A stock helical gear has a normal pressure angle of 20°, a helix angle of 25°, and a transverse diametral pitch of 6 teeth/in, and has 18 teeth. Find:
(a) The pitch diameter
(b) The transverse, the normal, and the axial pitches
(c) The normal diametral pitch
(d) The transverse pressure angle

Question

Accepted Answer

(a)

[latex]d =\frac{N}{P_{t}} =\frac{18}{6} = 3 in[/latex]

(b)

[latex]p_{t} =\frac{π}{P_{t}} =\frac{π}{6} = 0.5236 in[/latex]

[latex]p_{n} = p_{t} cos ψ = 0.5236 cos 25° = 0.4745 in[/latex]

[latex]p_{x} =\frac{p_{t}}{tan ψ} =\frac{0.5236}{tan 45°} = 1.123 in[/latex]

(c)

[latex]P{n} =\frac {P_{t}}{cos ψ} =\frac{6}{cos 25° } = 6.620 teeth/in[/latex]

(d)

[latex]\phi _{t} = tan^{−1} \left( \frac{tan \phi _{n}}{cos ψ}\right) = tan^{−1} \left( \frac {tan 20° }{cos 25°}\right) = 21.88°[/latex]

Question 13.2: A stock helical gear has a normal pressure angle of 20◦, a h...

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