T200 rotor stuck and rusted!

I have now changed 4 of my T200 thrusters because the rotor was rusted and got stuck. I tried to remove the propeller, but they had just rusted stuck to the rotor. I use my rov in saltwater, but these thrusters seems to not like it. Do you recommend some lubrication and maintenance on them? I wash and flush them with fresh water after every dive.

I have noticed that to… not our thruster has got stuck but there are parts that rusts. We use our ROV in seawater also, and as of now we have only been using it few times and lightly. I needed to take one thruster apart, because we got a leak from potted connector and when I open up the thruster to change the thruster core, to my sup price that there was a rust, still lightly one. And we take very well care of our equipment and rinse it very well with fresh water.

Hi @Jhans

We have been using the T200 for years in salt water, with intensive use, almost daily, especially in high season since we are a tourist project.
The first T200 that we used(5 years ago), rusted a lot and we had this problem quickly. With the newer thrusters, which are better encapsulated, this problem has been minimized.
But an essential procedure that has helped us significantly reduce this problem is the following:

  1. obviously sweeten a lot
  2. (after sweetening) activate all thrusters for about 5 seconda, resting the ROV on all four sides, face up, down and to the side, repeating the process.

By doing this process, we remove almost all of the water that accumulates on the rotors, which in my opinion is what causes most of the oxidation through scratches that occur on the rotor magnets. If we are not going to use the ROV in a few days, the next day we repeat the process again so that they dry completely.

In my opinion, this problem is due to the friction that occurs in the rotor magnets with external agents, such as sand, which scratch the paint protection and expose the magnet to the elements. Therefore, removing the water helps slow down the problem.

Another thing we do, when we see friction or resistance when turning the propeller by hand, a sign that the oxidation process has started, is to disassemble the rotors, remove the rust and paint the magnets with a small brush and epoxy. Thus we create a new protective film that again extends the life of the rotor.

By doing these steps at least we have tripled the life of the rotors.

I hope I have helped.
Regards

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Thanks! I will try that :slight_smile:

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Good advice and techniques to prolong the life of the thrusters. Thanks for sharing your knowledge and experiance.

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It seems like all of the thrusters i changed out is the previous revisions when they was not fully potted but only painted with epoxy. Seems like the newer versions is much better, but i might have to change out some bearings and lubricate the rotor with some wd40.

Indeed, if the vehicle is operated in water with sharp or abrasive particles they can end up wearing through the epoxy and expose the magnets to sources of corrosion. Avoiding this is the main reason for the abrasion shield that’s in the T500 design.

The bearings are made of plastic, and are intended to be water lubricated. The main lubrication recommendation is to make sure they’re not run in air at high speeds or for extended periods, as doing so can damage the bearings.

I asked internally and was told that the best preventative measure is dunking the vehicle in fresh water and running the thrusters for 5-10 seconds to rinse them out after they’ve been used in sandy/sediment-heavy/salty water.

Our maintenance recommendations also suggest checking for and removing any buildup in the rotors every 5-10 uses.

Beyond that, if you notice the magnet potting has been gouged or worn through and the magnet is starting to corrode, the only real maintenance that’s possible is to clean out the corrosion and apply some additional epoxy to fill the gap(s), being careful to ensure it doesn’t protrude far enough to rub against the stator once the rotor is re-installed.

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