Disclosure to Promote the Right To Information

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1 इ टरन ट म नक Disclosure to Promote the Right To nformation Whereas the Parliament of ndia has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of ndian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. ज न1 क अ+धक र, ज 1 क अ+धक र Mazdoor Kisan Shakti Sangathan The Right to nformation, The Right to Live प0र 1 क छ ड न' 5 तरफ Jawaharlal Nehru Step Out From the Old to the New S 5635 (1983): Automotive V-Belt Drives [PGD 31: Bolts, Nuts and Fasteners Accessories]! न $ एक न' भ रत क +नम-ण Satyanarayan Gangaram Pitroda nvent a New ndia Using Knowledge! न एक ऐस खज न > ज कभ च0र य नहB ज सकत ह ह Bhartṛhari Nītiśatakam Knowledge is such a treasure which cannot be stolen

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4 UDC : S : ndian Standard SPECFCATON FOR AUTOMOTVE V-BELT DRVES ( First Revision ) 1. Scope -Covers the requirements for V-belts and pulleys used for power transmission for automotive engines in mobile and static applications. 2. Terminology - For the purpose of this standard the definitions given in S : Glossary of terms and definitions relating to drives using V-belts and grooved pulleys along with the following shall apply. 2.1 Effective Belt Lengfh ( leff ) - The sum of the effective circumference of one of the two measuring pulleys ( measured at the effective pulley diameter ) and twice the distance between their centres when established under the conditions set out in Effective Pulley Diameter ( deff ) - The diameter at which the groove top width is equal to g that is the width specified in Table 5 and illustrated in Fig Be/f Length -The length equal to the effective length defined above. 2.4 Be/f S!ip -The difference, expressed in percentage, between the speeds of the driven and of the driver pulleys (see Appendix 6 ). 2.5 Matched Set - n order to avoid uneven distribution of load, belts used on a multi-belt drive shall be matched belts, and the maximum variation in length within a match set shall be within the tolerances shown in Table 2. Note - Aqe and storage conditions may alter a belt length and, therefore, users should ensure tlat the belt length is carefully checked immediately before use. t is also recommended that users should not mix belts of different makes on one drive. SECTON 1 V-BELTS 3. Materials -Automotive V-belts shall consist of fabric or cord and elastomeric compounds ( rubber and rubber like compounds ) or a combination of all three items, the whole being bonded together in a uniform manner and shape. 4. Dimensions 4.1 Nominal Cross Seclion of Be/f-The nominal dimensions of the belt cross sections shall be as given in Table 1 read with Fig Deferminafion of Ride Position -When mounted under the conditions described in on two standard measuring pulleys of dimensions given in Table 3, the ride position of the belt shall be within the limits given in Table Belt Lengfh Sfandard lengths - Belt lengths shall be selected from Table 4 as appropria e to their sezt:on Determination of belt letigfh - The effective belt length shall be determined when the belts are mounted on measuring fixtures having groove dimensions as given in Table 3 read with Fig. 2 and 3 and are positioned under tension in the grooves as detailed in Table The means of mounting the belt shall include two equal pulleys of outside and groove dimensions in accordance with those given in Table 3. The total tension shown shall be equally divided between the two strands of the belt by rotating the pulleys at least two turns to seat the belt prooerly. The effective belt length shall be calculated by adding the effective circumference of one of the two equal pulleys to twice the measured distance between their centres Tolerance on lengfh - The belt length determined as described in shall agree *with the selected standard length ( see ) to within the limits of tolerance set out in Table 2A. Adopted 29 September July 1984, S Gr 8 NDAN STANDARDS NSTTUTON MANAK SHAVAN. 9 SAHADUR SHAH ZAFAR MARG NEW DELH

5 S : F16. 1 BELT CROSS SECTON TABLE 1 DMENSONS OF NOMNAL CROSS SECTON OF BELT (Clause 4.1 ) Cross Section Symbol Nominal $p Width Nominal Height Nominal ncluded T An$e mm mm - - AVlO AV13 :: 1: t : DAMETER deff FG. 2 MEASURNG PULLEY TABLE 2 REQUREMENTS FOR NEW BELTS WHEN MOUNTED ON MEASURNG PULLEYS _- - Cross Section Symbol Nomint\ g;; Width mm ( Clauses 2.5, 4.2 and 4.3.2) T Total Force Ride Applied to Belt Positon* N mm AVlO 10 -_ _ AV13 13 L *8 -, *This is the position of the top surface of the belt with respect to the top of the measuring pulley groove. 2

