- re using wheel bearing
Bill, I think that although wheel bearings seem an obvious choice, because they fulfil the mechanical needs, the mounting would be difficult.
SKF to name just one do a good selection of industrial bearings that are self aligning, and have a 4 bolt flange.
I suspect, but could be wrong, that a simple ball bearing rather than a tapered roller type might be strong enough to take thrust?
The wheel bearings for a front wheel drive generally need a shaft under tension through the centre hole, to pull each side of the bearing towards each other. This would normally be a solid shaft, part of the CV axle. You could of course make something up out of tubing, but it would then need machining in the bore to fit the shaft. Then you still have to mount the housing somehow.
What I would like to know is an actual spec of a bearing that is proven.
In a direct drive, the electric motor bearings take the thrust, and I suspect that they are nothing special, as the thrust is not a heavy load, and decreases when underway.
Another way might be to combine a regular ball bearing with the flange, and a thrust bearing unit with the same flange specs. Then you could have them both mounted together, one on each side of the main 'chassis' plate. But that would only be required if a regular stock bearing cannot be found, which is unlikely seeing as there are presumably boats using them already.
In an ICE setup that has a transmission, I would guess that the thrust is not taken by the crankshaft thrust bearings (that are generally there to take load from any manual clutch disengagement pressure) but by the rearmost bearing on the output shaft off the transmission.
In an Atomic4 the trans and engine are sharing a heavy cast oilpan on which the motor mounts also fit. The trans has some kind of planetary thingy with a clutch pack like an automatic car transmission.
If the source of the bearing is industrial, you should be able to get the specification for the max amount of thrust load.
We know that a trolling motor is in the range of 30 to 60 pounds thrust. And we know that this amount will push a small boat.
Might be that the spec rating of a regular ball bearing allows something like 100 lbs thrust, or even more, could be as high as 300 lbs, who knows?
Failing any part numbers coming from group members that use indirect drives, I would suggest calling a bearing supply house, and give them the shaft size, and the flange requirement, and let them do the work and call back with the thrust capability. Then the decision can be made?
John
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