Vex VersaPlanetary Gearbox Heat Problem

[matthewkennedy]

We've been running a VEX VersaPlanetary gearbox on an AndyMark 550 set up as a 1:1 (basically just using it as a bearing). Even with such a simple setup, the gearboxes are generating an obscene amount of heat. With no load and the motor running at 12v, the gearbox gets very hot to the touch, almost immediately. We've taken a few of them apart, and found one bearing that had lost a ball. We also have another gearbox set up as a 100:1, and it also gets hot in the same manner.

Is it normal for these gearboxes to get so hot? Are we ruining bearings? It seems like if the gearboxes were designed for the motors, and if we assembled them correctly (which we THINK we did...), they shouldn't get this hot. None of our other types of gearboxes get this hot.

Thanks in advance for any help!