Worm gearing . uation 68^ Chap-ter IX) was per minute and (from equation 73,Chapter IX) the area of rear axle surface should be sq. ft. THE WIDTH OF THE WORM WHEEL 55 The actual surface was approximately 11 sq. ft. Fig. 22 showsa section of the worm wheel of which the original value of /?was 107° 45; under these conditions, the number of teeth incontact was 5 (equation 12, Chapter IV). The wheel was subse-quently cut down in width as shown in the figure. In Fig. 22, the gears are shown diametrically in section andplan, the lines AB, CD, indicate the original width of the gearsw
Worm gearing . uation 68^ Chap-ter IX) was per minute and (from equation 73,Chapter IX) the area of rear axle surface should be sq. ft. THE WIDTH OF THE WORM WHEEL 55 The actual surface was approximately 11 sq. ft. Fig. 22 showsa section of the worm wheel of which the original value of /?was 107° 45; under these conditions, the number of teeth incontact was 5 (equation 12, Chapter IV). The wheel was subse-quently cut down in width as shown in the figure. In Fig. 22, the gears are shown diametrically in section andplan, the lines AB, CD, indicate the original width of the gearswith /? = 107° 45. There are then five points of contact—a, h,c, d, and e. /? was then reduced to 72° as shown by lines EF and GH,The points of contact are thus reduced to three—h, c, and d. /? reduced again to 64°, still left three points of contact, butfurther reduction to 55° 30 as shown by lines IJ, KL left onlytwo teeth in contact at c. The following table shows the results obtained: TABLE IV No. 4. Subtended angle /? Revo, of worm Rubbing velocity v. Tooth pressure p Area at base of tooth Width of wheel Temperature attained t Temperature of air t No. of teeth in contact Pressure per tooth Estimated pressure per squareinch. 107° 45 72° 64° 2,000,211 775,008 1,590,000 4378 4378 4378 in. 2. 262 in. in. in. 2. 3437 in. in. 163° F. 412° F. 412° F. 75° 76° 74° 88° 336° 338° 5 3 3 875 1459 1459 5840 9730 9730 55° 30Failed 4378 in. 1. 8437 in. 500° F. 72° 428°2 2189 14,580 The failirre of the gears in Experiment No. 4 took place frompartial seizure. In the first three experiments, the durationwas sufficient to arrive at constant conditions and a maximumtemperature rise, but about twenty minutes running underconditions No. 4 showed the temperature rising so rapidly thatoperations were suspended and the gears examined. It wasplainly evident that failure was due to actual metallic contact 56 WORM
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyo, bookyear1916
