Page 689 - Rollingbearings

Design considerations
Design Fits

considerations Inch bearings

In contrast to metric bearings, which are
Single row and machined to a minus tolerance, inch bear-

matched tapered ings are machined to a plus tolerance
(table 9, page 45) Therefore, the devi-
roller bearings ations for shaft and housing diameters for
metric bearings are not applicable Suitable
Single row tapered roller bearings must be shaft and housing its for inch tapered roller
used either with a second bearing (ig. 21) or bearings are provided in table 9, page 688,
as a matched pair (ig. 10, page 670, and and table 10, page 689 These its are valid
ig. 11, page 670). The bearings must be for bearings with Normal tolerances in typ-
adjusted against each other until the requi- ical applications
site clearance or preload is obtained (Select-
ing preload, page 186). Matched bearings
When the operating clearance in a bearing
arrangement is too large, the load carrying The axial internal clearance of matched
capacity of both bearings cannot be fully bearings arranged face-to-face or back-to-
utilized. Excessive preload increases friction, back (table 6, page 679) provides an appro-
which increases the amount of frictional heat priate operating clearance when the bear-
and reduces bearing service life. ings are mounted on shafts machined to:

• d ≤ 50 mm → m5�
Adjustment procedure • 50 mm < d ≤ 140 mm → m6�
• 140 mm < d ≤ 200 mm → n6�
When adjusting tapered roller bearings • d > 200 mm → p6�
against each other, the bearings must be
rotated so that the rollers assume their cor- SKF recommends these shaft seat tolerance
rect position, i.e. the large end face of the classes for rotating loads on the inner ring
rollers must be in contact with the guide where P ≤ 0,06 C If tighter its are selected,
lange be sure that the bearings are not preloaded 8
and are able to rotate freely The reduction of
internal clearance caused by axial locating
forces should also be taken into consideration
For stationary outer ring loads, SKF rec-
ommends housing bore tolerance classes
J6� or H7�

Fig. 21
Single bearings mounted back-to-back

687