Worm gearing . easing n,and since n from the design of the gear is unalterable, it followsthat if /9 be reduced, the equation can no longer be satisfied. The alteration of /?, therefore, has a very important effect onthe behavior of the gears, since the specific pressure would byits decrease be augmented. B is thus given a new and impor-tant significance, for in addition to determining the strength ofeach individual tooth, it also governs the number of teeth inengagement at one time. 47 48 WORM GEARS Mr. John Younger has supplied the following means of obtain-ing the value of /3. The length of
Worm gearing . easing n,and since n from the design of the gear is unalterable, it followsthat if /9 be reduced, the equation can no longer be satisfied. The alteration of /?, therefore, has a very important effect onthe behavior of the gears, since the specific pressure would byits decrease be augmented. B is thus given a new and impor-tant significance, for in addition to determining the strength ofeach individual tooth, it also governs the number of teeth inengagement at one time. 47 48 WORM GEARS Mr. John Younger has supplied the following means of obtain-ing the value of /3. The length of the worm g is a multiple n of the circularpitch P, and it contains in its length a certain number ofthreads n of which it is most important to take the fullest pos-sible advantage. In order to ensure this, it is necessary to de-termine the width of worm surface, or in other words, the angleP, which will provide a wheel tooth to each thread of the can be determined graphically in the following manner:. Fig. 20. Let A 5 in Fig. 20 be the length of the worm = g; AC k theoutside circumference of the worm. From the point A, ADis drawn so that the angle DA C =a. From 5, the Ime BEis drawn perpendicular to AD. The distance A E is the lengthof the arc of the worm which must be subtended by the wormwheel in order that some part of every thread of the worm inthe length AB will touch one of the wheel teeth; from thisdiagram, the following equation is obtained from which thevalue of /? is at once found for any example. 360^ tan a (g2) P = 7:{d + i:So) THE WIDTH OF THE WORM WHEEL 49 when g is the total length of the worm = nP 2Xo = P = .6366P (63) Hence the equation becomes 360 g tan a (64) ^ nid+.63mP) In Fig. 21 the cross-section of the worm wheel is shown. Itwill be observed that the width of the wheel can be measuredat three points, viz., at the pitch line, at the root of the teeth,and at the outside, this last being somewhat deceptive as it hasno natural connection w
Size: 1870px × 1336px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublish, bookpublisheretcetc
