The simplest of the many systems used to protect bearings during operation is the application of commercially available seals, whose rubber or similar material lips is always in contact with the rotating shaft.

This system generates friction and cannot be used in high speeds applications. Efficient labyrinth seals are important in these cases. Their design varies according to available space, lubricant type and operating environment.
The seals illustrated herein are commonly used in the machine tool industry and are quite suitable for other applications with similar operating conditions.

Figure 7
The bearing is protected by the barrier created by the cover, with small clearance to the shaft. This solution, suitable for moderately dusty environments, is not recommended for liquid contaminants.

 

 

Figure 8
This is a slightly more complex but more efficient seal than the former. It features a supplementary internal barrier consisting of commercially available laminar rings that fit to the static housing. Rubbing on the rotating parts must be avoided.

Figures 9 and 10
These single and multiple type labyrinth seals are more elaborate than the previous ones but are more effective, especially in the presence of dust or coolant jets, etc.

Figures 11 and 12
These single and multiple type labyrinth seals are provided with drainage. The upper cover, showing Figure 12 (vertical axis), acts as a centrifugal ring and ensures additional protection against debris from the outside.

 

Figure 13 
This seal is very effective due to the presence of a pressure air barrier (p = 0.2 bar) in the labyrinth space. In this system, particularly suitable for grease lubrication, the air must be supplied filtered and dried, through a specific channel.
Oil lubricated bearings operate in a pressurized environment, so sealing efficiency is less important than for grease lubricated ones. All contamination should be avoided for oil lubricated bearings especially when a re-circulation circuit is provided