Labyrinth seal (bearing seal)

[smaty]

Hi All Dears:
I would like to know some detalis about Labyrinth seals.How much is the radial gap (between housing and seal)in this type of sealing?whether this type seals is prefered to contact seals for oil lubrication?

 

[Mendit]

Labyrinth seals, types are many and varied.
Fixed, by means of spigot locating to the bearing housing.
This is the most ineffective, often has a larger gap at the top of the shaft. Adjsutable, these are loose spigot fitted and loose bolted, they are minimal clearance to the shaft as small as 0.008 per side.
Floating, as used in the DIN standard bearings, (Renk) the seal is light weight plastic type materials (Ryton or Peek)
These typically only have 0.002 to 0.004 total clearance. They are not bolted to the housing but retained in a locating groove with a garter spring and anti rotation pin. Most seals are made of a soft forgiving materials to prevent shaft wear in the event of bearing failures.

 

[smaty]

Dear Mendit:
In fact for design of a labyrinth seal in a water pump i search for the amount of gap (radial or axial) between rotary and stationary parts in an application with 1500 rpm and oil lubrication.

 

[Tmoose]

Depending on shaft size you may find others use a packing to keep the water in, and a labyrinth to keep the oil in its chamber, with the water and oil seals well separated from each other.

 

[ejc]

A labyrinth seal is a non-contacting circumferential seal utilizing a tortured path for flow between the stationary and rotating parts. The design utilizes a series of pressure drops to reduce the leakage.

The problem with these types of seals is that they do not seal in a "flooded" application. Oil levels must be lower than the seal or it will eventually weep through the seal.

Clearances between the housing and the seal vary with the manufacturer. Some utilize a press fit, while others rely on o-rings to retain it in the housing.

Clearances between the internal parts of the seal vary from manufacturer as well. Generally, the closer the clearances, the better the seal tends to exclude contamination. However, the close clearance limits the amount of relative movement that the seal can handle.