin and 11 parts water are permitted to stand for 1 hour. There is thereafter added to parts of this solution 37 parts of an approximately 40 percent vinylpyridin latex, such is allowed to stand for several hours, and then is subsequently thinned with water to an approximately 25 percent total solid content and a pI-I-value of 7.4 to 7.9.

The cylindrical jacket now formed at the drum is either vulcanized in a press for minutes at a steam pressure of four atmospheres gauge, or vulcanized with an externally bearing rubber membrane (inside 4 atmosphere gauge, outside 10 atmospheres gauge steam pressure) for 15 minutes. The V-belts are removed in known manner from the vulcanized cylindrical jacket.

EXAMPLE II The V-belt back or top, preferably upon a separation foil, is initially built-up in the reverse manner from that described with respect to Example I. Initially a very wide meshed, diagonally cut polyamide fabric destined to serve as the cover layer, and which has been pre-prepared and imbued as described above for the fleece, is wound upon a forming core. In the same manner as in Example I, there are added the base plate, the cord winding and again a base plate. It has now been found advantageous, even though not absolutely necessary, if the thus formed pre-molded article is pre-vulcanized for about one-third of the above indicated vulcanization time. Subsequent thereto the mold core containing the V-belt back and if desired likewise prevulcanized is inserted into an outer mold or form which forms the core volume of the later single core belt. The core mixture is then now applied by means of injection or transfer molding. There is provided the advantage of an almost 30 percent saving in material because during removal now only the back layers of the V-belt need to be separated.

During this mode of operation it is possible to either dispense with the application of a base plate, or such can be applied in a subsequent separate work operation, in that, for instance, the V-belt is introduced into a second mold having a hollow compartment for the base plate and the base mixture is similarly formed as the core mixture. The V-belts are then turned prior to being used.

As already mentioned above, for the fabrication of the inventive V-belt there is preferably used for the cover layer 1 a non-compacted fiber fleece which, however, need not necessarily be formed of polyamide fibers, rather depending upon the desired properties can consist of polyester fibers, glass fibers, cotton or the like. Particularly interesting is the use of fleeces fonned of steel wool, as well as those formed of polyurethane fibers. The fleece can be completely unoriented i.e. consist of randomly arranged fibers. If there is present a light or more pronounced orientation, then such preferably should only be present in one direction, whereby the orientation of the fibers of the fleece during formation of the V-belt should be transverse to its travel direction. As a result, there is additionally provided an interesting reinforcement effect of the cover layer.

In the event a wide meshed fabric is employed, then the mesh width should be so large that the rubber layers provided at both sides of the wide meshed fabric are completely riveted to one another through a sufficient large number of cross or transverse connections. Naturally this is dependent upon the thickness of the threads or fibers, the orientation of the fibers and the plasticity of the mixture. The previously mentioned imbuing mixture can be, for instance, applied to a polyamide fabric of a surface weight 200 g/m formed of fibers of 840 denier with a fiber arrangement of fibers per 10 centimeters in the warp and weft. The fabric is preferably cut at an angle of 45, in order to ensure a sufficient elasticity and symmetry for the layer. In the event that a cover layer is used which is formed of two fabric layers, then the angles can also be smaller than 45, however preferably not smaller than 10.

As the elastomer, especially for the core mixture, apart from the previously known rubber mixtures and the chloroprene qualities described previously there can also be conceivably used polyurethane elastomers. In so doing, one is preferably concerned with linked products which, as in the examples described are connected in a build-up technique or, however, in an injection molding or casting technique, with the reinforcement inserts and the cover layers, whereby in the last-mentioned situation there can be employed a relatively thin-liquid two component mixture. In this case, the preparation for the fleece or the wide meshed fabric for the cover layer as well as for the reinforcement inserts should be appropriately compatible with polyurethane, and can for instance be formed on a isocyanate basis.

Suitable for the reinforcement inserts 2 of the invention are polyester cords as well as glass cords. It is here also remarked that the top cover layer serves as protection for the cords against external mechanical influences. The cord cannot be situated completely at the outside of the belt for reasons of deformation, rather must be located in the so-called neutral zone. Moreover, the back or top region of the belt must possess a certain rigidity or stiffness in order that it does not tend to assume a concave configuration when it is trained about the belt pulleys. As a general rule, the reinforcement cords are located approximately 1 to 2 mm beneath the upper external edges of the V-belt. Additionally, it is here mentioned that the core mixture should be electrically conductive owing to the static charge. In conventional belts with a wrapper the inner core must not be conductive, although the wrapper or enclosure should be, and specifically possesses a resistance of 10 ohms. The core mixture of the present invention, however, possesses an electrical resistance of only 10 to 10 ohms. This is attributable to the relatively large amount of carbon black. Furthermore, it is advantageous if the base cover layer 5 does not contain fleece, much less a fabric, because neither one or the other of these materials can be readily dammed-up or compressed. Yet, during deflection of the belt about belt pulleys possessing a small diameter, experience has shown that the base cover layer tends to markedly compress or dam-up.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

Accordingly what is claimed is:

l. A raw-edged V-belt comprising at least a top cover layer, reinforcement insert means disposed beneath said top cover layer, and a substantially trapezoidal-shaped core located beneath said reinforcement insert means, said top cover layer being formed of a material selected from the group consisting essentially of fiber fleece and wide-meshed fabric, completely impregnated with an elastomer.

2. A raw-edged V-belt as defined in claim 1, wherein said core contains an elastomer, and wherein the elastomer of said top cover layer possesses a lower modulus of elasticity and a higher breaking elongation than the elastomer of said core.

