# Spherical roller bearing clearance selection

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**Principles for selecting the clearance of spherical roller bearings:**

1. Use tight fit, where the temperature difference between the inner and outer rings is large, the friction torque needs to be reduced and the deep groove ball spherical roller bearings bear a large axial load or need to improve the self-aligning performance, the large clearance group should be used.

2. When the rotation accuracy is higher or the axial displacement needs to be strictly limited, the small clearance group should be used.

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**Factors related to play:**

1. The coordination of the inner ring of the spherical roller bearing and the shaft.

2. Coordination of the outer ring of the spherical roller bearing and the hole of the housing.

3. The influence of temperature.

Note: The amount of radial clearance reduction is related to the actual effective interference size of the matching parts, the size of the matching shaft diameter, and the wall thickness of the housing hole.

1. The actual effective interference (inner ring) should be: △dy=2/3△d–G*△d is

The nominal interference, G* is the flattened dimension of the interference fit.

2. The actual effective interference (outer ring) should be: △Dy=2/3△D–G*△D is

The nominal interference, G* is the flattened dimension of the interference fit.

3. The heat generated will cause the internal temperature of the spherical roller bearing to rise, which in turn will cause the shaft, the spherical roller bearing seat and the spherical roller bearing parts to expand. The clearance can be increased or decreased, depending on the material of the shaft and the spherical roller bearing seat,

And the temperature shaving between the spherical roller bearing and the spherical roller bearing support member.

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**Calculation formula of clearance:**

(1) Influence of cooperation

1. Spherical roller bearing inner ring and steel solid shaft: △j=△dy*d/h

2. Spherical roller bearing inner ring and steel hollow shaft: △j=△dy*F(d)

F(d)=d/h*[(d/d1)2-1]/[(d/d1)2-(d/h)2]

3. Outer ring of spherical roller bearing and steel solid shell: △A=△Dy*H/D

4. Spherical roller bearing outer ring and steel thin-walled shell: △A=△Dy*F(D)

F(D)=H/D*[(F/D)2-1]/[(F/D)2-(H/D)2]

5. Outer ring of spherical roller bearing and gray cast iron shell: △A=△Dy*[F(D)–0.15]

6. Spherical roller bearing outer ring and light metal shell: △A=△Dy*[F(D)–0.25]

Note:

△j--The expansion of the inner ring raceway rib diameter (um).

△dy—The effective interference of journal (um).

d--nominal dimension of spherical roller bearing inner diameter (mm).

h-- Diameter of inner ring raceway rib (mm).

B--Width of spherical roller bearing (mm).

d1--Inner diameter of hollow shaft (mm).

△A--The shrinkage of the outer ring raceway rib diameter (mm).

△Dy--The actual effective interference (um) of the diameter of the shell hole.

H--diameter of outer raceway flange (mm).

D--nominal diameter (mm) of the outer ring of the spherical roller bearing and the hole of the housing.

F--outer diameter of spherical roller bearing housing (mm).

(2): Influence of temperature

△T=Гb*[De*(T0–Ta)–di*(Ti–Ta)]

Compared with other types of bearings of the same size, deep groove ball bearings have a small friction coefficient, low vibration and noise, high limit speed, and high precision. They are the preferred bearing types for users when selecting models. However, this type of bearing is not resistant to impact and is not suitable for withstanding heavy loads.

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