Gearbox issues

[Tristan Lall]

You're going to have a power problem: those motors only output 0.3 W at their maximum power point. By comparison, the CIM motors that drive an FRC robot are good for around 340 W mechanical output each. With less than one thousandth the power of a CIM motor, I don't think these are the right motors for the job. (Those little motors are used in precision machinery—they're great, but not designed for this sort of application.)

The relationship between (output) power, speed and torque is simple: power = rotational speed × torque (in the proper units, [W] = [Hz] × [N·m]). Since you can figure out the rotational speed required (based on the wheel diameter and the linear speed you want to travel at), you'll find that either you won't get very much torque at a reasonable operating speed, or you'll get your torque at a very, very low speed. Plus, the bigger your wheel gets, the more gearing you'll need to slow the output down to something manageable.

Also, those motors are of the brushless DC variety—it's actually a 3-phase motor that uses a special speed controller and a series of sensors to indicate to the controller when to energize the coils. And because of their design, simply applying power to the terminals won't run the motor. We don't use them in FRC (yet), so you'll have to familiarize yourself with a slightly different technology.

So, can we interest you in a more powerful motor (or a smaller rollerblader)?

By the way, maybe it's just my copy of Acrobat, but there's a big black box where your CAD rendering should be in the third attachment.