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Function: Prevent external mud, water, and sand from entering the main bearing while retaining lubricating grease.
Structural Type: Typically uses multi-lip labyrinth seals (e.g., 3–5 lip seals in series) to form a progressive pressure barrier. Materials:
Nitrile Rubber (NBR): Resistant to mineral oil lubricants and cost-effective. Polyurethane (PU): High abrasion resistance, suitable for sandy soil layers.
Fluorocarbon rubber (FKM): Withstands high temperatures (above 150°C) and chemical corrosion under extreme conditions. Technical Challenges:
Must withstand 10–20 bar mud water pressure and eccentric oscillation of the main bearing. Dynamic sealing surfaces are often designed with spring compensation structures to compensate for wear.
Structural Type: Typically uses multi-lip labyrinth seals (e.g., 3–5 lip seals in series) to form a progressive pressure barrier. Materials:
Nitrile Rubber (NBR): Resistant to mineral oil lubricants and cost-effective. Polyurethane (PU): High abrasion resistance, suitable for sandy soil layers.
Fluorocarbon rubber (FKM): Withstands high temperatures (above 150°C) and chemical corrosion under extreme conditions. Technical Challenges:
Must withstand 10–20 bar mud water pressure and eccentric oscillation of the main bearing. Dynamic sealing surfaces are often designed with spring compensation structures to compensate for wear.
