- 1 - ICS 21.220.10 
G 42 
 
  
 
National Standard  
of the People's Republic of China 
  
GB 13552-XXXX 
 Replaces GB 13552-1998 
 
 
Automotive V – ribbed belts 
 
(ISO 9981: 1998 belt drives-pulleys and V -ribbed belts for the automotive industry-
PK profile: Dimensions, NEQ 
 
ISO 11749: 1995 Belt drive -V – ribbed belts for the automotive industry-fatigue test, 
NEQ) 
 
 
Draft Standard for approval 
 
 
 Issue Date: XXXX – XX – XX Impl ementation Date: XXXX – XX – XX 
 
 
 
Issued by General Administration of Quality Supervision, Inspection and 
Quarantine of the People 's Republic of China  
 
Standardisation Administration of the  People's Republic of China (SAC) 
 
 Foreword 
Article 4.2 of this Standard is manda tory, whilst the rest are recommended. 
 This Standard corresponds to  ISO 9981:1998, “Belt dr ives-pulleys and V-ribbed belts for the 
automotive industry – PK profile: Dimensions, NEQ” and ISO 11749:1995, “Belt drive-V-ribbed 
belts for the automotive industry – Fatigue test, NEQ) , the consistency degree of this Standard and 
ISO 9981:1998 and ISO11749:1995 is non-equivalent.  This Standard replaces GB 13552-1998, “Automotive V-ribbed belts”.  The main differences between this Sta ndard and ISO 9981:1998 and ISO 11749:1995 are: 
− The measurement methods for limit deviation of  effective length, the reference value of rib 
height, the rib angle, and the exposed height have been added in accordance with Standard 
JASO E109-1994, “Automotive V – ribbed belts” of Japanese Autom obile Manufacturers 
Association; 
− the transmission power of three-pul ley fatigue testing machine, te nsion and fatigue life-span of 
belts have been added in accordance with JASO E109-1994; 
− the tensile characteristics, low-temperature resi stance characteristics and appearance qualities of 
belts have been added in accordance with JASO E109-1994; 
− inspection, symbol, packaging, transport and storage rules have been added. 
 The main changes to this Standard compared to GB 13552 – 1998 are: 
− the limit deviations of the effective length are mo re strictly regulated (Section 4.5.4 of Edition 
1998, Section 3.5.4 of this Edition); 
− specific requirements for fatigue testing equipmen t have been added, as well as test procedures 
and specific requirements for equipment of two-pulley testing machine (See A.2, A.4.2.1.2); 
− the fatigue testing index of V-ribbed belts has be en increased from 50 hours to 80 hours (Article 
5.2 of Edition 1998, Article 4.2 of this Edition); 
− the fatigue testing methods of V-ribbed belts have been moved from the main Section to 
Appendix A (Article 6.2 of Edition 1998, Appendix A to this Edition). 
 
Appendix A to this Standard is a normative annex.  This Standard is proposed by China Petroleum and Chemical Industry Association.  This Standard is under the jurisdiction of the Technical Committee of Chemical Industry Rubber 
Belts for Standardisation.  The organisations that participated in the drafting of this Standard are:  
Guizhou Dazhong Rubber Co., Ltd; Hangzhou Jintai Belt Co., Ltd; Zehjiang Zijingang Rubber Belt Co., Ltd; Ningbo Fengmao Far-east Rubber Co., Ltd; China Wuxi Belt Co., Ltd; Northwestern Polytechnic University; Qingdao Rubber Industry Research Institute. The main draughters of this Standard: Xiang Xuew ei, Song Huiyan, Wang Jinfang, Chen Hai, Zeng 
Jun, You Jianping, Li Shujun, Han Deshen, Deng Ping, Xu Zhe. 
  This standard replaces the pr eviously issued Standards: 
GB 13552-1992, GB 13552-1998.  
Automotive V-ribbed belts 
 
1 Scope 
This Standard specifies the product categories,  requirements, test methods, inspection rules, 
markings, packaging, storage and transport of auto motive v-ribbed belts (herei nafter referred to as 
the belts).  This Standard applies to transmission belts fo r fans, motor, pumps, compressors, power steering 
pumps and superchargers etc. of intern al combustion engines for automotives. 
2 Normative References 
The provisions of the following documents become  provisions of this Standard after being 
referenced. For dated reference documents, a ll later amendments (excluding corrigenda) and 
versions do not apply to this Standard; however, the parties to the agreem ent are encouraged to 
study whether the latest versions of these doc uments are applicable. For undated reference 
documents, the latest versions apply to this Standard.  GB/T 11357 Quality, Surface-roughness and balan ce of transmission pulleys (GB/T 11357-1989, 
eqv ISO 254:1981)  GB/T 17516.2 V-and ribbed belt drives – Dynamic test  to determine pitch zone  location – Part 2: V-
ribbed belts. (GB/T 17516.2, idt ISO 8370-2:1993) 
3 Requirements of shapes, di mensions and raw materials 
3.1 Model 
The models of the belts are used to represent the section shapes and dimensions. The PK model 
is normally adopted for automotive v-ribbed belts. 
3.2 Specifications, markings 
The dimension characteristics of automotive v-ribbe d belts include the number of ribs, model and 
effective length, and the belts are marked  with the following numbers and letters: 
a) the first group of numbers re presents the number of ribs; 
b) the group of letters represent the model; 
c) the second group of numbers represents the effective length in millimetres. 
 
  
3.3 Shapes and structures 
Automotive v-ribbed belts are endless belts as shown in the section view in Figure 1. 
 
  
3.4 Materials applied 
3.4.1 Rubber 
The constitution of the adhesion rubber and the rib rubber sh all be uniform. 
3.4.2 Belt-back fabric 
Belt-back fabric is a textile woven from cotton fibres,  synthetic fibres or a blend of the said fibres. The 
density of the warp-wise and weft-wise of the fabric shall be even, with no defects or twist deformations. 
3.4.3 Tension member 
Tension member is a cotton rope made of synthe tic fibres; its yarn twists shall be uniform. 
3.5 Dimensions 
3.5.1 Section dimensions 
The reference values for the section dimensions of the belts are shown in Figure 2 and Table 1. 
Figure 1 Structure of V-ribbed belt   
 
 
Table 1 Section dimensions of belt  Unit: mm 
Name Dimension 
Rib spacing P b 3.56 
Rib angle a 40o 
Arc radius of the rib-root r t 0.25 (maximum) 
Arc radius of the rib-top r b  0.5 (minimum) 
Belt thickness h 4 ~ 6 (reference) 
Rib height h t 2 ~3 (reference) 
Note: the rib spacing and rib height as set out in the table are only reference 
values. The accumulated tolerance of rib spacing is an important index, but it is normally very often affected by the tension force when the belt is working and the modulus of the tension member. 
Figure 2 Section View of Belt   
3.5.2 Effective line differential and exposed height 
See Figure 3 for the effective line differential and the exposed height of the belt. The measurement 
of the exposed height shall be conducted in accordance with the method specified in 5.1; the 
measurement of the effective line differential shall be conducted in accordance with the method 
specified in GB/T 17516.2. The nomin al value and the limit deviation of the exposed height and the 
effective line differential shall be decided thr ough consultation between the supplier and buyer. 
 
3.5.3 Minimum pulley diameter 
In order to enable the belt to meet its specified se rvice life, the diameter of  the pulley selected shall 
not be smaller than the values set out in Table 2.  
Table 2 Minimum pulley diameter  Unit: mm 
 Forward bending Reverse bending 
Effective diameter 55 - 
External diameter - 85 
 
3.5.4 Limit deviation of  effective length 
The length of the belt is represented by eff ective length; its measur ement is conducted in 
accordance with the method specified in 5.1. The eff ective length is usually an integral number of 
times of 10mm. See Table 3 for the limit deviation thereof.    
Figure 3  Table 3 Limit deviation of effective length Unit: mm 
Effective length L e Limit deviation 
≤ 1000 ± 5.0 
> 1000, ≤ 1200 ± 6.0 
> 1200, ≤ 1500 ± 8.0 
> 1500, ≤ 2000 ± 9.0 
> 2000, ≤ 2500 ± 10.0 
> 2500, ≤ 3000 ± 11.0 
Note: when the effective length is greater than 3000mm, its limit deviation 
shall be decided by the agreement between the supplier and the buyer. 
 
