Mechanical drawing self-taught: comprising instructions in the selection and preparation of drawing instruments, elementary instruction in practical mechanical drawing together with examples in simple geometry and elementary mechanism, including screw threads, gear wheels, mechanical motions, engines and boilers (1883)
stration. iMgiire 255 will serve also to call atten-tion to another serious circumstance, whi» h is, that DRAWIXG GEAR WHEELS. 2irj although the ellipses are alike, the wheels are not;nor can they be made so if there be an even numberof teeth, for the obvious reason that a tooth upon onewheel must… … the major axes must coincide: at another, the minoraxes, as In Figure 255. If, then, we use even num-bers, the distribution, and even the forms of the teeth,are not the same in the two wheels of the pair. Butthis complication may be avoided by using- an oddnumber of teeth, since, placing a tooth at…
Mechanical drawing
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