What Is Phớt labyrinth? — Bearing Glossary

Labyrinth seal is a non-contact sealing type formed by interlocking grooves and ridges in an S-shape or zigzag pattern between the rotating and stationary parts, preventing oil/grease from escaping and contaminants from entering through flow resistance barriers without any mechanical friction.

Unlike lip seals that contact the shaft surface directly, a labyrinth seal has a small clearance (typically 0.2–0.5 mm) between the rotating and stationary elements — no contact point exists. This completely eliminates seal wear and friction losses, allowing bearings to operate at high speeds with no seal-imposed speed limit, per SKF bearing sealing solutions. Compare all seal types and their appropriate applications at bearing seals and shields guide and browse deep groove ball bearings suited for labyrinth seal pairings at high speed.

The operating principle relies on two mechanisms: (1) flow resistance — grease or oil must pass through multiple successive turns, with pressure dropping progressively across each groove; (2) centrifugal force — at rotational speed, grease and contaminant particles are flung outward by inertia rather than passing through the grooves.

Labyrinth Seal Types and Applications

Three labyrinth configurations are common in industrial bearing practice. First, simple labyrinth — one or two parallel grooves, used in medium-sized electric motors and high-speed gearboxes. Second, V-ring labyrinth — combines a centrifugal deflector flange with a V-shaped groove, widely used in high-speed industrial fans. Third, packed labyrinth — grooves filled with grease to create an additional physical barrier, used in heavy dust environments.

Practical example: centrifugal fan bearing 22222 EK/C3 (d = 110, D = 200, B = 53 mm, C = 340 kN) running at 1,500 rpm in a cement plant. A packed labyrinth seal replaces 2RS contact seals because the ambient temperature frequently reaches 55°C — accelerating rubber aging even though shaft surface velocity of 8.6 m/s (1,500 rpm × 110 mm diameter) is still within 2RS limits. Packed labyrinth extends the relubrication interval from 1,500 hours to 3,000 hours.