Axial location of bearings

Locating bearings

An interference fit alone is not sufficient to axially locate a bearing ring. It is usually necessary to use a suitable locking device to secure the ring in place.

Both rings of a locating bearing should be located axially on both sides. The bearing rings generally have an interference fit and are usually supported on one side by a shaft or housing shoulder. Inner rings should be axially secured on the opposite end by one of the following options:

  • a plate bolted to the shaft end (fig. 1)
  • a spacer sleeve between the ring and a neighbouring machine component (fig. 2)
  • a retaining ring (circlip)

Outer rings are generally retained by the cover of the housing bore (fig. 1 and fig. 2).

Non-locating bearings

For non-locating bearings, the outer ring (which normally has a tight fit) is axially located while the inner ring is free to move axially on the shaft (fig. 3).
Note that for bearings in the GEP series (fig. 4), which have a radially split outer ring, expansion forces are produced under purely radial load; the axial components of these forces act on the housing cover. The axial load acting on the cover may be as much as 30% of the radial load. This must be taken into account when dimensioning the housing cover and selecting the size and number of the attachment bolts.
If shaft and/or housing shoulders are undesirable because of manufacturing or assembly considerations, spacer sleeves or rings can be inserted between a bearing ring and an adjacent machine component (fig. 5). Axially locating a non-separable bearing with locating rings saves space, enables quick mounting and dismounting and simplifies the machining of the seats. If larger axial forces have to be accommodated, a support ring (fig. 6) should be placed between the bearing ring and the locating ring, so that the locating ring is not subjected to excessive bending moments.
To locate the bearing, retaining rings (also known as circlips) with a constant radial width in accordance with DIN 471:1981 or DIN 472:1981 can be used.

Abutment and fillet dimensions

The abutment and fillet dimensions should be such that:

  • A sufficiently large support surface is available for the bearing ring.
  • Moving parts of the bearing arrangement cannot contact stationary components.
  • The fillet radius should be smaller than the chamfer of the bearing.
Appropriate abutment dimensions (fig. 7) are provided for each bearing in the product tables. The transition from the bearing seat to the shaft or housing shoulder can be either a simple fillet (fig. 8) or an undercut (fig. 9). Dimensions for ramax and rbmax are listed in the product tables.
Dimensions for undercuts are provided in table 1.
The larger the fillet radius (for the simple form) of the transition to the shaft shoulder, the more favourable is the stress distribution in the shaft fillet area.
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