6 S: TABLE 2A TOLERANCE ON BELT LENGTH ( Clause ) All dimensions in millimetres. Standard Belt LW,,U, Range Tolerance on Distance Maximum Variation Between Pulley Centres in Belt Lengths ( Matched Belts ) Up to 1250 f to t FG. 3 MEASUREMENT OF EFFECTVE PULLEY DAMETER USNG GAUGE BALL OR ROD TABLE 3 DMENSONS OF PULLYES FOR MEASURNG NEW BELTS ( Clauses 4.2, 4.3.2, and Fig. 2 and 3) Cross Section Symbol - _- Nominal Top 1 Width of Belt W Pulley Circumference at Effective Diameter Minimum Groove Depth D All dimensions Top Width of Groove at Effective Diameter g in millimetres. Effective Diameter d efl Groove Angle Aa G;aURe or Rod Diameter dg 2k -- Overall Diameter &r+2 k AVlO _- O & flo fo.18 AV kO zt Quality of Manufacture 5.1 The belts shall be free from tears, cracks, unseated inserts or shape defects. 5.2 The surface of the belt shall be finished in such a manner that the internal structures of the belt shall not be adversely affected by moisture under normal operating conditions. 3

7 S : ; TABLE 4 STANDARD LENGTHS ( Clause ) Cross %%fl?r Cross %% ;z _ _ Ail dimension8 in miiiimetres > :;c j- _ - Crops %r : K Note 1 -Other lengths as agreed to between the purchaser and the supplier may be used. Note 2 -- Age and storage conditions may alter a belt length and therefore the user should ensure that the belt length is carefully checked immediately before use. it is also recommended that the users should not mix belts of different makes on one drive, for purpose of the acceptance the length measurement shall be carried out within six weeks after the supply of batch is made to the purchaser. Note 3 -For tolerances see Tables 2, 2A and for measurement of belt length see Since the temperature at which a V-belt operates has a significant effect on its life, the user should consult the belt manufacturer when extreme temperatures are expected. For the purpose of this standard such temperatures shall be regarded as those lying outside the range of -20% to +70 C in the engine compartment. 6. Marking - t is recommended that. in addition to being marked with any existing part or trade number, all V-belts manufactured in accordance with this ndian Standard should be marked legibly and durably by vulcanizing or printing on the top surface with a symbol indicating the belt cross section, and with the standard belt length expressed in millimetres. 7. Designation - Automotive V-belts shall be designated by the cross-section symbol, the belt length and the number of this standard. 4

8 Example : S : An automotive V-belt of cross-section symbol AVlO and standard length mm shall be designated as : AVlOjl 250 S : Sampling - Unless otherwise agreed to between the purchaser and the supplier, the procedure given in S : 25CC ( Fart 1 ) Sampling inspecticn tables: Part 1 nspection by atributes and by count of defects ( firsf revision ) shall be followed for sampling inspection. For inspection for the dimensions of the belts a single sampling plan inspection level and AOL 2.5 percent given in Tables 1 and 2 of S : 2500 ( Part 1 ) shall be followed. 9. Tests 9.1 Tensile Test - Finished belts when tested by the method of tensile test given in Appendix A shall meet the following requirements : Tensile Sfrengfh Elongation Percent N, Min Max AVlO / AV Fatigue Test - Finished belts when tested by the machine and method of test given in Appendix B shall meet the requirements given in Appendix C. However, this test is optional ( see Explanatory Note ). SECTON 2 PULLEYS FOR V-BELTS 10. Materials -The pulley shall be made of cast iron or steel, but other materials may also be used provided that they can be shown to have adequate stiffness, resistance to abrasion and suittible. thermal properties appropriate to the specified service conditions. n particular, the stiffness, whicb is a combination of material and design, shall be such that no deflection of the pulley sides occur&t service, Further, the tensile strength of the material used shall be sufficient to take into account the centrifugal stress to be imposed. 11. Dimensions 11.l Measurement - The pulley dimensions may be measured either directly or by means of gauge rods or balls; for this latter means, additional appropriate data is given in Table 5 read with Fig ndividual Pulleys - The dimensions of each pulley shall be in accordance with those given in Table 5 read with Fig. 4. TABLE 5 DMENSONS OF V-GROOVED PULLEYS ( Clauses 2.2, 11.1, 11.2, 11.3; and Fig. 3 and 4) All dimensions in millimetres. Cross Nominal Effective Groove Section Top Pulley j Angle Symbol Width of 1 Diameter E d eff / A AVlO ( lo 05 and over 36kO.5 AV and over 36jzO.5 ~- - Minimum Top Diameter -1 Tolerance Depth of of Gauge on Over- Groove %Sf Ball or 2k all Diameter* D g RdOd g fO zto6 / fO.13 / l.11 / 6 00 f 0 6 *The overall diameter is deli f 2 k. 5