4 Requirements 
4.1 Appearance requirement 
There shall be no harmful faults such as tw isting, crookedness, cracking, bubbling or foreign 
articles etc. on the surface of the belt. 
4.2 Fatigue life 
According to the actual conditions of use of the belt or in accordance with the agreement between 
the supplier and the buyer, select a two-pulley, three-pulley or four-pulley bench te sting machine to 
determine the fatigue life of the belt in accordance with  the test method specified in Appendix A. 
When the test time reaches the prescribed test r unning time, there shall be no damage to the belt, as 
shown in Figure 4. The fatigue life of the belt shall not be shor ter than 80 hours. 
4.3 Tensile characteristics 
The tensile characteristics of the be lt shall be tested in accordance with the method specified in 5.3; 
its tensile strength and its elongatio n of reference tension shall conform to the requirements of Table 
4. 
Table 4 Tensile Characteristics 
 
Number of 
ribs Tensile strength 
kN Elongation of 
reference tension 
% Reference tension kN 
3 ≥ 2.40 0.75 
4 ≥ 3.20 1.00 
5 ≥ 4.00 1.25 
6 ≥ 4.80 1.50 
More than 7 ≥0.8 x n ≤ 3.0 
0.25 x n 
Note: n is the number of ribs. 
  4.4 Low-temperature resistance characteristics 
The low-temperature resistance characteristics of  belts shall be tested in accordance with the method 
specified in 5.3; no cracks shall appear on the belts.  
 
5 Test methods 
5.1 Measurements of the length and exposed height 5.1.1 Equipment 
The measurement of the effective length of the belt is conducted after wrapping the belt on the 
measuring equipment constructed with the following parts. Illustrated in Figure 5: 
 
5.1.1.1  Two of the same diameter pulleys, one is fixe d and the other is movable. The pulley groove 
section and the section dimensions  of the two pulleys sh all conform to the re quirements of Figure 6 
and Table 5. The recommended applicable effectiv e diameter may be determined by the magnitudes 
set out in Table 6.  5.1.1.2  Load applying device, used to apply tota l measuring load to the movable pulley. 
 5.1.1.3  Measuring device used to measure the dist ance between the centres of the two pulleys. 
5.1.2 Measuring load 
The measuring load applied, for the purpose to m easure the effective length of the belt, shall 
conform to the requirements of Table 6. 
5.1.3 Procedures 
When measuring the effective lengt h of a belt, rotate the belt fo r at least two rounds, enable the
 belt 
Figure 4 
Figure 5 Measuring equipment 
of length and exposed height  ribs and the pulley grooves to be correctly matched, distribute the measuring load on the two 
straight sections of the belt ev enly. Next, measure the distance E between the centres of the two 
pulleys; the effective length (L e) of the belt and the exposed height (b o) shall be determined by the 
following formula: 
Le=EmaxEminUe 
Where: 
Le  - the effective length of the belt; 
Ue – the effective circumference of the measuring pulley; 
Emax – the maximum distance value between  the centres of the two pulleys; 
Emin – the minimum distance value between  the centres of the two pulleys. 
bo=S−de 
Where: 
bo – the exposed height, unit is mm; 
de – the effective diameter of the pulleys, unit is mm; 
S – Values used for calculation (see Figure 5), unit is mm. 
 
