1Which of the following is true about the selflocking reduce

1.Which of the following is true about the self-locking reducer worm gear set?

A. The worm is the driver

B. The set is irreversible

C. The friction angle is greater than the lead angle

D. The gear can also drive the worm

E. All of the above

2.Which of the following statements is NOT true about the train value?

A. The train value is the overall velocity ratio of a gear train

B. The train value is the sum of the velocity ratio of the individual mating gear pairs

C. The train value is positive when the input and output shafts rotate in the same direction

D. The train value is negative when the input and output shafts rotate in opposite directions

E. None of the above

3.Which of the following statements is true about the train value?

A. The train value is the arithmetic mean of the velocity ratio of the individual mating gear pairs

B. The train value is the geometric mean of the velocity ratio of the individual mating gear pairs

C. The train value is the product of the velocity ratio of the individual mating gear pairs

D. The train value is the harmonic mean of the velocity ratio of the individual mating gear pairs

E. None of the above

4.Which of the following statements is NOT true about planetary gear train?

A. The center gear is called sun

B. The planets revolve around the sun

C. The carrier holds the planets gear in orbit

D. The ring is the internal gear that commonly encased the train

E. All of the above

5.Which of the following is NOT true about an idler gear?

A. The idler gear alters the direction of the output motion

B. The size and number of teeth of an idler gear do affect the train value

C. The idler gear can be used to adjust the center distance on the input and output shafts

D. An idler gear must have the same diametral pitch and pressure angle as the gears it meshes with

E. All of the above

6.Which of the following is NOT a belt shape?

A. Timing belt

B. V-belt

C. Cog belt

D. Multi V-belt

E. None of the above

7.Which of the following statements is NOT true about belt drives?

A. Belts stretch over time

B. Idler pulley can be used to compensate for the stretch

C. Idler pulley is usually placed on the tight side of the belt

D. Idler pulley is used to maintain

8.Which of the following is NOT true about a worm gear set?
A. The number of worm teeth is called thread
B. The number of gear teeth is called thread
C. The worm is an extreme case of a helical gear with a large helix angle
D. The lead angle of the worm must be equal to the helix angle of the worm for shafts at 900
E. None of the above

Book: Machines and Mechanisms 4th edition

Solution

correct options are provided and in 6. all are belt shapes

1. The friction angle is greater than the lead angle

2. The train value is negative when the input and output shafts rotate in opposite directions

3.The train value is the product of the velocity ratio of the individual mating gear pairs

4. The ring is the internal gear that commonly encased the train

5. An idler gear must have the same diametral pitch and pressure angle as the gears it meshes with

6.none of the given.

7. Idler pulley is usually placed on the tight side of the belt

8. The number of gear teeth is called thread.