Page 592 - Rollingbearings

7 Needle roller bearings
Needle roller / thrust ball • can be mounted back-to-back (ig. 27), for NX series bearings
bearings short shafts and where changes in length • consist of a radial needle roller bearing
due to thermal expansion are relatively and a full complement thrust ball bearing
SKF supplies needle roller / thrust ball bear- minor (ig. 28)
ings in two series (ig. 25): For these types of arrangements, SKF • are suitable for applications where there
recommends preloading the thrust ball are moderate radial loads and lighter, sin-
• NX series with a full comple ment thrust bearings with Belleville washers (cup gle direction axial loads
ball bearing springs). This preload helps to prevent the • have low cross-sectional height, which
• NKX series with a thrust ball bearing with balls from skidding if one of the thrust enables shaft centrelines to be positioned
a cage bearings becomes unloaded. Preload also close together like for multi-spindle drills
improves performance of the thrust ball • can be mounted with a snap ring, or
These combined bearings: bearings while reducing noise levels. against a shoulder in the housing bore, for
axial support
• consist of a radial needle roller bearing The snap ring groove in the outer ring
and a thrust ball bearing provides a cost-effective and axially
• are supplied without an inner ring space-saving solution (ig. 29 and prod-
• can be combined with an inner ring uct tables, 7.8, page 654)
(ig. 26), where the shaft cannot be hard- • are most often oil lubricated and therefore
ened and ground (product tables, supplied without grease
page 654 and page 656, must be ordered • have a stamped steel cover that
separately) – extends over the shaft washer of the full
• can accommodate axial loads in one direc- complement thrust ball bearing
tion and, therefore, locate the shaft in one – is irmly attached to the radial needle
direction only roller bearing
– makes these bearings non-separable
Fig. 25 – has lubrication holes as standard
Needle roller / thrust ball bearing – has no lubrication holes for bearings
with designation sufix Z (ig. 28)
7 These bearings can be grease
lubricated.

Full complement Thrust bearing
thrust bearing, NX with a cage, NKX

Fig. 26 Fig. 27
NX series bearing with an inner ring NKX series bearings arranged back -to -back, incorporating Belleville washers

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