Needle Roller Bearings - Ntn-snr.com

Sealing Devices
NTN
Table 9.2 Seals (Contact seals)
Seal type
Seal using mainly direct contact
Contact seals
Seal using mainly fluid lubrication and boundary lubrication
Seal name
Seal ring (felt seal, etc.)
O-ring,
piston ring
Oil seal,
V-shaped ring seal,
mechanical seal
Features
This seal type seals a fluid perfectly by pressing its elastic body
onto the sliding surface with a constant contact pressure.
Generally the contact seals are more excellent in sealing
performance than the non-contact seals, but the friction torque
and temperature rise thereof are greater than those of the
non-contact seals.
This is the simplest of the contact seals, which is mainly used for
grease lubrication and suited to prevention of fine dust, but oil
penetration and outflow are occasionally unavoidable to some
extent.
< Oil seal >
This seal type intended to seal lubricant at the sliding portion
between its lip and a shaft has good sealing effect and is an
effective seal in the most frequent use.
The lip must be oriented outward to prevent invasion of water
content and foreign matter from outside and oriented inward to
prevent lubricant from leaking out of the housing. Furthermore,
another seal type with two or more lips is also available for
preventing lubricant leak and dust-proofing individually.
Fig. 9. 7 Felt seal
Application examples
Fig. 9. 8 Z type grease seal
Fig. 9.10 Oil seal
Fig. 9. 9 GS type grease seal
A-46