Based on the fixed-end beam calculation. Includes the majority of effects.
Dynamic Load
F d = F t2 K v
where:
|
F t2 |
Poisson's ratio (material value) |
|
|
|
circumferential force factor |
|
|
v 2 |
gear circumferential speed [ft/min] |
Allowable Bending Force
F s = S n b 2 p y ≥ F d
where:
|
S n |
limiting bending strength (material value) |
|
|
b 2 |
gear width |
|
|
p |
gear pitch |
|
|
y |
form factor (Lewis factor) |
Allowable Contact Force
F w = d 2 b 2 K w ≥ F d
where:
|
K w |
limiting contact strength (material value) |
|
|
b 2 |
gear width |
|
|
d 2 |
gear pitch diameter |
Increase of Temperature Check
Q max ≥ P z
where:
|
P z = P (1 - η + 0.3) |
lost power |
|
|
Q max = C A (t max - t 0 ) / 33000 |
heat conducted away in oil |
|
|
t max - t 0 = 120° F |
allowable temperature drop |
|
|
A |
gearbox surface, which conducts away the heat, A ≈ 0.3 a 1.7 for well ribbed gearbox |
|
|
C |
transfer of heat factor, C ≈ 0.0356 n 1 + 20 for the gearbox with fan and bottom worm |