Which Gearbox Should I Use?

[SeanFitz]

Originally Posted by ehfeinberg

It's great to see that your team wants to experiment in the offseason with different drive trains! My team tried building a 6 wheel WCD in the off season a few years ago and probably wont go back for a long time.

It's hard to say what gear ratios you need without knowing anything else about your drive train plans. Are you planning to have a directly driven center wheel? Live axle/dead axle? And most important for determining your gearing is what wheel size are you planning on using? Before we recommend a gear box or a gear ratio we need to know more about your set up.

If you are asking for generalized speeds for how fast your high and low gear speeds should be, it is generally considered for a low gear the gear ratio should be set for somewhere around 4-6 (maybe even a little higher) feet per second. And a high gear around 14 -16 feet per second. (Some teams gear their high gear for 18 - 20 fps even). It really depends on the game to determine the exact ratios. If you feel that there will be a lot of defense like this last year then having a low gear on the bottom end could be of value, but if the field is also open and you need to move fast having a upper end of the high gear values is also very realistic.

My plan so far is a 1/8th dropped center wheel direct driven by the gearbox and the two other wheels either belted or chained to the center wheel. All wheels would be 6".

What I really want is a gear ratio that can give me a lot of torque. I've noticed over my years in FIRST that most teams either get pushed around or stalemate with other robots on the field. Teams that can push others around are always recognizable and are almost always picked for alliances, even if it's just to play defense (Team 2013 was a perfect example of that this year). And even in games where speed is important (2013), I always see cases where being able to downshift would have given a team a boost to victory.