Metrology and Quality Control - Mechanical Engineering (MCQ) questions and answers for Q. 4863

Q.  A gear has 30 teeth with module 4 mm and pressure angle of 20o. Calculate length of base tangent in a gear over 7 teeth space.
- Published on 07 Aug 15

a. 21.25 mm
b. 90.23 mm
c. 62.53 mm
d. None of the above

ANSWER: 90.23 mm
 

    Discussion

  • Sravanthi   -Posted on 26 Oct 15
    Given: number of teeth = 30, module = 4 mm, pressure angle = 20°

    Formula: Tm cos Φ [ (tan Φ – Φ) + (π/2T) + (Sπ/T)]

    here,

    T = number of teeth
    Φ = pressure angle
    S = teeth space

    Solution:

    Substituting the given values we get,

    Base length tangent = Tm cos Φ [ (tan Φ – Φ) + (π/2T) + (Sπ/T)]

    = 30 x 4 x cos 20 [(tan 20 – (20 x π/180)) + (π/2 x 30) + (7π/30)]

    = 90.24 mm

    Length of base tangent is 90.24 mm

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