DOUBLE ROW ANGULAR CONTACT BALL BEARINGS
They are like arranging two single row angular contact ball bearings back to back, with inner & outer ring as one piece respectively therefore they are narrower. They can take axial load in either direction. The contact angle is 30 degree.
Bearing series 32 & 33 are with filling slot while series 52 & 53 are without filling slot. (Therefore can accommodate axial loads of some magnitude in both direction)
They have normal axial internal clearance or any desired smaller or larger clearance.
Increased misalignment increases ball loads & cage stresses, reducing bearing life & increasing running noise. There self-aligning capability is very limited.
Pressed steel cages are generally used. For high speed precision applications with a contact angle less then 30 degree, polyamide resin cages are used. Additives in lubricating oil or aged oil or higher temperature may reduce these cage life.
Generally the maximum attainable speed of rolling bearing is dictated by the permissible operating temperature which is turn depends upon in addition to frictional heat generated with in the bearing also on surrounding parts, environment, oil viscosity, load type etc.
But generally mechanical limits are decisive criteria.