BS 6168:1987
Current
The latest, up-to-date edition.
Specification for non-metallic spur gears
Hardcopy , PDF
English
31-03-1987
Foreword
Committees responsible
Specification
1 Scope
2 Definitions and symbols
3 Basic rack tooth profile
4 Normal modules and normal diametral pitches
5 Fabrication
6 Accuracy
7 Measurement
8 Gear errors and tolerances
9 Hub and rim proportions
10 Allowances for thermal and hygroscopic expansion
11 Information to be given on drawings
Appendices
A Materials
B Lubrication of plastics gears
C Tables of tolerance values
D Addendum modification
E Example calculations of maximum centre distance
and total gear and housing expansion
F Recommended method for calculation of gear
stresses
Tables
1 Normal modules
2 Normal diametral pitches
3 Gear errors and tolerances
4 Tolerance on cumulative tooth pitch error over a
sector of k pitches (Fpk) or arc length L
5 Adjacent pitch error (transverse) tolerance fpt
6 Radial run-out tolerance Fr
7 Radial tooth-to-tooth composite error tolerance
fi"
8 Radial composite error tolerance Fi"
9 Radial indicator reading tolerance Fl
10 Tooth profile error tolerance ff
11 Tooth alignment error tolerance on face width b,
F beta
12 Centre distance error tolerance fa
13 Gear blanks tolerances
14(a) Cumulative tooth pitch error tolerance Fpk
(metric units)
14(b) Cumulative tooth pitch error tolerance Fpk
(imperial units)
15(a) Adjacent pitch error (transverse) tolerance fpt
(metric units)
15(b) Adjacent pitch error (transverse) tolerance fpt
(imperial units)
16(a) Radial run-out tolerance Fr (metric units)
16(b) Radial run-out tolerance Fr (imperial units)
17(a) Radial tooth-to-tooth composite error tolerance
fi" (metric units)
17(b) Radial tooth-to-tooth composite error tolerance
fi" (imperial units)
18(a) Radial composite error tolerance Fi" (metric
units)
18(b) Radial composite error tolerance Fi" (imperial
units)
19(a) Radial indicator reading tolerance Fl (metric
units)
19(b) Radial indicator reading tolerance Fl (imperial
units)
20(a) Tooth profile error tolerance ff (metric units)
20(b) Tooth profile error tolerance ff (imperial units)
21(a) Tooth alignment error tolerance F beta (metric
units)
21(b) Tooth alignment error tolerance F beta (imperial
units)
22(a) Tolerances on radial and axial run-out of
reference surfaces of wheel blanks (metric units)
22(b) Tolerances on radial and axial run-out of
reference surfaces of wheel blanks (imperial
units)
23(a) Values of IT (metric units)
23(b) Values of IT (imperial units)
24 Coefficient of friction mu
25 Dimensionless experimental factor Ka
26 Correction coefficient Kb
27 Gear material constant KM
28 Maximum bulk temperature for non-metallic
materials for continuous operation
29 Application factor KA for speed reducing gears
30 Poisson's ratio
Figures
1 Basic rack tooth profile for normal modules
2 Limits of tip relief of modified basic rack tooth
profile for normal modules
3 Test loads
4 Tolerance on cumulative tooth pitch error over k
pitches Fpk
5 Tolerance factor phi p
6 Adjacent pitch error (transverse) tolerance fpt
7 Radial run-out tolerance Fr
8 Radial tooth-to-tooth composite error tolerance
fi"
9 Radial composite error tolerance Fi"
10 Radial indiator reading tolerance Fl
11 Tolerance factor phi f
12 Tooth profile error tolerance ff
13 Tooth alignment tolerance on face width b, F beta
14 Plastics moulding on metal hub
15 Plastics moulding without hub
16 Plastics moulding with hub
17 Example of a typical drawing
18 Thermal expansion rates
19 Hygroscopic expansion rates
20 Pinion with 10 teeth
21 Tooth form factor YF as a function of number of
teeth z for different values of addendum
modification coefficient x
22 Endurance limit for bending stress versus gear
life (unlubricated PA 66)
23 Endurance limit for bending stress versus gear
life (unlubricated POM)
24 Size factor YX as a function of gear module
25 Young's modulus versus temperature
26 Endurance limit for contact stress versus gear
life (unlubricated PA 66)
27 Endurance limit for contact stress versus gear
life (unlubricated POM)
Access your standards online with a subscription
Features
-
Simple online access to standards, technical information and regulations.
-
Critical updates of standards and customisable alerts and notifications.
-
Multi-user online standards collection: secure, flexible and cost effective.