Page 118 - The Tribology Handbook

Selection of rolling bearings A20

LU B RICATIO N

G reme lubrication Table 20.4
Grease lubrication is generally used when rolling bearings
operate at normal speeds, loads and temperature condi- Bearing gpe Factor k for
calculation of re-
tions. For nonmal application the bearings and housings lubrication interval
should be filled with grease up to 30-50% of the free space.
Overpacking with grease will cause overheating. When Spherical roller bearings, tapered roller 1
selecting a greiise, the consistency, rust-inhibiting proper- bearings
ties and temperature range must be carefully considered. Cylindrical roller bearings, needle roller 5
The relubrication period for a grease-lubricated bearing is beatings
related to the service life of the grease and can be estimated Radial ball bearings 10
from the expression :

The amount of grease required for relubrication is
obtained from:
where : G = 0.005 DB
tf = service life of grease or relu brication interval, hours
k = factor dependent on the type of bearing (Table where:
20.4) G = weight of grease, g
n = speed, revlmin D = bearing outside diameter, mm
d = bearing bore diameter, mm B = bearing width, mm
or from the curves given in Fig. 20.5.

k=l
c
L
c

20 000 -
15000-
k=l0
20 050 10000-
7500 -

4 0 OD0 5000 -
0000 4000 -
6000 3000 -
5000 2500 -
4000 2000 -
3000 ?500-
2000 1000 -
1500 750 -
250 "1
1000

500

A20.5