Page 185 - Rollingbearings

Selecting internal clearance or preload
Importance of • consider the reduction of clearance caused • select the required minimum initial in ternal
selecting correct by temperature difference between the clearance (page 185)
shaft, bearing rings and housing
clearance/preload (page 184) In case of doubt, contact the SKF application
• consider the reduction of clearance caused engineering service for support
The operating clearance or preload in a by other inluences (page 185)
bearing inluences, among other things, the • consider the required minimum initial
friction, load zone size and fatigue life of a internal clearance (page 185)
bearing The relationship between these
parameters is shown in diagram 1 The dia-
gram is generalized and based on rolling Diagram 1
bearings under radial load Operational clearance or preload versus main operational criteria
For general applications, the operating
clearance range should be within the recom- Ratio min max
mended zone shown in diagram 1 2,0
2)
1,8
3) Recommended zone of operating
Selecting initial 1,6 clearance for general applications

internal clearance 1,4

1,2
The operating clearance required for a bear-
ing to perform satisfactorily is application 1)
dependent (Importance of selecting correct 1,0 Bearing frictional moment
clearance/preload). 0,8
You must ensure that the bearing has a 2)
minimum initial internal clearance of a size
0,6
that, when it is reduced by the effects of Bearing life
mounting and other inluences, is equal to or 0,4
greater than the required minimum operat-
ing clearance 0,2
To achieve this, follow this procedure: Load zone Bearing execution
0
• consider the reduction of clearance caused -2 -1 0 1 2 3
by interference its (page 184) Preload Clearance
1) A ratio of 1 means that all rolling elements are loaded B.7
2) The dotted line indicates potentially unstable working conditions
3) Limits of range are determined by initial clearance, it and temperature effects

Fig. 2
Initial internal clearance and operating clearance

Unmounted Mounted Operating

Initial Reduced Cold
clearance clearance
Compression
Further
reduced
Interference clearance
it
Expansion

Warm

183