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

1)   What is the shortest distance between worm gear and axes of the worm for a worm gear pair designated as 2/40/10/8?

a. 50 mm
b. 200 mm
c. 320 mm
d. 360 mm
 Answer  Explanation ANSWER: 200 mm Explanation: No explanation is available for this question!

2)   What is the effect of large diametral quotient on worm and worm wheel?

a. Strength and rigidity of worm shaft is high
b. Efficiency of worm shaft increases
c. Worm shaft becomes weaker
d. All of the above
 Answer  Explanation ANSWER: Strength and rigidity of worm shaft is high Explanation: No explanation is available for this question!

3)   Which of the following relations is true?
(where nw  = worm speed, ng  = worm gear speed, zg = number of teeth on worm gear, zw = number of starts on worm)

a. nw α (1/zg)
b. nw / ng = zg /zw
c. nw / ng = zw /zp
d. nw zg = ng zw
 Answer  Explanation ANSWER: nw / ng = zg /zw Explanation: No explanation is available for this question!

4)   The shortest distance between worm gear and axes of the worm is given as ______________

a. m (zw + zg) / q
b. m (zw + zg) / 2
c. m (q + zg) / 2
d. √m (q + zg) / 2
 Answer  Explanation ANSWER: m (q + zg) / 2 Explanation: No explanation is available for this question!

5)   A standard worm gear pair is designated as 4/40/10/8, what does number 10 in it indicate?

a. Number of starts on worm
b. Diametral quotient
c. Centre distance
d. Module
 Answer  Explanation ANSWER: Diametral quotient Explanation: No explanation is available for this question!

6)   A worm gear pair is designated as 1/30/10/8. What is the face width of the worm gear?

a. 30 mm
b. 53.07 mm
c. 58.4 mm
d. 62.3 mm
 Answer  Explanation ANSWER: 58.4 mm Explanation: No explanation is available for this question!

7)   A worm gear pair has 2 starts on worm thread, 11.2 as diametral quotient, 2 as module and 38 number of teeth on worm gear. How is the gear pair designated with these specifications?

a. 2/11.2/38/2*
b. 11.2/2/38/2
c. 2/38/2/11.2
d. 2/38/11.2/2
 Answer  Explanation ANSWER: 2/38/11.2/2 Explanation: No explanation is available for this question!

8)   If pressure angle is 22o and coefficient of friction is 0.05. What is the axial force acting on the worm gear designated as 1/40/10/5, if tangential force of 1200 N acts on it?

a. 1241.2 N
b. 2618.4 N
c. 7755.1 N
d. 7847.4 N
 Answer  Explanation ANSWER: 7755.1 N Explanation: No explanation is available for this question!

9)   What is the axial force acting on a worm gear for a worm gear pair 1/40/9.5/10, if tangential and axial force of 6213 N and 9236 N act respectively on the worm? ( Φn  = 25o & μ = 0.04)

a. 6213 N
b. 9263 N
c. 3050 N
d. Insufficient data
 Answer  Explanation ANSWER: 6213 N Explanation: No explanation is available for this question!

10)   A gear box having surface area of 0.30 m2 has overall heat transfer coefficient of 23 W/m2 oC,when a fan is mounted on worm shaft to circulate air on fins. What is the power transmitting capacity of a gear box based on thermal considerations, if temperature rise of lubricating oil is 50 oC? (Assume λ = 6o, Φn  = 22o & μ = 0.05)

a. 1.023 kW
b. 1.006 kW
c. 1.227 kW
d. 2.000 kW
 Answer  Explanation ANSWER: 1.006 kW Explanation: No explanation is available for this question!