SKF - Rolling Bearings

Design considerations
Table 3
Fits for solid steel shafts (for thrust bearings) 1)
Conditions Shaft diameter [mm] Tolerance class 2)
Axial loads only
Thrust ball bearings – h6
Combined radial and axial loads on
spherical roller thrust bearings
Stationary load on shaft washer ≤ 250 j6
> 250 js6
Rotating load on shaft washer,
≤ 200
k6
or direction of load indeterminate
> 200 to 400 m6
> 400 n6
1) For cylindrical roller thrust bearings † Cylindrical roller thrust bearings, page 1037. For needle roller thrust bearings
† Shaft and housing tolerance classes, page 1068.
2) All ISO tolerance classes are valid with the envelope requirement (such as h7VE ) in accordance with ISO 14405-1.
Table 4
Fits for non-split cast iron and steel housings (for radial bearings) 1)
Displacement
Conditions Examples Tolerance
class2) 3)
of outer ring
Rotating outer ring load
Heavy loads on bearings in thin-walled
housings, heavy shock loads (P > 0,1 C)
Roller bearing wheel hubs, big-end
bearings
P7
Cannot be displaced
Normal to heavy loads (P > 0,05 C)
Ball bearing wheel hubs, big-end
bearings, crane travelling wheels
N7
Cannot be displaced
Light and variable loads (P ≤ 0,05 C)
Conveyor rollers, rope sheaves,
belt tensioner pulleys
M7
Cannot be displaced
Direction of load indeterminate
Heavy shock loads Electric traction motors M7 Cannot be displaced
Normal to heavy loads (P > 0,05 C), axial
displacement of outer ring unnecessary
Electric motors, pumps,
crankshaft bearings
K7
In most cases, cannot
be displaced
Accurate or quiet running 4)
Ball bearings Small electric motors J6 5) In most cases, can be
displaced
Tapered roller bearings 6)
1) For drawn cup, alignment and combined needle roller bearings † Shaft and housing tolerances, page 716.
2) All ISO tolerance classes are valid with the envelope requirement (such as H7VE ) in accordance with ISO 14405-1.
3) For ball bearings, when D ≤ 100 mm, IT6 tolerance grade is often preferable and is recommended for bearings with thin-walled
rings, such as in the 7, 8 or 9 diameter series. For these series, total radial run-out tolerances IT4 are also recommended.
4) For super-precision bearings to tolerance class P5 or better, other recommendations apply. For additional information,
refer to the information available online at skf.com/super-precision.
5) Tolerance class H6VE can be selected instead of J6VE to facilitate axial displacement in the housing bore.
6) Contact the SKF application engineering service.
174