Author Topic: More bearing problems!! (Read 10171 times)

jarrod9155 · « **on:** April 02, 2011, 11:19:56 PM »

Well just got my turbine backup fling since a blizzard took it down totally wrecking everything . I had 18 foot blades and went with 20 foot blades for the new setup . The first month no problem till this weekend I noticed the the mill not spinning in a 25 mph wind not good . Lowered it and the found the bearings were locked right up . Raised it back up till I could get back to fixing it well some how lockup as it was it broke loss the next day and hit the stator with the magnets and that caused a ground fault that shut the inverter off and she was free spinning minus stator drag ,look like a welder up at the top of my pole welding sparks and all not cool !!!. Let it down to find the stator was totaled and the magnets not sure yet .
Now I believe this windmill design is great for 6 to 14 foot turbines but over that there most be a better way . The thrust on theses tapered bearing or trailer hubs is not taking the abuse I'm seeing any were from 30 mph to 90 mph winds . This last time I took all the right steps to insure the bearings would last, I balanced the blades added a grease buddy and so on this was the third set off bearings .
Having this mill grid tied or mppt allow it to speed up in rpms during high winds and I believe this with big blades is killing the bearings heating them up and with just a little play in the bearing is quickly not enough do to the stator clearance .
I like Chris idea in the turbine transmission getting away from trailer hubs . Has any one tried a different idea with just a direct drive mill I don't see me rebuilding this one with a trailer hub . I will say this mill took 5 days of winds gusting 20 to 60 mph and produced 60 kW I'm sure this stretch of wind did it in .

I think this is now a HOBBY !, LOL

DanB · « **Reply #1 on:** April 02, 2011, 11:43:54 PM »

It'd be interesting to know more details about your machine and the problems. To date - since I've been involved with this stuff, I have seen 1 bearing failure (on a 10' diameter machine). My 20' turbine has bearings which I really think are probably too small but it's been fine so far (knocking on wood). We learn the most from failures though. In my mind now... maybe you didn't adjust them right, or grease them properly..... or just had 'bad luck'....
or maybe it's just a bad design. Perhaps time will tell but the devil is in the details.

ruddycrazy · « **Reply #2 on:** April 03, 2011, 01:34:14 AM »

Hi Jarrod,
From your description it is plain to see the tapered bearing were loose with end play and the axial thrust off those 20' blades would of caused the rear bearing that takes all the axial trust to hammer against the bearing cup. Personally if I was going to hang 20' blades off a trailer hub I'd put around 0.003" crush on the bearings which would show a slight drag turning the hub but the blades would overcome any drag. Also putting too much grease will cause bearing to overheat aswell.

Regards Bryan

Flux · « **Reply #3 on:** April 03, 2011, 04:49:08 AM »

I am not familiar with those trailer hubs you are using so it is difficult to comment but I seriously doubt that the thrust is causing the problem. It may be the gyroscopic loading that is causing you trouble or it may just be factors that I couldn't know about without seeing the hub and the bearings after the problems.

The fact that Dan hasn't had problems makes me think it is a local problem. As you say your speed will be a lot higher but still it will be low in comparison with the maximum speeds of those bearings. Lack of pre-load or too much grease are the usual things to kill taper roller bearings, but it may just be that the hub design is just not up to the job.

At 20ft you are near the point where a transmission becomes worthwhile but that does not affect the bearing issue, whatever method you use you will have to support the prop in satisfactory bearings, the thrust and gyro loading will be the same.

To go the transmission route you will virtually have to have decent engineering facilities and anyone with these facilities would be capable of building a satisfactory hub for the direct drive low speed alternator.

Starting from scratch with a hub for taper rollers you would probably want to considerably increase the distance between the bearings for this type of duty. The fits and tolerances of the various races in the bores and on the shafts is also fairly critical and these cheap trailer hubs may not be good in that respect. For a wheel with load always in one direction you can get away with things that may not work with the gyro force of a 20ft prop waggling the thing in all directions.

