WORM GEARING
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When the spiral angle B > m = 0, the bevel gear is called a Zerol bevel gear. The calculation equations of Table Figure 8-12 8-2 for Gleason straight bevel gears are applicable. They also should take care again of the rule of hands; left and right of a pair must be matched. is a left-hand Zerol bevel gear. Addendum Angle Fig. 8-12 Left-Hand Zerol Bevel Gear Example Pinion Gear Table 8-6 The Calculations of Spiral Bevel Gears of the Gleason System ItemNo. Symbol Formula Shaft Angle Outside Radial ModuleNormal Pressure AngleSpiral AngleNumber of Teeth and Spiral HandRadial Pressure AnglePitch DiameterPitch Cone AngleCone DistanceFace WidthAddendumDedendumDedendum AngleOuter Cone AngleRoot Cone AngleOutside Diameter Pitch Apex to CrownAxial Face WidthInner Outside Diameter 1 2 3 4 5 6 7 8 910111213141516 17181920 3 90 320а 35 20 (L) 40 (R)23.9568060 120 26.56505а 63.4349567.0820420 3.4275 1.6725 2.2365 3.9915 1.90952а 3.40519 3.40519а 1.90952 29.97024а 65.34447 24.65553а 60.02976 66.1313 121.4959 58.4672 28.5041 17.3563 8.3479 46.1140 85.1224 m A > n B > m z > 1 , z > 2 A tan tan > Ж1 cos > D > 2 1 ֖֖֖ 2sin d R > 2 e D > 2 It should be less than R /3 or 10 m b > e h > a 1 1.700 m ֖ h > a 2 h 0.390 0.460 m + ֖֖֖֖ m > a 2 h > f 1.888 m ֖ h > a Q > 1 f tan ( h > f / > R e ) Q > a 1 Q > f 2 Q > a 2 Q > f 1 D > a D + > a D > f D ֖ Q > f d > a d + 2h > a cos D XX R > e cos D h > a sin D ֖֖֖ cos b cos D > a b Q > a d 2 d ֖ ֖֖֖ cos b sin D > a i a Q > a SECTION 9 WORM MESH The worm mesh is another gear type used for connecting skew shafts, usually 90ְ. See Figure 9-1 . Worm meshes are characterized by high velocity ratios. Also, they offer the advantage of higher load capacity associated with their line contact in contrast to the point contact of the crossed-helical mesh. Fig. 9-1 Typical Worm Mesh 8.5.4 Gleason Zerol Spiral Bevel Gears >

9.1.1 Worm Tooth Proportions Worm tooth dimensions, such as addendum, dedendum, pressure angle, etc., follow the same standards as those for spur and helical gears. The standard values apply to the central section of the mesh. See Figure 9-3a . A high pressure angle is favored and in some applications values as high as 25 and 30а are used. Figure 9-2 , reveals a rack-type tooth of the worm, and a curved involute tooth form for the worm gear. However, the involute features are only true for the central section. Sections on either side of the worm axis re- veal nonsymmetric and noninvolute...

Table 9-3 The Calculations of Axial Module System Worm Gears (See Figure 9-5 ) No.Item SymbolFormula Example Worm Wheel 1 2 3 4 5 6 7 8 910111213 Axial ModuleNormal Pressure AngleNo. of Threads, No. of TeethStandard Pitch DiameterLead AngleCoefficient of Profile ShiftCenter DistanceAddendumWhole DepthOutside DiameterThroat DiameterThroat Surface RadiusRoot Diameter m > x A > n z > w , z > 2 30 (R) 44.000 90.000 7.76517 Ж 0 67.000 3.000 3.000 6.750 50.000 99.000 96.000 ֖ 19.000 36.500 82.500 d > 1 Q m > x Note 1 d > 2 z > 2 m > x G > 1 x > a 2 a ֖֖֖ + > 1 2 x d + d 21.00 x > a 2 m > x h > a...