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As part of the international standardisation work, the life adjustment factor a_{DIN} was renamed as a_{ISO} but without any change to the calculation method. 
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The
basis of the rating life calculation in accordance with 
The method “Expanded calculation of the adjusted rating life” takes account of the following influences: 

The influencing factors, especially those relating to contamination, are extremely complex. A great deal of experience is essential for an accurate assessment. As a result the Engineering Service of Schaeffler Group Industrial should be consulted for further advice. 
The tables and diagrams can only give guide values. 
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Dimensioning of 
The required size of a rolling bearing is dependent on the demands made on its: 

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Dynamic load 
The
dynamic load carrying capacity is described in terms of the basic dynamic
load ratings. The basic dynamic load ratings are based on 
The basic dynamic load ratings for rolling bearings are matched to empirically proven performance standards and those published in previous FAG and INA catalogues. 
The fatigue behaviour of the material determines the dynamic load carrying capacity of the rolling bearing. 
The dynamic load carrying capacity is described in terms of the basic dynamic load rating and the basic rating life. 
The fatigue life is dependent on: 

The
basic dynamic 

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Calculation of the rating life 
The methods for calculating the rating life are: 
The
basic 

The
equivalent dynamic 
The load value P gives the same rating life as the combined load occurring in practice. 

This calculation cannot be applied to radial needle roller bearings, axial needle roller bearings and axial cylindrical roller bearings. Combined loads are not permissible with these bearings. 
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The 

or 

This
calculation method was replaced in 

The 
Good cleanliness
and suitable additives Very high cleanliness and low load Contamination in the lubricant a_{3} = life adjustment factor κ = viscosity ratio Figure 1 
The 

The 
The
nominal viscosity of the oil at 
Taking
account of EP additives in calculation of the expanded adjusted 
ν_{1} = reference
viscosity d_{M} = mean bearing diameter n = speed Figure 2 
ν = operating
viscosity ϑ = operating temperature ν_{40} = viscosity at Figure 3 
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L_{nm} is calculated as follows: 

The
values for the 

The
standardised method for calculating the 


Taking account of EP additives in the lubricant 
In
accordance with 

Figure 4 
Figure 5 
Figure 6 
Figure 7 
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The 
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Life adjustment factor 
The life adjustment factor for contamination e_{c} takes into consideration the influence of contamination in the lubrication gap on the rating life, see table. 
The rating life is reduced by solid particles in the lubrication gap and is dependent on: 

Due
to the complex nature of the interaction between these influencing
factors, only an approximate guide value can be attained.
The values in the tables are valid for contamination by solid particles

Under
severe contamination 
Table 2 


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The
rating life formulae assume a constant 
The
equivalent operating values calculated here already take account
of the 
If
the load and speed vary over a 
If
the load and speed vary in steps over a 
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Variable load at constant speed 
If
the function F describes the variation in the load over a 
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Load varying in steps and 
If
the load varies in steps over a 
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Constant load at variable speed 
If the speed varies but the load remains constant, the following applies: 
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Constant load with 
If the speed varies in steps, the following applies: 
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Under oscillating bearing motion 
The equivalent speed is calculated as follows: 
The formula is valid only if the angle of oscillation is greater than twice the angular pitch of the rolling elements. If the angle of oscillation is smaller, there is a risk of false brinelling. 
Figure 8 
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If no information is available on the rating life, the guide values from the following tables may be used. 
Do
not overspecify the bearing. If the calculated life is 
Table 3 

Table 4 

Table 5 

Table 6 

Table 7 

Table 8 

Rolling mills, steelworks equipment Table 9 

Table 10 

Table 11 

Gearboxes in Table 12 

Table 13 

Table 14 

Table 15 

Table 16 

Table 17 

Table 18 

Table 19 

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The operating life is defined as the life actually achieved by the bearing. It may differ significantly from the calculated value. 
This may be due to wear or fatigue as a result of: 

Due to the wide variety of possible installation and operating conditions, it is not possible to precisely predetermine the operating life. The most reliable way of arriving at a close estimate is by comparison with similar applications. 
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Axial load carrying capacity 
Radial cylindrical roller bearings used as semilocating and locating bearings can support axial forces in one or both directions in addition to radial forces. 
The axial load carrying capacity is dependent on: 

Ribs subjected to load must be supported across their entire height. 
The 
The 
The
ratio 
Continuous axial loading without simultaneous radial loading is not permissible. 
In the case of bearings of TB design, the axial load carrying capacity has been significantly improved through the use of new calculation and manufacturing methods. 
Optimum
contact conditions between the roller and rib are ensured by means
of a special curvature of the roller end faces. As a result, axial
surface pressures on the rib are significantly reduced and a lubricant
film with improved loadcarrying capabilities is achieved. Under
normal operating conditions, wear and fatigue at the rib contact
running and roller end faces is completely eliminated. The axial frictional
torque is reduced by up to 
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Permissible and 
F_{a per} and F_{a max} are calculated as follows: 

Misalignment
caused by shaft deflection for example, may lead to alternating
stresses on the inner ring ribs. In this instance, the axial load
must be restricted to F_{as} in accordance with
the formula where the bearing is tilted up to a maximum of 
For more severe tilting, a separate strength analysis is required. 
Factor k_{S} Table 20 


Table 21 

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Very high static loads or shock loads can cause plastic deformation on the raceways and rolling elements. This deformation limits the static load carrying capacity of the rolling bearing with respect to the permissible noise level during operation of the bearing. 
If
a rolling bearing operates with only infrequent rotary motion or completely
without rotary motion, its size is determined in accordance
with the basic static 
According
to 

The
basic static 

Under
normal contact conditions, this load causes a permanent deformation
at the contact points of approx. 
In addition to dimensioning on the basis of the fatigue limit life, it is advisable to check the static load safety factor. The guide values and shock loads occurring in operation to table must be taken into consideration, see table, link. 
The static 

Guide values for axial spherical roller bearings and high precision bearings: see corresponding product description. 
For
drawn cup needle roller bearings, 
Guide values Table 22 

The
equivalent static 
P_{0} induces the same load at the centre point of the most heavily loaded contact point between the rolling element and raceway as the combined load occurring in practice. 

This calculation cannot be applied to radial needle roller bearings, axial needle roller bearings and axial cylindrical roller bearings. Combined loads are not permissible with these bearings. 
For
radial needle roller bearings and all radial cylindrical roller bearings, 
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