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HOME | Main Menu | Our Company | Recent News | Employment | Contact Us Standard Bearings | Special Bearings | Technical Information | Applications |
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TECHNICAL INFORMATION Internal clearance
The radial clearance corresponds to the relative radial displacement under no load of one ring compared to the other.
The radial clearance is not considered a quality criteria. A radial clearance, which is not correctly adapted to the fit on the shaft and on the housing nor to the operational conditions, may have an influence over the behavior and service life of the bearing.
The normal radial clearance CN is defined in order to get a final, requested positive clearance after assembly in normal adjustment and operating conditions. Other standardized clearances are ranged into classes according to the following designations:
● C2 Clearance smaller than CN ● CN (C0) Normal clearance ● C3 Clearance greater than CN ● C4 Clearance greater than C3
In addition, WIB has defined two non-standard radial clearance ranges, for which the centre value may freely be defined. They are identified as:
● R (Regular): band width 6 µm. ● L (Large): band width 10 µm.
In the bearing designation, the R or L designations are followed by the centre value of the selected clearance.
Example 1) 623-2Z Y P5R20 - Indicates a radial clearance of 6 µm with values between 17 and 23 µm: (17+23)/2=20.
Example 2) 623-2Z Y P5L20 - Indicates a radial clearance of 10 µm with values between 15 and 25 mm: (15+25)/2=20
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The operational clearance corresponds to the residual radial clearance after assembly and in normal operating conditions. It is determined by the radial clearance before assembly, corrected by the reductions due to fitting constraints and thermal expansion.
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The
axial clearance corresponds to the maximum axial displacement of
one ring compared to the other ring under no load. It depends on the radial
clearance and on the internal construction of the bearing. The axial
clearance may be adjusted by modifying the raceway radius. The use of paired
ball bearings allows one to precisely control the axial clearance. |
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The
angle of contact ß° is determined by the line going through the
contact points of the balls in the raceway and a line which is
perpendicular to the bearing axis. This is in a position of maximum axial
displacement of one ring compared to the other. The angle of contact
depends on the radial clearance and the raceway radius and will be
slightly increased by applying an axial load. |
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The misalignment angle aº of a bearing is defined by the variation of the angular position of one ring compared to the other. The value of this angle depends on the radial clearance, the raceway radius and the internal construction of the ball bearing. It should be noted that an angle that is too large can increase the noise level.
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WIB - Wälzlager Industriewerke Bulle AG |
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Tel: (+41) 26 919 11 22
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The
internal clearance of a ball bearing is composed of a radial component,
the radial clearance, and an axial component, the axial clearance. Both
clearances are determined before assembly and zero load. The operational
clearance is the residual radial clearance after assembly at normal
working conditions of the ball bearing.
