US2107013A

US2107013A - Belt

Info

Publication number: US2107013A
Application number: US65096A
Authority: US
Inventors: Delevan F Morgan
Original assignee: NUCORD Co
Current assignee: NUCORD Co
Priority date: 1936-02-21
Filing date: 1936-02-21
Publication date: 1938-02-01
Anticipated expiration: 1955-02-01

Description

D. F. MORGAN Feb. 1, 193s.

BELT

Original Filed Sept. 12. 1955 ramas rsh. i, 193s aromas l ,man

PATENT' '1T FFIC BMT noord Company, of Illinois r'. Marsan, oak Park, nl., mmm-'tn Chicago, lll., a corporation i continuation or application 'serial No. 40,275,

September 12, 1935.

This application February 2l, 1936, Serial No.` 65,096

dclaims.

construction as to provide for an increased trac-A 5 tive eort and lflexibility with a resulting increased driving emciency and prolongation of belt life. 4

Heretofore, it was found that where flat belts are employed with crowned pulleys, the point of l greatest tension on the belt is at the highest portion of the pulley crown, because of the greater diameter of the pulley at this point.I The most eifecti've driving is done at this high point and its adjacent surfaces while the traction is lower l andthe driving emciency less at the outer portions .of the belt and pulley. This uneven traction ls-due to the stiffness of the belt and its in- 'ability to adapt itself to the contour of the crowned pulley during the driving operation.

This stiffness is increased as the speed of the belt progresses, the outer portions of the belt away from the high point of thel crown tending to assume a raised position out of contact with the lower portions of the crown, therebyv reducing the driving emciency and putting the greater burden of the pulling load upon the central portion of the belt which is in contact with the surface of the high portion of the pulley crown.

Another factor reducing the tractive eiliciency 80 of the averagebelt on both crowned and straight pulleys is the formation of an air cushion between the pulley and belt.C As the belt moves at normal operating speeds, a layer of air adjacent its pulley contacting surfaceis carried along a5 and compressed between the pulley andthe belt, forming an air cushion upon which the belt rides up `out of contact with the pulley. As'the speed of the driving pulley is increased, an increasing amount of air intervenes between the belt and 40 the pulley, until a point is reached when thebelt slips ofi. 'Ihls latter disadvantage is a limitation on the amount 'of power that vcan be transmitted and also on the rate of speed at which such belts may be safely driven.

Therefore, it is an object of my invention to provide a belt having a superior quality of traction.

Another object is the provision of a belt having w lateral and longitudinal flexibility enabling the belt to closely adapt itself to the contour of a crowned pulley.

A further object is the provision of 'a belt having the ability to prevent the formation of an u intervening air cushion between the belt and (Cl. 'I4-232) the pulley, thereby increasing the ability of the belt to cling to the pulley surfaces.

A still further object is the provision of a belt having a maximum exibility and the ability to prevent the formation of an air cushion between the belt and the pulley so as to enable it to closely adhere to the pulley surface throughout being had to the accompanying drawing in.

which:

Figure 1 is a perspective view of a portion of a belt embodying my invention;

Fig. 2 is an enlarged lateral cross-section through a portion of. the belt;

Fig. 3 is a diagrammatic sectional view of the belt; s

Fig. 4 is a sectional view through ythe belt and a crowned pulley while in driving relationship;

Fig. 5 is an enlarged sectional view of a grooved portion of the belt in driving position on a portion of a crowned pulley.

This application is a continuation of my copending application for United States Letters Patent for Belts, Serial Number 40,275, led September l2, 1935.

Referring to the drawing, there is illustrated my improved belt I0 which is comprised of a plurality of fabric webs and cords held together by a coating of rubber material in which they are embedded. More particularly, the belt I0 has a ply or webof fabric I I which is substantially the width of the completed belt end which is coated with an elastic bonding material or rubber solution I3. Extending lengthwise of the ply il and adhesively amxed thereto are a plurality of substantially inextensible cords I2v which are arranged in spaced groups transversely of the ply, the spaces between the groups being substantially less .than the width of the groups. 'I'hese groups are also maintainedas units by the bonding material I3. An outer fabric ply or web I 4, also coated with the bonding material, is provided in a dimension of slightlymore than twice "the width of the finished belt so that it can be wrapped around the web Il and the cords I2 to enclose andv protect the same from injurious contacts and substances encountered -in certain industrial fields. LAnother fabric .web i5. alsocoated with the rubber material, is disposed as a seal upon the surfaces of the edge portions i4 of the web Il which have been folded into abutting relation over the cords i2. These above elements are vulcanized into a permanent union in a mold which depresses the'web Il, the edges IIb of the web i4, the web i5. and the bonding material to form a plurality of grooves i8 extending lengthwise of the belt and parallel to the cords in the portions of the upper surface |4 between the spaced groups of cords. The lower surface i4l of the ply il, however, is formed flat.

In Fig. 4, there is illustrated my improved belt I in driving position on a crowned pulley i1,

althOdgh it must be understood that the belty I0 is applicable with equal efficiency to other types of pulleys. As constructed, the belt possesses a limited amount of elasticity that is sufficient to allow the belt to be stretched into operable position over the driving and driven pulleys with a reserve amount of elasticity remaining in the same to allow for any furtherA stretch encountered during operation. The aforedescribed belt structure is designed for a maximum of tractive emciency. In operation, it is preferably the lowstretched to a greater degree because of theer surface il* of lthe belt which is in driving contact'with the pulley l1.

