CA1161281A - V-belt - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A novel central neutral axis V-belt is provided herein. It includes an endless tensile member; at least two layers, of which the first and second layers are principally composed of elastomeric material and have substantially the same thickness, the first layer being disposed inwardly and the second layer being disposed outwardly of the tensile member, each of the first and second layers having a plurality of randomly arranged fibres therein which allow longitudinal flexibility yet provide transverse rigidity for the belt free of shear planes parallel to the first and second layers; transverse support means for transversely sup-porting the tensile member, a first ply of bias fabric disposed substan-tially at the outer peripheral surface of the first and the second layer, the first ply being disposed substantially equidistant from the tensile member and having an angle A between weft and warp threads of between 95°
160°: and a second ply of bias fabric disposed at the outer peripheral surfaces of the first ply of bias fabric substantially equidistant from the tensile member.

Description

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This invention relates to endless power transmission belt struc-tures, particularly neutral axis V-belt structures.
This application is a division of application Serial No. 257,432 filed July 21, 1976.
Most endless power transmission belts of trapezoidal cross-sectional outline, or so-called V-belts, in current use are made with a load-carrying section which is arranged closer to the wider parallel side of the trapezoidal cross section because heretofore such arrangement has proven superior in many respects. Ilowever, many of such currently used V-belts are inherently comparatively expensive because there is consider-able scrap produced when cutting such V-belts from the usual cylindrical sleeve produced by many well-known techniques.
To reduce the cost of V-belts by reducing scrap, proposald have been made heretofore to cut the usual cylindrical sleeve in what is often referred to as a balanced manner. Examples o~ this are shown in United States Patents Nos. 1,432,973 issued to ; 1,924,355 issued to ; 2,153,966 issued April 11, 1939 to L.S.M Lejeune;
and 2,661,045 issued December 1, 1953 to W.E. Iluber. -It is also well known to provide belts of substantially trape-zoidal cross-sectional configuration having a load-carrying section or so-called neutral axis which is located centrally, as shown, for example, in two of the above-mentioned United States Patents Nos. 1,924,355 and 2,661,045. U.S. Patent No. 2,661,045 further teaches the provision of at least one fabric reinforcing layer on each side of the tension member to provide high compressive and tensile moduli in the transverse direction of the belt. However, belts of the type disclosed in these two patents are comparatively expensive to produce.

