Machinery's Handbook, 31st Edition
Spur Gearing 2213 Table 3. Gear Tooth Parts for American National Standard Coarse Pitch 20- and 25-Degree Pressure Angle Gears Dia. Pitch Circ. Pitch Stand. Addend. a Stand. Dedend. Spec. Dedend. b Min. Dedend. Stand. F. Rad. Min. F. Rad.
r f
r f
P
p
a
b
b
b
0.3142 0.3307 0.3491 0.3696 0.3927 0.4189 0.4488 0.4833 0.5236 0.5712 0.6283 0.6981 0.7854 0.8976
10.
3.1831 3.0239 2.8648 2.7056 2.5465 2.3873 2.2282 2.0690 1.9099 1.7507 1.5915 1.4324 1.2732 1.1141 1.0000 0.8000 0.6667 0.5714 0.5000 0.4444 0.4000 0.3636 0.3333 0.3077 0.2857 0.2667 0.2500 0.2222 0.2000 0.1818 0.1667 0.1538 0.1429 0.1333 0.1250 0.1176 0.1111 0.1053 0.1000 0.0909 0.0833 0.0769 0.0714 0.0667 0.0625 0.0588 0.0556 0.0526
3.9789 3.7799 3.5810 3.3820 3.1831 2.9842 2.7852 2.5863 2.3873 2.1884 1.9894 1.7905 1.5915 1.3926 1.2500 1.0000 0.8333 0.7143 0.6250 0.5556 0.5000 0.4545 0.4167 0.3846 0.3571 0.3333 0.3125 0.2778 0.2500 0.2273 0.2083 0.1923 0.1786 0.1667 0.1563 0.1471 0.1389 0.1316 0.1250 0.1136 0.1042 0.0962 0.0893 0.0833 0.0781 0.0735 0.0694 0.0658
4.2972 4.0823 3.8675 3.6526 3.4377 3.2229 3.0080 2.7932 2.5783 2.3635 2.1486 1.9337 1.7189 1.5040 1.3500 1.0800 0.9000 0.7714 0.6750 0.6000 0.5400 0.4909 0.4500 0.4154 0.3857 0.3600 0.3375 0.3000 0.2700 0.2455 0.2250 0.2077 0.1929 0.1800 0.1687 0.1588 0.1500 0.1421 0.1350 0.1227 0.1125 0.1038 0.0964 0.0900 0.0844 0.0794 0.0750 0.0711
3.6828 3.4987 3.3146 3.1304 2.9463 2.7621 2.5780 2.3938 2.2097 2.0256 1.8414 1.6573 1.4731 1.2890 1.1570 0.9256 0.7713 0.6611 0.5785 0.5142 0.4628 0.4207 0.3857 0.3560 0.3306 0.3085 0.2893 0.2571 0.2314 0.2104 0.1928 0.1780 0.1653 0.1543 0.1446 0.1361 0.1286 0.1218 0.1157 0.1052 0.0964 0.0890 0.0826 0.0771 0.0723 0.0681 0.0643 0.0609
0.9549 0.9072 0.8594 0.8117 0.7639 0.7162 0.6685 0.6207 0.5730 0.5252 0.4775 0.4297 0.3820 0.3342 0.3000 0.2400 0.2000 0.1714 0.1500 0.1333 0.1200 0.1091 0.1000 0.0923 0.0857 0.0800 0.0750 0.0667 0.0600 0.0545 0.0500 0.0462 0.0429 0.0400 0.0375 0.0353 0.0333 0.0316 0.0300 0.0273 0.0250 0.0231 0.0214 0.0200 0.0188 0.0176 0.0167 0.0158
0.4997 0.4748 0.4498 0.4248 0.3998 0.3748 0.3498 0.3248 0.2998 0.2749 0.2499 0.2249 0.1999 0.1749 0.1570 0.1256 0.1047 0.0897 0.0785 0.0698 0.0628 0.0571 0.0523 0.0483 0.0449 0.0419 0.0392 0.0349 0.0314 0.0285 0.0262 0.0242 0.0224 0.0209 0.0196 0.0185 0.0174 0.0165 0.0157 0.0143 0.0131 0.0121 0.0112 0.0105 0.0098 0.0092 0.0087 0.0083
9.5
9.
8.5
8.
7.5
7.
6.5
6.
5.5
5.
4.5
4.
3.5
1.
3.1416 2.5133 2.0944 1.7952 1.5708 1.3963 1.2566 1.1424 1.0472 0.9666 0.8976 0.8378 0.7854 0.6981 0.6283 0.5712 0.5236 0.4833 0.4488 0.4189 0.3927 0.3696 0.3491 0.3307 0.3142 0.2856 0.2618 0.2417 0.2244 0.2094 0.1963 0.1848 0.1745 0.1653 0.1571
1.25 1.5 1.75 2.25 2.5 2.75 2. 3.25 3.5 3.75 3.
4.
4.5
5.
5.5
6.
6.5
7.
7.5
8.
8.5
9.
9.5
10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20.
0.0500 0.0079 a When using equal addendums on pinion and gear the minimum number of teeth on the pinion is 18 and the minimum total number of teeth in the pair is 36 for 20-degree full depth involute tooth form and 12 and 24, respectively, for 25-degree full depth tooth form. b The dedendum in this column is used when the gear tooth is shaved. It allows for the higher fillet cut by a protuberance hob. The working depth is equal to twice the addendum. The whole depth is equal to the addendum plus the dedendum. 0.0625 0.0675 0.0579 0.0150
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