9 4A PRESSED STEEL PULLEY LB MACHNED PULLEY FG. 4 STANDARD V-GROOVED PULLEY 11.3 Multi-Grooved Machined Pulleys The distance between grooves of multi-grooved machined following limits of tolerance appropriate to the belt cross-section: pulleys shall be within the AVO 13.0 f 0.25 mm AV f mm When gauge ball or rods are used, the overall diameter, measurement, deff + 2 k ( see Table 5 ) shall not vary from groove to groove by more than 0.05 mm per 25 mm of the overall diameter, with an upper limit of 0.30 mm. 12. Quality of Manufacture 12.1 Surface of Grooves -The belt contact surface of the pulley grooves shall be free from tool marks and the surface finish shall be according to S : V-grooved pulleys for V-belts groove sections A, B, C, D and 5. The groove surface of steel pulleys shall have a hardness number of not less than 130 BHPJ Cast ron Pulleys - Pulleys made of cast iron shall be close grained and free from porosity or blow holes in the groove after machining, 12.3 Side Wobble, Run Out and Balancing of Pulleys - The side wobble and the run-out (eccentricity) of the pulley on its shaft shall not exceed mm/mm of pulley diameter. n general, except for cast iron pulleys, balancing of the finished pulley should not be necessary, but special cases may rise where balancing is required that is when a pulley has to run at high speeds. 13. Designation - A pulley for automotive V-belts shall be designated by number of grooves, groove profile, effective diameter and number of this standard. 6

10 S : n the case of heterogenous pulleys, the pulley elements of each pulley shall be designated successively: Example: A single groove pulley of AV 13 cross-section of 450 mm effective diameter shall be designated as: Pulley l/avl3/450/ls : Sampling - Unless otherwise agreed to between the purchaser and the supplier the procedure given in S : 2500 ( Part 1 ) shall be fcliowed for sampling inspections. The sampling plan with inspection level and AQL 1 percent given in Table 1 of S : 2500 ( Part 1 ) shall be followed for.inspection for dimensions,.workmanship and side wobble and runout. SECTON 3 NSTALLATON OF BELTS AND PULLEYS AND MARKNG 15. nstallation and Take-up 15.1 Belt installation and subsequent tensioning shall be facilitated adjustment of pulley centres: 4 b) cl by providing the following The installation shall permit the unstretched belt to be fitted on the pulleys by hand. The adjustable pulley shall move inwards from the initial designed running position by an amount equal to belt section thickness. This prevents damage to new belt during installation. The adjustable pulley shall move outwards from the initial designed running position by an amount sufficient to take up at least 3 5 percent of normal original belt length. This provides adequate adjustment to take up belt stretch and wear during total belt life. Axial misalignment between pulleys reduces belt life hence, this should be reduced to minimum possible. 16. Belt Speed and Speed Ratios 16.1 Except where special conditions are imposed, it shall be sufficiently accurate to use the effective pulley diameter ( see 2.2 ) in calculating the speed ratios of automotive V-belt drives., 16.2 n any installation, the maximum belt speed recommended by the manufacturer should not be exceeded in service. 17. Power Application -The user shall satisfy himself that the belt is suitable for the intended power application to the drive. The factors to be considered and step-by-step worked example are set out in Appendix D. However, as the factors influencing belt performance can be numerous, users are urged to consult the belt manufacturer when a new installation design is being prepared. 18. S Certification Marking - Details available with the ndian Standards nstitution. APPENDX A ( Cause 9.1 ) METHOD OF TENSLE TEST A-l. Apparatus A-l.1 The accuracy of the tensile testing machine shall be within fl percent. A-l.2 The range of the machine shall be so chosen, that the loads to be measured fall within 10 percent and 90 percent of the full scale deflection. A-l.3 The load shall be applied smoothly and the rate of traverse of the driven grip shall be 50 f 2 mm per minute. A-l.4 The method of holding the test piece shall be such as to ensure proper alignment of the test pieces eliminating slip or damage during testing. The use of transverse serrated grips as illustrated in Fig. 5 is permissible. 7

