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HUB Design question, need your input.
By xymox, Section Wind Posted on Wed Sep 07, 2005 at 03:56:28 PM MST
HUB Design question, need your input.

Hello All, I am continuing this post from a previous one that I started with a subject line that actually has something to do with what I want to find out.
The hub that I want to use for my alternator looks exactly like the following picture.

The problem is some folks think that this is not a well designed hub/bearing combo for use in a windmill. My feedback so far has been that the hub portion of the assembly may eventually walk it self off with vibration and time.
Facts.
My main goal is weight savings in this phase of my design.
Questions.
1. What is the best way to make sure the hub stays where it is and does not slide out of the bearing?
I have attached the following illustration for reference. The through bolt was just an idea I sketched, This could be a spindle or whatever. I dont want to have to use another heavy chunk of metal or another bearing in the mount as I think that would cause to much drag. But If I have to I will. Eager for your imput.

note: I do not want this advice. lol

HUB Design question, need your input. | 19 comments (19 topical)

Re: HUB Design question, need your input. (3.00 / 0) (#1)
by kitno455 on Wed Sep 07, 2005 at 11:00:32 AM MST

ok, you are still missing my point- lets try an immage, and a glossary.

spindle is the 'upright' that has balljoints and/or a strut and the steering arms connected to it. it has nothing to do with the hole in the center of the hub. that is where the cv joint end, or half-shaft drive end goes.
this thing has more parts that you realize. that silver ring with the beveled inner hole is generally a separate piece. it is pressed on after the bearings, and makes contact with the inner race of the inboard bearing.
the cv joint makes contact with the inner surface of that ring, and the outer surface of the hub. It does NOT make contact with the spindle or the hub carrier, hence, your idea of another bearing or a huge washer or a bolt into your mounting is wrong.

try the below picture, i turned your drawing into more of a true cross-section. note the blue ring. it will slip off the hub, and then the hub will walk out the front of the two bearings. washers reach out to stop that, though the end of the cv would work better.

there is no additional drag from this design, you are just keeping the bearings held in place.

allan

Re: HUB Design question, need your input. (3.00 / 0) (#2)
by xymox on Wed Sep 07, 2005 at 11:22:35 AM MST

I think I am beginning to understand. I was not aware that the beveled ring was a seperate piece. This was my original idea more or less, but I was not sure how the bearings were situated in there and secured, If the rings purpose is to secure the bearing position that makes sence then.

I do feel better about this design, providing that I have enough pressure keeping everything intack with a head bolt or something similar in function.
I was even going to extend the "bottom washer in green highlight" past the diameter of the "bearing container" so that if there was any movement it would only move about a 1/8th of an inch and keep it from falling off completely. Of course by that time I'm sure the stator would be chewed to bits by what would be disk 2.

I wonder if there is a type of bearing that I can fasten before the bottom washer goes on that would remain in contact with the bearing container and allow it to maintain adequate pressure and not add a signifigant amount of drag. probably not neccessasary though.

Your insights are really appreciated.
Beat the system, do as much as you can do.
[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#6)
by kitno455 on Wed Sep 07, 2005 at 12:15:48 PM MST

if you wanted to extend the washer out so that the hub cannot fall out, that would be fine. however, the only reason that washer would ever make contact with the hub carrier, would be that the bolt has broken or stretched. in that cause, the larger washer wont be connected to anything :)

if you are really concerned about contact, and you want a bearing in there, look at torrington needle bearings from most any transmission. they do exactly what you want, but are not cheap, and have flimsy races usually, so you have to machine the parts well. i dont think you need them, just use the bigger washer with the 1/8th gap out to the hub carrier, and dont worry about it.

if you use a head bolt, make sure to use locking nuts, or crossdrill (or weld!), and be aware that modern headbolts are designed to stretch, so i recommend a used head bolt (though it sounds crazy).

allan

[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#3)
by brian2034 on Wed Sep 07, 2005 at 11:29:44 AM MST

Save yourself the problems go to a scrap yard and get a hub off of the back of a dodge K-car,shadow,caravan etc they bolt on with for bolts and bearing are cheap they don't require a stub axle to hold it all togather.

Re: HUB Design question, need your input. (3.00 / 0) (#4)
by xymox on Wed Sep 07, 2005 at 11:38:16 AM MST

Tempting, My father in law actually has an old dodge caravan that he refuses to fix. I've commondeered it on more than one occation for picking up the seasonal christmas tree.

However I am really focused on weight savings. Im even using 3/16" plasma cut steel disks for the rotors plus I'm looking for a design that requires a minimun amount of welding (if any).

I was at fleet farm yesterday holding in my hands a 4 stud trailer hub and the straight spindle that it uses and said to myself, (man this is heavy) and left it right where I found it. I believe that by reducing the overall weight, I can reduce the amount of stress on the crucial parts.

This is of course only a theory.
Beat the system, do as much as you can do.
[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#5)
by kitno455 on Wed Sep 07, 2005 at 12:01:55 PM MST

you interest in weight is unfortunately misguided. the forces the prop will experience during a storm or precession during yawing will FAR FAR outweigh the one or two lbs you save at this point. oh- and the weight near the center is of almost no consequence, as the mass near the center has such a low polar moment. this is why figureskaters spin faster when standing vs with their arms and legs stuck out.

allan

[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#7)
by xymox on Wed Sep 07, 2005 at 12:26:23 PM MST

Point taken, I am also thinking about tower streangth. If I make it lighter, or as light as I can it should decrease the needed rigidity of whatever pole it is going to be fixed to.
Beat the system, do as much as you can do.
[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#8)
by kitno455 on Wed Sep 07, 2005 at 12:43:23 PM MST

no. that is exactly what i am saying. if you have a decent sized prop, you've got 500+ lbs of horizontal force on the tower. your saving two lbs of vertical load makes NO difference at all. none. nada. zip.

the few lbs saved is actually much smaller than our measurement tolerance on the horizontal load, and once you add a safety factor of 1.5 to 2, you toss out minor weight savings as completely and totally irrelevant.

the only question is 'will it survive'. make sure the material is not useful to that end before you cut it off.

allan

[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#9)
by whatsnext on Wed Sep 07, 2005 at 02:15:28 PM MST

One other thing. FWD hubs usually have substantial preload on the bearings when properly installed. You should be able to reduce drag considerably by using a more standard spindle. Even more so when the proper bearings are used. Look at a bicycle hub bearing for inspiration.
John.........

