Sealed or serviceable bearing: your choice?

[MTGreen]

Filling a regular sealed bearing with grease is also a friction generator/life shortener.

I suspected as much, thanks for confirming

 

[nova3930]

Great topic…I’ve been a ball bearing engineer for over 36 yrs. Here’s a bearing guys perspective and sorry for the long post, but ask an engineer what time it is and they tell you how to build the clock….,
Basically, all greases are not compatible. I avoid EP Moly based grease in a rolling element bearing. I have seen many bearings ordered from the factory only to see the OEM call out an incompatible grease , different grease for maintenance. Lithium complex greases tolerate water intrusion better than clay based greases. Not all synthetic oil base greases are compatible with mineral oil base.
If it’s sealed, the bearing was designed with a specific clearance, load-speed capacity, installation fit, grease fill percentage of the internal cavity void, for the very reason many have referenced on the seals blowing out, but percent fill of lube is really controlled to maintain the film thickness between the rolling elements permitting minimal heating of the grease in shear flow…..a ball or roller bearing is only suppose to run on a film or lube and it acts lube an oil pump internally, never touching metal on metal…..I’ll stop here.
A sealed maintenance free bearing really shouldn’t use a clay based grease. A relube bearing is more costly, and has special seals and lube passages, but these are mainly on the sliding bearings, spherical plain bearings (ball joints, tie rods, journals).
Injecting grease in a failing rolling element bearing with a needle could work, but it probably is failing by that point. If it made noise, it’s failing.
Spindle bearings are specially designed for relube and are damaged if done incorrectly, wrong grease, over pressured, etc.
if a bearing is designed for relube, it will always outlast a sealed maintenance free, if maintained. Those special holes and lube grooves are not expensive to machine, but all the cost is in the debur operation in manufacture and OEMs don’t like the added cost. Depending on the bearing, load and speed, rubber seals may not survive and hence the steel shields/slingers, which don’t work well in wet-muddy areas. The designer had to make a trade off, load capacity for long life.
Bearings are designed to wear out, keeps me employed, but I hate nothing than a bearing failure on my personal equipment and the needle injection is my last ditch effort to buy time, waiting for the replacement.

What's your opinion of calcium sulphonate and polyurea based greases?

 

[ottr1967]

My take would be, first, how would one install a grease zerk on an idler pulley? There's no place for it.

In the hub of the pulley. I do prefer greasable but dont have any hard evidence that the overall life is better (so long as the sealed bearing is of high quality).

 

[MossRoad]

In the hub of the pulley. I do prefer greasable but dont have any hard evidence that the overall life is better (so long as the sealed bearing is of high quality).

There's a shaft in the hub.

 

[WayneGasMan]

Hi All, this is a very interesting discussion. Please allow me an anecdote. Some years ago I bought an old Komatsu forklift to help me shift 100lb LPG cylinders around ( I was an LPG dealer for a few years). Had a professional forklift technician come out to give the machine a deep service. In the course of our conversation we talked about bearings, and I commented about popping the rubber seals on sealed bearings and replacing the factory grease with better product. The tech became quite incensed. He had worked for a company which supplied a major customer with a lot of bearings. This customer insisted on repacking the new bearings before installing them. They had failures. Tech asked the customer about their "dirt count". ??? Tech had worked for a major bearing manufacturer and explained that factory lube in sealed bearings is "sterile", no microscopic dust included at all. So it might look like vaseline, but apparently factory lube is OK.
Other side of the coin, the quill bearings on my ride on mower lasted one season with factory sealed bearings, and 2 to 3 seasons if I repacked them from new with a high quality grease. Go Figure!! (I'm an Aussie, but the comment seems appropriate).
Hope this is interesting. I Enjoy Tractor ByNet. My little old 1500DT just keeps chugging along.
Best to all.

 

[RandyT]

What I do / did was pull the mower spindles and pop the inner seals on the spindle bearings so they get grease. For some odd reason, mower spindles come with grease fittings but have sealed bearings which is counter productive. never figured that out actually. Easy to pop off the seals with a pen knife.

The seals bearings with the grease nipple are for people that feel that they need to grease their spindles, but really doesn't have much benefit because most people will never grease them and on some mowers with grease nipples you either can't see them because of covers or not convenient to get to without standing the mower on its tail.

 

[big bubba]

points well taken, although not all people are created equal in their maintenance as you suggest, regards

 

[5030]

The seals bearings with the grease nipple are for people that feel that they need to grease their spindles, but really doesn't have much benefit because most people will never grease them and on some mowers with grease nipples you either can't see them because of covers or not convenient to get to without standing the mower on its tail.

On both of mine the zerks are on top of the spindles and the spindles are cross drilled to allow the grease to enter the cavity. I stand my mowers up regularly anyway to clean the decks off.

 

[kioti28527]

Lube question. so i've replaced a number of idler pulleys on my zero turn, a few on my pickup. never seen a grease serviceable idler pulley, all sealed.
asked an engineer friend who designed pulleys, and a good small engine guy why so...they both said sealed bearings are superior & will outlast grease serviceable, due to contaminants, etc.

your take? do you agree w/engineers & mechanics above based your own experience? btw, i'm glad to have grease serviceable mower spindles & front end zerks on my old pick up. thx in advance

Ive heard the same thing with ujoints without zerks are best and last years longer.
With zerk fittings i found you have to use the exact same grease everytime,never mix,then you always have to remember or if sold to someone else let them know what you used,this season on the JD zero turn i grabbed 1 of 3 grease guns because it had grease in it,looked like a black molly and regreased the spindles,10 minutes after cutting heard a grinding noise from the deck,i knew i had been using Red and tacky for years,after pushing all the black out with new red and tacky grinding noise stopped,so what ever you start with always use the same or compatable

 

[big bubba]

ScottG mentioned the same in an earlier post. point well taken, & something i haven't considered in the discussion. i should pay more attn to grease type. maybe grease serviceable bearing types are more forgiving to different grease types than generic sealed bearings.

one way to address sealed bearing failure would be to manufacture a pulley with a replaceable slip fit sealed bearing. in fact my older Toyota pu has one larger pulley made that way. all i did was to replace the $15 bearing.

manufacturers aren't going to do that in general. so i'll just keep swapping out idler pulleys on my zero turns. glad to see now that i can plug in the pulley part # on amazon, & usually get several hits. thx for your comment, regards