| SECTION 19
FEATURES OF TOOTH SURFACE CONTACT Tooth surface contact is critical to noise, vibration. efficiency, strength, wear and life. To obtain good contact, the designer must give proper consideration to the following features: - Modifying the Tooth Shape Improve tooth contact by crowning or relieving. - Using Higher Precision Gear Specify higher accuracy by design. Also, specify that the manufacturing process is to include grinding or lapping. -Controlling the Accuracy of the Gear Assembly Specify adequate shaft parallelism and perpendicularity of the gear housing (box or structure). Surface contact quality of spur and helical gears can be reasonably controlled and verified through piece part inspection. However, for the most part, bevel and worm gears cannot be equally well inspected. Consequently, final inspection of bevel and worm mesh tooth contact in assembly provides a quality criterion for control. Then, as required, gears can be axially adjusted to achieve desired contact. |
JIS B 1741
classifies surface contact into three levels, as presented in Table
19-1. The percentage in Table 19-1 considers only the effective width and height of teeth.
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438 