3. A raw-edged V-belt as defined in claim 1, further including a bottom cover layer disposed beneath said core.

4. A raw-edged V-belt as defined in claim 3, wherein said core contains an elastomer, and said bottom cover layer contains an elastomer possessing a lower modulus of elasticity and a higher breaking elongation than the elastomer of said core.

5. A raw-edged V-belt as defined in claim 3, wherein the modulus of elasticity of the elastomer of said cover layers amounts to less than one-third of the modulus of elasticity of the elastomer of the core.

6. A raw-edged V-belt as defined in claim 5, wherein the modulus of elasticity of the elastomer of said cover layers amounts to about one-sixth of the modulus of elasticity of the elastomer of the core.

7. A raw-edged V-belt as defined in claim 5, wherein the breaking elongation of the elastomer of said cover layers is more than twice the breaking elongation of the elastomer of the core.

8. A raw-edged V-belt as defined in claim 7, wherein said breaking elongation of the elastomer of said cover layers amounts to about four times the breaking elongation of the elastomer of the core.

9. A raw-edged V-belt as defined in claim 5, wherein the Shore-A-Hardness of the elastomer of said cover layers is in a range of about 10 to about 30 lower than the Shore-A-Hardness of the elastomer of the core.

10. A raw-edged V-belt as defined in-claim 9, wherein the Shore-A-Hardness of the elastomer of said cover layers is preferably about less than the Shore-A-Hardness of the elastomer of the core.

11. A raw-edged V-belt as defined in claim 1, wherein said fiber fleece is formed of randomly oriented fibers.

12. A raw-edged V-belt as defined in claim 1, wherein said fiber fleece possesses fibers which are slightly oriented in a direction transverse to the direction of travel of the V-belt.

13. A raw-edged V-belt as defined in claim 1, wherein said fiber fleece is a polyamide fiber fleece.

14. A raw-edged V-belt as defined in claim 1, wherein the V-belt contains an elastomer incorporating a sulphurmodified chloroprene.

15. A raw-edged V-belt as defined in claim l, further including adhering layers disposed at both sides of said reinforcement insert means.

16. A raw-edged V-belt as defined in claim 1, wherein said wide-meshed fabric consists of polyamide fibers.

17. A raw-edged V-belt as defined in claim 1, wherein said fiber fleece is formed of steel wool.

18. A raw-edged V-belt as defined in claim 1, wherein said fiber fleece is formed of polyurethane fibers.

19. A raw-edged V-belt comprising at least a top cover layer, reinforcement insert means disposed beneath said top cover layer, and a substantially trapezoidal-shaped core located beneath said reinforcement insert means, said top cover layer being formed of fiber fleece impregnated with an elastomer.

Claims

2. A raw-edged V-belt as defined in claim 1, wherein said core contains an elastomer, and wherein the elastomer of said top cover layer possesses a lower modulus of elasticity and a higher breaking elongation than the elastomer of said core.
3. A raw-edged V-belt as defined in claim 1, further including a bottom cover layer disposed beneath said core.
4. A raw-edged V-belt as defined in claim 3, wherein said core contains an elastomer, and said bottom cover layer contains an elastomer possessing a lower modulus of elasticity and a higher breaking elongation than the elastomer of said core.
5. A raw-edged V-belt as defined in claim 3, wherein the modulus of elasticity of the elastomer of said cover layers amounts to less than one-third of the modulus of elasticity of the elastomer of the core.
6. A raw-edged V-belt as defined in claim 5, wherein the modulus of elasticity of the elastomer of said cover layers amounts to about one-sixth of the modulus of elasticity of the elastomer of the core.
7. A raw-edged V-belt as defined in claim 5, wherein the breaking elongation of the elastomer of said cover layers is more than twice the breaking elongation of the elastomer of the core.
8. A raw-edged V-belt as defined in claim 7, wherein said breaking elongation of the elastomer of said cover layers amounts to about four times the breaking elongation of the elastomer of the core.
9. A raw-edged V-belt as defined in claim 5, wherein the Shore-A-Hardness of the elastomer of said cover layers is in a range of about 10 to about 30 lower than the Shore-A-Hardness of the elastomer of the core.
10. A raw-edged V-belt as defined in claim 9, wherein the Shore-A-Hardness of the elastomer of said cover layers is preferably about 20 less than the Shore-A-Hardness of the elastomer of the core.
11. A raw-edged V-belt as defined in claim 1, wherein said fiber fleece is formed of randomly oriented fibers.
12. A raw-edged V-belt as defined in claim 1, wherein said fiber fleece possesses fibers which are slightly oriented in a direction transverse to the direction of travel of the V-belt.
13. A raw-edged V-belt as defined in claim 1, wherein said fiber fleece is a polyamide fiber fleece.
14. A raw-edged V-belt as defined in claim 1, wherein the V-belt contains an elastomer incorporating a sulphur-modified chloroprene.
15. A raw-edged V-belt as defined in claim 1, further including adhering layers disposed at both sides of said reinforcement insert means.
16. A raw-edged V-belt as defined in claim 1, wherein said wide-meshed fabric consists of polyamide fibers.
17. A raw-edged V-belt as defined in claim 1, wherein said fiber fleece is formed of steel wool.
18. A raw-edged V-belt as defined in claim 1, wherein said fiber fleece is formed of polyurethane fibers.
19. A raw-edged V-belt comprising at least a top cover layer, reinforcement insert means disposed beneath said top cover layer, and a substantially trapezoidal-shaped core located beneath said reinforcement insert means, said top cover layer being formed of fiber fleece impregnated with an elastomer.