 
 
 
Figure 6 Section view of pulley groove   
Table 5 Groove dimensions of PK type pulley   Unit: mm 
Item Limit deviation Prescribed value 
Groove pitch (e) ±  0.05a,b 3.56 
Groove angle of 
measuring pulley (ac) ±  0o15' 40o 
Groove angle of drive 
testing pulley and actual 
pulley (ac) ±  1o 40o 
rt Minimum value 0.25 
rb Maximum value 0.5 
Diameter of measuring 
ball (or column) d B ±  0.01 2.5 
2x Nominal value 0.99 
2Nd Maximum value 1.68 
f Minimum value 2.5 
a - the e tolerance value used to check th e interval spacing between the axes of the 
two adjacent pulley grooves. b
 – the deviation sum of e value of any gr oove of any pulley shall not exceed ±  0.3. 
c – the angle between the centre line of the gr oove and the axis of  the pulley shall be 
90o ± 0.5o. 
Cdc – the N value is independent from the no minal diameter of the pulley; it is the 
radial distance from the contact point betw een the measuring ball (or column) inside 
the pulley groove and the groove to the outer margin of the measuring ball ( or column). 
 
Table 6 Measuring pulley and measuring load 
Item Value  
Effective circumference (U e) of the 
measuring pulley (on the end point of the effective diameter)/mm 300 
Pulley diameter at the outer margin of the 
ball (or column) k/mm 96.48 ±  0.13 
Measuring load of each rib F/N 100 
 
5.2 Tensile test 
5.2.1 Samples 
Cut out three sample pieces of a length of 250mm fr om one belt. In the middle of each sample draw 
two marking lines with a distance  of 100mm between them, in orde r to determine the elongation. If  it is not possible to cut out three samples from the same belt, then the number of samples shall be 
decided through agreement between the manufacturer and the buyer. 
5.2.2 Test procedures 
In an ambient temperature of 25oC ± 5oC, perform the tensile test on the samples using a tensile 
testing machine. The test speed shall be 50m m/min ± 5mm/min. The maximum pulling force which 
makes the sample fracture shall be regarded as the tensile strength. 
 In general, the mean value of the three determined  values after being rounded to two decimal places 
shall be taken as the standard determined value.  The value determined when a frac ture occurs at the clamping lo cation shall not be taken into 
account; the test shall be carried out on additional sa mples cut from the same belt in order to satisfy 
the determined value shortage. 
5.3 Low temperature resistance test 
5.3.1 Samples 
Cut out three samples in accordance with the met hod specified in 5.2.1. Carry out pre-treatment for 
70-72 hours in an ambient temperature of 100
oC ± 2oC. 
5.3.2 Procedures 
Cool the samples to room temperature and l eave them in an ambient temperature of  
-30oC±  1oC for 70 ~ 72 hours, then remove them out and carry out the bending test on a cylinder in 
accordance with Table 7. The bending angle shall be at least 90o. 
 Select the bending condition A2 or bending condition B2 in accordance with the state of the belts 
during use. 
 
Table 7 Bending conditions 
Item Condition A2 Condition B2 
Laboratory 
temperature, o C 25 ±  5 25 ±  5 
Cylinder diameter, mm 40 70 
Bending direction Forward bending Reverse bending 
Note: if the rib part of the belt bends to medi al side this shall be considered as forward 
bending; if the rib part of th e belt bends to the lateral si de shall be considered as 
reverse bending. 
 