[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#10)
by xymox on Wed Sep 07, 2005 at 02:18:10 PM MST

Thanks for the imput. One of you guys should sell a hub kit with a flange built on it. so it can be bolted to anything.
I'd pay 50$
Beat the system, do as much as you can do.
[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#11)
by kitno455 on Wed Sep 07, 2005 at 06:14:30 PM MST

the OEM's are expecting 140+ degrees F due to the brake rotors and engine exhaust. i think if you can get one of these units apart (though you will need a six ton press to do it) and replace the grease with something lighter and trash the lipseals since you dont have that kind of heat, the preload is negligable in a tapered roller bearing.

this is one advantage of the std ball bearing in this application, though the tapered rollers clearly win in service life in the automobile.

allan

[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#12)
by whatsnext on Wed Sep 07, 2005 at 09:13:39 PM MST

Of course you'll never see those kind of loads in a windmill. Look at angular contact type bearings and let them run a bit free. This is one reason why I would recomend building your own hubs but I also understand that it's beyond the scope of a lot of people. Very handy to use Volvo hubs and we know they work. Ball bearings, by their nature, tend to be much easier to turn.
John.........

[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#13)
by steak2k1 on Wed Sep 07, 2005 at 10:55:01 PM MST

John:

You're talkling about angular bearings..by that do you mean the tapered type with cylindrical rollers..? I am looking at using a trailer hub and spindle which has these type of bearings. Similar/same to the type I have seen on my tent trailer. I repack these trailer bearings once a year in order to prevent the grease from breaking down. They seem to turn fairly well - albeit with a wheel on them...but a dual rotor genny would have similar weight and inertia (unloaded I think). (my) Trailer uses 12" wheels - 4 stub hub. geez may have to wreck it..!! LOL, then I can build two gennys.

These spindle / bearing combo's looks to be perfect IMHOP for a larger 2 rotor wind genny..No..?? And from a wrecker close by in Edmonton, Ab, pretty cheap to acquire.

Good discussion..good comments on weight relevance. good info.

thanx in advanz,

rgds,

stk
Awwwwwwk....It's Kenner - it's FUN.!!
[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#14)
by xymox on Thu Sep 08, 2005 at 07:11:02 AM MST

Yeah I like your point on weight. I dont see the need to have these 200 Lb chunks or iron floating around on a stick 50' up.

I think those that do make a production out of this i.e. a business, make things as light as they can while maintaining the performance and reliability.
Beat the system, do as much as you can do.
[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#18)
by whatsnext on Thu Sep 08, 2005 at 02:01:01 PM MST

I was referring to angular comtact ball bearings. They act like tapered rollers but carry less load and have less frictional losses. It's just a thought.
John.........

[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#15)
by xymox on Thu Sep 08, 2005 at 07:17:10 AM MST

I chose this particlar hub/bearing because it spun the best out of about 100 that I went through. Cheers for the autozone guy who let me rummage through all his new parts. I think I may have a convert tho! I think with some rotors on there and some mass that thing should spin for about at least a minute if I give her a good spin by hand.

I also asked autozone guy if they tend to spin better as they wear out. He said, "generally they do."
Beat the system, do as much as you can do.
[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#16)
by kitno455 on Thu Sep 08, 2005 at 07:33:12 AM MST

yes, in fact i have a pile of used hubs from 4x4 s10 chevies that i was planning to do something similar with :) the used ones turn more freely, and are available for a couple bucks at the salvage yard...

basically- tapered roller bearings have more load carrying and heat transfer capacity, due to increased surface area. they are also self aligning, even without preload. they are higher drag though, because there is more 'glueing' effect with the grease on all that surface area.

ball bearings have adjustable preload, and less surface area, so they can potentially turn more freely. i dont know of any modern car that still uses them, but some brake-less trailers still do.

i think the difference is not worth worrying about, if it spins good by hand, it will do so with a prop on it.

allan

[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#17)
by ghurd on Thu Sep 08, 2005 at 09:46:22 AM MST

Old old VW Beetles, like 1960's, used ball bearings.
It was common to replace the front drums with disk brake kits.

The later VW Karmen Ghia came with ball bearings and front disks.

Maybe a trip to the junk yard, or a look at JC Whitney?
G-

[ Parent ]

Re: HUB Design question, need your input. (3.00 / 0) (#19)
by dalbert1 on Sun Sep 25, 2005 at 06:36:35 PM MST

From my experience look for an old Audi that's not all wheel drive, 80's and above. Use the rear hub on those models, the best I find are those on Audi 5000 series. They give the best strenght to weight ratio, trust me on that, those german's make good solid stuff for the Autobahn. That's what I'm using on my 13 foot prop and it turns in pratically no wind. Also you can flush mount them, nothing sticking out at the rear of the spindle which makes installing much easier, glad I found them.

Just look how tight my air gap is, this is how much I relly upon them.

Lasted a year now, just blade problem's that's all, big thank's to Hugh though.

Good luck to you.

[ Parent ]

HUB Design question, need your input. | 19 comments (19 topical)

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