11 S: : L- 50 mm mm. PREFERABLY 75mm FG. 5 TRANSVERSE SERRATED GRPS FOR TENSLE TEST OF V-BELTS A-2. Test Piece A-2.1 Cut three test pieces of about 400 mm in length leaving a clear length of 250 mm between the grips. Prepare 12 packing pieces of approximately 75 mm long each from the remaining portion of the belt from which the test pieces are cut and place the packing pieces on either side at the top and bottom of the test piece by using either adhesive tape string or suitable adhesive so that the two sides of the test piece are in intimate contact with the corresponding sides of the packing pieces. The manner of assembling the packing pieces with the test piece is shown in Fig. 6 and 7. A-2.2 Pads of approximately 100 x 60 mm and approximately 6 mm thick cut from transmission belting and conveyor belt carcass on suitable fabric layers may be inserted between the test piece and the jaw faces of the tensile test machine, if necessary, Alternatively emery paper ( 36 grit) with the abrasive face of the emery paper put in contact with the test piece can be employed for this purpose. The position of the pad with respect to test piece is also indicated in Fig. 6 and 7. A-3. Conditioning A-3.1 The test pieces shall be taken from belts not less than 2 days from the date of manufacture of the belt. The test pieces shall be conditioned for 3 days at 27 f 2% end 65 f 5 percent relative humidity and tested at the same conditions of temperature and humidity. Conditioning may be increased to a maximum of 14 days when agreed between the manufacturer and the purchaser. A-4. Procedure A-4.1 The three test pieces as prepared under A-2 shall be subjected to tensile test and the tensile strength and elongation at break shall be recorded. A-4.2 For measuring the elongation at break, a bench mark of 100 mm may be employed. A-4.3 f the break or rupture of the test piece or slippage of the test piece from the jaw occurs before the tensile load reaches the specified value in 9.1, the results of such tests shall be discarded, but if the results of such tests are required they shall be reported as jaw break or slippage as the case may be. APPENDX B ( Clauses 2.4 and 9.2 ) FATGUE TEST MACHNE AND METHOD OF TEST B-l. Dynamic Test Machine - The test machine should consist essentially of: a) a driving pulley and suitable mechanism for driving it; b) a driven pulley to which a suitable power absorption unit ( see also B-l.2 ) is connected; 8

12 .3 : PADS 100x60x6 FG. 6 METHOD FOR TENSLE TEST OF FULL SECTON AUTOMOTVE V-BELT 9

13 S : PACKNG FiECE TEST PECE LENGTH = 75 mm LENGTH =.4OOmm 1 f- loox60x6mm PADS 100 mm 1 SECTON AA /EST PECE LENGTH = LOOmm FG. 7 METHOD FOR TENSLE TEST OF FULL SECTON AUTOMOTVE AND V-BELT c) an idler pulley and arrangement through which tension can be applied to the belt; and d) a means of determining belt slip with an accuracy of fl percent. This can be determined by an electronic digital counting technique or, alternatively, the instrument used for measuring belt slip shall be calibrated and checked periodically by electronic digital counting. B-l.1 The machine shall be of robust design so that all components will withstand, with virtually no deflection, the stresses to which they are subjected. B-1.2 The power absorption unit shall be adoptable to accurate calibration by using dead weights, B-l.3 n order to be able to apply. satisfactorily, tension to the belt, and in order to allow for belt stretch, the idler pulley and its bearing assembly shall be free to slide, as and when necessary, in its support bracket along the line of application of the tensioning force as shown in Fig. 8. The line of 10

