FundamentalConceptsforGears

T h th o tablesg iven insectio n1312shig ley7 edorbud

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Unformatted text preview: helix angle o f the gear. For a specified pinio n, the largest number of teeth on the helical gear with interference­free will 2 N p sin 2 f - 4 2 cos 2 y k t be N G = 4 cosy - 2 N p sin 2 ft k o po ssible int er ference correct io n t echnique: und ercutt ing, using a larger pressure ang le, etc. CONTACT RATIO 5 MECH323 – 2007 o CR ind icat es t he average nu mber o f t eet h in cont act o gearset sho uld have a cont act rat io o f at least 1.2 GEARS____________________________ o Inaccuracies in mo u nt ing may reduce co nt act rat io , consequent ly increases no ise and po ssibilit y o f impact o Greater CR makes qu ieter and smo ot her gear meshing o Can be calculated as CR rap , rag , where p b = addendum radii o f the mat ing pinio n and gear = ra2p - rb2 + ra2g - rb2 - c sin f p g rbp , rbg = base circle radii o f the mat ing pinio n and gear base pitch, p = p cos f , (similarly, d b = d cos f , rb = r cos ) f b TOOTH SYSTEMS o St andards exist which specify relat io nship s invo lving addendu m, dedendu m, work ing depth, toot h thickness, and pressure angle. t h th o Tables g iven in sectio n 13­12 [Shi...
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