Lewis Bending Stress: Why Does Lewis Factor Depend on x?

AI Thread Summary
The discussion centers on the Lewis bending equation for spur gear teeth and the dependency of the Lewis form factor on the vertical distance x, which is derived from the geometry of the tooth. Participants clarify that x represents the cantilever length used in the simplification of the tooth's structure. There is debate about the relevance of x, with some suggesting that standard derivations based solely on cantilever length are more appropriate. The source of the figure illustrating this parameter is questioned, as it appears to be less common in existing literature. Overall, the conversation emphasizes the need for clarity on the role of x in the Lewis bending stress calculations.
dsaun777
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How come in the lewis bending equation for spur gear tooth does the lewis form factor depend on x? x being the vertical distance measured from the triangle that is formed from the base t and fillet a. I know that you can express the height h and width t in terms of x such that x= t^2/4h, but why?

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The distance ##x## is the length of the cantilever to which the tooth is simplified in this method. Good explanation and derivation is provided in "Shigley's Mechanical Engineering Design".
 
FEAnalyst said:
The distance ##x## is the length of the cantilever to which the tooth is simplified in this method. Good explanation and derivation is provided in "Shigley's Mechanical Engineering Design".
No, h is the length, t is the width and F is the face. X is a separate parameter that deals with the tooth.
 
dsaun777 said:
No, h is the length, t is the width and F is the face. X is a separate parameter that deals with the tooth.
Right, I didn’t look closely at the image. What is the source of this figure ? I haven’t seen this parameter being used in literature. Standard derivations with just the cantilever length seem more reasonable.
 
FEAnalyst said:
Right, I didn’t look closely at the image. What is the source of this figure ? I haven’t seen this parameter being used in literature. Standard derivations with just the cantilever length seem more reasonable.
Agreed.
 

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