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{\pi }{P_t}=\frac{\pi}{6}=0.5236 in [/latex]

[latex]p_n = p_t cos \psi = 0.5236 cos 25° = 0.4745 in[/latex]

[latex]p_x=\frac{p_t}{ an \psi }=\frac{0.5236}{ an 45°} =1.123 in [/latex]

(c) [latex]p_n=\frac{p_t}{\cos \psi }=\frac{6}{\cos 25°} = 6.620 teeth/in[/latex]

(d) [latex]\phi _t= an ^{-1}\left(\frac{ an \phi _n}{\cos \psi } ight) = an ^{-1}\left(\frac{ an 20°}{\cos 25°} ight)=21.88° [/latex]

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

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