,Since a crow'ned pulley has its greatest diameter at the highest point I8 of the crown, it is obvious that the greatest stretch of the belt occurs at its central portion causing the two central groups of cords to stretch longitudinally to 'a greater extent than the outer cord groups adjacent the edges of the pulley. 'I'hese outer cord groups away from the pulley crown remainsubstantially unaffected by the stretch of the central cord groups, and are able to closely adhere' to those surfaces of the pulley where the diameter is reduced. 'I'his ability of the belt to readily adapt itself to the contour of the crowned pulley I1 is dueto its great-lateral and longitudinal ilexibility.' By providing laterally spaced groups of substantially inextensible cords and by providing grooves in the upper surface of the belt between the cord groups. the effect secured is that of a plurality of individual belts of different lengths adapted to the various diameters of a crowned pulley although the belt is a strong unitary structure. 'I'he portions of the belt between the cord groups being substantially more elastic and of lesser section allow'the cord groups to move ,longitudinally relatively to each other and also permit great lateral exing which would be reduced toa minimum were the cords extended throughout the width of the belt. Thus, the belt may be curved laterally to adapt itself to the crown contour so that the outer belt portions willclosely adhere to the -outer pulley surfaces without being raised out of engagement therefrom when the central portions of the belt are greater pulley diameter at their points of tact.

The tractive efficiency of the belt is further increased because of the ability of the belt to prevent the formation of an undesirable air layer or cushion which tends to form between the belt and the pulley. As the belt I0 is bent around v' -the pulley under driving tension. a relatively shalface, the grooves I 8 thus reversing themselves. The formation of these grooves 20 is due, perhaps, to the coaction of two forces. As the belt contacts the pulley under driving tension. the relatively inextensible cords l2 in groups squeeze down on the softer cushioned portions formed by the two plies Il and. Il* embedded in the rubber solution I8, these plies expanding laterally in both directions to a limited extent. with the result that a buckling upwardly oi' the belt portions between the groups of cords occurs. The

buckling is upwards because of the unyielding4 surface of the pulley and because the relatively elastic portions between the cord groups are under a relatively lesser degree of tension. A second factor which may also cause the formation of the grooves 20 is the stretching of the upper ply I 4e. In riding around the pulley, the upper ply I4 is stretched to such an extent that the portions forming the grooves I 6 are pulled up slight-- ly, thereby reducing the depth of the grooves I6 and pulling up the other two plies which are adhesiveLv united to the under surface of the ply I at a plurality of points. It is to be understood that the two above factors are merely theories as to formation of the grooves, but the fact remains that whatever may bethe cause for formation, are created as the belt comes into contact with theupulley and is curved about its surface. 'I'hese shallow grooved portions are the only points of the pulley-contacting surface which maintain their original unworn appearance after a long period of operation.

'Ihe grooves 20 prevent the formation of the undesirable air layer apparently for the following reason: As the cords I2 squeeze down on the two underlying plies II and Ile, the air car- 4 ried by those portions of the surface' I4* under the cord groups is squeezed or pumped laterally into the newly formed grooves 20 which are nlled up with this air and through which it may escape longitudinally of the belt. Another factor causing the air to be drawn intothe grooves 20 is that when they are formed thereis a tendency to create a vacuum at these groove points so that the unequal air pressure causes the air on the under surface to rush into the grooves. In a sense the air may be said to be sucked from they surfaces under the cord groups as the grooves 2li are formed.

The ability of the belt to adapt itself to the contour of the pulley and its ability to prevent the formation of an air cushion between itself and the pulley promotes and increases the tractive eiliciency with benencial results. More power will be transmitted with less loss. Also the life of the belt will be prolonged since the wear will be equalized with the outer belt portions 'bearing their time of the vload along with time. portions contacting theltop of the crown.

Although the foregoing description has set forth one form or belt, it will be understoodv belt and arranged in a series of spaced groupsacross substantially the full width of said belt, the space between said groups being of substantially less width than ,the width of said groups, a web supporting saidL groups of cords. andan elastic bonding material in said space and joinlng said cords and said supporting web together 76 cords, said bonding material being formed with a groove in one surface parallelto said cords and being at on its other surface, whereby a normally at pulley contacting surface is formed in which e longitudinal air relief groove is created under the first mentioned groove during operation of the belt over s pulley.

2. A power transmission belt comprising a nlurality of cords extending longitudinally of said belt and arranged in a series of spaced groups across substantially the full width of said belt, the space between said groups `oeing of substantially less widthtthan the Width of said groups, an elastic bonding material in said space yand joining the cords together while permitting iirnited relative longitudinal and transverse movement between said groups of cords, said bonding material being formed with a groove in one surface parallel to the cords and being flat on its other surface, and a fabric cover enclosing and following the contour of lthe aforementioned elements, whereby a normally not pulley contasting surface is formed in lwhich a longitudinal air relief groove is created under the rst mentioned groove during operation of the belt over a pulley.

3. A power transmission belt comprising a plu-A aforementioned elements, whereby a normally hat pulley contacting surface is formed in which a longitudinal air relief groove is created under the rst mentioned groove during operation of the belt over a pulley.

t. A power transmission belt comprising a.

plurality of cords extending longitudinally of said belt and arranged in a series of spaced groups across substantially the full width of said belt, the space between said groups being of substantially less width than the width of said groups, e, web supporting said groups of cords, an elastic bonding material in said space and joining said cords and said supporting web together while permitting limited relative longitudinal and transverse movement between said groups of cords, said bonding material being formed with a groove in one Surface parallel to seid cords and being nat on its other surface, and a fabric cover surrounding and following the contour of the aforementioned elements, whereby a noily fiat contacting pulley surface is formed in which a. longitudinal air relief groove is created under the first mentioned groove during operation of the belt over a pulley.

- DELEVAN F. MORGAN.

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