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A V-belt which, in essence, uses the prior art features of the above-mentioned patents is disclosed in United States Patent No. 3,869,933 issued March 11, 1975 to M.I. Dorf. In that patent it is stated that the belt of this latter-mentioned patent may also use fibre-loaded elastomeric material as disclosed in United States Patent No. 3,416,383 issued December 17, 1968 to H.J. Jensen et al. However, in ~igure 5 of United States Patent No. 3,869,933 and the associated description in the specifi-cation emphasize that a belt having a central load-carrying section and made with fibre-loaded material and layers of stretchable fabric to define lo its top and bottom surfaces loses its transverse stiffness and sags.
Accordingly, great emphasis is given in U.S. Patent No. 3,869,933 to the use of so-called fabric reinforcing layers which have high compressive and tensile moduli to provide transverse rigidity. However, it is well known that fabric reinforcing layers used in the manner disclosed in this last-mentioned patent result in sharply defined shear planes which cause a belt made in this manner to delaminate after a comparatively short service life.
In any event, any V-belt which requires a large number of differ-ent layers with each different layer being required to impart a special desired characteristic to the V-belt usually results in adding to the cost of such belt.
Recently, the autornobile industry has shown considerable interest in balanced cut V-belts with centrally located load-carrying sections because of the potential cost savings, due to reduced scrap alone, in pro-ducing such belts as compared with the usual belts having eccentric load-carrying sections. However, it is a problem to provide such a balanced cut belt with a central neutral axis at minimum cost yet assure the belt is capable of being reliably operated at high speeds over a plurality of small diameter sheaves of the type used on accessories of an automobile engine, for example, for an extended service life.
It is an object of one aspect of this invention as provided by the present divisional application to provide a simple, economical, and reliable balanced-out belt structure having a central load-carrying section or central neutral axis which has longitudinal flexibility enabling it to be used over small diameter sheaves yet has sufficient transverse rigidity to enable such a belt to be used under normal load conditions for any particular belt size.
It is an object of another aspect of this invention as provided by the present divisional application to provide an endless power trans-mission belt structure of trapezoidal cross-sectional outline having one or more of the novel features set forth above or hereinafter shown or des-cribed.
An object of a further aspect of this invention as provided by the present divisional application is to provide an endless power trans-mission belt structure having a long1itudinal dimension and a trapezoidal cross section or outline at each position along the longitudinal dimension and with the belt structure being made primarily of an elastomeric material.
The central neutral axis V-belt structure according to a broad aspect of this invention as now provided by the present divisional appli-cation comprises: an endless tensile member; at least two layers, of which the first and second layers are principally composed of elastomeric material and have substantially the same thickness, the first layer being disposed inwardly and the second layer being disposed outwardly of the tensile member, each of the first and second layers having a plurality of randomly arranged fibres therein which allow longitudinal flexibility yet provide transverse rigidity for the belt free of shear planes parallel to the first and second layers; trarlsverse support means for transversely 2 ~ 1 supporti~g the tensil.e member, a first ply of bias fabric disposed sub-stantially at the outer peripheral surfaces of the first and the second layers, the first ply being disposed substantially equidistant from the tensile nlember and having an angle A between weft and warp threads of between 95 and 160 ; and a second ply of bias fabric disposed at the - outer peripheral surfaces of the first ply of bias fabric substantially e4uidistant from the tensile member.
By a variant thereof, the first and the second layers are cut to form the oppositely facing side of the V-belt.
By another variant, the V-belt includes additional plies of bias fabric disposed in each of the first and the second layers substantially equidistant fro~ the tensile member, the threads of the additional plies of bias fabric having an included angl~ between weft threads and warp threads that is no greater than that angle between weft threads and warp threads of the first ply.
~y a further variant, each layer has the same number of plies of bias :Eabric.
By a further variant, the angle between weft threads and warp threads is between 95 and 155.
In the accompanying drawings, FIG. l is a perspective view illustrating one exemplary embodiment of an endless power transmission belt of an aspect of this invention as provided by this divisional application in a drive system used on an in-ternal combustion engine such as, for example, an automobile engine;
FIG. 2 is an enlarged cross-sectional view of the belt utilized in FIG. l;
FIG. 3 is a perspective view with certain parts broken away and other parts shown schematically particularly :illustrating the manner in ~ ~ 6~

which a mandrel supporting a belt sleeve utilized to make a plurality of endless power transmission V-belts of aspects of this invention as pro-vided by the present divisional application is cut with an associated cutti.ng device to define such belts;
FIG. 4 is a fragmentary perspective view particularly illustra-ting a typical fibre-loaded layer and a typical fabric layer provided in both the tension and compression sections of the V-belt of an aspect of this invention as provided by the present divisional application;
FIG. 5 is a fragmentary cross-sectional view taken longitudinally through the belt sleeve of FIG. 3 FIG. 6 is a fragmentary cross-sectional view taken essentially on the line 6-6 of FIG. 2;
FIG. 7 is a view similar to FIG. 2 illustrating another exemplary embodiment of the V-belt of another aspect of this invention as provided by the present divisional application;
FIG. ô is a view similar to FIG. 2 illustrating another exemplary embodiment of the V-belt of another aspect of this invention as provided by the present divisional application; and FIG. 9 is a graph illustrating that the improved V-belt of an aspect of this invention as provided by the present divisional application may be operated in associated test sheaves at belt speeds which are com-paratively higher than similar belts of previously proposed construction with eccentric neutral axes and with the same top width.
Reference is now made to Figure 1 of the drawings which illus-trates an exemplary automobile engine 20 having an endless power transmis-sion belt dri.ve system 21 which utilizes an endless power transmission V-belt structure or V-belt 22 of an aspect of this invention as provided . - 5 -1:~6~2~1l by the present divisional application which operatively associates with driving sheave 23 and a plurality of driven sheaves which are designated by the reference numerals 24, 25, 26 and 27. The sheaves 24-27 are suit-ably operatively connected to the usual automobile assemblies or acces-sories to drive same and as is well known in the art. The drive system 21 of this example is shown utilizing a belt tensioning apparatus 30 for the purpose of providing controlled tension to the V-belt 22 as it moves in its endless path about its associated sheaves; however, the belt 22 may be operated with or without a belt tensioning apparatus, as desired.
The V-belt 22 is of the usual endless variety having a longitu-dinal dimension which, in essence, is defined by the developed length of the endless belt and such belt has a trapezoidal cross-sectional outline, as illustrated in Figure 2, at each position along its longitudinal dimen-sion. The V-belt 22 is made primarily of elastomeric material in each of its various belt sections. The belt 22 is comprised of a pair of oppo-sitely arranged surfaces disposed in spaced relation to define what will be referred to as an outside surface 31 and an inside surface 32, with the term outside surface referring to the fact that the wider of the parallel sides of the trapezoidal cross section of the belt is normally arranged outwardly of its associated sheaves or pulleys and as will be readily apparent from Figure 1.
Referring now to Figure 2, the V-belt 22 has a load-carrying section which is designated generally by the reference numeral 33 which is arranged midway between the outside surface 31 and the inside surface 32.
lnasmuch as this section of a trapezoidal belt is often referred to as the neutral axis of such belt, the positioning of this section midway between surfaces 31 and 32 has resulted in the V-belt 22 being popularly referred to as being a central neutral axis V-belt.

