1、BRITISH STANDARD BS ISO 9981:1998 Belt drives Pulleys and V-ribbed belts for the automotive industry PK profile: Dimensions ICS 43.060.10BSISO9981:1998 This British Standard, having been prepared under the directionof the Engineering SectorCommittee, was publishedunder the authority ofthe Standards
2、Committee andcomes into effect on 15 January 1999 BSI 05-1999 ISBN 0 580 32035 9 National foreword This British Standard reproduces verbatim ISO9981:1998 and implements it as the UK national standard. It supersedes BS AU248:1993 which is withdrawn. The UK participation in its preparation was entrust
3、ed to Technical Committee MCE/10, Belts and pulley drives, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor rela
4、ted international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may
5、 be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British S
6、tandards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theISOtitlepage, pageii, pages1 to6, an inside back cover
7、 and a backcover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date CommentsBSISO9981:1998 BSI 05-1999 i Contents Page National forew
8、ord Inside front cover Foreword ii Introduction 1 1 Scope 1 2 Normative references 1 3 Pulleys 1 4 Belts 5 Annex A (informative) Bibliography Inside back cover Figure 1 Cross-section of pulley grooves 2 Figure 2 Pulley diameters 3 Figure 3 Determination of pitch diameter 4 Figure 4 Cross-section of
9、belt 5 Figure 5 Measuring fixture to determine effective length 6 Table 1 Dimensions of PK pulley grooves 3 Table 2 PK belt dimensions 6 Table 3 Measuring pulley and measuring force 6ii blankBSISO9981:1998 ii BSI 05-1999 Foreword ISO (the International Organization for Standardization) is a worldwid
10、e federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that
11、 committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by
12、the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least75% of the member bodies casting a vote. International Standard ISO9981 was prepared by Technical Committee ISO/TC41, Pulleys and belts (including veebelts),
13、 Subcommittee SC1, Veebelts and grooved pulleys. This second edition cancels and replaces the first edition (ISO9981:1990), which has been technically revised. In particular, a subclause on the tolerances on the diameters over balls (3.3.4) has been added. Annex A of this International Standard is f
14、or information only. Descriptors: Road vehicles, internal combustion engines, belt drives, pulleys, grooved pulleys, belts, power transmission belts, V-belts, dimensions, designation.BSISO9981:1998 BSI 05-1999 1 Introduction A V-ribbed belt drive is composed of an endless belt with a longitudinally
15、ribbed traction surface which engages and grips, by friction, pulley grooves of similar shape. The belt ribbed surface fits the pulley grooves to make nearly total contact. 1 Scope This International Standard specifies the principal dimensional characteristics of V-ribbed pulley groove profiles, tog
16、ether with the corresponding endless V-ribbed belts of PK profile which are used predominantly for automotive accessory drive applications. The complete array of V-ribbed belts and pulleys of PH, PJ, PK, PL and PM profile for industrial and other non-automotive applications is the subject of ISO9982
17、. PK belt profile dimensions and tolerances are the same in both International Standards. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of the publication, the editions indica
18、ted were valid. All standards are subject to revision, and parties to agreements based on the International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid Inter
19、national Standards. ISO 254:1998, Belt drives Pulleys Quality, finish and balance. ISO 4287:1997, Geometrical product specification (GPS) Surface texture: Profile method Terms, definitions and surface texture parameters. 3 Pulleys 3.1 Groove dimensions and tolerances The groove dimensions of PK pull
20、eys are shown inFigure 1 andFigure 2, and given inTable 1.BSISO9981:1998 2 BSI 05-1999 Figure 1 Cross-section of pulley groovesBSISO9981:1998 BSI 05-1999 3 Table 1 Dimensions of PK pulley grooves 3.2 Minimum effective diameter The minimum recommended effective diameter, d e , for PK pulleys is45mm.
