Trailer wheel hub selection.

[41south]

Hi all,

I have available to me 2 versions of trailer hubs for constructing axial flux wind generators. They differ only in the type of bearings used. One uses sealed bearings that require no greasing, the other a tapered roller bearing that is open and does require greasing. So my question is, does anybody have any opinions on which sort may be better given the reasonably hard life such a hub may get given the application. The sealed units obviously are reasonably maintenance free and replacement bearing units are cheap, but will they last as long or do as good a job? I am not near a coastline so salt spray conditions are not an issue.

Thanks.

[nanotech]

As far as "the beating they take", remember that trailer bearings support the entire weight of thier cargo, generally unsprung!!

So you wanna talk abuse??  

In my opinion, unless you're running a 24 foot 6 blader mounted down in amongst a bunch of buildings and trees (to develope maximum turbulence) I don't think you're going to stress the bearings any.  I would be surprised if the bearing wasn't the absolute last thing to grenade....

[nothing to lose]

Hey you forgot to add about the 1200rpm or more

 Many of those trailers have small tires that turn alot faster than a large car tire turns, and at 60Mph the bearings have to keep up with that too while being hammered by the pot holes in the road and carring that weight, wild sharp turns on winding roads. Dirt road dust and grime.

 Then you get to the lake, drowned the bearing an hour while you launch the boat

Or as at least one woman has done, drowned the bearing for a few hours, then complain about how slow and slugish the boat is and hard to handle, not steer right etc..

 Her husband was rather ticked when he went out to see what was wrong with his boat! He never let her launch it again by herself after that

Yes, it's true, she ran the boat acrossed the lake with the trailer still straped onto it, she just removed the coupler from the truck and set sail...

 Man that  bearing up on the tower has an EASY life compared to his boat trailer cousin

About the hubs too, make sure you do have the correct center size if that is important to your blade hub! I have a bought 8' set of blades and when I went to buy a 4 bolt trailer hub the center did not fit my blade hubs center hole, I could have reamed out the hole in the hub, but I decided to just wait and get a different hub that fits right. I think the bolts were spaced correct, but the hub was heavier duty and the bearings had a larger center hub area.

[elvin1949]

build 2 gennies

see which last's longer.

elvin

[picmacmillan]

only thing i could add that the others havent stated already, is if the hub has 5 studs, it is better than 4, but, in this case i would think if it is "free"(as in no cost to you),then that is the right bearing to use ..also, take out the back seal, and remove some of the grease on the spindle, as too much grease will cause an excessive amount of drag..just a bit of grease makes the whole system turn freely so your rpm's can increase with smaller amounts of wind..just my humble opinion...pickster

[Jon Miller]

well these bearings have lasted years on a frequantly used trakter tailer.  they dont turn fast and they where never gressed but they are free moving.  I rekon that building two wind turbines sounds like a good idea.  batch production and all that.

[DanB]

Just from my experience with wheel bearings so far...

I would get the tapered roller bearings so that you can maintain, and adjust them.

Some of the volvo struts I was getting had ball bearings in them, they were not to be adjusted.  They fail more frequently - and, they are stiffer to turn.

If the 'sealed' ball bearings are at all stiffer to turn (often times just the seal is a problem in low winds) I would avoid them.  

I like tapered roller bearings and I like to leave the rear seal out of them.  So far I've had no problems, but time will tell!

[RobC]

Tapered roller bearing are stronger all the way around I prefer them myself. RobC

r

[nothing to lose]

Well,

I geuss I agree  with the other guys now about the drag on the bearings if you have any. Not all sealed bearings spin forever with a little flick of a finger. I am used to the ones that do spin freely, but then maybe they are looser built? Some I have removed the seal cleaned and greased sealed ones in the past also

 Probably most can't be done to easy, I only did a couple.

Thinking the life of the bearing I don't really think for this use either is all that much better or worse, but for adjustments and drag etc.. maybe a tapered roller bearing would be better.

[41south]

All,

Thank you most kindly for your comments. It looks like the open tapered variety get the nod. I have found the sealed variety to be a bit stiffer in the past, and I like the fact that the tapered ones have some adjustment. And building 2 gens is an excellent idea ! :-)