Answer:
a)
normal circular pitch = 7.8539 mm
transverse circular pitch = 9.0689 mm
axial circular pitches = 15.7077
b)
transverse diametral pitch is 0.3464 teeth/mm
transverse pressure angle is 22.8°
c)
Addendum = 2.5 mm
dedendum = 3.125 mm
pinion diameter = 54.8482 mm and Gear diameter = 164.5448 mm
Explanation:
Given that;
module m = 2.5 mm
Number of teeth on Gear nG = 57 TEETH
Number of teeth on Pinion nP = 19 TEETH
Helix angle W = 30°
Normal Pressure angle β = 20°
finding the circular pitch
Pc = πm
we substitute
Pc = π * 2.5 mm = 7.8539 mm
now the diametral pitch p = π / Pc
= π / 7.8539
= 0.4 teeth/mm
a)
So the normal circular pitch
Pn = π / P
Pn = π / 0.4
Pn = 7.8539 mm
the transverse circular pitch
Pt = Pn / cosW
Pt = 7.8539 / cos30°
Pt = 9.0689 mm
for axial circular pitches
Px = Pt / tanW
Px = 9.0689 / tan30°
Px = 15.7077
b)
The transverse diametral pitch and the transverse pressure angle.
The transverse diametral pitch Pt = PcosW
= 0.4 * cos30°
= 0.3464 teeth/mm
transverse diametral pitch is 0.3464 teeth/mm
transverse pressure angle β1 = tan^-1 ( tan βn / cos W)
= tan^-1 ( tan20° / cos 30°)
= tan^-1 ( 0.42027 )
β1 = 22.8°
transverse pressure angle is 22.8°
c)
The addendum, dedendum, and pitch diameter of each gear
Now from table standard Tooth proportions for Helical Gears;
Addendum a = 1/p
= 1 / 0.4
= 2.5 mm
dedendum b = 1.25 / p
= 1.25 / 0.4
= 3.125 mm
now pinion diameter dP = Np / PcosW
= 19 / 0.4 (cos30°)
= 54.8482 mm
Gear diameter dG = nG / pcosW
= 57 / 0.4 (cos30°)
= 164.5448 mm
