Page 49 - needle bearings

Sealing Devices
NTN

9. Sealing Devices

lubricating condition, environmental condition, economical
9.1 Non-contact seal and contact seal merit, etc., so that bearing running is not inversely
The purpose of using a seal is to prevent a lubricant affected by the sealing device.
held in a bearing from leaking outside the bearing and to The bearing seals are mainly classified into non-contact
prevent powder, water content, etc. from invading into the seal, contact seal, etc. as shown in Tables 9.1 and 9.2,
bearing from outside. which must then be selected correctly according to each
It is very important to design a sealing device with good application,under full consideration of the characteristics
care, under full consideration of the operating conditions, of each sealing type.

Table 9.1 Seals (Non-contact seals)
Non-contact seals
Type Seal type using a spacing Seal type using a centrifuge Seal type using air pressure

Seal name Labyrinth seal (axial, radial) Slinger seal Air seal
Oil groove seal

<Oil groove seal> In oil lubrication, this seal has
This seal is fitted at either one side of a housing or a shaft, or an effect in slinging and returning
fitted at the both sides for sealing action. In this case, this seal the oil flown out along its sleeve
has also an effect in preventing invasion of foreign matter from by a centrifugal force if its sleeve
outside by holding grease in the oil groove.
is provided with projections.
Features < Labyrinth seal > A seal example illustrated in
This seal having a high sealing effect due to its multi-stage
Fig. 9.6 prevents invasion of
labyrinths and long passage is mainly used for grease lubrication.
Generally it is suited to high speed bearing running, but it has a foreign matter from outside.
dust-proofing effect even under low speed running if the seal
grooves are filled up with grease. It is convenient if this seal is
provided with a grease nipple.

Fig. 9.1 Oil groove seal Fig. 9.4 Slinger with projections
Application examples

Fig. 9.2 Axial labyrinth seal Fig. 9.5 Slinger intended for back flow of flown-out oil by centrifuge

Fig. 9.3 Radial labyrinth seal Fig. 9.6 Slinger provided at outer side

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