The load-carrying section 33 may be made of any suitable material or materials and in this example is comprised of an endless tensile member in the form of a helically wound load-carrying cord 60 which is embedded in a gum-like elastomeric matrix 61, e.g., neoprene rubber, to provide a cushion on opposite sides of and completely around the cord 60. The gum-like elastomeric matrix also provides transverse support means being dis-posed in the first and in the second layers substantially equidistant inwardly and outwardly from the tensile member. The cord 60 is wound so that a line through the centres of the turns at any cross section is, in essence, line 57 and is positioned midway between the outside surfaces 31 and 32 of the belt. The helically wound load-carrying cord 60 may be made of any suitable material known in the art, and similarly the elastomeric matrix or cushion 61 may also be made of any suitable material which is compatible with the cord 60. The material 61 is also of a material com-patible with the materials used to define layers 35 and 42 (to be described hereinafter) to assure a tenacious bond therebetwcen. It will also be appreciated that instead of providing a helically wound load-carrying cord 60 any other endless tensile member suitable load-carrying means may be provided in the ~-belt 2~.
The belt 22 has a tension section 34 which has a plurality of layers. The tension layer includes a first layer primarily composed of elastomeric materia] but being a fibre-loaded layer 35 disposed adjoining the load-carrying section 33 and three fabric layers 36, 37 aned 38 with the fabric layer 38 being disposed remote from the lo~d-carrying section and having a surface which will be referred to as an outside surface and which defines the outside surface 31 of the belt. It will be seen that the other two fabric layers 36 and 37 of the tension section 34 are arranged such that the layer 36 adjoins the fibre-loaded layer 35, the fabric layer 37 adjoins the layer 36, and the remote layer 38 adjoins the layer 37.
It is preferred that the first ply of bias fabric 36 be disposed substantially at the outer peripheral surface of the first layer 35 with the first ply being disposed substantially equidistant from the tensile member 60 and having an angle A between weft and warp threads of between 95 and 160 . A second ply of bias fabric 37 is disposed substantially equidistant from the first ply of bias fabric 36 in the first layer 35.
The V~belt 22 also has a compression section which is designated generally by the reference numeral 41. This is comprised of a plurality of layers including a second layer principally composed of elastomeric material, but being a fibre-loaded layer 42 and three fabric layers 43, 44, with 45 being remote from the load-carrying section 33 and the layer 45 having a surface which may be considered an exposed outer surface which defines the inside surface 32 of the belt 22. The fabric layer 43 is arranged adjoining fibre-loaded layer 42 followed by the fabric layer 44 disposed against the layer 43 and the remote layer 45 disposed against the fabric layer 44. The fabric layers for the compression section are sub-stantially the same as for the tension section. In addition, these bias layers are substantially as described hereinafter with reference to Figure 4.
As seen in Figure 2, there are additional p]ies of bias fabric, i.e., 38, 45 disposed in each of the first and second layers 34, 41 sub-stantially equidistant from the tensile member 60. The threads of the additional plies of bias fabric preferably have an included angle between weft threads and warp threads of the first ply.
Each oE the fibre-loaded layers 35 and 42 has a plurality of randomly arranged fibers embedded therein and a representative few of such fibres have been designated by the same reference numeral 46. The fibres 46 allow longitudinal flexibility for the entire belt 22 as it moves in its endless path, yet provide transverse rigidity, i.e., transverse or perpen-dicular the parallel sides of the trapezoidal cross section, so that upon loading the belt 22 in the transverse direction as indicated by arrows 47 in Figure 2, the belt is prevented from bowing or what is popularly referred to as dishing, whereby the top surface 31 is prevented from assum-ing an outwardly concave configuration as viewed in Figure 2.
The fibers 46 are randomly arranged in a substantially infinite number of planes whereby, with such an arrangement, the fibre-loaded layers 35 and 42 of the V-belt 22 are free of clearly defined shear planes 1~ parallel to the load-carrying section 33. It has been found by tests that when reinforcing layers of the type defined by various woven fabrics, so-called tire cord fabrics, and the like, are arranged parallel to and closely adjacent a load-carrying section of a belt having a central neutral axis, there is a tendency for such reinforcing layers to define shear planes or areas parallel to the load-carrying section (when viewing the belt in cross section) whereby such belt tends to delaminate or pull apart at such shear planes.
The V-belt 22 not only provides the fibre-loaded layers 35 and 42 which are substantially free of shear planes but also provides layers 36-38 and 43-45 which are a substantial distance from the load-carrying section 33 yet provide some transverse rigidity. The fabric layers 36-38 and 43-45 cooperate with the fibre-loaded layers 35 and 42 to increase the transverse rigidity of the V-belt 22 and to assure satisfactory operation thereof in associated sheaves and with the belt operation being in a non-dishing manner, yet all of these layers cooperate to assure that the V-belt 22 will operate with optimum longitudinal flexibility.
As previously indicated, each of the fibre-loaded layers 35 and 42 has a plurality of randomly arranged fibres 46 eMbedded therein. Each & ~

