Tribology (MCQ : MODULE - 6)


Question 1: What is a typical radial clearance between journal and bearing bore in hydrodynamic journal bearings ?

A. One tenth of a percent of bearing-bore radius.
B. One percent of bearing-bore radius.
C. One tenth of a percent of bearing-bore diameter.
D. One percent of bearing-bore diameter.

(A)
(B)
(C)
(D)

Question 2: Maximum value of contact pressure in Hertzian contact occurs at :

A. Centre of contact region.
B. Periphery of contact region.
C. One third of contact radius beneath the contact surface.
D. One third of contact radius beneath the contact surface in line of contact force.

(A)
(B)
(C)
(D)

Question 3: In contact of two cylinders, contact geometry comes out to be :

A. Ellipse.
B. Rectangle.
C. Square.
D. Circle.

(A)
(B)
(C)
(D)

Question 4: Bore diameter of 6205 metric series of rolling bearing is :

A. 25 mm
B. 30 mm
C. 20 mm
D. 5 mm

(A)
(B)
(C)
(D)

Question 5: Preload in rolling bearing is caused by :

A. Negative clearance between rolling elements and rings.
B. Normal stretching of rings.
C. Excessive lubricant supply.
D. Excessive leakage of lubricant.

(A)
(B)
(C)
(D)

Question 6: Which one of the following sentence is the most appropriate?

A. Seals may be contact or non-contact type. B) C) D)
B. Shields are used to avoid any leakage of lubricants.
C. Seals are mainly used to prevent dust ingress in rolling bearings.
D. Shields are subjected to excessive elastic deformation and that is why shields are known for their zero leakage performance.

(A)
(B)
(C)
(D)

Question 7: Hydrostatic bearing (HSB) is different compared to hydrodynamic bearing (HDB). For same load capacity of bearings which one of the following is INCORRECT?

A. Design of HSB housing is far simpler than HDB housing.
B. Initial cost of HSB is higher than the cost of HDB.
C. Supply pressure for HSB needs to be higher than required supply pressure for HDB.
D. HSB is preferred for precision position of rotating shaft.

(A)
(B)
(C)
(D)

Question 8: The most common method to install ball bearing on the shaft is by means of :

A. Transition to interference fit.
B. Key.
C. Screw.
D. Sprocket.

(A)
(B)
(C)
(D)

Question 9: Rolling element bearings are most commonly made of :

A. Chromium steel.
B. Vanadium steel.
C. Tungsten steel.
D. High carbon steel.

(A)
(B)
(C)
(D)

Question 10: The service life of rolling bearing is often predicted using :

A. Lundberg and Palmgren method.
B. Priest and Dowson method.
C. Hamrock and Harris method.
D. Tichy and Dowson method.

(A)
(B)
(C)
(D)

Question 11: In a ball bearing outer race diameter is represented as do, inner ring diameter as di, and ball diameter as d. Diametral clearance, Cd, in unloaded condition will be expressed as

A. Cd = do - di - 2d
B. Cd = do + di - 2d
C. Cd = do - di - d
D. Cd = do + di - d

(A)
(B)
(C)
(D)

Question 12: If ceramic balls are compared with steel balls in a ball bearing, which of the following is INCORRECT about ceramic balls?

A. Require more lubricant.
B. Harder.
C. Lighter.
D. Can operate at higher temperature.

(A)
(B)
(C)
(D)

Question 13: Relative movement may be possible in :

A. Clearance fit
B. Transition fit.
C. Interference fit.
D. Both in clearance and transition fits.

(A)
(B)
(C)
(D)

Question 14: The most critical design parameter in hydrodynamic bearings is :

A. Radial clearance.
B. Shaft radius.
C. Fluid pressure.
D. Fluid viscosity.

(A)
(B)
(C)
(D)

Question 15: High operating temperature requires :

A. Larger bearing clearance at room temperature.
B. Smaller bearing clearance at room temperature.
C. Initially larger and subsequent smaller bearing clearance at room temperature.
D. Temperature does not affect bearing clearance.

(A)
(B)
(C)
(D)

Question 16: Which is true about pitting failure?

A. It is a fatigue failure.
B. Reversible stresses are main cause of such failure.
C. Generation of cracks on or near the surface of component are responsible for such failure.
D. All of the above.

(A)
(B)
(C)
(D)

Question 17: Gear ratio of a single stage spur gear train (pinion and gear) is 4. The pinion has 18 teeth and module 3mm. Module of gear shall be :

A. 3 mm
B. 0.75 mm
C. 1.5 mm
D. 1.33 mm

(A)
(B)
(C)
(D)

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