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

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

Accepted Answer

(a)

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

(b)

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

[latex]p_{n}=p_{t} \cos \psi=0.5236 \cos 25^{\circ}=0.4745 ext { in }[/latex]

[latex]p_{x}=\frac{p_{t}}{ an \psi}=\frac{0.5236}{ an 45^{\circ}}=1.123 ext { in }[/latex]

(c)

[latex]P_{n}=\frac{P_{t}}{\cos \psi}=\frac{6}{\cos 25^{\circ}}=6.620 ext { teeth } / in[/latex]

(d)

[latex]\phi_{t}= an ^{-1}\left(\frac{ an \phi_{n}}{\cos \psi} ight)= an ^{-1}\left(\frac{ an 20^{\circ}}{\cos 25^{\circ}} ight)=21.88^{\circ}[/latex]

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

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