You may get a better idea when you strip the bearings out and examine them.

Flux

jarrod9155 · « **Reply #4 on:** April 03, 2011, 07:29:54 AM »

This was my third bearing installation on this hub , this time I used the Info gained from months ago on the board . Here what I did I installed everything in the shop on a stand with just the hub no blades . I installed the castle nut hand tight then tourqed it to 45 lb s to set the races or new cups then loosen back up and went hand tight and backed it off to the next slot and installed the pin it left me with a little slop maybe a 1/16 enough to insure the stator would not have any problem with contact from magnet rotor . And I installed a bearing buddy to insure grease was always there . All I can think is the rpm I am able to hit in big gust before it furls is heating the bearings up .

halfcrazy · « **Reply #5 on:** April 03, 2011, 07:44:29 AM »

Jarrod

We to ran into bearing issues on the 17ft machine we built for my neighbor. But here is my logic on my failure and I hope others will chime in. The Mill spun clockwise for 6 months making tons of power then we had a clearance issue between one blade and the tower. It was down for a few months and went back up the other day with a set of blades from Dave the 222 design and they spin counter clockwise. The bearings where left hand tight originally and this trip turned them to the next slot tighter on the nut. They still seem to work fine but have a little noise to them at low wind speeds that go away when the wind speed picks up. We have new high quality bearings and some day soon when it is nice we will let the mill down and change them and check it all out again.

I am suspecting 3 things here

A-cheap bearings one is from China and one from Russia "They came with the trailer hub"
B-The bearings actually need some preload on them not hand tight "This is my big question"
C-We changed the direction of rotation and they did not like that?

Jarrod mentions letting the mills spin faster with MPPT heating the bearings up? I really do not suspect this is an issue but the 17ft machine is running into 2 Classics and we let it go to 130-140vdc from its original cut in of 64vdc so we are spinning it faster then the ones going direct to battery.

jarrod9155 · « **Reply #6 on:** April 03, 2011, 08:27:35 AM »

jarrod9155 · « **Reply #7 on:** April 03, 2011, 08:41:57 AM »

The last photo was the reapairs to mill after it made a crash landing .

Flux · « **Reply #8 on:** April 03, 2011, 08:52:17 AM »

Maybe that if so many people are having trouble the hub is not up to the job. Can't see from the pictures how big the hub is.

If the 1/16 slack was on the tips of the blades then fine, but if on the magnet rotors then it is too slack. I don't know what a grease buddy is but if you have an overheating problem it will be too much grease. I don't know how good a fit the adjustable bearing inner is on the shaft or how effective the lock nut scheme is but some of the stuff I have seen doesn't inspire me.

There may be an issue with bearings that have run in one direction for some time and then get reversed but if everything is right there ought not be an issue, there are many devices built for reversing duty with taper roller bearings but they may be oil lubricated and reversed more often.

There is also the issue of crap bearings these days. Some work fine, others fail quickly and you can never be totally sure that supposed well known brands are not made on the cheap and sold on as the proper thing. If there is enough market to do this with semiconductors there must be a profit in doing it with bearings.

Flux

jarrod9155 · « **Reply #9 on:** April 03, 2011, 08:59:16 AM »

There some idea of the machine , I really would like to try a diffrent idea on the bearings . Just last week Hughs blog had a mill that had stator damage that in turn caused it to throw a blade durring over spinning now this mill had been up a while but add bigger blades and the time frame could be shorter life span and it all started from the bearings and the minute the magnets hit the stator your starting over most of the time with the stator and at a average of 250 us dollars per cast if it cant be reapaired . I just dont like the blades and the magnet rotors flexing or moving on the same shaft . I understand this sytem works and is proven and I would build it this way again just not so big ,but if I stay with these big blades another setup may be in order

bj · « **Reply #10 on:** April 03, 2011, 09:00:21 AM »

