What is the difference between using a shield or a seal as a ball bearing closure?
Shields or seals are often installed to retain lubricant and to prevent contamination from entering the bearing. While a shield contacts the outer ring and does not come in contact with the inner ring, the seal generally comes in contact with both the inner and outer rings. Torque or drag is lower with a shield than with a seal. Alternately, the seal provides a higher degree of protection from contamination. Shields and seals are available in a variety of materials and configurations.