T-154
17.1.5 Life Factor, KL
We can choose the proper life factor, KL, from Table 17-2. The number of cyclic
repetitions means the total loaded meshings during its lifetime.
Table 17-2 Life Factor, KL
NOTES:
(1)
Cast iron gears apply to this column.
(2)
For induction hardened gears, use the core hardness.
17.1.6 Dimension Factor of Root Stress, KFX
Generally, this factor is unity.
KFX = 1.00
(17-10)
17.1.7 Dynamic Load Factor, KV
Dynamic load factor can be obtained from Table 17-3 based on the precision of the
gear and its pitch line linear speed.
Table 17-3 Dynamic Load Factor, KV
Precision Grade of Gears
from JIS B 1702
Tangential Speed at Pitch Line (m/s)
Tooth Profile
Unmodified
Modified
1
2
3
4
5
6
1
2
3
4
––
––
––
––
––
1.0
1.0
1.0
1.1
1.2
––
1.0
1.1
1.2
1.3
1.4
1.5
1.0
1.05
1.15
1.3
1.4
1.5
1.0
1.1
1.2
1.4
1.5
1.1
1.2
1.3
1.5
1.2
1.3
1.5
1.3
1.5
Under 1
1 to less
than 3
3 to less
than 5
5 to less
than 8
8 to less
than 12
12 to less
than 18
18 to less
than 25
Number of Cyclic
Repetitions
Hardness (1)
HB 120 … 220
Hardness (2)
Over HB 220
Gears with Carburizing
Gears with Nitriding
Under
10000
Approx. 105
Approx. 106
Above 107
1.4
1.2
1.1
1.0
1.5
1.4
1.1
1.0
1.5
1.5
1.1
1.0
