Page 288 - needle bearings

Snap rings
NTN

Snap Rings

These snap rings are used exclusively for fixing or
guiding a needle roller bearing ring or cage in axial Composition of nominal number
direction. Furthermore, these snap rings have the profile The snap ring nominal number is composed of type
identical to C-type concentric snap ring specified in JIS B code (WR or BR) and dimension code. The dimension
2806 and, in addition, snap rings with smaller section code represents applicable shaft diameter in Type WR
height (b) and also available in smaller dimension range and applicable housing bore diameter in Type BR.
are manufactured according to application of needle roller
bearings. These snap rings are manufactured using hard
steel wire rod and, after manufactured, chemical
conversion treatment is applied to the surface thereof. WR 38

Dimension code
Types of snap ring
Type code
Two types of snap ring are available; one is Type WR
designed for application to shaft and another is Type BR Fig. 3
for application to bearing housing.

Allowable running speed
The allowable running speed for Type WR for shaft
application is as described in applicable Dimensions
Table. This means the running speed when snap ring
begins to get loose with opening of its cut ends.

Mounting relation
It is recommended to insert a spacer between snap ring
and cage for guiding the cage in axial direction. On
Fig. 1 WR snap ring occasion, snap ring is difficult to remove, but limited to a
portion in which a pull-out
tool can not be inserted easily. In such a case, it is
necessary to consider the use of general snap rings
specified in JIS B 2804 (C-type snap rings) or B 2806 (C-
type concentric snap rings).

Fig. 2 BR snap ring

Table 1 Cut section angle of snap ring (Ћ)
Type Nominal number Cut section angle(Ћ)
WR4ɼWR5 40˃
Type WR
Type WR6 up to 60˃
Type BR All nominal numbers 90˃

B-226