layer 35 and 42 is made of an elastomeric compound which, in this example, is a rubber compound 48 which serves as a matrix for such fibres. The fibres may be made of any suitable material and are preferably non-metallic organic fibres each having a diameter ranging between 0.001 inch and 0.050 inch and a length ranging between 0.001 inch and several inches. It will be appreciated that the size (diameter and length) of the fibres in a belt is in general determined by the size of the endless power transrnission belt being made utilizing such fibres and the application of such belt.
Accordingly, belts having a top width generally of the order of a quarter of an inch would use smaller fibres while belts having a top width of the order of 4 to 6 inches would use larger fibres. It is to be understood that the belt of an aspect of this invention as provided by the present divisional application may be made in any suitable size length including belts having top widths falling within the range of 1/4 inch through 6 inches.
The fibres 46 may be made of any suitable organic material including but not being limited to nylon, cotton, polyester, and rayon.
Further, the fibres 46 may also be made of blends or mixtures of these materials.
Each of the fabric layers 36, 37 and 38 in the tension section, and 43, 44 and 45 in the compression section has a transverse rigidity which is greater than its longitudinal rigidity. Accordingly, each of these layers 36-38 and 43-45 has a ]ongitudinal flexibility which enables the V-belt 22 utilizing such fabric layers easily to be flexed over pulleys or sheaves, including small diameter sheaves, yet the V-belt 22 has suffi-cient transverse rigidity to prevent dishing or bowing thereof and as pre viously described. In partic~llar, each fabric layer 36-38 and 43-45 has a stiffness ~ransverse the belt which ranges between 105 and 172 percent greater than the stiffness along the longitudinal dimension of the belt.
or most automotive applications the optimum belt construction has a stiff-ness transverse the belt which is roughly 125 percent greater than the stiffness along the longitudinal dimension of the belt.
Reference is now made to Figure 4 of the drawings which illus-trate the fabric layer 36 which is typical of the fabric layers 36-38 and 43-45. Fabric of the type used in these layers is well known and disclosed in United States Patent No. 3,478,613.
The fabric layer 36 has warp threads 50 and weft threads 51 which are disposed at an angle 52 ranging between 95 and 155 degrees with each other. Each of the warp and weft threads 50 and 51, respectively, is disposed at the same angle, which is one-half of angle 52, relative to a central plane bisecting a transverse cross section of trapezoidal belt 22 along the longitudinal dimension thereof and for simplicity such plane is indicated by a dot-dash line 53 in Figure 4.
To assure that there will be no tendency for the V-belt 22 to delaminate due to the fabric layers 36-38 and 43-45 being too close to the central load-carrying section 33, it will be seen that these layers are kept at a substantial distance away from such load-carrying section or central neutral axis. It has been found that by keeping each innermost fabric layer, e.g., 36 and 43, so that an associated inside surface 55 and 56, respectively, of each layer is located at least 25 percent of one-half of the thickness of the belt structure away from a central plane, indicated by a dot-dash line 56, bisecting the load-carrying section when viewing the belt structure in cross section, there is no tendency for delaminating at the clearly defined planes or areas created by surfaces 55 and 56.
Thus, the V-belt structure 22 has no significant tendency to delaminate yet has all of the advantages inherent in the V-belt 22 due to its central neutral axis.
The fibre-loaded layers 35 and 42 provide the desired transverse rigiidty for the V-belt 22 in cooperation with the fabric layers and with the individual fibres 46 of the fibre-loaded layers being arranged in a random manner in an infinite number of planes and locations. As will be readily apparent from Figure 4, each fibre 46 is arranged substantially at a 90 degree angle to the longitudinal dimension or axis of the belt; how-ever, it will be appreciated that the fibres 46 may be arranged at other angles, as desired, further to control the transverse rigidity of the V-belt 22.
It is preferred that each layer have the same number of plies of bias fabric, and that the angle between the weft threads and the warp threads is between 95 and 155.
The V-belt 22 is made from a belt sleeve indicated generally by the reference numeral 62 in Figure 3. The belt sleeve 62 is made using a suitable rotatable mandrel assembly 63 in accordance with any tendency known in the art. The belt sleeve 62 and assembly 63 may be supported and rotated in accordance with known techniques to enable cutting of a plura-lity of V-belts 22 from a sleeve and a cutting device which is designated generally by the reference numeral 64 is used for this purpose.
The cutting device 64 may be of any suitable type capable of being moved inwardly and outwardly into engagement with the belt sleeve 62.
In this example, the device 64 is shown as having a circular cutting knife 65 which is rotated by a suitable drive mechanism 66 while rotating the mandrel assembly 63 and with the knife 65 in cutting engagement with the sleeve 62 and in accordance with techniques known in the art.
The cutting device 64 is used to provide a plurality of so-called _ 12 -balanced cuts along the length of the sleeve 62 and a representative few of such cuts are designated by the same reference numeral 67 in Figure 5.
The cuts 67 are suitably spaced and inclined in alternating directions along the length of the sleeve 62 whereby a plurality of belts 22 may be defined along the length of the sleeve 62 without scrap or loss of material.
The cuts 67 define trapezoidal belts 22 each having a pai} of non-parallel raw-edged sides 68 and it will be appreciated that alternating belts along the sleeve upon being turned inside out are identical to the other belts defined in a normal manner along the sleeve. It will be seen that the first and second layers are thus cut to form ~he oppositely facing side of the V-belt.
Other exemplary embodiments of the belt structure or belt of other aspects of an aspect of this invention as provided by the present - divisional application are illustrated in Figures 7 and 8 of the drawings.
The belts illustrated in Figures 7 and 8 are similar to the Y-belt 22;
therefore, such belts will be designated by the reference numerals 22A and 22B, respectively, and representative parts of each belt which are similar to corresponding parts of the V-belt 22 will be designated in the drawings by the same reference numerals as in the V-belt 22 (whether or not such representative parts are mentioned in the specification) followed by an associated letter designation, either A or B and not described again in detail. Once those component parts of each V-belt 22A and 22B which are different from corresponding parts of the V-belt 22 will be designated by a new reference numeral also followed by the associated letter designation and described in detail.
The only difference between the V-belt 22A and the V-belt 22 is that the V-belt 22A instead of having a lurality of fabric layers compris-ing its tension section 34A and a plurality of fabric layers comprising its .
.

