Ball and Roller Bearings - Ntn-snr.com

Bearing Load Calculation
4.5 Allowable axial ioad for cylindrical roller
bearings
Cylindrical roller bearings having flanges on both the
inner and outer rings can be loaded with a certain axial
force at the same time. Unlike the basic dynamic load
rating with is determined by the development of rolling
fatigue, a permissible dynamic axial load of a rolling
cylindrical roller bearing is determined by heat generation,
seizure, etc., at the sliding contact surfaces of the guide
flanges and end faces of the rollers. The allowable axial
load is approximated by the formula below which is based
on past experience and experiments.
Pt kd 2 Pz (4.23)
where,
PtAllowable axial load during rotation Nkgf
k Coefficient determined by internal bearing
geometry (Please refer to Table 4.6)
d Bore diameter of the bearings mm
PzAllowable face pressure (bearing stress) of the
collar MPa (Please refer to Fig. 4.13)kgf/mm 2
However, if the ratio axial load/radial load is large,
normal rolling motion of the roller cannot be achieved.
Therefor, a value exceeding Fa max shown in Table 4.6
should not be used.
Moreover, when applying axial loads, the following
guidelines are important;
(1) Be carful to specify proper radial internal clearance.
(2) Use a lubricant containing an extreme pressure
additive.
(3) The shaft and housing abutment height must be
enough to cover those of the flanges.
(4) In case of severe axial loads, increase the mounting
accuracy and perform test running of the bearing.
Allowable face pressure
P MPa
200
150
100
50
Grease
lubrication or
oil lubrication
Instant axial load
Intemittent axial load
Normal axial load
dPitoh circle diameter of rollers mm
d(Bearing bore diameter
+ Bearing outer diameter)/2
nRevolution per minute r/min
Fig. 4.13 Allowable face pressure of rib
Table 4 Value of coefficient k and allowable axial (Fa max)
Bearing type k Fa max
NJNUP10
NJNUPNFNH2
NJNUPNH22
NJNUPNFNH3
NJNUPNH23
NJNUPNH2E
NJNUPNH22E
NJNUPNH3E
NJNUPNH23E
NJNUPNH4
SL01-48
SL01-49
Mainly oil lubrication
shows grease
lubrication
0
0 5 10 15 20 25 30
dn 10 4 mmrpm
0.040
0.065
0.050
0.080
0.100
0.022
0.034
SL04-50 0.044
0.4F
0.4F
0.4F
0.4F
0.4F
0.2F
0.2F
0.2F
In cases of axial loads being placed on large cylindrical
roller bearings (for example, bearing diameters of 300mm
or more), large axial loads being on the bearing under low
speed consult conditions, or forces bearing applied,
please consult with NTN Engineering. For cylindrical roller
bearings subjected to high axial use Type HT, Please
consult NTN Engineering.
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