21、3.3 Tolerances on finished pulley 3.3.1 Checking conditions Profile, diameter and run-out tolerances shall be checked on the finished pulley without surface coating. 3.3.2 Groove-to-groove diameter tolerances The variation in diameters between the grooves in any one pulley shall not exceed0,15mm. Th
22、is variation is obtained by comparing the diameters over balls or rods. 3.3.3 Radial and axial circular run-out Radial and axial circular run-outs shall not exceed0,25mm full indicator movement (FIM). Run-out in the two directions is measured separately with a ball mounted under spring pressure to e
23、nsure contact with the groove as the pulley is rotated. 3.3.4 Diameter over balls The tolerances on the diameters over balls (K) shall not exceed 0,6mm. Figure 2 Pulley diameters Dimensions in millimetres Groove pitch, e 0,05 ab 3,56 Groove angle, c , for measuring 0 15 40 Groove angle, c , for test
24、ing and actual use 1 40 r t min. 0,25 r b max. 0,5 Checking ball or rod diameter, d B 0,01 2,5 2x nom. 0,99 2N d max. 1,68 f min. 2,5 a The tolerance on e applies to the distance between the axes of two consecutive grooves. b The sum of all deviations from the nominal value e for all grooves in any
25、one pulley shall not exceed 0,3. c The centreline of the groove shall make an angle of90 0,5 with the axis of the pulley. d N is not related to the nominal diameter of the pulley but is measured from the actual ride position of the ball or rod in the pulley.BSISO9981:1998 4 BSI 05-1999 3.3.5 Groove
26、finish The pulley grooves shall have a surface roughness Ra k 3,24m. SeeISO254 and ISO4287 for definitions and the method of measurement. 3.4 Pitch diameter, dp The fit of a V-ribbed belt in the corresponding pulley is shown inFigure 3. The true pitch diameter of a V-ribbed pulley is slightly larger
27、 than the effective diameter and its exact value is determined with the particular belt being used. A nominal value of the effective line differential, b e , of2mm may be used to calculate the speed ratio. If more precision is required, the belt manufacturer should be consulted. Further information
28、is given in ISO8370. Figure 3 Determination of pitch diameterBSISO9981:1998 BSI 05-1999 5 3.5 Designation of pulleys A V-ribbed pulley for the automotive industry is characterized by the number of grooves, the profile and the effective diameter. It is designated by a series of numbers and letters as
29、 follows: a) the first letter “P” means “Pulley”; b) the first set of numbers indicates the number of grooves; c) the second set of letters indicates the groove profile; d) the second set of numbers indicates the effective diameter, in millimetres. EXAMPLE 4 Belts 4.1 Belt dimensions The dimensions
30、of the PK belts are shown on Figure 4 and given inTable 2. Figure 4 Cross-section of beltBSISO9981:1998 6 BSI 05-1999 Table 2 PK belt dimensions 4.2 Measurement of the effective belt length 4.2.1 Measuring fixture (seeFigure 5) The effective belt length shall be determined by placing the belt on a m
31、easuring fixture composed of the following elements. 4.2.1.1 Two pulleys of equal diameter, one of which is fixed and the other movable. Their profile shall comply withFigure 1 and Table 1, and their recommended effective diameter shall be determined from the values given in Table 3. 4.2.1.2 Device
32、for applying a total measuring force to the movable pulley. 4.2.1.3 Device for measuring the centre distance between the two pulleys. 4.2.2 Measuring force The measuring force to be applied for measuring the effective length of belts is given inTable 3. Table 3 Measuring pulley and measuringforce 4.
33、2.3 Procedure To measure the effective length of a belt, rotate the belt at least two revolutions to seat it properly and to divide the total force equally between the two strands of the belt. Then measure the centre distance between the pulleys, E, and calculate the effective length, L e , of the b
34、elt using the following formula: L e= E max+ E min+ U e where 4.3 Designation of belts A V-ribbed belt for the automotive industry is characterized by the number of belt ribs, the profile and the effective length. It is designated by a series of numbers and letters as follows: a) the first set of nu
35、mbers indicates the number of belt ribs; b) the letters indicate the belt profile; c) the second set of numbers indicates the effective length, in millimetres. EXAMPLE Dimensions in millimetres Rib pitch, p b 3,56 r b min. 0,5 r t max. 0,25 Belt height, h . 4 to 6 NOTERib pitch and belt height are s
36、hown as reference dimensions only. Cumulative rib pitch tolerance is an important value but it is frequently affected by the tension at which the belt operates and the modulus of the tension member. Figure 5 Measuring fixture to determine effective length Dimensions in millimetres and measuring forc
37、e in newtons Pulley effective circumference (atlevel of effective diameter), U e 300 Diameter over balls or rods, K 0,13 96,48 Measuring force per rib, F 100 U e is the effective circumference of the measuring pulleys; E max is the maximum centre distance between the pulleys; E min is the minimum ce
38、ntre distance between the pulleys.BSISO9981:1998 BSI 05-1999 Annex A (informative) Bibliography 1 ISO 8370-2:1993, Belts drives Dynamic test to determine pitch zone location Part2: V-ribbed belts. 2 ISO 9982:1998, Belt drives Pulleys and V-ribbed belts for industrial applications PH, PJ, PK, PL and
39、PM profiles: Dimensions.BS ISO 9981:1998 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal
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