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compression section 41A has a single fabric layer 70A in its tension section 34A and a single fabric layer 71A in its compresSiOn section 41A.
The fabric layers 70A and 71A are substantially identical to the layers 36-38 and 43-45 previously described. Accordingly, it will be appreciated that in the V-belt 22A the outside surface 31A thereof is defined by the outside surface of the single layer 70A while the inside surface 32A
thereof is defined by the outside surface of the fabric layer 71A. Simi-larly, the layer 70A has an inside surface which is designated by the reference numeral 55A while the layer 71A has an inside surface which is designated by the reference numeral 56A and each of these inside surfaces is located at least 25 percent of one-half of the thickness of the belt structure away from the centre 57A of the load-carrying section 33A when viewing the belt structure in cross section.
The V-belt structure 22B of Figure 8 has a tension section 34B, a load-carrying section 33B, and a compression section 41B. It will be seen that the tension section 34B and compression section 41B in each instance has a pair of fabric layers provided therein and the fabric layers in tension section 34B are designated by reference numerals 72B and 73B
while the fabric layers in the compression section 41B are designated by 20 the reference numerals 74B and 75B. In this instance, the outside surface of the layer 73B defines the outside surface 31B of the belt 22B while the outside surface of the layer 75B defines the inside surface 32B of such belt. Also, in a similar manner as described previously, the inside sur-face of the innermost layer 72B in the tension section 34B has an inside surface 55B and the innermost layer 74B in the compression section 41B has arl inside surface 56B with the surfaces 55B and 56B being located at least 25 percent of one-half of the thickness of the belt structure away Erom the central plane or line 57B bisecting the load-carrying section 33B

