Worm gearing . read. The entire surface of the toothis, therefore, subject to wear. The hob is, in this case, at itsfinishing end, an exact duplicate in its profile of the worm itself. If a hob be made of the curved form and a blank be cut withit, the tooth of the resulting wheel will be perfectly straightand the wheel will be flat on the points of the teeth. Fig. 9is a photograph of such a wheel cut by Brown & Sharpe forthe experiments already referred to. It is seen that the wormis really the wheel, and the wheel, the ordinary straight worm,the relative diameters of the two having been rever
Worm gearing . read. The entire surface of the toothis, therefore, subject to wear. The hob is, in this case, at itsfinishing end, an exact duplicate in its profile of the worm itself. If a hob be made of the curved form and a blank be cut withit, the tooth of the resulting wheel will be perfectly straightand the wheel will be flat on the points of the teeth. Fig. 9is a photograph of such a wheel cut by Brown & Sharpe forthe experiments already referred to. It is seen that the wormis really the wheel, and the wheel, the ordinary straight worm,the relative diameters of the two having been reversed from the 30 WORM GEARS usual. Such a gear works well as shown by the experimentalresults. So far as the authors information goes, however, it isnever used in automobiles. It is, nevertheless, the true Hind-ley worm, and, as a section through it shows, it makes contactat all points across the teeth, the entire tooth being subject towear exactly as is the case with the straight gear, which ineffect it Fig. 9. The gear first employed by Lanchester is not, however, atruly developed gear at all as both the worm and the wheel arehollow and such a wheel can only be hohhed with a very short hoband driven with an equally short worm. It has, however, thispeculiarity that a section on the center of the worm shows aperfect contact along all the worm teeth at once. In otherwords, the worm applied to the wheel will shut out daylightentirely along its center line and if say four teeth of the wheelare subtended by the worm, all will be in contact at once. In PRESSURE ANGLE AND FORM OF THREAD 31 Fig. 10, which represents any worm gear, let the lines A, B,C, Dand E represent planes of section. Then in a Lanchester worm,a section of plane C will show every tooth in contact over itswhole depth. Similar sections on B and D show decreasingcontact, and sections on A and E show no contact at all. Ifthe same section be taken on a straight worm gear, it will befound that on each plane there is
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyo, bookyear1916
