Bearing arrangement selection

Bearings in rotating machinery have different performance requirements depending on the application, but two or more are generally used on a single shaft. To locate the shaft axially, one is often used as the fixed side and the others as the free side.

Fixed-side and free-side bearings

Category	Description	Applicable bearing types
Fixed-side bearing	Used to locate and fix the shaft in the axial direction. Choose a type that can carry axial load as well as radial load. It carries axial load in both directions, so consider strength according to the load.	Deep groove ball bearing / matched angular contact ball bearings / double-row angular contact ball bearing / self-aligning ball bearing / cylindrical roller bearing with ribs (NUP, NH type) / double-row tapered roller bearing / spherical roller bearing
Free-side bearing	Used to accommodate thermal expansion and contraction of the shaft during operation and to adjust the axial mounting position. A type that carries only radial load and allows the inner and outer rings to separate is suitable. When a non-separable type is used, make the fit between the outer ring and housing a clearance fit to accommodate expansion and contraction (it may also be accommodated at the shaft-to-inner-ring fit).	Separable: cylindrical roller bearing (NU, N type) / needle roller bearing (NA type, etc.) Non-separable: deep groove ball bearing / matched angular contact ball bearings (back-to-back) / double-row angular contact ball bearing / self-aligning ball bearing / double-row tapered roller bearing (TDO type) / spherical roller bearing
When the fixed and free sides are not distinguished	When the bearing spacing is short and the effect of shaft expansion is small, two bearings that can carry axial load, such as angular contact ball bearings or cylindrical roller bearings, are used facing each other. The axial clearance after mounting is adjusted with nuts or shims.	Deep groove ball bearing / angular contact ball bearing / self-aligning ball bearing / cylindrical roller bearing (NJ, NF type) / tapered roller bearing / spherical roller bearing
For vertical shafts	For the fixed side, use a bearing that can carry both radial and axial load. When the axial load is large, use a thrust bearing together with a radial bearing. For the free side, choose a bearing that carries only radial load so that shaft expansion can be accommodated.	Fixed side: matched angular contact ball bearings (back-to-back) / double-row tapered roller bearing (TDO type) / a thrust bearing used together with a radial bearing

Examples of bearing arrangements

Key points and application examples of typical bearing arrangements. Please refer to the source catalog for the arrangement diagrams.

Arrangements distinguishing the fixed and free sides

Example	Notes	Application examples
Example 1	Suitable for high-speed rotation and widely used in general. Not suitable when misalignment between bearings or shaft deflection is expected.	Medium electric motors, blowers, etc.
Example 2	Suitable for high-speed rotation and for larger loads or shock loads than Example 1. Being a separable type, it suits cases requiring an interference fit on both rings. Not suitable when misalignment or deflection is expected.	Traction motors for rolling stock
Example 3	Suitable for even larger loads or shock loads than Example 2. An arrangement requiring high rigidity on the fixed side, used back-to-back with preload. Make both the shaft and housing accurate to keep mounting error small.	Steel-mill table rollers, lathe spindles
Example 4	Suitable when the axial load is smaller than Example 3, or for high-speed rotation. Suits cases requiring an interference fit on both rings. A double-row angular contact ball bearing may be used on the fixed side instead of a matched pair.	Electric motors
Example 5	Suitable when not much axial load is applied. Also applicable when an interference fit is required on both rings.	Paper-mill calender rolls, diesel locomotive axles
Example 6	Suitable for applications with high-speed rotation, large radial load, and some axial load. Provide clearance between the outer diameter and the housing bore so that radial load is not applied to the deep groove ball bearing.	Diesel locomotive transmissions
Example 7	The most commonly used arrangement. It can carry some axial load in addition to radial load.	Pumps, automotive transmissions
Example 8	Suitable when a relatively large axial load acts in both directions. A matched pair of angular contact ball bearings may be used on the fixed side instead of a double-row angular contact ball bearing.	Worm gear reducers
Example 9	The most suitable arrangement when there is mounting error or shaft deflection. It can carry some axial load in addition to a large radial load.	Steel-mill table roller reducers, overhead crane travel wheels
Example 10	The most suitable arrangement when there is mounting error or shaft deflection. An adapter makes mounting and removal easy, suiting long shafts without steps or threads. Not suitable when axial load must be carried.	General industrial machinery, counter shafts
Example 11	The most suitable arrangement when there is mounting error or shaft deflection. Suitable for larger loads or shock loads than Example 10. It can carry some axial load in addition to radial load.	Steel-mill table rollers

When the fixed and free sides are not distinguished

Example	Notes	Application examples
Example 12	The most commonly used arrangement for small machines with small loads. To apply a light preload, insert a spring or a thickness-adjusting shim against the side of one outer ring.	Small electric motors, small reducers, small pumps
Example 13	Suitable when preload is applied to give the shaft rigidity. Often used where the axial load is relatively large and high-speed rotation is required. Back-to-back mounting suits cases where a moment acts. When using preload, take care with its adjustment.	Machine tool spindles
Example 14	Suitable for even larger axial or shock loads than Example 13. Suitable when preload gives the shaft rigidity. Back-to-back mounting suits cases where a moment acts; face-to-face mounting is advantageous when the inner ring needs an interference fit or when there is mounting error. When using preload, take care with its adjustment.	Reducers, automobile axles
Example 15	Suitable when light-load, high-speed, high-precision rotation is required. Suitable when preload gives the shaft rigidity. Besides back-to-back, face-to-face or tandem arrangements may also be used.	Machine tool spindles
Example 16	Withstands heavy loads and shock loads. Can also be used when both rings need an interference fit. Take care that the internal axial clearance does not become too small during operation.	Construction machinery, final reduction gears

For vertical shafts

Example	Notes	Application examples
Example 17	An example using a matched pair of angular contact ball bearings on the fixed side and a cylindrical roller bearing on the free side; suitable for high-speed rotation.	Vertical electric motors, vertical pumps
Example 18	Suitable for low-speed, heavy loads where the axial load is larger than the radial load. Being self-aligning, it suits cases where misalignment between bearings or shaft deflection is expected.	Crane center shafts, vertical pumps

Summarized with reference to rolling bearing catalogs and handbooks. Please refer to the original sources for figures such as arrangement diagrams.