Jarrod: I'm sure this is where frustration has set in. Can you take some pics of the failed bearings, and spindle? Cleaned up?
Seeing how they failed, and where on the bearing, and all the associated stuff would help a lot.
Good taper rollers can take a lot, but it doesn't take a lot of misalignment to ruin them. I am wondering
if the turbine had a previous crash, is it possible the spindle has a slight bend?
I have more questions than answers, I know.

jarrod9155 · « **Reply #11 on:** April 03, 2011, 09:09:11 AM »

To Flux ,
Your right the bearings could just be crap I really have tried everthing buy trade I am a ASE certified auto tech 15 years exp and I have done everthing I know .
The grease buddy is a devise that boat trailers use that has a spring load that allows you to preload grease in the front bearing cup so as it needs grease it is all ways there .

jarrod9155 · « **Reply #12 on:** April 03, 2011, 09:13:50 AM »

Bj,
That is my thought maybe it got bent but I did inspect it pretty well and the way it landed was tail first then the blades side ways didnt even bend the studs on the hub but I still replaced them . I will add some updated photos of the bearings but there isnt much left it looks like a total loss .

fabricator · « **Reply #13 on:** April 03, 2011, 09:27:18 AM »

Quote from: jarrod9155 on April 03, 2011, 07:29:54 AM

This was my third bearing installation on this hub , this time I used the Info gained from months ago on the board . Here what I did I installed everything in the shop on a stand with just the hub no blades . I installed the castle nut hand tight then tourqed it to 45 lb s to set the races or new cups then loosen back up and went hand tight and backed it off to the next slot and installed the pin it left me with a little slop maybe a 1/16 enough to insure the stator would not have any problem with contact from magnet rotor . And I installed a bearing buddy to insure grease was always there . All I can think is the rpm I am able to hit in big gust before it furls is heating the bearings up .

If that is how you set the bearings on a stand with no blades that is WRONG, that would cause the bearings to fail, that setting would turn the rear bearing to junk in a short time, with just the hub on the stand you should have some resistance on the hub, my 17' mill has been flying since last spring with no issues, it does have Timken bearings, there is no way I'd waste my time and effort on chinese bearings, it is a known issue some chinese factories regularly ship lots where the races and rollers have not been heat treated, Timken and SKF have factories in china but they hold to their high quality standards.

bj · « **Reply #14 on:** April 03, 2011, 09:42:06 AM »

Jarrod: just a hope that pics might help. Only thing for sure at this point, is that the failure was not caused by a lack
of effort on your part. Every failure has a cause, that's easy. The why is sometimes tough.

Flux · « **Reply #15 on:** April 03, 2011, 09:52:51 AM »

Not a lot more I can add except that your description of the grease buddy makes me think it is intended for low speed operation in or near water. If it keeps the bearings full then it has no place on a wind turbine.

The other issue you mention about flexing makes me wonder how the magnet rotors are attached. If it is the way I often see with things overhung on threaded rod and nuts then I would also question it. The only way I would accept is with one magnet rotor directly on the hub flange and the other spaced off by a series of strong spacers or better still a spacer ring between the two discs and the remote disc actually a spigot fit on to a track turned on the non flange part of the hub. I would also try to have the prop hub not being directly attached to the magnet discs. There is an awful lot of gyro force on this lot when it yaws violently and I am sure there can be serious movement if the set up is not right.

Magnets hitting the stator is certain disaster, if it is actually due to bearing failure then that is an issue to be solved but if it is from flexing then the bearings may not be the first cause of failure.

For the smaller sizes of machine that Hugh promotes for third world countries the main issue is being able to built it with limited facilities, for someone building something as large as 20ft for grid tie then attempting to build it without decent engineering facilities is not the best approach.

Even for smaller machines I never could be bothered to crawl round scrap yards collecting bits off old cars when it is just as quick to machine up a decent hub that is suitable for the job in hand. I have never attempted anything near 20ft but at that size I would be wary of using some random hub and making it do best you can, I have never seen a cast hub that is anywhere near true and it would at least need a lathe to get some discs mounted on it sensibly.