14 S : action of the tensioning force shall bisect the belt layout angle at the pass through the axis centre of the idler pulley, and shall be in the groove of the idler pulley. idler pulley (see Fig. 8), shall plane through the centre of the DRECTON OF ADJUSTMENT OF DRVEN PULLEY DRVEN PULLEY 1 c 2 DLER PULLEY SE1 c BELT TENSON c 2 CRECTONS OF ADJUSTMENT OF DLER PULLEY ASSEMBLY AN0 TS SUPPORT BRACKET i DRVNG PULLEY DRECTON OF ADJUSTMEN OF DRVNG PULLEY Note-The centre line of all the three pulley grooves shall be within 0 25 mm of same plane. FG. 8 TEST MACHNE LAYOUT B-l:,4 fn order to accommodate different lengths of belts, the position of the relevant driving members, and/or the relevant driven members, and the position of the idler pulley and/or its support bracket shall be adjustable so that the test layout of the pulleys (see B-3 ) is attainable for each belt length. B-l.5 The pulleys shall be made of steel to grade 40Cr 4Mo3 of S : Specification for plane and induction hardening steels ( first revision ). The dimensions and tolerances of the pulleys and pulley grooves for belt sizes shall be as given in Table 6 read with Fig. 3 and 9. The groove profile shall be as shown in Fig. 9. The pulley groove face surface finish shall be 0.8 r:m Ra ( see S : Assessment ofsurface roughness ). B-2. Test House Conditions -The ambient temperature of the test house shall be 18 C to 30 C. The atmosphere in the vicinity of the test drive shall be free of draughts resulting from sources other than the test belt drive itself. B-3. Test Method - For each test the general lay-out of the pulleys in relation to each other shall be as specified in Table 6 and as shown in Fig. 8, the centre distance between the driving and driven pulleys within f 0.5 mm of the value determined from the formula: 2 414C=L0 785(3D+d) -(D-d) where C = centre distance between driving and driven pulleys; L = nominal length of belt, $0.3 percent; D = diameter of both driving and driven pulleys; and d = diameter of idler pulley. 11

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16 S : f, : L---- r7 / OD ACTUAL b A -- R1.5 d +_l FG. 9 PROFLE OF TEST PULLEY B-3.1 After mounting the belt on the pulleys the test tension (see Table 7) shall be applied to the belt and, leaving the idler pulley support bracket free to move in its slide, the drive shall be brought up to full test speed and the relevant load (see Table 7 ) applied to the driven pulley as soon as possible. The drive shall be run under these conditions for O min f 15 s including starting and stopping time. TABLE 7 BELT TEST CONDTONS ( Clauses B-3.1, B-3.3, B-3.4, C-l and C-l.1 ) Belt Type AVlO Unnotched AVlO Notched AVt3 Unnotched AV13 Notched Running-in load (kw) Revolutions pei minute of driving pulley during the running-in test periods Running-in tensions force applied to idler pulley (N) Test load (kw) ,O Test tension force applied to idler pulley (N) Note 1 - For full pulley details see Table Note P-The maximum number of retentions permitted, excluding those made during the running-in period, is two. - B-3.3 The drive shall then be immediately manually rotated for several revolutions of the belt and, by means of e dial indicator mounted in contact with the idler pulley support bracket, the extreme limits of travel of the pulley bracket shall be noted. The bracket shall then be immediately locked in the position midway between the two limits of travel. B-3.3 The machine shall be re-started, the drive brought up to full test speed, the test load (see Table 7) applied to the driven pulley and the drive allowed to run continuously under these conditions until either the belt fails or belt slip reaches the value of 3 percent. B-3.4 f belt slip reaches 3 percent, before belt failure, then the machine shall be stopped, the idler pulley support bracket unlocked and the operations described in the above two paragraphs shall again be carried out immediately before re-running the belt as soon as possible under the appropriate test conditions f see Table 7 ). B-3.5 The test shall be continued on these lines until the belt fails, the belt being retensioned as above whenever belt slip reaches 3 percent. B-3.6 The number of hours run to belt failure and the number of the belt retensions shall be recorded, 13

