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Unformatted text preview: o r wo rm) is mu ch larger than helical gears’ o Teet h o f o ne o r bot h gear wrap part ly aro und t he ot her o S ing le envelo p ing and do uble envelo p ing worm gear sets o Mo st ly u sed whe n speed ratio o f t he t wo shaft s are hig h o Much lo wer mechanical efficiency, but hig h heat generat io n, due to hig h slid ing velo cit y NOMENCLATURE: 1 MECH323 – 2007 GEARS____________________________ th Fig. 135 Nomenclature of spur gear teeth (Budynas, 8 ed.) th Fig. 1312 Tooth action (Budynas, 8 ed.) 2 MECH323 – 2007 GEARS____________________________ Quantity Pitch circle Pitch diameter Diametral pitch Circular pitch Module Symbols d P p m Definition Theoretical circle on which calculat ions are based; Pitch circles of a pair of mat ing gears are tangent to each other Diameter of the pitch circle Ratio of number of teeth to pitch diameter P=N/d, used in imperial units, expressed as teeth per inch Distance measured on pitch circle fro m a point on one tooth to the corresponding point on the adjacent tooth Ratio of pitch diameter to number of teeth m=d/N; Index of tooth size in SI, measured in mm. Reciprocal of diametral pitch Radial distance between the top land and the pitch circle Radial distance between the bottom land and the pitch circle Amount by which the dedendum of one gear exceeds the addendum of the mating gear c = b1 – a2 Circle tangent to addendum circle o f the mating gear Sum of addendum and dedendum ht = a + b Who le depth subt...
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- Fall '09