OSI) NTERNATIONAL STANDARD 677 Straight bevel gears for general engineering and heavy engineering -- Basic rack Engrenages coniques a denture droite de mecanique generale et de grosse mecanique - Cremaillere de reference First edition -- 1976-06-15 677.1976 (E) UDC 621.833.2 Ref. No. ISO 677-1976 (E) Descriptors : gears, bevel gears, basic racks, profiles. CopyrightIntenationalOrganizationfor Standardization Price based on 2 pages ed without license from IHS Not for Resale FOREWORD ISO (the International Organization for Standardization) is a worldwide federation of national standards institutes (isO Member Bodies). The work of developing International Standards is carried out through iSO Technical Committees. Every Member Body interested in a subject for which a Technical Committee has been set up has the right to be represented on that Committee. International organizations, Draft International Standards adopted by the Technical Committees are circulated Bodies for approval before their acceptance as International to the Member Standards by the iSo Council. Prior to 1972, the results of the work of the Technical Committees were published as iSO Recommendations; these documents are now in the process of being trans- formed into International Standards. As part of this sprocess,Technical technically suitable for transformation. International Standard iSO 677 therefore replaces ISO Recommendation R 677-1968 to which it is technically identical. ISO Recommendation R 677 was approved by the Member Bodies of the following countries : Australia Germany South Africa, Rep. of Austria Hungary Spain Belgium India Switzerland Brazil Israel Turkey Italy United Kingdom Chile Czechoslovakia Netherlands U.S.S.R. France Poland Yugoslavia No Member Body expressed disapproval of the Recommendation. The Member Body of the following country disapproved the transformation of ISO/R 677 into an International Standard : Czechoslovakia International Organization for Standardization, 1976 : Printed in Switzerland Copyrightlnternational Oorganization for Standardization ed without license from IHS Not for Resale ISO 677-1976 (E) INTERNATIONAL STANDARD Straight bevel gears for general engineering and heavy engineering -- Basic rack 1 SCOPE AND FIELD OF APPLICATION 3 PROFILE Figure 1 represents the profile of the basic rack for gears This Internationat Standard specifies the dimensional of module m = 1 and of diametral pitch P = 1. characteristics of the basic rack of straight bevel gears, for general engineering and heavy engineering, having a For a module or a diametral pitch differing from 1, the constant bottom clearance. In these gear pairs the tip linear dimensions which are indicated have to be multi angle of one gear is equal to the difference between the plied by this module or by the inverse of this diametral designed shaft angle and the root angle of the mating gear. pitch. The dimensional characteristics apply within the follow- ing limits1) : 2 DEFINITIONS 1 ≤m≤50 2.1 basic rack : Rack, the profile of which corresponds to 20 ≥P≥0,5 a section of the tooth surface of a crown gear of infinitely large diameter on a plane at right angles to the tooth 4 NOTES surfaces. 4.1The profile of the standard basic rack refers to bevei This profile is used as the basis of a system of bevel gears gears with involute teeth. This profile has substantially straight sides and the following characteristics : having straight teeth. pressure angle 20°; height of tooth 2,20 m (dimensions in millimetres). 2.2 reference line : Straight line on the profile of the basic rack, with reference to which the tooth dimensions 2.20 or (dimensions in inches). are specified. P 3,1416 0,6 max. 1,5708 1,5708 0,02 max. Reference line Normally r = 0,3 max. 2 (see 4.3) FIGURE 1 -- Profile of basic rack 1) See ISO 678, Straight bevel gears for general engineering and heavy engineering - Modules and diametral pitches. Copyright International Organization for Standardization 1 Not f