Answer:
2.Bearing lubrication is vital for preserving the performance and lifespan of rolling element bearings. Lubrication helps separate moving parts relative to one another, such as rollers and raceways or balls, to prevent wear and tear and friction.
3.Prevents dust from entering from the outside to protect packings and bearings. Mainly used to keep outside liquids like cutting fluid out. Rubber-coated at outer ring circumference. It can also prevent dust from entering from the outside to protect the packing or bearing.
