Page 317 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Helical Gear Ibnnulae Stmulard Gearing 297
n cos Q
16. P = P cos 'Y n
t n 19. 4 =
D
T cos 4 P cos Y
n
b
-
17. pN - n
P N cos 9,
n 20. Db =
18. sin '4 = sin Y cos 4 P cos @ b
n
b n

21. 2 =
2

Y = Helix angle
C = Center distance
P = Nom1 diametral pitch
P" = Transverse diametral pitch
n t = Number teeth, pinion
N = Number teeth, gear
a = Addendum constant of cutting tool
bC = Lkdendum constant of cutting tool
$ = Whole depth of tooth
= Pitch diameter, pinion
D = Pitch diameter, gear
d = Outside diameter, pinion
Do = Outside diameter, gear
= Root diameter, pinion
D
d;
R = Root diameter, gear
n = Revolutions per minute, pinion
P
m = Gear ratio
v: = Pitch line velocity (ft.hin.1
= Tangential load on tooth
Et = Radial load on tooth (separating)
Wr = Axial load on tooth (thrust)
PX = Service or transmitted horsepower
= Normal pressure angle
= Transverse pressure angle
!t = Normal base pitch
Y: = Base helix angle
d = Base circle diameter, pinion
Db = Base circle diameter, gear
Zb = Length of line of action