Ball bearings manufactured by YJ can be classified as"open", " shielded", or" sealed". (1)Single -row deep groove ball bearings They can sustain radial loads mainly and can also sustain some axial load in either direction. The bearings have low friction and very little noise or vibration, Thess characteristics make them to be available for situations of high speed, high precision, low friction and low noise operations. (2)Shielded and sealed bearings: Deep groove ball bearings often have shields or seals installed on both sides and are factory - packed with a lubricant. The use of such bearings simplifies the structure of installation. lt also eliminates the need for relubrication and,therefore, reduces maintenance costs. There are three types of such closed bearings: shielded bearings, contact sealed bearings, and noncontact sealed boarings.(a)Shielded bearings -2Z(-Z) Shielded bearings are protected by a shield plate of pressed steel. The shields can be made of either low carbon steel or stainless steel. (b)Contact sealed bearings: -2RS(-RS) Sealed bearings have superior sealing effectiveness compared to shielded bearings, particularly, the contact type sealed beartings which prevent the intrusion of dust from outside because the seal plate lip slides on a seal groove in the inner ring. The torque is , however, high due to the friction of seal lip. (c)Non-contact sealed bearings: -2RZ(-RZ) Bearings with low friction seals which provide efficient sealing together with low friction torque. The speed and low friction abilities of non -contact sealed bearings are similar to sheilded bearings. However, when high speed and low friction are critical, the shielded execution may show slight advantage since due to possible excentricity. Lip contact may occur between seal and shoulder of inner ring.
