Thorne, William H[enry], 1847- [from old catalog] · Philadelphia, Williams, Brown & Earle · leaf 84
dum-line, s s, of a rack cuts it. Tofind this point, t, use the triangle, moving it so that one side of its right-angle is incontact with p, and the other with o, until the corner touches the line s s, and draw o t,11. The angle, t, o, p, will be found to be about 23°. Calculation shows it to be… … proportional to cosiue 23° or .92 radius ofpitch-circle, and p t and p t will be pro-portional to sine 23° or .39 radius of pitch-circle. Hence, to draw this line of action,describe an arc of radius equal to .92 pitchradius from the centre of the wheel and in-tersect it by an arc of radius equal to…
Mechanical drawing
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