What is a floating labyrinth oil seal?

What is a floating labyrinth oil seal?

A floating labyrinth oil seal is a type of oil seal that combines “floating” and “labyrinth” sealing mechanisms.Primarily used for the shaft-bearing seals

of high-voltage motors, it employs a split-type design and labyrinth grooves to effectively contain lubricating oil and facilitate its return.

1.The polyimide labyrinth floating seal ring is a two-half ring structure, which is composed of an oil return hole, a positioning pin and a spring groove.

2.The labyrinth floating seal ring has four grooves in the inner ring and one groove in the outer ring for snap springs.

3.The labyrinth floating seal ring positioning pin contain three round holes, and three round holes in the opposite position, and the left round hole

is the oil return groove.

What is the operating principle of a floating labyrinth oil seal?

1.Labyrinth-based flow restriction

The inner side of the oil seal features a series of continuous annular grooves, which create a tortuous, labyrinth-like flow path. As lubricating oil attempts to  leak outward, it undergoes a repeated process of “throttling/pressure reduction” followed by “cavity expansion” at each groove: As the oil passes through a narrow gap, its flow velocity surges and its pressure drops. Upon entering the cavity of a groove, the volume expands suddenly;kinetic energy is converted into thermal energy, and the pressure is unable to recover. After passing through multiple grooves, the oil pressure is dissipated stage by stage. This significantly increases resistance to leakage, effectively eliminating the driving force behind outward seepage.

2.Floating dynamic compensation

The oil seal utilizes a split, semi-ring structure combined with elastic elements (such as springs or O-rings) to allow for radial floating:

If the motor shaft experiences eccentricity, vibration, or axial movement, the sealing ring can automatically slide radially within its groove, compensating for shaft misalignments of up to ±1.5°. As the sealing surfaces wear down, the elastic elements release stored energy, continuously exerting axial pressure to automatically compensate for the wear and ensure the surfaces remain in close contact over the long term.

3.Self-sealing via an oil film

Driven by capillary suction, centrifugal force generated by the rotating shaft, and internal pressure resulting from temperature rises within the sealing chamber, lubricating oil is precisely directed into the sealing gap:

A uniform oil film—only microns thick—forms between the two precision surfaces sliding against each other. This creates a liquid barrier that completely blocks the leakage path, while simultaneously lubricating and cooling the sealing surfaces to prevent overheating and damage caused by dry metal-on-metal friction. In conjunction with the oil-return holes provided on the oil seal, a small amount of oil that enters the labyrinth grooves can flow back through these channels into the bearing oil chamber, establishing a virtuous cycle of “sealing – returning – resealing.”

What products are floating labyrinth oil seals used for?