Flux

fabricator · « **Reply #16 on:** April 03, 2011, 10:14:33 AM »

The hub I used on my 17' machine was terribly out of true on the back side,( in it's intended application this is not important) it required the removal of close to 1/8 inch of material on one side to get a true surface to mount the rear rotor to.
If you mount the rear rotor to the front (flat) side of the hub and are building a 16' or larger machine you are getting into completely unacceptable over hung loads.

zap · « **Reply #17 on:** April 03, 2011, 10:14:49 AM »

I'm not sure about the "grease buddy" either... he may be talking about a "Bearing Buddy"? Nomenclature...

http://www.bearingbuddy.com/why.html

fabricator · « **Reply #18 on:** April 03, 2011, 10:34:46 AM »

It has to be a bearing buddy, they are used to keep a constant positive pressure inside the hub, mostly used on boat trailers to keep water out of the hub.
If his final adjustment was as he explained in his last post, the failure was positively caused by way to little preload, that 1/16" slop he mentioned turned into 3/16 to 1/4" slop in short order, I tightened the bearings on my 17' machine several times over the course of months to get to a place where they now are not getting sloppy any more.

jlt · « **Reply #19 on:** April 03, 2011, 10:43:17 AM »

I see from your pictures you are using a five bolt hub. All of the 5 bolt hubs that i have seen are rated between 1000 lbs to 3500 lbs capacity . Not enough For a 20 ft machine.

fabricator · « **Reply #20 on:** April 03, 2011, 10:47:31 AM »

Quote from: jlt on April 03, 2011, 10:43:17 AM

I see from your pictures you are using a five bolt hub. All of the 5 bolt hubs that i have seen are rated between 1000 lbs to 3500 lbs capacity . Not enough For a 20 ft machine.

Agreed, not even close.

jarrod9155 · « **Reply #21 on:** April 03, 2011, 10:49:45 AM »

It's a bearing buddy , and yes the first rotor is mounted behind the hub after it was turned on a lathe and the second rotor was spaced on the other side with washers and then from there I used about 3 washers and one 3/4 bolt and the hub mounts there everything is real close to the hub and the studs are 3/4 stainless and the hub was bought new rated at 3,500 pounds from a rep-able trailer supply store .this was by no means a backyard build or third world country build .my goal has been to put power back in the grid and lower my electric bill I pay 17 cents a kilowatt so it makes cents and yes it has worked great minus the blizzard with recorded 90 mph winds and bearing failure . I don't want to give up yet just seeing if any one else has thought of some different designs before I start building something different . The reason for the 20 foot blades is in the summer the wind are 10 mph to 20mph and that's it .but winter really picks up and this winter was one storm after another .
Fabricator

I have in the past tried tightening a little more a then a week later check it and so on . I keep a tight a gap do to the inverter mppt tracking it really needs to be able to control the load quickly and adjust to gusting wind . I tried a bigger gap and the mill would over shot and start stalling or over spinning and the efficiency would start falling . I have been leaving about 3 millimeter on each side with a 1/2 inch stator .

jarrod9155 · « **Reply #22 on:** April 03, 2011, 10:55:12 AM »

If this 3500 pound is to small then maybe that could be it but with the 18foot blades it was also wrecking bearings , I agree if I go with this style again I will step up to a 5,000 pound plus hub for sure.

Flux · « **Reply #23 on:** April 03, 2011, 11:10:05 AM »

I agree you are doing things right, I really have no idea if the hub is big enough but it sounds as though it probably isn't. 3mm clearance either side of the stator should be plenty if things are working as they should.

Flux

jarrod9155 · « **Reply #24 on:** April 03, 2011, 11:12:10 AM »

Quote from: fabricator on April 03, 2011, 10:34:46 AM

It has to be a bearing buddy, they are used to keep a constant positive pressure inside the hub, mostly used on boat trailers to keep water out of the hub.
If his final adjustment was as he explained in his last post, the failure was positively caused by way to little preload, that 1/16" slop he mentioned turned into 3/16 to 1/4" slop in short order, I tightened the bearings on my 17' machine several times over the course of months to get to a place where they now are not getting sloppy any more.