17 s : $ APPENDX ( Clause 9.2 ) C FATGUE TEST CONDTONS C-l. The recommended test condition shall be as given in Table 7. C-l.1 The revolutions per minute of the driving pulley shall, except during acceleration and declaration, be within fl percent of the values given in Table 7, during both the runnmg-in time and the belt life time. C-l.2 The minimum individual belt life and the average of the total number of belts tested as agreed to between the user and the manufacturer, shall be not less than those defined by the respective curves shown in Fig MNMUM AVERAGE LF NOMNAL BELT EFFECTVE LENGTH, mm FG. 10 MlNlMUM DURABLTY ( HOURS) OF BEtT UNDER TEST APPENDX ( Clause 17) D RECOMMENDATONS FOR AUTOMOTVE V-BELTS DRVES D-l. Factors The principal factors to be considered when establishing a new automotive belt design are as follows: a) Actual operating time of the drive compared with the total time desired between belt replacements; b) Probability of longer and more severe usage than normal; c) Warranty period to be placed on the engine; d) Degree of uncertainity about loads the drive will carry; e) Possibility of heavier drive loads when optional- or auxiliary equipment is added to the engine or vehicle;

18 S : )s f) Accuracy of alignment of the pulleys ( 3ny deviation reduces belt life ); - g) Pulley grooves as illustrated in Fig. 4 ( any deviation reduces belt life); h) The necessity of adhering to be maximlin V-belt tensions in relation to the pulley diameter given in Fig. 11 to ensure that reascnable belt life is obtained. D-1.1 Since so many other factors influence belt performance, it is suggested that designers may find it extremely helpful to consult the belt manufacturer when any new design is being considered. 3ootti i i EFFECTVE PULLEY DAMETER,mm FG. 11 RECOMMENDED MAXMUM BELT TENSON (Tt) N RELATONiT EFFECTVE PULLEY DAMETER Note 1 -Notching is recommended for the dashed portions of the curves. Note 2 - Recommended minimum pulley diameters : AV13 Section 100 AVlO Section 75 mm. Note 3 - Adherence to maximum V-belt tension in relation to the pulley diameters given above will ensuie that reasonable belt life is obtained. However, as so many factors influence belt performance, it s suggested that designers will find it helpful to consult the belt manufacturer when any new design is being considered. D-2. Calculation Note - For a worked-out example of this calculation, see O-3 ( read with Fig. 11). D-2.1 Make a sketch of the drive indicating diameters, maximum power at constant speed, rad/s of driver pulley (V), arc of contact at each pulley, moment of inertia of driven components and maximum possible speed change at driver pulley. D-2.2 Note the direction of rotation of the drive, and number the pulleys in the opposite direction starting at the driver pulley as No. 1. Construct a table, giving the following (letter references in brackets are to the worked-out example in D-3) : Power at each pulley Pulley diameter Belt speed Moment of inertia of driven components Maximum rate of speed change of the driving pulley 15 Reference to Worked-out Example in D-3 (b) (cl Cd) (4 (f)

