Lubricating sealed bearings?

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bugbear
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Lubricating sealed bearings?

(slightly off topic - this is about a modern raker/scarifier)

A couple of years ago I attempted to use my Al-Ko scarifier to get the moss out of my lawn. The engine seemed to be labouring a bit, but since the grass at the edge (where I started) was a little long, I kept going. Then the smoke started coming out, so I stopped. As you do. It turned out...

... that the bearing fixed to the end of the scarifier drum had seized since last use, and the 1000W motor was simply turning the entire bearing within the plastic mounting, which promptly melted and sealed itself shut. The manual (I post-checked) makes no mention of checking or lubricating this bearing.

I have now found that I can get the mount point apart (brutality, knives, saws and mole grips were involved), and that the mount point is in fact a replaceable sub-assembly, available as a spare part (which may raise suspicions as to its design life). I also cleaned up the old seized bearing, so I could read its model number; turns out to be 6001-zz.

https://www.bearing-king.co.uk/bearing/6001-2z-skf/4185

I have replaced the seized bearing with a lovely new bearing, and bolted it in place, and used the specified-in-the-manual theadlock.

Now to my actual question: in a once bitten, twice shy, kind of way, I intend to check that this bearing turns OK before each use (I don't scarify very often, so this is not a major issue). But is there any kind of maintainance/lubrication I can perform on a shielded bearing ?

http://www.bearingtips.com/difference-bearing-shields-bearing-seals/

   BugBear

hortimech
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The whole idea behind sealed

The whole idea behind sealed bearings is that you don't have to lubricate them, I tended to pop a seal out and put a bit more grease in before installing them, but don't overfill.

Are you sure it was a lack of lubricant ? it could have been debris that had got wrapped around the shafts and had forced its way into the bearings.

 

hillsider
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Hortimech makes a good point

Hortimech makes a good point about the need or not to top up the grease in sealed bearings, I have found that the mainstream branded bearings are more likely to have enough grease in them to survive in service for longer than the cheaper unbranded bearings. 

Even sealed bearings are prone to some moisture passing through the seals especially if a hose jet is aimed directly at the seal. 

 

 

bugbear
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Is it easy/possible to remove

Is it easy/possible to remove, lube, replace the shield on a shielded bearing? I didn't "buy the best" :-)

 BugBear

hillsider
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It is not difficult to remove

It is not difficult to remove a shield from a bearing but you do need to be very careful not to damage the shield. I find that a dentist type of seal pick carefully inserted under the seal will normally allow the shield to be popped out without too much damage, a small amount of distortion can be rectified before refitting the shield.

As hortimech said don't over fill the bearing, you only need to fill with grease between 1/2 to 3/4 full.

wristpin
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Expanding on the good advice

Expanding on the good advice given above; in the dim distant past I was told that over packing a bearing could cause the balls to skid round the bearing without rotating resulting in it failing due to overheating.

bugbear
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My thanks to all, as always,

My thanks to all, as always, for your experience and kindness.

Since the scarifier drum is removeable (so you can switch between a raker drum and a hard-bladed scarifier) I am keeping both drums "on a shelf" and will fit a drum when I want to use the machine.

This should ensure that I remember to check the bearing, at least until I've learnt wether it's trustworthy, i.e. wether the first failure was a one-off.

  BugBear