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Gears: identify the correct statements about fundamental gear terms. Evaluate each statement about standard involute gears and choose the single best option that encompasses all true statements. • Addendum vs. dedendum magnitude • Relation between pitch circle diameter, module, and number of teeth • Relative size of pitch circle and base circle Choose the correct option.

Difficulty: Easy

Correct Answer: All of the above

Explanation:

Given concepts

  • Addendum ≈ 1×module; dedendum ≈ 1.25×module in standard gears.
  • Pitch circle diameter: D = m × Z where m = module and Z = number of teeth.
  • Base circle diameter: Db = D × cos φ (φ = pressure angle), so D > Db.


Reasoning
Since dedendum > addendum (standard proportions), statement (a) is true.Since D = mZ, statement (b) is true.Since cos φ < 1, base circle < pitch circle, so (c) is true.


Common pitfall
Confusing base circle with addendum circle; base circle is smaller than pitch circle for involute gears.


Final Answer
All of the above

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