Hub seizing hard to push- roll looks good inside

[thedarlington]

alright so things have been going great with this desheng hub, last week i was pulling another bike along for a good distance no problems, the motor was pretty hot when we arrived and a couple hours later had cooled but it had a real tough resistance when walking the bike, and giving it power wouldnt do anything either, i figured this was some sort of mehcanical issue since pushing it along felt like going up a bumpy ramp where it resists on n off each time u go up/down a bump like going up one of these



i opened the hub to see if something was broken or lose but didnt really find any problems, it seems its the magnets that are rubbing against the outer motor housing, and also the motor shifts from side to side like slightly tilted, but i just cant seem to shift it in a way that wont cause so much resistance, im almost sure this is due to the magnets and the housing since it resists when just pushing along and not powered, anyone ever had something similar to this? nothing seems melted or to have come lose, i have felt this problem before but i couldnt really describe it well so i think once i fix the mechanical issue it should go again, but i cant seem to figure out what it is, it just tended to go away without me knowing what i did so id atleast like to figure out what it could be, its not supposed to 'levitate' inside without touching im guessing, but i dont know why it feels like its rubbing so hard now either

it looks like the problem in this thread, http://endless-sphere.com/forums/viewtopic.php?f=10&t=15547
and its even looks exactly like that guys hub & controller, my ebikekits never had this issue after 2 years

he posted this vid, http://www.youtube.com/watch?v=NUQlRFTWBcQ
thats what it sounded like when i first tried using it, then it seized a bit more, and id spin it n give it gas and it went with those sounds but much slower, and now its just not going which is when we opened up the insides, and btw, it was working perfectly before, and im sure all wires are working and connected right id been riding it for a couple weeks already

 

[Drunkskunk]

Sounds like a blown FET in the controller, or a short in the wires. the wires may have melted in the heat and shorted.

Unplug the motor from the controller. If it's now easier to push, you popped the controller.

If not, check the phase wires for signs of melting. the most obvious place is were they enter the axle.

if all good there, its time to pop the cover on the motor.

 

[dogman dan]

It does sound a lot like a shorted phase wire. Could be in the axle, insulation melted there, or even in the windings. That is, if it doesn't go away when you unplug the controller. Hot motor makes me suspect melted motor more than blown fets.

Once you park a hot motor, it actualy gets a lot hotter for the next few min. No wind cooling anymore.

 

[thedarlington]

thanks guys well the thinkg is its not plugged in and its still hard to push, i cant find my camera to upload some pictures, but its as if the magnets suddenly dont fit inside the hub and the hub - housing does have some play but i just cant seem to readjust it to keep them from rubbing, im removing the wheel and will be soon taking it apart the wires all seem good and not melted, im almost sure this is some physical problem bc it does it when everythings disconnected, ill be swapping this hub out for my old ebikekit and try to use the same controller, that should also test to see if its a fet, ive been searching for this probelm all over the internet but cant find any that sound the same its been happening sometimes, even before overheating it, and doesnt seem like the heat did damage, but it did seize aftewards, now its still seized but not as severely just like if going through that bumpy ramp on top, ill try to post some pics soon

 

[dogman dan]

If you hear it rubbing in there, then yeah, likely something in there warped or melted and is rubbing.

But if it resists silent, but has that notchy feel to it, it's shorted phase wires. Often the problem is inside the axle, where the heat melts insulation, and allows two wires to touch. You may be able to fix it by pushing wire into the hub, and splicing it inside the hub.

 

[Ykick]

I'm in for the shorted phase wire too. Maybe try ohm meter between phases to see if there's any continuity between a pair?

 

[Spicerack]

If it's not electrical- have a look at stuffed bearings. They can give a cogging feel when they go. You have play in the motor which you probably shouldn't.

 

[John in CR]

Turn the wheel touching alternating phase wire ends together. If it's a shorted phase wire then the combo that doesn't increase turning resistance even more is where the short is. If you short 2 and it gets harder to turn, and short all 3 and it gets harder still (but probably less of that cogging feel), then the problem is elsewhere.

