# Duplex bearings

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Two deep groove ball bearings can be calculated as a set by selecting “Duplex bearings”. The same could be done by using a single deep groove ball bearing and a configuration of two bearings but the input is more flexible using “Duplex bearings”.

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The geometry data is defined for a single deep groove ball bearing, additionally the distance between the two rows is an input value. The input of the diametral clearance is for the single bearing only.

The clearance of the configuration can then be changed by an axial offset dCC between inner and outer ring of each bearing. Using the (./images/all_img4.png)-button it can be calculated from a given axial clearance, radial clearance or pretension force for the bearing configuration.

The free contact angle of the bearing a0 and a0eff are shown in the report and in the results overview.

Options for the bearing allow selecting of face-to-face or back-to-back configuration. This has an influence of the load distribution on moment loads or a tilted bearing. 

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There are four options for the calculation of load capacities:

1. _Load capacity of single deep groove ball bearing_: The input values are for a single bearing only. These are the values which are given in the documentation of the single bearing. In this case, the load capacities of the pair are shown as Csys in the report.

2. _Load capacity of paired deep groove ball bearings_: Here the calculation is done using load capacities for two paired deep groove ball bearings using factors of 20.7 for dynamic and 2 for static load capacity.

3. _Load capacity of double row deep groove ball bearing_: Here the load capacities are calculated using the factors for a double row bearing. The dynamic load capacity is smaller than for the second case.

4. _Load capacity of double row angular contact ball bearing_: Here the load capacity is calculated using the free contact angle of the bearings.

If thermal effects are considered, the axial offset dCC will be modified during the calculation to take the different axial elongation of inner and outer ring into account. The results are the same as if using a single radial deep groove ball bearing with a configuration of two bearings.