Spur Gears: Is Tangential Pitch Circle Necessary?

[aniruddha]

I have this doubt on spur gears
Is it necessary that the pitch circles of the two mating gears need to be tangential? or will a small gap of 0.3mm matter?

 

[elephunk]

I think a gap that large will cause slip. Thus I should think they need to be tangential. Hoping for someone to come in and confirm that though.

 

[jack action]

I'm not sure if this is what you're talking about, but you can read about http://www.meccanoscene.co.uk/html/articles/gears/gears.html" .

 

[elephunk]

I think he is talking about circular pitch. In which case I would think this has to be tangential.

I am trying to find some engineers who might know the exact answer.

 

[cstoos]

I always thought that the pitch circle was tangential by definition. Isn't it defined by the line of action?

[PLAIN]http://www.fi.edu/time/Journey/Time/Lessons/pitchgear.gif

Or are you talking about pitch as in teeth/length?