1. The expected life of a ball bearing subjected to a load of 9800 N and working at 1000 rpm is 3000 hours. What is the expected life of the same bearing for a similar load of 4900 N and speed of 2000 rpm.
(a) Unchanged
(b) 12000 hours
(c) 1500 hours
(d) 6000 hours
(1 Mark, 1987)

Ans: b
2. If the load on a ball bearing is reduced to half, the life of the ball bearing will
(a) Increase 8 times
(b) Increase 4 times
(c) Increase 2 times
(d) Not change
(1 Mark, 1988)

Ans: a
3. Starting friction is low in
(a) Hydrostatic lubrication
(b) Hydrodynamic lubrication
(c) Mixed (or semifluid) lubrication
(d) Boundary lubrication
(1 Mark, 1992)

Ans: a
4. Spherical roller bearings are normally used
(a) For increased radial load
(b) For increased thrust load
(c) When there is less radial space
(d) To compensate for angular misalignment
(1 Mark, 1992)

Ans: d
5. In thick film hydrodynamic journal bearings, the coefficient of friction
(a) Increases with increase in load
(b) Is independent of load
(c) Decreases with increase in load
(d) May increase or decrease with increase in load
(1 Mark, 1996)

Ans: c
6. To restore stable operating condition in a hydrodynamic journal bearing, when it encounters higher magnitude loads,
(a) Oil viscosity is to be decreased
(b) Oil viscosity is to be increased
(c) Oil viscosity index is to be increased
(d) Oil viscosity index is to be decreased
(1 Mark, 1997)

Ans: b
7. The dynamic load capacity of 6306 bearing is 22 kN. The maximum radial load it can sustain to operate at 600 rev/min, for 2000 hours is:
(a) 4.16 kN
(b) 3.60 kN
(c) 6.25 kN
(d) 5.29 kN
(2 Mark, 1997)

Ans: d
8. The basic load rating of a ball bearing is
(a) The maximum static radial load that can be applied without causing any plastic deformation of bearing component.
(b) The radial load at which 90% of the group of apparently identical bearings run for one million revolutions before the first evidence of failure.
(c) The maximum radial load that can be applied during operation without any plastic deformation of bearing components.
(d) A combination of radial and axial loads that can be applied without any plastic deformation.
(1 Mark, 1998)

Ans: b
9. Square key of side ‘d/4’ each and length l is used to transmit torque ‘T’ from the shaft of diameter ‘d’ to the hub of a pulley. Assuming the length of the key to be equal to the thickness of the pulley, the average shear stress developed in the key is given by
(a) \frac { 4T }{ ld }
(b) \frac { 16T }{ l{ d }^{ 2 } }
(c) \frac { 8T }{ l{ d }^{ 2 } }
(d) \frac { 16T }{ \pi { d }^{ 3 } }
(2 Mark, 2003)

Ans: c
10. Which one of the following is a criterion in the design of hydrodynamic journal bearings?
(a) Sommerfeld number
(b) Rating life
(c) Specific dynamic capacity
(d) Rotation factor
(1 Mark, 2005)

Ans: a
11. A ball bearing operating at a load F has 8000 hours of life. The life of the bearing, in hours, when the load is doubled to 2F is
(a) 8000
(b) 6000
(c) 4000
(d) 1000
(1 Mark, 2007)

Ans: d
12. A natural feed journal bearing of diameter 50 mm and length 50 mm operating at 20 revolution/second carries a load of 2 kN. The lubricant used has a viscosity of 20 mPa/s. The radial clearance is 50 \mu m. The Sommerfeld number for the bearing is
(a) 0.062
(b) 0.125
(c) 0.250
(d) 0.785
(2 Mark, 2007)

Ans: b
13. Two identical ball bearings P and Q are operating at loads 30 kN and 45 kN respectively. The ratio of the life of bearing P to the life of bearing Q is
(a) 81/16
(b) 27/8
(c) 9/4
(d) 3/2
(2 Mark, 2011)

Ans: b
14. A solid circular shaft needs to be designed to transmit a torque of 50 N.m. If the allowable shear stress of the material is 140 MPa, assuming a factor of safety of 2, the minimum allowable design diameter in mm is
(a) 8
(b) 16
(c) 24
(d) 32
(2 Mark, 2012)

Ans: b
15. A hydrodynamic journal bearing is subject to 2000 N load at a rotational speed of 2000 rpm. Both bearing bore diameter and length are 40 mm. If radial clearance is 20 μm and bearing is lubricated with an oil having viscosity 0.03 Pa.s, the Sommerfeld number of the bearing is _______.
(2 Mark, 2014[1])

Ans: 0.8
16. Ball bearings are rated by a manufacturer for a life of 10^{6}. The catalogue rating of a particular bearing is 16 kN. If the design load is 2 kN, the life of the bearing will be P × 10^{6} revolutions, where P is equal to _______.
(1 Mark, 2014[4])

Ans: 512
17. For ball bearings, the fatigue life L measured in number of revolutions and the radial load F are related by FL^{1/3} = K, where K is a constant. It withstands a radial load of 2 kN for a life of 540 million revolutions. The load (in kN) for a life of one million revolutions is _______.
(2 Mark, 2015[3])

Ans: 16.286
18. Which of the bearings given below SHOULD NOT be subjected to a thrust load?
(a) Deep groove ball bearing
(b) Angular contact ball bearing
(c) Cylindrical (straight) roller bearing
(d) Single row tapered roller bearing
(1 Mark, 2016[3])

Ans: c
19. A selfaligning ball bearing has a basic dynamic load rating (C_{10}, for 10^{6} revolutions) of 35 kN. If the equivalent radial load on the bearing is 45 kN, the expected life (in 10^{6 }revolutions) is
(a) below 0.5
(b) 0.5 to 0.8
(c) 0.8 to 1.0
(d) above 1.0
(2 Mark, 2018[1])

Ans: a