Single Row Angular Contact Ball Bearings feature raceways with high and low shoulders. These opposing raceways are designed to carry thrust load in one direction. These bearings may be preloaded at the factory so that the correct preload will develop within the bearing. The bearings in this series are assembled with a specific internal clearance so that they will have a specified contact angle under load. The standard contact load used by NTN is 30 deg, bearings made to a 40 °Contact angle carry the suffix B. For high speed grinding spindles, the 7000C, 7200C and the 7300C series are available. They are high accuracy bearings with a 15 °Contact angle, and phenolic resin cages for high speed operations. NTN Duplex Angular Contact Ball Bearing, Round Bore Small, Series: 72 Series, 20 mm Bore Dia, 47 mm Outside Dia, 1 Row, 28 mm W, 30 °Contact, Open Closure, 23600 N, High Carbon Chrome Steel Bearing, Pressed Steel Cage, 14000 RPM Grease/18000 RPM Oil Maximum, -40 to 120 °C