Engaging Gears Perpendicular to Shaft Direction?

[Matt Adams]

Originally Posted by KenWittlief

one drawback for this idea: when you have gears engaging you want the distance between the centers to be fairly precise and consistant the gears tend to want to push each other apart.

This is where I'm going to need a mechanical engineer with a little more experience than me...

1. With how much force will they want to push each other apart? I assume that this actually varies... so I guess I'm looking for the maximum force. I assume this is some ratio of the torque.

and the other obvious question is:

2. In which direction is this force applied? As for direction, I assume a significant amount of the force is pushing them directly tangent to where the teeth mesh, but I think this is this too much of a simplification. Is the direction actually related to the gears' pressure angle? What about with mutiple teeth engaging? This seems like it could develop into a rather complex problem...

I'll guess it's something like (T / (D/2))*SIN(PA) is the force pushing them apart in the plane of the shaft centers... but I'd really appreciate it if someone had something better than a guess.

Thanks in advance,

Matt