Spur Gear Pitch Selection

[Jason C]

I haven't been able to find guidelines for selecting a diametral pitch to fit my application. Basically I am looking for some direction on how to go about doing this, below is the application I am working on. (Just for your information this is for the Baja SAE vehicle that I am working on)

-Designing a double reduction gearbox using spur gears
-Gears will have approximately .5in - .75in face width (force, stress, fatigue calculations have been performed for a pitch of 10, 12, and 16 teeth/inch) - Is this near the range I should be looking at?
-Engine specs: 10hp/14ft-lbs @ 4000rpm
-CVT max/min ratio = 3.0/.50

The engine can rev to 4000rpm and then at high speeds be increased by the .5 ratio of the CVT which puts the rpm of the first pinion gear at a maximum of 8000rpm.

Thanks

[Jason C]

The conclusion that I have come to is that selecting a gears diametral pitch doesn't require a scientific process (aka no calculation needed). The goals of a project will determine the pitch size, so in my situation I need to be able to handle 14ft-lbs of torque. So basically any pitch, whether 10 or 32teeth/inch will work as long as the gear/pinion can handle the tooth bending stress, contact stress, and fatigue.

Basically I'm looking for anyone who agrees/disagrees with the above statement or that has other information to share.

[Kelly_Bramble]

The conclusion that I have come to is that selecting a gears diametral pitch doesn't require a scientific process (aka no calculation needed). The goals of a project will determine the pitch size, so in my situation I need to be able to handle 14ft-lbs of torque. So basically any pitch, whether 10 or 32teeth/inch will work as long as the gear/pinion can handle the tooth bending stress, contact stress, and fatigue.

Basically I'm looking for anyone who agrees/disagrees with the above statement or that has other information to share.

Yes and no on the diametral pitch statement. The diametral pitch is going to effect the aplpied or transferred torque and rotational speed of related gears. Moreover, a larger diametral pitch could allow for smaller driving torque as required by some applications.

Application dependant..