5.4 Fatigue test 
The fatigue test shall be perf ormed on the belt in accordance with  the provisions specified in 
Appendix A.  6 Inspection rules 
6.1 Belts shall be checked and a pproved by the manufacturer’s qual ity inspection department and 
issued with a quality certificate, after whic h they shall be ready to leave the factory. 
 6.2 Each belt shall be individually checked fo r appearance quality and effective length in 
accordance with 3.5.4 and 4.1. 6.3 One in every thousand belts shall be sampled for section dimensions measurement, and the 
tensile characteristics test shall be  conducted at least twice per month. 
 6.4 The low temperature resistance test shall be conducted at least once every three months. 
 6.5 With regard to belts of same model that are made of the same materials, two sample belts shall 
undergo the fatigue life test, which shall be  conducted at least once every six months. 
 6.6 If any item from the tests mentioned in 6.3, 6.4 and 6.5 fails, select double the quantity of 
samples from the same batch of belts and re-test the items that failed; if any item from the re-test fails again, then this batch of produc ts shall be considered unqualified. 
7 Symbols, tags, packaging, transport and storage 
7.1 Symbols 
A permanent clear visible symbol shall be pl aced on each belt, containing the following 
information: 
a) specification mark; 
b) manufacturer and trademark; 
c) production date. 
7.2 Tags and packaging 
Each belt shall be packed within  a paper bag or plastic film, a nd every 50 to 100 belts shall be 
packed within a packaging bag or box as appropriate. On the outside of each package the 
manufacturer, trademark, specifica tion, quantity and production date sh all be specified. A tag made 
of hardboard or plastic film shall be enclos ed in the box, and sha ll contain the following 
information: 
a) name of the manufacturer or trademark; 
b) specification mark; 
c) number of belts contai ned in the bag or box; 
d) production date; 
e) indication of the components  code required by the buyer; 
f) quality stamp of the qual ity inspection department. 
7.3 Transportation, storage 
7.3.1  During transportation or storage, direct exposure of the belts to sunlight , rain and snow should 
be avoided, as well as cont act with other articles that could be ha rmful to the quality of the belt such 
as acid, alkali, oil and organic solvent etc. The belts  should be kept clean. The storage location shall 
be at least one metre away from any heat source un it and during storage the belts should not be bent 
and squeezed.  7.3.2  During storage, the temperature of the st ore room shall be maintained within -15
oC- 40oC. The 
relative humidity shall be within 50%-80%.  Appendix A 
(Normative Annex) 
Belt drives – Automotive industr y V-ribbed belt – Fatigue test 
A.1 Outline 
 
Determine the transmission characteristics of the belt on a two-pulley, three-pulley or four-pulley 
testing machine as specified in A.2.1 in accordance with the following provisions.  
Note 1: the length of the V-ribbed belts that can be tested on a four -pulley testing machine 
shall be at least 1,000 mm (see Figure A.1); V-ribb ed belts of length within the range of 800 
mm - 1,000 mm shall be tested on a three-pull ey testing machine (see Figure A.2); belts 
which are shorter in length than abovementi oned range shall be tested on a two-pulley 
testing machine (see Figure A.3). See Table A.1 for details.  
Table A.1 Requirements of be lt for transmission test 
Test equipment Belt rib numbers Belt effective 
length/mm 
Three-pulley testing 
machine 3 800 ~ 1000 
Four-pulley testing 
machine 3 1000 ~ 1300 
 
During testing, for certain test conditions such as transmission power and minimum permissible 
life-span of belts (use hour as  unit), re-tension times shall be  decided through agreement between 
the manufacturer and the buyer.  If a belt no longer meets the specified requirements,  then it shall be consid ered to have lost its 
efficiency.  
A.2 Equipment 
 
