# Machine Design Questions and Answers – Strength of Bevel Gears

This set of Machine Design Multiple Choice Questions & Answers (MCQs) focuses on “Strength of Bevel gears”.

1. Lewis equation is used to obtain ____ strength of bevel gears.
a) Beam
b) Abrasive
c) Wear
d) Corrosive

Explanation: According to Lewis equation, Beam strength=product of module, face width of elemental section, permissible bending stress and Lewis form factor.

2. Beam strength of the bevel gear is independent of the cone distance.
a) True
b) False

Explanation: In other form S=mbσY[1- b/A] where A= cone distance.

3. Beam strength indicates the maximum value of the ___________ force at the large end of the tooth that the tooth can transmit without bending.
a) Tangential
c) Axial
d) None of the listed

Explanation: Beam strength is analysed by using the pitch radius at the larger end of the tooth.

4. Wear strength of the bevel gear can be calculated by using ________ equation.
a) Buckingham
b) Lewis
c) Newtonian
d) Rayleigh

Explanation: Bevel gear is considered to be equivalent to a formative spur gear in a plane which is perpendicular to the large end and hence Buckingham equation is applied.

5. If back cone distance is 10mm, then pitch circle diameter of the formative pinion is given by?
a) 10mm
b) 20mm
c) 5mm
d) 10√2 mm

Explanation: PCD=2xr.

6. The wear strength indicates the maximum value of radial force at the large end of the tooth that the tooth can transmit without pitting failure.
a) True
b) False

Explanation: It indicates the maximum value of tangential force.

7. If velocity is 5m/s, then velocity factor for a cut teeth is
a) 0.55
b) 0.66
c) 1.55
d) 1.66

Explanation: C=6/6+v.

8. If velocity is 5m/s, then velocity factor for generated teeth is
a) 0.71
b) 1.1
c) 0.9
d) 1.71

Explanation: C=5.6/5.6+√v.

9. Calculate the ratio factor Q if a pair of bevel gear consist of 25 teeth pinion meshing with a 40 teeth gear.
a) 1.964
b) 1.438
c) 1.554
d) 0.998

Explanation: tanϒ=25/40 or ϒ=32⁰. Q=2×40/ [40+25xtan(32)].

10. If surface hardness for a par of bevel gears is 400BHN, then material constant is
a) 3N/mm²
b) 2.56N/mm²
c) 0.98N/mm²
d) 1.44N/mm²

Explanation: K=0.16x[BHN/100]².

11. Calculate the wear strength for a pair of bevel gears having face width=20mm, module=5mm, No of teeth on pinion and gear 25 and 40 respectively and PCD of pinion=75mm.
a) 3668.5N
b) 4884.5N
c) 5126.6N
d) 4117.3N

Explanation: S=0.75xbxQxDxK/Cos ϒ. Tan ϒ=25/40 or ϒ=32⁰. Q=2×40/ [40+25xtan(32)] K=0.16x[BHN/100]².

12. If service factor is 1.4 & tangential ad dynamic load is 1180N and 1500N respectively, then calculate the effective load.
a) 3662N
b) 2889N
c) 3152N
d) 2236N

Sanfoundry Global Education & Learning Series – Machine Design.
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