Jammed Thrusters

I’m already in touch with OpenROV/SofarOcean support regarding this issue, which has come up in a few other threads, but I thought it would be best to document this here.

I received my Trident earlier this year and tested it in extremely silty saltwater off the western coast of India. It functioned really well then, and also a few weeks after that in very silty freshwater. Subsequently, I’ve been running it once every week or so to make sure everything’s fine. The Indian monsoon set in a few days ago, and humidity hit the +80% range. On my most recent test (day before yesterday) I discovered that the port horizontal thruster was completely jammed, that the starboard thruster was sticking and that the vertical thruster was completely fine. Some WD-40 and hand-turning got the starboard motor fully functional again, but the port motor did not respond to the same treatment.

There is a documented issue running the Trident in very silty water (https://blog.openrov.com/more-feedback-from-the-field-trident-kickstarter-update-28/) and others on this forum have had similar issues (Trident Vertical Thruster Motor is sticking and Left Forward thruster jammed [Resolved]).

I removed the port thruster using the recently-posted OpenROV guide (https://openrov.dozuki.com/Guide/Trident+Motor+Replacement+Guide/206) and disassembled it as well. Some of the silicone used to insulate the wires seemed to have dissolved and spread inside the motor; I carefully removed this using tweezers, applied more WD-40 and reassembled it.

It was no longer jammed, but was still not functional; there was a clicking noise as I hand-turned it. I disassembled it again and examined the inner surface of the bell, where I found a protrusion that is
possibly catching in the gaps between the magnets, leading to the clicking sound.

One comment on a different thread mentions that this is possibly due to “internal expansive corrosion” but I have no way of confirming this. My options at this point seem to be to replace the motor, or to sand down the inner bell till its smooth again, thus removing the anti-corrosion coating. I’d be grateful for any other ideas!

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Same problem with one of the 3 new replacement motors supplied for my Kickstarter Trident . 2 high spots on opposite sides of housing. No corrosion as it has very low time in fresh water. Used one of the original motors to replace it.