Page 294 - needle bearings

Seals
NTN

Seals

Seals Fitting relations
These are the special-purposed seals for needle roller The seal contact surface must be finished by grinding,
bearings whose cross sectional height is designed so after hardened, to get its good sealing performance. In
small as to match applicable needle roller bearings. addition, harmful flaw and indent are not allowed to exist
These contact seals are made of synthetic rubber on the seal contact surface. Where the inner ring raceway
reinforced with steel plate, being then used in operating surface is used as seal contact surface, a wide inner ring
temperature range of -25 to +120˚C and, under must be used.
continuous running, at 100˚C and less. Further, feel free When fitting a seal in a bearing, it is desirable to taper
to contact NTN for the use of these seals under special the shaft end face or the housing end face so as to
operating condition, e.g. operating temperature of over protect the seal lip and outer surface from damaging, as
120˚C. illustrated in Fig. 4. Where shaft end is not tapered or
chamfered (rounded), it is recommended to a fitting jig as
illustrated in Fig.5. Regarding the seal to housing
Types of seal interference, a adequate interference can be got in the
Two different seal types are available; one is Type G usual housing tolerance range of G7 toR7.
with one lip and another is Type GD with two lips. In Furthermore, it is recommended to apply pre-coat
addition to these two, sliding rubber seals (LEG, LEGD), of a lubricant to the seal lip before fitting seals G and
wherein lubrication property was assigned to a rubber GD, for better lubrication. Further, when fitting a seal
material fulfilling low torque under an non-lubrication and inserting it through a shaft, take good care to
environment, are also manufactured. Feel free to contact protect its lip from deforming.
NTN for the detail of these seal types.
Fitting jig
30˚

Fig. 4 Fig. 5

Seal application examples
Fig. 1 Type G (LEG) Fig. 2 Type GD (LEGD)
Figs.6 to 8 illustrate design examples using these seals.
Where seal contact surface and lubricating condition
are good, Type G with one lip can be used up to 10m/s
maximum at peripheral speed and Type GD with two lips
used up to 6m/s maximum.

This seal is intended to hold grease and to Fig. 6
prevent dust invasion from outside. It has no
function to hold lubrication oil, etc. unlike oil
seal.

Composition of nominal number
Nominal seal number is composed of type code (G, Fig. 7
GD) and dimension code (bore dia.ʷouter dia.ʷwidth).

G 20ʷ26ʷ4

Dimension code
Type code

Fig. 3 Fig. 8

B-232