PD 6457:1970
Current
The latest, up-to-date edition.
Guide to the application of addendum modification to involute spur and helical gears
Hardcopy , PDF
English
17-11-1970
Foreword
1. Introduction
2. Terminology, definitions and notation
3. Tooth design (general)
4. Tooth design: value of sigma x
5. Tooth design: division of sigma x between pinion
and wheel
6. Limiting values of sigma x
7. Limits to the individual values of x1 and x2
8. Application to internal tooth gearing
9. Centre distance modification coefficient
Appendix
A. Calculations and formulae
A.1 Calculation sequence and basic design formulae
A.2 Relative values for x1 and x2
A.3 Tooth thickness formulae
A.4 Base tangent span dimension
A.5 Diameter over gauge rolls or balls, of diameter dR
A.6 Tip diameter formulae
A.7 Root diameter formulae
A.8 Minimum values of x required for avoiding undercut
tooth profiles
Tables
1. Dimensions of standard long addendum spur pinions
in terms of unit module or diametral pitch
1A. Centre distances, in terms of unit module or
diametral pitch, at which standard long addendum
spur pinions and wheels having x2 = 0 engage without
backlash
2. Corresponding values of sigma x, y and alpha w for
alpha n = 20 deg
Figure
1. Examples of addendum modification
Charts
1. Limiting values of the sum of addendum modification
coefficients applicable to external tooth spur and
helical gear pairs
2. Limiting values for the addendum modification
coefficient applicable to an external spur or
helical gear
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