Waterproofing and bearing system for inrunner motor, how they do it!

As water tightness is some kind of an issue on most of the DIY propulsion systems, taught that it would be interesting to see how the professionals are doing it.

Minn Kota is mass producing direct drive trolling motors and some models are now doing relative high thrust and also higher voltage than the traditional 12V( in this case 36 V) . Not saying they are similar to what we need but anyway from a design point of view might be useful. Don’t having a cad system so wont be drawing anything but tried to check the parts and also cost of their bearing and seal system.

The design have changed during the years, choose one of the most resent models within the “Salt water series " Riptide Transom 112/T 112 LBS Thrust 36 Volt - 52 Amps”.
Starting from the “forward” part and then moving towards the propeller.

48 990-011 WASHER,SHIM OD 1",ID.630"SS $0.45 Looks like plain shim
50 992-011 WASHER,BELLEVILLE $1.05 2 pc needed, kind of a spring washer(coned- disc spring).
4 140-014 BEARING,BALL $1.65 The only(!) ball bearing used. Located front of rotor

Not 100% sure about the actual order, this i taken for the spare part drawings. Probably the deep groove(?)ball bearing takes the thrust from the rotor and lean against the the spring washer(s) softening any peak loads?

Then rotor, below parts aft of rotor

6 788-040 RETAINING RING $0.45
42 990-051 WASHER , STEEL THRUST $0.55
44 990-052 WASHER , NYLATRON $0.45
18 144-017 BEARING , FLANGE $3.75 Looks like simple a brass friction bearing
20 880-025 SEAL $1.05 Looks like double lip oil seal
22 725-095 PAPER TUBE , SEAL BORE $0.10 No idea what this is?, cheap though…:slight_smile:
20 880-025 SEAL $1.05 Looks like double lip oil seal

So these parts take care of reverse thrust and sealing of the whole system.

  • the Nylatron washer probably act as a thrust bearing in reverse mode.
  • These are spare part prices, considering that, amazing low cost for complete sealing and bearing system!
  • only one ball bearing i think(!?), unless there is such inside the brass flange bearing.

The “paper tube” part is interesting, wonder how that works, some kind o seal function it must have, or then to lubricate maybe if it is greased?

Maybe some of this can be incorporated into our designs, cost is at least minimal…

Did not post a picture due to possible copyright issues but here a link to the page: