Mounted bearing units - sources, care and feeding

madsci

1 mW
Joined
Jun 25, 2017
Messages
14
This is a more generic mechanical topic, but my recently completed EV project used a dozen 4-bolt mounted bearings, all the same generic < $7 model. They're supposed to be self-adjusting with the bearing able to swivel within the housing, but they've been inconsistent - some swivel easily out of the box, some take a bit of force to get moving, and some I just can't get to swivel at all. I can't see any obvious cause.

Some of the bearings spin noticeably more easily than others, though I don't think any have enough resistance to be a real problem at low speed. The inconsistency bothers me, though. And about half of them had their grease fittings fall out after the first 12 hours of use.

Are these cheap bearings worth using? McMaster-Carr's equivalents are about 5x the price. If the $7 bearings are no good, what's a decent quality alternative?

Do their grease fittings work right, assuming they're not missing? If I give one a shot of grease, most seems to come out between the bearing and housing. There are holes in the outer race so I'm assuming that's how the grease is supposed to get in, but I don't know how much is getting in there.

I was using them in an environment of extraordinarily fine and powdery alkali dust, and some of them came out pretty funky. I've disassembled the entire vehicle down to the last nut and bolt to clean and rebuild it. My dust protection idea failed and ended up shoveling dust directly into the chains and bearings. When I rebuild it I want to add better protection, and components more resistant to dust and corrosion when the protection fails.

Thanks!
 
madsci said:
This is a more generic mechanical topic, but my recently completed EV project used a dozen 4-bolt mounted bearings, all the same generic < $7 model.
Some pictures of them might help to know exactly what you're looking for. I think I can see them in the pic already attached to the post above, but I can't see any of the details you mention below.



They're supposed to be self-adjusting with the bearing able to swivel within the housing, but they've been inconsistent - some swivel easily out of the box, some take a bit of force to get moving, and some I just can't get to swivel at all. I can't see any obvious cause.
By swivel do you mean like a rose-heim ball joint, but with the outer race of the bearing being the ball?

Or do you mean something else?

The ball joints I've used (like on CrazyBike2's remote-steering rod) are there to allow the rod to move relative to the bolts securing it's ends to the fixed points at different angles and movement ratios without bending the rod or torsioning it.

What purpose does the swivel serve in your application?



And about half of them had their grease fittings fall out after the first 12 hours of use.
That sounds like just junk parts. :(

Are these cheap bearings worth using? McMaster-Carr's equivalents are about 5x the price. If the $7 bearings are no good, what's a decent quality alternative?
Cheapness is relative to the project importance. If the bearings function well enough for the short time each year a project like this one gets used, there's no reason to spend a fortune on better parts. ;)

If it's something you'll use a lot, especially if the bearings are very important to the safety of the project, where a failure would cause a crash that could injure or kill, then cost isn't as big a limiting factor in proportion to risk.

you might find it's cheaper to just replace them when they fail, than to get better ones.

I don't know good sources for things except salvaging stuff, as I rarely can afford to go buy new parts. I did do this once for CrazyBike2's tie-rod bearings and bolts and rod, just because of the problems I'd had with my homemade ones over the years, and the safety risk if that rod fails (no steering, potentially flipping the bike end for end, etc). Even then, if it weren't for donated funds I wouldn't have been able to do it.


Do their grease fittings work right, assuming they're not missing? If I give one a shot of grease, most seems to come out between the bearing and housing. There are holes in the outer race so I'm assuming that's how the grease is supposed to get in, but I don't know how much is getting in there.
It sounds like they're not well-built, and stuff just doesnt' fit like it's supposed to. I don't know if this will help, but if you have to keep using these, you might be able to make seals this way
https://endless-sphere.com/forums/viewtopic.php?f=28&t=12644&p=188254#p188254




Also, most of the stuff below
https://endless-sphere.com/forums/search.php?keywords=bearing*&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search
has no relevance, but there may be some in the list that have useful info for you.
 
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