Mechanical Engineering - Machine Design - Discussion
Discussion Forum : Machine Design - Section 1 (Q.No. 42)
42.
Which of the following statement is correct for gears?
Discussion:
22 comments Page 3 of 3.
Rathi said:
1 decade ago
Why dedendum is larger than addendum?
Meshing of mating teeth should occur on the involute portion of teeth. The teeth have involute profile from the base circles to addendum circles. If there is inaccuracy in manufacturing of gears, then the tip of tooth of one gear (always lies on its addendum circle) will dig the bottom portion of mating gear that results in interference. To avoid this bottom land of gears are lowered such that it lies on the periphery of the dedendum circle. The dedendum circle is made smaller than the base circle and also lies below the pitch circle at distance, 'b'. Addendum circle lies at distance 'a', beyond the pitch circle, such that b > a.
Meshing of mating teeth should occur on the involute portion of teeth. The teeth have involute profile from the base circles to addendum circles. If there is inaccuracy in manufacturing of gears, then the tip of tooth of one gear (always lies on its addendum circle) will dig the bottom portion of mating gear that results in interference. To avoid this bottom land of gears are lowered such that it lies on the periphery of the dedendum circle. The dedendum circle is made smaller than the base circle and also lies below the pitch circle at distance, 'b'. Addendum circle lies at distance 'a', beyond the pitch circle, such that b > a.
M.tariq said:
1 decade ago
The first answer (A) is incorrect it should be reversed to be "The dedendum is less than addendum".
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