You're looking for detailed opinions/experiences and not really giving anyone much detail

99502H Bearing
Rubber Sealed Deep Groove Ball Bearings: One of the most commonly used bearings, these types are manufactured with rubber seals inserted into the outer raceway and in contact with the inner race providing protection against the ingress of moisture, dust and other foreign matter and serve to retain the pre-filled grease in the bearing
Seals can be easily removed for applications that only require 1 seal.

16232RS Rubber Sealed Deep Groove Ball Bearing 0.625×1.375×0.4375 inch, almost the same description as above.

Seems either will be suitable for your use but best to have spares in stock to replace as required, a similar type of use in an agressive environment was discussed in this forum some time ago.

Emgee

99502H Sealed Deep Groove Ball Bearing with Special Bore 5/8"x35mmx11mm

1623-2RS Imperial Sealed Ball Bearing 15.88mm x 34.93mm x 11.11mm (5/8" x 1 3/8" x 7/16" )

So not quite identical sizes.

Edited By David Jupp on 26/11/2020 11:27:29

Some sites show the 99502H as all imperial rather than just the 5/8 bore so be careful what you need.

The suffix is only true if the XXXX in both cases is in the same language. In the case of the bearing under discussion, 99502 is not an ISO designation (I have failed to determine to which, if any, naming standard it does belong), whereas 1632 is ISO and the chart to which you link is specifically for NTN bearings*.

Other references, and indeed the original poster, refer to it as an agricultural bearing. Many of the listed applications are ride-on mowers, hardly an application for high temperature tool steel. (https://bearingsdirect.com/agricultural-ball-bearings/99502h-agricultural-ball-bearing-5-8×1-3-8×7-16-sealed-sc0228lu)

It is interesting that some of the descriptions of the 99502 bearing market themselves as being made from a special chrome tool steel, which, when you check the standard mentioned (SAE-52100) is a standard bearing steel. The snake oil is marketing this bearing to mower people is probably the same as that marketing gold plated plugs to hifi people.

* I particularly want to buy a C2 bearing off them, to check it the table is correct.

if you spend enough time on bearing manufacturers websites trying to sort out the terminology the use so you can compare the various bearings between suppliers you will become more confused and frustrated. Unless the bearing is a very special application that requires high precision and high speed operation, just measure the ID, OD, and width and pick a bearing. If the lip seals won't keep the dust out, nothing will. Greasing the bearing won't be of much help as you can't push out all the dust that is in the bearing but simply dilute the grease/dust mix that is in there. Hopefully the location of the bearing will make for easy replacement. Buy 2 or more and store the spares where you can find them.

As a hint for All Who grace this forum, I have a dollup of advice to add. It's best not to order bearings by number alone. I work with a Friend Who worked the Customer counter at a Bearing house for years and He agrees with My experience. Some bearings are stock sizes used for customization. A 6202 bearing can have the OD or ID changed to make it a different size and They WILL NOT change the numbers on the bearing. It's best to measure every dimension to see if it agrees with Your expectations.

I can't help you with the specs of the bearings, but it would appear that the premature failure is due to poor seals and I would suggest putting an additional seal to prevent the dust getting to the normal seal. A seal to protect a seal in effect.

Many years ago when I worked for Timken Bearings we specified metal seals which cut into the edge of the bearing. I can't remember the trade name now but they were very thin, so didn't take up much room in the assembly. They proved very effective in hostile environments.

Having done a quick search I found Nilos rings, which appear to do the same thing. I hope that has been of some help.