A.2.1 Fatigue testing machine 
 
The structure of the fatigue testing machine shall be stable and strong; al l the components of the 
machine shall be able to bear the stresses cau sed during the test, and shall not be damaged. 
 The main components of a testing machine ar e (see Figure A.1 Figure A.2 and Figure A.3): 
a) a drive pulley and suit able driving devices; 
b) a driven pulley and a suitable power-absorbing device which is connected to the drive 
pulley; 
c) the power-absorbing device shall be  accurate and able to be co rrected using an appropriate 
method (such as using weights); 
d) a reverse bending tensioner pulley, only used on four-pulley testing machine (see Figure 
A.1); 
e) a component which can directly bear the test tension load: 
For three-pulley and four-pulley testing machines, this component shall be a tensioner pulley. (See 
Figure A.1 and Figure A.2);  For two-pulley testing machines, this component shall be a m ovable pulley (see Figure A.3); 
f) for devices used for the measurement of the belt  slippage the measurem ent precision shall be 
± 1%. 
See Figures A.1, A.2 and A.3 for an illustration of  the arrangement and rotational direction of 
pulleys.  In order to enable the testing machines to be suitable for belts of any length, the position of the 
drive pulley and driven pulley, the position of th e tensioner pulley and its support base (for three-
pulley testing machines), and the position of the reversed bending tensioner pulley (for four-pulley testing machines) shall be adjustable, so as to enab le the arrangement of the pulley and to satisfy the 
requirements of belts of any length.  In order to ensure the tension load can be corr ectly applied to the belt, while meeting the belt 
extension, the tension app lied on the support base (where necessa ry) and its bearing device can slide 
freely along the tension line.  For four-pulley testing machines under this condition, the tension line  shall be located on the same 
plane where the centres of the pulleys are; divide  the angle formed by the V-ribbed belt at the 
tensioner pulley and at the re verse bending tensioner pulley. 
 For three-pulley testing machines under this conditi on, the tension line shall be located on the same 
plane where the centres of the pulleys are, and di vide the angle formed by the V-ribbed belt at the 
tension pulley.  For two-pulley testing machines, one of the pulleys (drive pulley or driven pulley) shall be movable 
in order that the testing machine can test V belt w ith a length of 800mm. There shall be a fastening 
device on the testing machine, which shall be able  to fix the position of the movable pulley when 
the belt is bearing the specified tension force. In order to ensure the specified tension force can be applied to the belt correc tly, while meeting the belt extension, the tension line shall pass through the 
centre of the driver pulley and the centre of the pulley shaft of the driven pulley, and shall be 
located on the same plane as the centre s of the two pulleys (see Figure A.3). 
 
A.2.2 Test pulley 
 
The arithmetic mean value of th e surface-roughness R (see GB/T 1135)  of the groove sides of the 
test pulley shall not exceed 0.8µm. The dimensi on requirements of the test pulley are shown in 
Figure A.4 and Table A.2.  
A.3 Laboratory conditions 
 
The ambient temperature of the test shall be: 
a) the temperature in the laboratory shall be 18
oC-32oC. During the test, the surroundings of 
the test transmission equipment shall not have  any other airflow except from the equipment 
itself; 
b) the temperature inside of the ther mostat shall be controlled at 85oC ±5oC. 
 
Note 1: The radial run-out value and axial r un-out value (Total Indi cated Run-out) shall not 
exceed 0.25 mm, and both run-outs shall be de termined by measuring the radial run out of 
eccentricity of the ball which has a good cont act with the pulley groove by the spring 
pressure when the pulley is in operation.   
2. The surface roughness of the pulley groove with Ra as th e index shall be smaller 
than 0.8µm. As under such situation, the Ra is  a main parameter of the test pulley, so 
the value of Ra is determined as 0.87. S ee GB/T 11375 for the definition of Ra and 
its measuring method. 
 
Figure A.1 Arrangement of four-pulley testing machine 
Note: the angle formed by the plane which the fitted belt is on and the plane which is 
determined by the centres of the pul leys shall be adjusted to ±15'. 
 The value 45
o shall be the test beginni ng of said angle, which can change due to the 
retension of the belt during the test process  
A.4 Test methods 
 
A.4.1 Test conditions 
 
The rotational speed of the drive pulley shall be 4900r/minute; the limit deviation of the rotational 
speed shall be ±2%. The recommended transmission pow er (use 3 ribs as reference) for three-pulley 
 or four-pulley fatigue testing machines shall be 8kW, and the tension force shall be 680 ±30N. In 
respect to V-ribbed belts with 3-5 ribs; if any sp ecial requirements are requested by the buyer, they 
can be agreed upon between the manufacturer and th e buyer. The specific test conditions shall be 
determined by the following formula.  Use the rotational speed of the drive pulley to calcu late the torque. The torque shall be constant 
when it does not have to make up the speed loss of  the driven pulley caused  by the slippage of the 
belt.  The torque M shall be determined by the following formula: 
 
