I currently have a tank drive with two 393 motor (high speed configuration) and a gear ratio of 1:3 for speed. I’ve been having some problems when running it and after a while, the motors won’t move. I think it might be a stalling issue.
The motors have an internal PTC that will trip when the motor becomes too hot, keeping the motor from running for a few seconds (usually around +/-10 seconds) in order to keep the motor from causing internal damage to itself. Here is a quote from the 2-Wire Motor 393’s VEX Wiki page:
A 1:3 ratio, even on a tank tread drive using the 15-tooth tank tread drive wheel, seems a bit fast for only two 393 motors. I would suggest either changing it to direct drive (you could swap the 393 gears to put it into the high-speed configuration, which would give you a 1:1.6 gear ratio) or adding another set of motors, to have four.
First calculate how much current the motors are using by measuring their speed when you are driving and using the data here. With this information you can decide if a change of gearing or adding motors will help. It also seems odd to me that you lost control of both motors at the same time, what is driving the motors? Perhaps the PTC in the controller is tripping.
To my eye, the speed of this robot does not indicate it is radically over-geared. As a suggestion, try moving the position of the track tensioners so that the tracks have less tension on them. This can make quite a difference to the load on the motors. If this does not help, then upping to 4 motors should do the trick.
What ports do you have your motors on? If they are both on 2-5 then move one of them to 6 or higher. That will distribute the current load between the 2 internal breakers of the Cortex instead of just 1.