Bearing Arrangements | Mounting | Non-Locating | Adjusted | Floating | Back-to-Back | Face-to-Face

There are three main types of shaft bearing arrangements: fixed–free (locating–non-locating), adjusted (preloaded or paired), and floating. The most common is the fixed–free arrangement. In this setup, the locating bearing secures the shaft both radially and axially, while the non-locating bearing only supports it radially and allows axial movement to compensate for thermal expansion, preventing stress in the assembly. The locating bearing is secured by pushing the inner ring against a shaft shoulder and locking it axially with a washer, locknut, and locking plate. The outer ring is clamped between a housing shoulder and a cover. The non-locating bearing does not require axial fixation; cylindrical roller bearings of type NU are often used. They are held on the shaft by a retaining ring, while the outer ring is secured by shoulder and cover. This allows axial displacement while still ensuring stable radial guidance.

When designing shafts, fits, surface roughness, and hardness at the bearing seats are crucial. Shoulders must allow smooth mounting without damage. Relief grooves, chamfers, and radii help to avoid stress concentrations and ease installation. Bearing rings usually require interference fits to prevent micro-movements and fretting corrosion. For assembly, they are heated or pressed onto the shaft. Bearing clearance – the axial or radial play – is influenced by mounting and temperature and must be carefully chosen. At high speeds with low loads, preload may be applied to eliminate play, though it must be controlled to avoid overheating or damage.

Various bearing types can serve as locating bearings. Deep-groove ball bearings are common; double-row angular contact bearings in back-to-back arrangement provide higher rigidity, while matched tapered roller bearings offer very high load capacity and stiffness. Cylindrical roller bearings with flanges or combinations such as a cylindrical roller bearing for radial loads and a four-point bearing for axial loads are also used. For significant misalignments, CARB toroidal roller bearings are employed as non-locating bearings, often paired with spherical roller bearings as locating bearings. Alternatively, axial displacement can be allowed via a clearance fit on the outer ring.

Whether axial displacement is realized at the inner or outer ring depends on the load. The ring subjected to circumferential load must always be mounted with an interference fit, while the one carrying point load may be fitted with clearance to allow axial movement.

The adjusted bearing arrangement is chosen when maximum precision and zero play are required, such as in machine tool spindles. Two tapered or angular contact bearings are mounted so that they share radial forces but each takes axial load in only one direction. In back-to-back or face-to-face arrangement, the bearings can be preloaded, creating a stiff, play-free support. The preload must be adjusted carefully, considering thermal expansion, to avoid excessive stress during operation.

The floating arrangement is the simplest and most economical solution. Bearings are radially fixed but axially movable within certain limits, usually by providing a clearance fit in the housing. This allows thermal expansion without stress. It is used in less precise machinery, though it is less suitable when axial loads change frequently. Alternatively, cylindrical roller bearings of type NJ can provide internal axial displacement, offering stiffer radial support while avoiding wear from clearance fits.

00:00 Fixed-non-locating bearing Arrangement (Fixed-Free Mounting)
00:52 Fixing the Inner Ring on the Shaft (Locknut)
02:29 Fixing the Outer Ring in the Housing (Cover)
03:13 non-locating bearing
04:49 Shaft Design
06:33 Fits
08:10 Bearing Clearance
09:48 Double-Row Angular Contact Ball Bearings as locating bearings
10:24 Matched Single-Row Tapered Roller Bearings as locating bearings
11:49 Cylindrical Roller Bearings as locating bearings
12:45 Four-Point Bearings and Cylindrical Roller Bearings as locating bearings
13:19 Fixed–non-locating bearing Combinations for Movable Bearings (CARB Toroidal Roller Bearings)
14:50 Spherical Roller Bearings as non-locating bearings (non-locating bearing via Outer Ring and Housing)
15:57 Deep-Groove Ball Bearings as Fixed and non-locating bearings
16:43 Circumferential Load on the Inner Ring and Point Load on the Outer Ring
18:14 Circumferential Load on the Outer Ring and Point Load on the Inner Ring
18:55 Circumferential Load and Point Load in Imbalances
20:39 Preloaded Bearing Arrangement in Back-to-Back Configuration
22:46 Preloading in a Preloaded Bearing Arrangement in Back-to-Back Configuration
24:19 Preloaded Bearing Arrangement in Face-to-Face Configuration
25:39 Preloading in a Preloaded Bearing Arrangement in Face-to-Face Configuration
26:41 Floating Bearing Arrangement