The Ball Retainer separates the balls from each other, minimizing noise and contact friction between balls. This enables higher operating speeds. Shields and Seals help keep contaminates out of the bearings. A shield is generally made of steel. A shield can be used by itself or in conjunction with a seal, in which case, the shield will also protect the seal from damage.
Seals are available in Teflon, felt, rubber, nylon and mylar.
Seals affixed to the outer race also contact the inner race. They create a slight frictional drag, but seal out contaminants while helping to retain grease within the bearing. Standard seals are suitable for temperatures up to 225 F. Bearing Lubrication Oiled bearings are generally used in gravity applications requiring a low coefficient of friction. The temperature range of standard oil is 0 to 200 F. Grease Packed bearings are generally used in powered applications. They are suitable for higher humidity applications.