Bearing seals, which one?

A visual check to see if they are metal or rubber is the easiest way to identify what type of seal your bearing has. Bearings can come with 3 main sealing options, open (no seals), Z (metal shields) and RS (rubber seals).

• Open (no seals), usually specified when the bearing is lubricated by the machine oil such as in a crank casing.
• Z (metal shields), usually specified when the bearing is dealing with higher speeds. Shields are fitted in the outer ring of the bearing and do not make contact with the inner ring, forming a very narrow gap with it & allowing for higher speeds & reduced friction.
• RS (rubber seal), usually specified when the bearing requires good sealing capabilities.

Bearings usually come stamped with 6204-Z,  6204-2Z, 6204-RS or 6204-2RS on the shield/seal. -2Z & -2RS refer to there being 2 of the shield/seal. If you have a bearing stamped -Z or -RS it will still be 2Z or 2RS. Some manufacturers use different codes to refer to the seals such as 2RSH, 2RS1, DD, 2NSE etc but they are the same as 2RS. You can also get bearings with non-contact type rubber seals which can be operated at the same speeds as bearings with shields but with improved sealing effectiveness.