Now do you worry about heat and expansion if there tight are you leaving enough room for that ?

ChrisOlson · « **Reply #25 on:** April 03, 2011, 11:34:28 AM »

Quote from: jarrod9155 on April 02, 2011, 11:19:56 PM

I like Chris idea in the turbine transmission getting away from trailer hubs . Has any one tried a different idea with just a direct drive mill I don't see me rebuilding this one with a trailer hub

Jarrod, I have build several direct drive turbines similar in design to a Proven with a rear mount generator on the mainshaft.

You're an ASE certified tech so you'll understand what I'm talking about here; in an automotive application the trailer spindles everybody is using are designed to carry the majority of their radial loads on the inner bearing. That's why it's bigger than the outer one and why the wheel is offset, etc.. You put this on a wind turbine and it's all backwards. Now you got the small outer bearing carrying most of the radial load and it's impossible to keep bearings adjusted properly because the hub and bearing assembly is being use for something it was never designed for. It's a bad design from the word "go". It works on smaller turbines, but once you get to the size you got I wouldn't even consider it. You don't see Vestas building turbines by cobbing a spindle and hub off a CAT end loader and hanging 274 foot blades on it. They got mainshafts with bearings that can handle the loads.

Secondly, using a transmission or direct drive design with the generator on the rear of the mainshaft distributes the loads better over the structure of the turbine head. On my 12G machines the distance between the front and rear main bearings is 13.620" and the front bearing alone is rated at higher radial and axial loads than your whole 7500 lb trailer spindle unit.

To gain a basic understanding of how your loads are distributed on the turbine head and bearings, take a 2 x 4 and place it on a fulcrum of some sort. Then place a weight on one end of it. Now, try lifting that weight by pushing on the 2 x 4 only 4" or so from the fulcrum, then try it at 13-14" from the fulcrum. This is a good demonstration of the loading on your bearings on your trailer spindles vs my geared machines with a wide spacing on the bearings and a long input shaft.

Add to that the fact that the loads are transferred to a massive transmission case that can be run over by a D-9 dozer without hurting it, and the fact that the transmission case transfers loads to the tower over 12.7" of the yaw tube instead of a just a little offset pipe or tube with gussets, and you got a much stronger and more durable machine. With the geared unit the loads the rotor transfers to the transmission and tower are also separate from the generator because it's on a different shaft that's spinning at much higher speed. So the generator is much smaller and lighter. This allows balancing the machine on the yaw shaft so it's slightly nose heavy static, but in normal operation rotor thrust balances the machine on the yaw shaft to minimize wear and loading on the shaft - again improving durability and longevity of the machine.

Now I'm sure people are going to claim the current homebrew designs are adequate because they've never seen one break. But because of how they're designed, and the way loads are transferred to the structure, they flex in 60+ mph winds. And you know what happens to a trailer spindle that is flexed by being overloaded - it eats bearings up because tapered roller bearings have to run in PERFECT alignment or the outer race and rollers get galled and everything goes downhill from there.

I supposed it will be discussed ad nauseum while you're having bearing failures and how you're doing this and that wrong, etc., etc., etc.. But it's not even a mystery to me. The problem is in the design. You're flying a design that can not handle the loads in 60-80 mph winds with a 20 foot rotor hanging on it. Period.

Email me offline and I got plenty of pictures I can send you of machines I have build using a direct-drive design similar to Proven's. As flux noted, building a geared unit requires some engineering and machining facilities that are beyond most homebrew shops. But a direct-drive that doesn't use a trailer spindle is quite easy to build and you can re-use your existing generator rotors and stator, etc..
--
Chris

Flux · « **Reply #26 on:** April 03, 2011, 11:41:07 AM »

What do you mean by 1/16" play? I assumed it was at some point on the edge of the discs or at the end of the prop or something, that would be a very tiny clearance within the bearing and not detectable axially.

