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
View Answer
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
View Answer
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
b) Radial
c) Axial
d) None of the listed
View Answer
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
View Answer
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
View Answer
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
View Answer
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
View Answer
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
View Answer
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
View Answer
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
View Answer
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
View Answer
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
View Answer
Explanation: Effective load=1.4×1180 + 1500.
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