 

[thedarlington]

i finally found my android so here are the pics, i really wasnt able to find anything wrong with this other than the hub middle seeming like it doesnt fit into the housing, also u can tell it seems to be closer to one side than to the other, its almost as if it needed greasing between the magnets and housing

http://i.imgur.com/g9P18.jpg

http://i.imgur.com/i00Rl.jpg

edit please let me know if theres anything u guys want closeups of

 

[John in CR]

First, put the covers back on. I hope you marked each cover with it's corresponding position on the magnet retaining ring, because putting them back on in a different position often causes the rubbing you were worried about.

You need to test for a short in the phase wires. Disconnect the motor from controller ensuring the 3 phase wire ends are separate. If it doesn't spin more freely, then short the ends of 2 phase wires together. It should become more difficult to turn. Then short the 3rd one together too, and it should become even more difficult to turn yet smoother. Your notched resistance to turning sensation is exactly the feeling of a phase short, which can occur inside a failed controller or in the wiring to or inside the motor, so until you do the simple test about you're just spinning your wheels. It's not something always easily visible or easily tested with a multimeter, but spinning the wheel and creating known shorts can tell you instantly and easily. Mechanical failure modes are unlikely and they're nearly impossible to duplicate that effect without a grinding or rubbing noise that would be quite obvious but very unlikely to create that notched turning sensation.

 

[Blueshift]

I am a total newb so my opinion is worth about a grain of salt but to me it seems like there might be some excessive play through the center. Would it tug normally if you were to lift the back wheel up and apply some friction to the top or middle height instead? Could play through the middle of the motor bring parts too close to each other and cause a short that way? Perhaps the malfunction or short is caused not by just making the motor work but by having play through the axel from the weight of the bike... pushing parts together that shouldn't be.(Something is lose enough causing a short/disconnect when the weight of the bike is applied but is fine when the weight isn't applied) orrrrr a bad conncection maybe pinched and almost broken has occured somewhere in all of your wiring(from motor to controller etc.). Would it also be good to check to see any tight places that might occur when you let the bike down on its back wheel?

It's either that or i have no idea what i'm talking about. Im sleep deprived and chatty.. Best of Luck!

 

[thedarlington]

damm well thats gonna be tough didnt mark em, however, when uncovered shouldnt the motor be easy to turn? i also dont have it plugged in so i dont see how it would influence it shorting, i have in the past wired it wrong and i know what thats like, but this is a mechanical friction - resistance issue that does not let it turn, it is so odd that no one's ever had something like this especially after all the hardcore modding done here, i merely rode this the designated speed and only once forced it, im going to see if anyone at school might be able to help with brushless motors in general and post about this if so, the school does have a couple miles electric cars so im gonna start asking of where they take these to

 

[dogman dan]

Plenty have had this issue. How did the bearings look when you had the covers off? It's likely either bearing failure, or it's phase shorting. If it goes away when you unplug the controller, it's the controller where the phase shorts are.

Re reading the original post, sounds like a bearing died, then the motor can slop around enough to let the magnets touch the stator.

 

[thedarlington]

lets see if this works out i took a bunch of pictures last week, dogman which bearings do u reffer to? i think this is a direct drive so it may not have any, waht i do see is some abrassion like the body inner part was too bit for this armature but at other times it slid great, while electronics and halls may be an issue, the issue im trying to get to here is strictly some sort of friction / mechanical seizing, however i cant see what this could be, the video is old, now its just seized, bonus pics for anyone wondering what these things look like from inside, surprisingly simple which adds to how this is a weird problem, not many parts to fail

http://www.youtube.com/watch?v=mylmJvQAWao&context=C4a30695ADvjVQa1PpcFPuFtsleOkWoKj_nxJJr-aU3EGFiZk9Sdk=

 

[itchynackers]

The motor may not be easy to turn with the cover off. In fact the magnets may be touching the stator (making it tough to turn). This doesn't mean it rubs with the covers ON. The cover will center the stator as you tighten the cover screws. Then it will turn normally, unless you have shorted halls/phases etc... My bet is that it isn't rubbing when the covers are on.

 

[thedarlington]

no its not the covers which rub those are fine, its the surrounding armature with the magnets which is laced to the rim, i was trying to upload the images by thumbnails maybe they wherent up yet, but now you can see

 

[John in CR]

Thedarlington,

There is a bearing in each cover. Of course the rotor will rub the stator with one or both covers off, so don't even try, because both covers are needed to center the rotor properly. The motor was overheated towing something else, which is unlikely to stuff the bearings. They typically wear with use, though big impacts like potholes can do them in. Since you have the covers off, the bearings are easy enough to check by simply sticking your finger in the hole and give the cover a spin. Don't be surprised by a significant out of balance of the cover or a tick in the rotation of the cheap bearings, both of which are probably unrelated to your problem. It's always a good idea to replace stock bearings with good ones if you have the cover off anyway.

