標準號：IS 12328 Pt.3-1988
發布日期：1989/9/1 12:00:00
實施日期：1999/12/31 12:00:00
適用范圍：1.Covers bevel gear systems applicable to zerol bevel gears.1.1 Covers recommended tooth proportions for generated zerol bevel gears for gear ratios in general use and the same are applicable for other manufacturing methods such as moulded or precision forged.1.2 Covers ratios having 15 or more number of teeth in the pinion and adopts symmetrical rack tooth proportions for pinion and gear for approximately equal strength, wherever tooth toplands do not exceed a ratio of 1.5:1.1.3 Stipulates basic standard normal pressure angle of 20°. When the number of teeth in pinion is less than 15, higher pressure angles are used to avoid undercut. In this system, undercut is eliminated by the use of higher pressure angles of 221/2 and 25°, where necessary. The higher pressure angle accompanied by the stipulated tooth topland ratio of 1-5 : 1 will facilitate the use ol minimum number of teeth in pinion up to 13.1.4 System is generalized to include angular bevel gears.1.5 Covers the methods of calculation for gear blank dimensions and tooth elements.1.6 The standard presumes that size and type of the gear has been established according to load rating requirement for the application.