Question 1:
I have been performing ISO 6336 vs. AGMA 6014 rating comparisons with some colleagues from our home office. They use a software which produces both 6336 and AGMA ratings. This has led to a question about AGMA 908-B89 latest edition page 11, section 5.2, table 5-1, Limiting Variation in Action for Steel Spur Gears for Load Sharing.
The instructions how to apply the values in table 5-1 are vague at best.
Since this information is not in the 908 calculation, I am concerned some spur gear ratings may be incorrectly rated using Highest Point of Single Tooth Contact (HPSTC) instead of tip loading. HPSTC yields significantly higher J factors and therefore higher calculated strength ratings. I’d like to correct this but as I have already stated it is not clear to me how tip loading should be implemented.
Question for Interpretation: Since this information is not in the 908 calculation, I am concerned some spur gear ratings may be incorrectly rated using Highest Point of Single Tooth Contact (HPSTC) instead of tip loading. HPSTC yields significantly higher J factors and therefore higher calculated strength ratings. I’d like to correct this but as I have already stated it is not clear to me how tip loading should be implemented.
AGMA’s response:
It is suggested to Revise AGMA 908-B89 to clarify the subject:
- Revise Clause 5.2 of AGMA 908-B89 to include the definition of the difference in base pitch tolerance of the pinion and gear given by equation e = |fpbT1 – fpbT2|.
- Expand AGMA 908-B89 Table 5-1 to include 15-teeth to 35-teeth.
- Include the equations for expanding AGMA 908-B89 Table 5-1 in the revision of AGMA 908-B89 per the chart below.
| Table 3- Equations for extended Table 5-1 | |
| load | Equation |
| 90 N | 0.01778-0.000508*z1 |
| 175 N | 0.02540-0.000508*z1 |
| 350 N | 0.05461-0.001270*z1 |
| 700 N | 0.08763-0.001778*z1 |
| 1400 N | 0.15240-0.003048*z1 |