THE COST OF PRODUCTION IS LOW. WHICH OF THESE STATEMENTS ARE CORREC...

4. The cost of production is low.

Which of these statements are correct?

(a) 1, 2 and 3

(b) 1, 2 and 4

(c) 2, 3 and 4

(d) 1, 3 and 4

IES-40Ans. (a) Cost of production of conjugate teeth, being difficult to manufacture is high.

IES-41. Which one of the following is correct?

[IES-2008]

When two teeth profiles of gears are conjugate, the sliding velocity

between them

(a) Is always zero, all through the path of contact?

(b) Is zero, at certain points along the path of contact?

(c) Is never zero anywhere on the path of contact?

(d) Can be made zero by proper selection of profiles

IES-41Ans. (a)

IES-42. Which one of the following is the correct statement?

[IES 2007]

In meshing gears with involute gears teeth, the contact begins at the

intersection of the

(a) Line of action and the addendum circle of the driven gear

(b) Line of action and the pitch circle of the driven gear

(c) Dedendum circle of the driver gear and the addendum circle of the driven gear

(d) Addendum circle of the driver gear and the pitch circle of the driven gear

IES-42Ans. (a)

IES-43. Common contact ratio of a pair of spur pinion and gear is [IES-2008]

(a) Less than 1·0

(b) equal to 1

(c) Between 2 and 3

(d) greater than 3

Design of Power Transmission System

S K Mondal’s

Chapter 3

IES-43Ans. (c) The ratio of the length of arc of contact to the circular pitch is known as

contact ratio i.e. number of pairs of teeth in contact. The contact ratio for gears is

greater than one. Contact ratio should be at least 1.25. For maximum smoothness

and quietness, the contact ratio should be between 1.50 and 2.00. High-speed

applications should be designed with a face-contact ratio of 2.00 or higher for best

results.

IES-44. Interference between an involute gear and a pinion can be reduced by

which of the following?

[IES-2008]