Back to your problem. Rubbing or grinding would be quite obvious and most commonly would come from magnets coming unglued after overheating. A slight rubbing can come from covers installed in a different position (you can probably match the marks left by sealant or the marks you made removing the covers), but wouldn't create the notched sensation you felt before.

Your original symptom is exactly that of 2 phase wires shorted together. Refer to my earlier post for how to test for a phase wire short. FWIW a phase wire short can occur quite easily with an overheated motor as the insulation melts and they fuse together, often inside the axle where the wires are grouped tightly. It can also happen in the windings, but that is less common due the the varnish on magnet wire having higher temp handling than the plastic insulation.

Phase wires are connected together at the other end inside the motor, so it's not just a simple measurement with a multimeter to check for a short. I told you the easy way, and a BLDC motor without a phase wire short will get progressively harder to turn as you short 2 and then all 3 phase wires together. 2 is typically a more notched sensation.

John

 

[thedarlington]

thanks i checked these bearings but they are perfect, the resistance is from the internal rotor rubbing up against the magnets on the inside of the hub (the part that laces to the spokes almost as if that rotor part was made too big for the hub, here are some pictures of the bearing, does anyone know if there are any refference books on rebuilding larger brushless motors like these??

 

[dogman dan]

Wierd that the bearings would be good if the stator is rubbing the magnets.

What's the rest of the story? What bent the rotor? What melted the epoxy and let the magnets shift positions? My bet, you melted er down pulling the other bike and the magnets moved. At 350F, the epoxy could get like bubble gum on a hot day.

 

[John in CR]

I'm with Dogman. A hubbie doesn't go from working fine to rubbing the magnets unless the one or more of the magnets became unglued.

However, rubbing would make an obvious grinding noise, and noise was never mentioned. My money is still on a phase wire short, which can only be dismissed after the very simple test.

 

[thedarlington]

thanks for the responses, well this hubs been weird ever since i got it from the cycle9 sale, it would get this like bumpy reistance as i mentioned on top with the pic of the kids, then it would work awesome, then suddenly it would come again i never figured out why and this was all mechanical/frictional, not due to electronics sensors or mixed cables, now its just an always hard resistance, it could be about the glue how could i check that? it doesnt seem messed up or anything but it does seem tighter now more resistance than before, i didnt think epoxy could get gummy once hard, and nothings been bent everything looks in like new condition

 

[bjosta]

then suddenly it would come again i never figured out why and this was all mechanical/frictional, not due to electronics sensors or mixed cables, now its just an always hard resistance

Have you actually done the phase wire test mentioned several times in this thread? If you have then just say so It feels like you have decided that's not the cause but never said that you confirmed that it is not. Not trying to be an ass, just curious

 

[dogman dan]

The bearings are in the covers, between the axle and the cover. If they wear out and allow the axle to slop around, the magnets would rub on the stator. A phase short, in the wires, in the windings after an overheat, or by a blown fet in the controller will also cause a strong resistance.

Looking at those pics, the motor does not have that toasty winding cooked motor look. No black windings.

 

[thedarlington]

it was working fine for about six months, on and off and i did the 36 different combinations test one time it gave me problems and know that the configuration was right bc while it still had that bumpy resistance, it also didnt run and sounded more forced, when i returned it it still struggled a bit but spun eventually

also bearings dont have any play besides the smooth rotation, nothing's jiggly and this problem came before taking the covers off when the screws still held everything in place so this isnt it either

 

[bjosta]

it was working fine for about six months, on and off and i did the 36 different combinations test one time it gave me problems and know that the configuration was right bc while it still had that bumpy resistance

That's not the phase wire test I was talking about. To exclude the possibility of shorted phase wires you need to do the following:

Turn the wheel touching alternating phase wire ends together. If it's a shorted phase wire then the combo that doesn't increase turning resistance even more is where the short is. If you short 2 and it gets harder to turn, and short all 3 and it gets harder still (but probably less of that cogging feel), then the problem is elsewhere.