In chinese bearing, the letters RL and LL indicate the type of lubrication used.
RL stands for “grease lubricated”.
Bearings designated with RL, like 6202RL, are lubricated with a general purpose grease.
LL stands for “lithium grease lubricated”.
Bearings marked LL, like 6202LL, are lubricated with a lithium-based grease.
Lithium greases tend to have better high-temperature performance and oxidation resistance compared to general purpose greases. So LL bearings can often operate at higher temperatures.
Some other things to know about RL and LL in bearing designations:
Not all bearing types come with an RL or LL designation. It depends on whether they are lubricated or not. Unlubricated bearings will not have either RL or LL marked.
RL and LL just specify the lubricant used. They do not indicate any other properties of the bearing like size, load rating, accuracy grade, etc. You need to consider the full bearing designation for those details.
Sometimes bearing OEMs and manufacturers may use their own proprietary grease blends, so RL and LL are not always strictly accurate. They just aim to provide a general sense of the lubrication.
For high-performance bearings, especially high-speed ones, some manufacturers may specify a customized grease formulation beyond just RL or LL.
Re-lubricating RL or LL bearings may require disassembling them, cleaning parts, and re-packing with fresh grease. Not always possible or practical.