INFILTRATION 2. SIZING 3. HEAT TREATMENT 4.COINING SELECT THE CORRE...

1. Infiltration 2. Sizing

3. Heat treatment 4.Coining

Select the correct answer using the code given below:

(a) 1 and 2

(b) 2 and 3

(c) 2 and 4

(d) 1 and 4

IES-26Ans. (a)

IES-27. In sliding contact bearings, a positive pressure can be built up and a load

supported by a fluid only by the use of a:

[IES-2005]

(a) Diverging film

(b) Converging-diverging film

(c) Converging film

(d) Flat film

IES-27Ans. (c)

IES-28.

Which one of the following is correct?

[IES-2008]

A hydrodynamic slider bearing develops load bearing capacity mainly

because of

(a) Slider velocity

(b) wedge shaped oil film

(c) Oil compressibility

(d) oil viscosity

IES-28Ans. (b) A hydrodynamic slider bearing develops load bearing capacity mainly because

of wedge shaped oil film.

IES-29.

Assertion (A): In steady rotating condition the journal inside a hydrodynamic

journal bearing remains floating on the oil film.

[IES-2008]

Reason (R): The hydrodynamic pressure developed in steady rotating conditions in

journal bearings balances the load on the journal.

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is NOT the correct explanation of A

(c) A is true but R is false

(d) A is false but R is true

IES-29Ans. (a) The film pressure created by the moving surface itself pulling the lubricant

into a wedge shaped zone at a velocity sufficiently high to create the necessary

pressure required to separate the surface against the load on the bearings.

Hydrodynamic lubrication is also called as full film lubrication or fluid lubrication.

So Assertion and Reason both are correct and A is the correct explanation of R.

S K Mondal’s

Chapter 4

IES-30. Increase in values of which of the following results in an increase of the

coefficient of friction in a hydrodynamic bearing?

[IES 2007]