# Helical Gears - Mechanical Engineering (MCQ) questions and answers

1)   A helical gear made of plain carbon steel has face width 10 times the normal module. If number of teeth on pinion and gear are 20 and 60 respectively, then what will be the wear strength of helical gear? (Assume mn = 5, BHN = 200 & Ψ = 24o)

a. 5751.30 N
b. 5230.19 N
c. 6295.58 N
d. 6891.37 N
 Answer  Explanation ANSWER: 6295.58 N Explanation: No explanation is available for this question!

2)   A helical gear has normal module of 6 mm. What is the transverse module if helix angle is 25o?

a. 4.95 mm
b. 500 mm
c. 5.43 mm
d. 6.62 mm
 Answer  Explanation ANSWER: 6.62 mm Explanation: No explanation is available for this question!

3)   Which of the following statements is/are true?

a. Helical gears have high contact ratio than spur gears
b. Axial thrust is created by helical gears on bearings
c. Crossed helical gears are used for power and motion transmission
d. All of the above
 Answer  Explanation ANSWER: All of the above Explanation: No explanation is available for this question!

4)   To avoid interference the minimum number of teeth required on helical pinion decreases as helix angle ________

a. decreases
b. increases
c. does not affect number of teeth
d. none of the above
 Answer  Explanation ANSWER: increases Explanation: No explanation is available for this question!

5)   Which of the following formulae is used to determine minimum number of teeth required on helical pinion to avoid interference?

a. (2ha cos3 Ψ) / (mn sin2 Φn)
b. (mn zp / 2 cos Ψn)(1+G)
c. 1.15 π mn / sin Ψn
d. None of the above
 Answer  Explanation ANSWER: (2ha cos3 Ψ) / (mn sin2 Φn) Explanation: No explanation is available for this question!

6)   What is the minimum face width required for a helical gear which has helix angle of 23o and normal module of 7?

a. ≥ 64.72
b. ≥ 56.28
c. ≥ 33.35
d. ≥ 8.74
 Answer  Explanation ANSWER: ≥ 64.72 Explanation: No explanation is available for this question!

7)   Angle made by ________ with axis of rotation is called as helix angle.

a. only helix
b. only teeth
c. helix or teeth
d. none of the above
 Answer  Explanation ANSWER: helix or teeth Explanation: No explanation is available for this question!

8)   A helical gear transmits power of 2050 W and has helix angle of 25o. If pitch line velocity is 15 m/s then what is the maximum tangential force acting on helical gear tooth? (Assume Ka = 1 & Km = 1.2)

a. 113.88 N
b. 136 N
c. 164 N
d. None of the above
 Answer  Explanation ANSWER: 164 N Explanation: No explanation is available for this question!

9)   Which of the following formulae of velocity factor (K) is considered if helical gears of medium accuracy are manufactured by hobbing process followed by shaving?

a. 5.6 / (5.6 + √V)
b. √5.6 / (5.6+ √V)
c. 6 / (6+V)
d. 0.85
 Answer  Explanation ANSWER: 5.6 / (5.6 + √V) Explanation: No explanation is available for this question!

10)   What is the axial pitch for helical gears if helix angle is 25o and normal module is 7?

a. 50.55 mm
b. 52.03 mm
c. 32.15 mm
d. 11.31 mm
 Answer  Explanation ANSWER: 52.03 mm Explanation: No explanation is available for this question!