bearing choice for axial load, subject to impulse force 2

[polished]

For years I have been trying to find a bearing which will allow a hub to gimble at the end of a spindle, and support 1000lbs of axial load. The machine loads, processes, and unloads on a regular basis, which accounts for regular impulse load higher than the operating load of 800lbs. This is where I believe the bearing failure I am experiencing is occuring. 2206 and 22206 bearings eventually fail in the outer race, or dig pivots in the inner or outer race (the bearing does not rotate so the balls are always located in the same spot) preventing the hub from gimbling. I have also tried a maintenance free sperical plain thrust bearing (GAC-30F) and two different sizes of maintenance free plain sperical bearings. The problem with the spherical bearings is the liner wears, cracks, or is pressed out, leaving metal on metal contact, and once again, preventing the hub from freely gimbling. As the bearing is not easily accessible, maintenance free was thought to be the way to go.

Is there another bearing style or type that would be better suited. There is not much motion in the bearing. It simply needs to keep the hub parallel to the table below it as the spindle it is attached to rotates, as well as transfer the load. Torque is transfered seperately. The bearing sizes mentioned above is about as much room as I have.

Since the impulse force seems to be the wearing factor on the bearings, are their dampeners on the market which can be placed in line with the bearing?

Any ideas are welcome?

 

[diamondjim]

Have you ever tried a needle
bearing in this application?
Is the id and od the only
restraint or is the width
critical as well?

 

[polished]

I am somewhat restricted to ID, OD, and width dimensions. The current range I can work in now is as follows:
width: 0.787 to 1.009 in
ID: 0.997 to 1.116 in
OD: 2.127 to 2.463 in

Small variations can be made as the hub joint is under development, and the spindle will be modified to fit accordingly. The overall height of the joint is the limiting factor.

Needle bearings have not been considered. What are the advantages to this bearing? Can they accept this type of load and are they more resiliant to the impulse stress of loading and unloading.

 

[GregLocock]

No they aren't.

If you want to handle impulsive loads then plain bearings are the best bet.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[sreid]

I would think that a spherical bearing without a liner would be the way to go. I'dContact Aurora Bearing.

http://www.aurorabearing.com/

 

[polished]

Thanks for your replies.

My concern in not using a maintenance free bearing is lubrication. The bearing is not easily accessed for routine lubrication. There is no easy way to put oil seals in the room available. Bearings with oil seals do not work as the oil seals pop out over time, causing more problems.

Granted, there is little motion. At most, there is 1 degree of gimble throughout the rotation of the hub, and no bearing rotation within the race. The hub is rotating at 100 rpm. As mentioned before, the bearing is carrying an axial load of 800lbs during the processing step. Would a spherical bearing with no liner, with a light coat of machine oil or some other lubricant work in this environment. Is there a lubricant that would better in this situation. If so, how often would I need to access the bearing for lubrication.

 

[diskullman]

You might want to take a look at the Fafnir airframe control bearings, possiblyKSP or MKSP, or MDSP styles.

Russell Giuliano