There are many different suffixes for deep groove ball bearings that can look very similar and be confusing. Bearings such as 6205-2RS that end in –ZZ or -2RS respectively have either shields or seals but what about when a C3 or C3P6QE6 is added to the end of the -2RS or –ZZ to form a 6205-2RSC3?

C3 and C3P6QE6 are special bearings for an electric motor fit. These bearings have a special C3 clearance: a type of finish on the bore to fit into electric motor applications. This extra clearance also helps motor heat dissipate quickly. You must use an electric motor bearing (either C3 or C3P6QE6) to fit an electric motor. “C3P6QE6″ are extra quiet electric motor fit bearings. The internal manufacturing of the bearing is made so the track and bearing balls have as little clearance as possible, thus minimizing any room for noise made by vibrations, rattling, etc. Electric motor bearings are virtually indistinguishable to the common eye and look just like regular deep groove ball bearings.

C3 isn’t the only bearing type with a special clearance for electric motor fit though. There is a wide range of internal bearing clearancesthat are governed by ISO (International Organization for Standardization) and the ABMA (American Bearing Manufacturers’ Association). These clearance suffixes are: C1, C2, C3, C4 and C5, where no suffix indicates normal clearance(like a standard 6205-2RS). C1 is a clearance range less than C2. C2 is a clearance range less than normal. C3 is a clearance range greater than normal, C4 is a clearance range greater than C3 and C5 is a clearance range greater than C4.

Precision is a range of tolerance on bearing dimensions. ISO and ABMA govern the precision ranges. ISO uses Class 0, Class 6, Class 5, Class 4, and Class 2 and ABMA uses ABEC 1, ABEC 3, ABEC 5, ABEC 7 and ABEC 9, respectively the systems are generally interchangeable.