We are planing on having 4 gear boxes each with a Cim and a Bane Bot RS-775 in a CIM-U-LATOR each hooked up to a victor. If we place the victors in breake mode should we be worried that the gears will get destroyed from 1 motor stopping faster then the other?
I don’t think so, though I assume you’re talking about a toughbox or a similar AM transmission.
Are you using an 8-motor drivetrain?
We are using 8 drive motors paired in 2’s to go through AM though boxes with a 14.88:1 reduction to drive our mecanum wheels. Acurding to This link we found, we should be able to travel the field in 7 seconds and still be able to push reasonably well for a omni directional robot.
Yes and Yes, We are using 8 motors running in pairs each set going into a AM thought box with a 14.88:1 reduction running 8" mecanum wheels.
No. You will not destory the gearboxes.
The brake mode on the Victors shorts the motor wires to ground. Because the wires are connected together, the power generated by moving the motor drives the motor in the other direction, resulting in a braking effect. This is not a very strong force.
It is a very strong force at high speeds. At rated free speed, the motor braking torque is equal to rated stall torque.
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So your saying that if we are standing still and a robot with a higher pushing force starts to push us we will push back until they reach a pushing force equal to our maximum pushing force. At which point we will be pushed backwards and our motors will stop working because we would have reached the motor braking torque.
Your motors would have to reach free speed and in that case, you are already being pushed faster than your motors maximum speed.
BRAKE mode won’t BREAK your motors, and it won’t keep you from being pushed, but it will drive a little bit different, and resisit slight bumps from other robots.
Sorry, I can’t untangle that sentence.
A spinning motor with its leads shorted generates braking torque proportional to its speed. In fact, the braking torque follows the motor’s speed-torque curve… with the stall torque and zero swapped, of course: at zero speed there is zero braking torque, and at rated free speed the braking torque is the same as the rated stall torque.
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Sorry about that.
The order of events which I was trying to express are:
- Our robot’s sitting still.
- Another robot begins to push our robot.
- The other robot which is geared to push better then our robot over powers our motors
- We get pushed backwords
At this point are our motors broken or not?
Based on Jeffys response:
Your motors would have to reach free speed and in that case, you are already being pushed faster than your motors maximum speed.
BRAKE mode won’t BREAK your motors, and it won’t keep you from being pushed, but it will drive a little bit different, and resisit slight bumps from other robots.
It does not seem that we will have to fear about our motors breaking.
Thank you for all of the help.
If you are being pushed backwards and your wheels are turning then your motors will be braking, but they won’t be breaking.
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my team used essentially the same setup last year, and i can tell you that long before you are going to have any problems with motors the mechanum wheels will skid along the ground. this will not damage your motors at all, and as long as it is driven on carpet it wont damage your wheels either, if you were going to do demonstrations on rough surfaces like asphalt, i would recommend setting the motors to coast to avoid wheel wear. (learned this the hard way, our 8 inch mechs are pretty ruined) 
Holy overkill batman… I hope you can do all of your manipulation with window motors… how long does your battery last with such a powerful drivetrain?