Sealed or serviceable bearing: your choice?

[MTGreen]

Regarding the several comments about the small amount of grease in a sealed bearing -
I was replacing the spindle bearings in one of my milling machines. The design took 2 angular contact high precision bearings which were sealed only on the outside surface and the spindle was set up to use grease only.
Because these were high dollar and a pita to replace, I used the exact amount of high dollar grease recommended by SKF which to my mind was a very small amount of grease -nowhere near full and nothing like trailer hub bearings.

Makes me wonder if there is a real world lifespan difference in popping a seal and filling fuller than factory fill.
I'm thinking if it's jam packed too full the expansion contraction properties may pop the seals.

 

[5030]

To me it makes no sense not to remove the seals and grease the bearings regularly. The spindles on both our Zero Turns have never been replaced because when I bought them, first thing I did was remove the inner seals on the spindles and keep them greased. The spindles already had grease fittings but greasing them did nothing because the upper and lower bearings were sealed... Both of them have Chinese bearings btw.

 

[5030]

Regarding the several comments about the small amount of grease in a sealed bearing -
I was replacing the spindle bearings in one of my milling machines. The design took 2 angular contact high precision bearings which were sealed only on the outside surface and the spindle was set up to use grease only.
Because these were high dollar and a pita to replace, I used the exact amount of high dollar grease recommended by SKF which to my mind was a very small amount of grease -nowhere near full and nothing like trailer hub bearings.

Makes me wonder if there is a real world lifespan difference in popping a seal and filling fuller than factory fill.
I'm thinking if it's jam packed too full the expansion contraction properties may pop the seals.

Interesting comment. I've replaced the spindle bearings on both my Bridgeport Versa Trak as well as my Series One with SKF bearings and on both my Bridgeports, the bearings are lubricated with spindle oil via oil cups.

If I remember correctly, ABEC Class 5's. Both my surface grinders have sealed bearing heads that are filled with lubricating oil from the factory, though they do have drain and fill ports but I've never fiddled with the at all.

 

[MTGreen]

Interesting comment. I've replaced the spindle bearings on both my Bridgeport Versa Trak as well as my Series One with SKF bearings and on both my Bridgeports, the bearings are lubricated with spindle oil via oil cups.

If I remember correctly, ABEC Class 5's. Both my surface grinders have sealed bearing heads that are filled with lubricating oil from the factory, though they do have drain and fill ports but I've never fiddled with the at all.

I haven't needed to replace the ones in my Taiwanese heavy Bridgeport clone yet. These were ABEC 7s in a workbench size mill head. I would have been fine with the ABEC 5s but I got a screaming deal surplus on the 7s which otherwise would likely have cost as much as a new head assembly

 

[MossRoad]

true, & would require balancing as well. many idler pulley arms have zerks, just not pulleys. a lot of heat is generated from belt to idler pulley on my zero turn, just wonder of regular lube would lengthen pulley life

Question:

How many cars with serpentine belts are running around with the original idler pulley that's never been lubricated in 100,000+ miles of operation?

Answer:

Tens of Millions.

It's not worth reinventing the wheel for this application.

 

[big bubba]

and many with failed idlers too. guess it's all about one's empirical history in the field. if given the choice, i'd always favor grease serviceable pulley bearings.
have yet to see one...

 

[MossRoad]

and many with failed idlers too. guess it's all about one's empirical history in the field. if given the choice, i'd always favor grease serviceable pulley bearings.
have yet to see one...

My 2003 suburban has 52,000+ hours on it. I doubt it's the original idler pulley. However, even it it's used 3 over it's life of 189,000 miles, that's over 60,000 miles or over 14,000 hours per bearing.... How many hours does your tractor have?

What I'm getting at is that the reason you've never seen a greasable idler or pulley bearing is because it's not necessary.

 

[big bubba]

What I'm getting at is that the reason you've never seen a greasable idler or pulley bearing is because it's not necessary. Moss Road

respectfully disagree. again, it's empirical & the luck of the draw given ones own experience. having replaced idler pulleys several times (on zero turn, not tractor, it doesn't have any idler pulleys) leads me to think grease serviceable pulley bearing would outlast sealed (in my circumstance)
btw i do enjoy the different takes on the issue from members as yourself, good discussion
best regards, bb

 

[MTGreen]

I'm thinking the shock and side loading system characteristics for a zero turn belt idler are going to be a different/harsher operating environment than a relatively more rigid and relatively cleaner serpentine system with a robust constant force tensioner in an automotive application

 

[big bubba]

good point. hadn't thought that, but variable deck heights probably do put lateral stress on pulley bearings. in addition to heat of course. i probably am making too much of the issue.

wish Jacks Small Engine were back online (NTool is worthless in things like this).
do excuse my ramblings. just venting a frustration. I ask a lot of my commercial mowers & carefully maintain as well. idler pulleys are the weak link, i can live with that... meanwhile where's that grease gun, couldn't live w/o it