If you have 1/16 actual end float then no chance. Tapers like a pre-load but for most uses just tightening them until the slack is obviously out is good enough. I have run them that way on a wind turbine and even if set up with a small pre-load this usually eases off after a while.

The whole assembly is steel, except for the hub which may be cast iron but that has near identical expansion coefficient so once set up the clearance doesn't alter with temperature. I would expect very little temperature rise anyway unless it is by conduction and radiation from the stator. If you have heat the most likely reason is churning in excessive quantities of grease. I don't know hoe bad it is at such low speeds but it will wreck bearings in an electric motor at 1500rpm.

Flux

Flux · « **Reply #27 on:** April 03, 2011, 11:58:56 AM »

Chris is basically right about the design of the hub for this duty, the thrust is no problem, it is taken on the big bearing and will be no issue. I agree that the bearings will be too close for best results but it seems most likely that the whole set up is too small anyway. I questioned the fit of the small bearing inner race on the shaft as it is normally lousy. This works for axle type loads but even I am not sure why ( it only works with taper rollers if there is slack) . For the yawing loads then it becomes far more of a problem.

If you find the failure started on the small bearing then it indicates things being too small, If the back one failed then I would be surprised.

If you go the transmission route then you have a chance for a complete redesign, but there is no real reason why the existing scheme can't work if it is adequate for the job and made properly. if not using a commercial hub i would increase the bearing separation but that is again a redesign.

jarrod9155 · « **Reply #28 on:** April 03, 2011, 12:20:17 PM »

As for amour of play I would say if you grabed about 4 feet down the blade and tried to look for slop by shaking back and fourth you would only fill a slight gap or play really like 2 to 3 millemeters that's the best I can do to explain something of this nature . Most of my coworker all have different ways of setting preload and bearing grease and so on plus I had started a thread a few months ago on setting the bearings and I took all of this together and have found they keep falling I truly believe the hub is to small or could have a hair line fracture from crash landing . I just would like to try something of a diffrent design so maybe next winter my wife will stop telling me I should of invested in electric solar .
Really thanks for all the good ideas on why the bearings keep falling I'm sure it's a combination of small hub , big blades , high winds , and so

jarrod9155 · « **Reply #29 on:** April 03, 2011, 12:26:10 PM »

Chris I will for sure throw you email tonight
Thanks

Sorry guys if my spelling and grammar is a little off trying to use a I phone and type are not the easiest things !!!

JW · « **Reply #30 on:** April 03, 2011, 01:50:25 PM »

Jarrod9155,

I fixed the 3rd picture in your post, on page 1, so if you see that I edited that post, thats why.

"« Reply #7 on: Today at 06:41:57 AM »"

JW

zvizdic · « **Reply #31 on:** April 03, 2011, 01:54:56 PM »

Jarrod

Chris is right you cant put a beast on a little china bearings .
This hubs a rated for i assume 3000 pounds radial and your trust is all on one bearing .
Windmill is axial machine almost like live center on a lathe machine.If you disassemble live centre you well see a big axial bearing on a front and a small radial bearing on a back.

My 10' is on a Bridgeport milling machine spindle angular contact bearing 7000 pounds load carrying capacity.
The other bearing is a small radial bearing same ID 1.377" the distance is not that important (bigger is beater).

Engineers like to put small safety overkill i like big and no worry.

ChrisOlson · « **Reply #32 on:** April 03, 2011, 04:12:39 PM »

Quote from: zvizdic on April 03, 2011, 01:54:56 PM

This hubs a rated for i assume 3000 pounds radial and your trust is all on one bearing .

Even a 7000-7500# spindle (#42) only uses like a Timken 1412 outer bearing with a 1.25" journal, which is too small for a 20 foot wind turbine. If you get rid of the grease in the hub and go to oil bath like all heavy duty trucks use so you can run decent preload on the bearing set - then it might take it for awhile. But otherwise you're barking up the wrong tree and it will only last on a poor wind site where it doesn't get pushed very hard.
--
Chris

News:

Author Topic: More bearing problems!! (Read 10171 times)