19 S : Constant speed of effective tension Ts (cl) Speed change effective tension Ta (h) Note - D, = crankshaft pulley diameter, = inertia value for the appropriate driven component, D = diameter of each of the driven pulleys, and T.., = for crankshaft pulley = sum of TAs at each of the other pulleys. Add the values of (g ) and ( h ) to give effective belt tension T, Arc of contact e at each pulley K factor for each pulley ( see Table 8 ) Minimum tight side tension T necessary to ensure no slip at any pulley Actual tight side tension 7, at each pulley (established by inspection ). TX for No, 2 pulley equals TX for No. 1 pulley; T, for No. 3 pulley equals T1 for No, 2 pulley minus To for No. 2 pulley. These are actual 71 values. All values given in (p) should be equal to or greater than the corresponding values in line (n). f so, omit the next step. (i) (k) (n-d O-0 (P) f a value in line (n) is greater than the corresponding value in line (p), subtract the smaller from the larger and increase all values in line (p) by this difference. Using the largest value in (p), refer to the recommended maximum belt tension graph ( Fig. 11 ) and select the appropriate belt section. Calculate the centrifugal tension Tc ( using Table 9) which is the same for each pulley. Add the tensions in (p) and (q) for each pulley to obtain Tt Using Fig. 11, check that tension values against appropriate pulley diameters do not exceed the recommended maximum tension for the belt section already chosen. f they do not, the belt selected shall be deemed to be satisfactory. Note - f the belt selected is unsatisfactory : a) select another belt and repeat the procedure from line Cq); or b) increase pulley diameters and re-calculats drive; or c) resort to a multi-belt drive. [n this case, divide values in (p) by the number of belts and proceed as before. ] D-2.3 t is recommended that calculation should be carried out at both maximum and minimum belt speeds (V) in order to ensure that maximum belts loading conditions are ascertained, (4) () D-3. Worked-out Example Crankshaff ( Driving Pulley ) (1) Power transmitted Pulley dia D Arc of contact Rate of speed change Angular velocity N A = 4 1 kw = 140 mm, hence radius R = 0 07 m = 130 = lad!.+ = 575 rad/s LAYOUT OF PULLEY 4 Pulley b) Power W ( watts ) cl d) Pulley diameter D ( mm ) Belt speed V - N x R ( m/set ) Alternafer (2) Power absorbed = 2.2 kw ( Max at constant speed ) Moment of inertia = 0, kg/m2 Puliey dia D = 76 mm, hence radius R = O-038 m Arc of contact = 110" Fan and Water Pump (3) Power absorbed = 1 9 kw ( Max at constant speed ) Moment of inertia = 0 CC2 63 kq m? Pulley dia D = 127 mm hence radius = R O.C6 35 m Arc of contact = Driving (1) Driven (2) Driven (3)

20 S ; Moment of inertia ( kg, m2 ) - 1) Speed change A at crankshaft ( rad/s2) ) Constant speed effective tension T 3 al- newtons ) h) Speed change effective tension TA t + x 2 ( newtons, N ) i) W ml n) P) Effective belt tension Te = Ts + TA ( newtons ) Arc of contact at each pulley ( degrees ) Kl (from Table 8 ) Minimum tight side tension T, = K, x T, ( newtons, N ) Actual T of AVlO belt selected ( newtons ) q) Centrifugal tension Tc = K2 x V2 (newtons, N ) 140 r) Total tension Tt = Tl f Tc ( newtons) Maximum required tension = 319 N Maximum allowable tension from Fig. 11 = 272 N Therefore one AVlO AV13 section belt. section belt is deemed to be unsatisfa story and calculations should be repeated for TABLE 8 FACTOR K, --w-. ( Clause D-2 2 ) - Arc of Contact Degrees K, ii ii 1'13 1' '31 1'35 1'40 1'46 1'52 1' ' TABLE 9 FACTOR KS ( Clause D-2.2 ) Belt Cross Section K, p--p.._~~ AVlO standard AV13 standard

21 S : EXPLANATORY NOTE This standard was first published in Since the publications of this standard considerable progress has been made regarding manufacture and testing of belts throughout the world. This revision of the standard was taken up to incorporate the latest thinking in the field. The belts have now been designated as AVlO' and AV13 in place of FBO and FB13. Tensile test and method to carryout tensile test has been incorporated as a measure of quality although it does not retlect complete performance of belt, Fatigue test has also been added but it has been made optional as sufficient data is not yet available in the country on it. Data will be collected and in the next one to two years this test which at present is of recommendatory nature will be made obligatory, While preparing this standard considerable assistance has been derived from the following: BS AU 150 : 1973 Specification for automotive V-belt drives. British Standards nstitution. S Narrow V-belt devices for automotive industry - Dimensions. nternational Organization for Standardization ( S0 ). S Narrow V-belt drives for the automotive industry - Fatigue Test. nternational Organization for Standardization ( S0 ). 18 Printed at Arcee Press, New Delhi, ndia

22 AMENDMENT NO. 1 OCTOBER 1987 TO S: SPECFCATON FOR AUTOMOTVE V-BELT DRVES (First Revision) (Page 11, clause B-3, formula) - Substitute the following for the existing formula: ' C = - L (3D - + d) - (D - d)' z.- ; L- (Page Substitute 'Test (EDC 42) 13, Table 7, first column, fourth entry) the following for the existing matter: load (kw) +O.l kw' - Reprography Unit, BS, New Delhi, ndia