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Seized Thruster Bearings

What kind of behavior can be observed if the bearing overheat and seize up?

@DJ95 Your thruster rotor will not be able to freely rotate anymore and your thruster will not work. Can you post a couple images of what your bearings look like?

To give a bit of a preview, I was trying to see if all the motor directions are correct or not, so to do that I connected the rov to QGC and went in the motor mode to manually arm the drone and test it. I turned on the arm button, bumped up the PWM value for one motor a little and within 3-5 seconds a message popped up saying “10 second cooldown”, I tried doing this 2, 3 times without any success and it would show “10 second cooldown” within few seconds. Then I deployed the bluerov in water and noticed that it would start spinning (clockwise) when armed.

Here are the images of 4 thrusters which cause the ROV to turn.

Hi DJ.

It’s very unlikely that the bearing siezed (after the 100+ hrs of dives we’ve done Ive never had that issue). Much more likely that the waterproofing coating on the inside of the motor bell has failed and the magnets have corroded (this is the most frequent maintenance item for us). It’s hard to say why this happens, but debris getting into the thruster is the most likely cause. Some sediments have high amounts of ferrite that can make this more frequent.

This is a simple fix, but you will need a spare motor bell that you can get from the Bluerobotics site. You can then take out the thruster without disconnecting them, but you will need to remove the buoyancy holders to get to the thruster mounting screws. You can then quickly disassemble the motor. The whole job should only take 15 mins if you know the process.

The bearing were not seized, everything is fine now.