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when viewing the V-belt structure 22B in cross section.
Each of the V-belts 22, 22Aand 22B may be of any suitable size ranging from a quarter of an inch top width to six inches top width, for example,as previously mentioned. For a typical automotive application as shown in Figure 1, exemplary detailed dimensions will now be given for a V-belt 22, 22A or 22B having a belt top width 76 (shown in Figure 2) of 0.422 inch plus or minus 0.032 inch. For such a 0.422 inch top width belt, the included angle between the non-parallel sides of the trapezoidal con-figuration are 36 degrees plus or minus 2 degrees. The thickness of such a belt as measured by the perpendicular distance between the parallel outside surfaces of the trapezoidal c}oss section is 0.281 inch plus 0.015 minus 0.032 inch. The overall thickness of the load-carrying section 33, 33A or 33B is generally of the order of 0.040 inch with the thickness of each associated fabric layer being of the order of 0.040 inch also. It will be appreciated that the thicknesses of the fibre-loaded layers adjoin-ing the load-carrying section and the thicknesses of each of the fabric layers will be adjusted to arrive at the desired belt thickness for a particular application, provided that the innermost fabric layer whether 24 it be the innermost layer of a belt having one, two, three, or more fabric layers in each of its tension and compression sections is arranged at least 25 percent of one-half of the thickness of the belt structure away from a central plane bisecting the load-carrying section when viewing the belt structure in cross section to assure that there will be no delamina-tion of the character previously described.
The number of fabric layers in each of the tension and compres-sion sections may be increased to more than 3 for certain applications pro--vided that the other siæe parameters disclosed herein have been satisfied.
As is well known in the art for a basically raw edged belt, the number of fabric layers, in essence, control the amount of friction and ease with which it moves in and out of associated sheaves.
The central neutral axis V-belt st}ucture of an aspect of this invention as provided by the present divisional application whether in the form of V-belt 22, 22A, 22B, or some other belt having more than 3 fabric layers in each of its tension and compression sections, in each instance in addition to offering the advantages of economical fabrication while using comparatively inexpensive materials has excellent flex life. The V-belt of aspects of an aspect of this invention as provided by the present divisional application has excellent flex life even in applications where the V-belt is bent reversely because with the neutral axis located centrally there would be minimum stresses imposed on the belt.
In high speed applications the V-belt of an aspect of this inven-tion as provided by the present divisional application is superior to belts in which the normal neutral axis is located eccentrically or closely adja-cent the wide parallel side of the trapezoidal belt. To illustrate this feature, reference is made to Figure 9 of the drawings which presents in graph form a plurality of curves of various belts tested over a pair of pulleys in the form of a 7.86 inch diameter driver pulley 77 and a 2.62 inch diameter driven pulley 78. The graph of Figure 9 presents a plot of driver pulley revolutions per minute or RPM as the ordinate and proba-bility of belt flip-off in percent as the abscissa.
The curve oO illustrates the V-belt of an aspect of an aspect of this invention as provided by the present divisional application having a 0.422 inch top width and shows that the belt tended to flip off of its pulleys at a median speed of 8942 RJPM. The curve 81 is of a three ply V-belt of standard construction having the same 0.422 top width and this belt tended to flip off at an average speed of 7800 RPM. The curve 82 is of a 0.422 inch heavy dutry V-belt and this belt tended to flip off at an average speed of 7471 RPM. The curve 83 is of another heavy duty 0.422 inch top width wrapped belt and this belt tended to flip off a~ an average speed of 6796 RPM. Thus, it is apparent that the central neutral axis V-belt of aspects of an aspect of this invention as provided by the present divisional application has superior stability when operating at high speed in associated sheaves.

Claims (5)

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

1 . A central neutral axis V-belt comprising: an endless-tensile member; at least two layers, of which the first and second layers are principally composed of elastomeric material and have sub-stantially the same thickness, the first layer being disposed inwardly and the second layer being disposed outwardly of the tensile member, each of said first and second layers having a plurality of randomly arranged fibres therein which allow longitudinal flexibility yet provide transverse rigidity for said belt free of shear planes parallel to said first and second layers; transverse support means for transversely sup-porting said tensile member, a first ply of bias fabric disposed sub-stantially at the outer peripheral surfaces of said first and said second layers, said first ply being disposed substantially equidistant from said tensile member and having an angle A between weft and warp threads of between 95° and 160°; and a second ply of bias fabric disposed at the outer peripheral surfaces of said first ply of bias fabric substantially equidistant from said tensile member.

2. A belt as set forth in claim 1 wherein said first and said second layers are cut to form the oppositely facing side of the V-belt.

3. A belt as set forth in claim 1 and comprising additional plies of bias fabric disposed in each of said first and said second layers substantially equidistant from said tensile member, the threads of said additional plies of bias fabric having an included angle between weft threads and warp threads that is no greater than that angle between weft threads and warp threads of said first ply.

4. A belt as set forth in claim 1 wherein each layer has the same number of plies of bias fabric.

5. The V-belt of claims 1, 2 or 3, wherein the angle between said weft threads and said warp threads is between 95° and 155°.