Where: M – the torque, unit is Newton.meter (Mm); 
Ps – the specified transmission power, unit is kilowatts (kW); 
 
 Note: the angle formed by the plane which the fitted belt is on and the plane which is 
determined by the centres of the pul leys shall be adjusted to ±15'. 
The value 45o shall be the test beginning of the said  angle, which can change due to the 
retension of the belt during the test process.  
Figure A.2 Arrangement of three-pulley testing machine 
 
V – Rotational speed of the drive pulle y, unit is rotation per minute (r/min). 
The test equipment shall be correctly maintain ed; the additional load caused by the bearing 
loss, lubrication etc. shall be kept  to a minimum as far as possible. 
 
A.4.2 Procedures 
 A.4.2.1 Test preparations 
 
A.4.2.1.1 Preparation of three-pulley or four-pulley testing machines 
 
Method A 
 
Wrap the belt onto the pulley and apply the test tension force to the tensioner pulley (see A.4.1).  
Start the testing machine where the supporting base of the tensioner pulley can move freely in the 
sliding groove, and enable the transmission equi pment to meet the rotational speed (see A.4.1). 
Apply the specified load to the driven pulley as  quickly as possible, making the power-absorbing 
device absorb the specified power.  
When the operation of the transmission equipmen t has been kept in th is condition for 5min ±15s 
(exclusive of starting time and braking time), stop the testing machine for at least 10 minutes. Next, 
use hands to rotate the pulley, rotating the belt fo r a few cycles, then immediately fix the position of 
the supporting base of the tensioner pulley.   
Note: the angle formed by the plane which the fitted belt is on and the plane which is 
determined by the centres of the pulleys shall be adjusted to ±15'. 
 
Figure A.3 Arrangement of two-pulley testing machine 
 
 
Method B: 
 
Wrap the belt onto the pulley and apply the test tension force to the tensioner pulley (see A.4.1), 
making the supporting base of the tensioner pulley move freely in the sliding groove, then use 
hands to rotate the pulley, rotati ng the belt for a few cycles, then  fix the position of the supporting 
base of the tension pulley as quickly as possible.  
Note: if a new pulley is selected for this test, then a non-testing belt s hould be used to carry 
out run-in for at least 48 hour s in accordance with the test procedures, after which the 
fatigue test can be conducted.  
A.4.2.1.2 Preparation of two-pulley testing machines 
 
Carry out preparation in accordance with th e procedure specified in A.4.2.1.1, however, the 
supporting base of the tensioner pu lley should be changed to the supporting base of the movable 
pulley.  
  
Table A.2 Dimensions of testing pulley 
Item Symbol Value Limit deviation 
Groove number  3  
Groove spacing e 3.56 ±  0.05a)b) 
Groove anglec)  40o ±  0o30' 
arc radiusd) of groove root  r b 0.5 0 
-0.05 
arc radiuse) of groove top  r t 0.25 +0.10 
0 
Effective diameters of drive pulley and driven pulley
e) de1 121 ±  0.02 
Effective diameter of tensioner pulley
5) de2 45 or 55f) ±  0.2 
Effective diameters of drive pulley and driven pulley
g) de2 63 ±  0.2 
External diameter of reverse bending tensioner pulley d
r3 60 or 76) ±  0.2 
Pitch diameter10) dp dp = d e + 2b e - 
Effective line differential b e 2 Nominal value 
Spacing between the 
paralleled circumscribed planes of the measuring ball or column
11) K K =  d e + 2x - 
Spacing between the external surface of the pulley to the circumscribed plane of the measuring ball or column 2x 0.99 - 
Diameter of the measuring 
ball or column dB 2.5 ±  0.01 
Spacing between the pulley 
surface and the centreline of the  groove f >2.5 - 
a – the distance deviation between the sy mmetry axis of two adjacent grooves. 
b - the cumulative departure of the overal l sum of e-value for one pulley shall not 
be greater than ±  0.3mm. c – the angle between the symmetry axis of the groove and th e axis shall be 90
o+ 
0.5o. 
d – In this standard, the limit deviation of rb and rc are specified (there is no such specification in ISO9981), because they ar e important parameters for the testing 
pulley.  e – only applies to three-pulley or  four-pulley testing machines. 
f – 45mm is the minimum recommended va lue set in ISO9981; for this reason, 
this value can be used for the tests, and 55mm is the best recommended value for actual designing.  g – only applies to two-pulley testing machines. h – only applies to four- pulley testing machines. 
i – shall not conduct specifi ed standardisation on the smallest diameter for 
reverse bending pulley. 60 mm is only used  during testing and cannot be used for 
actual transmission equipment. j – the actual pitch diameter when the be lt is matched with the pulley shall be 
slightly bigger than the effective diamet er of the pulley; the exact value can only 
be determined when the selected belt is fitted onto the pulley and is in operation, the approximately calculated transmission ra tio can be considered as the nominal 
value ( b
e = 2mm) of the effective line differential. When more accuracy is 
required, the belt manufacturer should  be consulted. See GB/T 17516.2-1998 for 
the calculation formula. k – The differential value of the diam eters measured on the grooves of a pulley 
shall not be greater than 0.15mm. The sp acing comparison of the circumscribed 
planes of the measuring ball or column  can be used to indicate the diameter 
comparison of each groove.  
 
A.4.2.2 Tests 
 
After the inside temperature of the thermostat has reached 85oC ±5oC, start (in A shall be ‘restart’) 
the testing machine, enable the transmission equi pment to meet the specified rotational speed. 
Apply the test load to the driven pulley and determ ine the slippage rate of the belt between the drive 
pulley and driven pulley.  Allow the testing machine to continuously operate under this condition until the belt loses efficiency or the incremental of the slippage rate (g) reaches 4%. 
 The incremental of the slippage rate (g) shall be  represented by percentage  and can be determined 
by the following formula:  
g=io−it×100 
Where: 
io = n o/No 
it = n t/Nt 
no – the initial rotational speed of the driven pulley; 
nt – the rotational speed of the driv en pulley at the end of the test; 
No – the initial rotational speed of the drive pulley; 
Nt – the rotational speed of the driv e pulley at the end of the test. 
All rotational speeds in this formula sha ll be rotational speeds under the test load.   
 
Enlargement of Part W: 
 
A.4.2.3 Retension of belt 
Before the belt loses its efficiency, when the incremental of the slippage rate reaches 4% 
immediately stop the testing machine for at least 20 minutes (cool to 15oC ~ 35oC), then loosen the 
supporting base of the tensioner pulley (only for three-pulley or four-pulley testing machines). 
Apply the test tension to the belt,  use hands to rotate the pulley fo r 2 ~ 3 cycles, fix the position of 
the supporting base of the tensioner pulley agai n in accordance with A.4.2.1, and repeat the test 
procedure as set out in A.4.2.2.  A.4.2.4  Use this as the starting time of the fatigue life span, operate for 10 hours then determine the 
slippage rate every two hours. Stop the machine to check the state of the da mage done to the belt, 
and then re-start the testing machine.  A.4.2.5  When the slippage rate reaches 4% for the th ird time, or when the belt is damaged as shown 
in Figure 4, terminate the test and reco rd the fatigue life span of the belt. 
 
 A.5 Test report 
 
The test report shall contain at least the following information: 
a) indication that the tests were conducted in accordance with this standard; 
b) the mark of the test belt; 
c) the model of the testing mach ine used (where necessary, the effective diameter of the 
tensioner pulley or the external diameter of the reverse bending tensioner pulley shall be indicated); 
d) the test preparation method used (method A or method B); 
e) the operating time which meets the prescr ibed requirement (hour as the unit); 
f) the transmission power and the ri b numbers of the v-ribbed belt; 
g) retension times and operating hours of each retension (hour as the unit); 
h) the average ambient temperature during the test period; 
i) the date of the test.