Mechanical Engineering Machine Design - Set 11 - ObjectiveBooks

# Practice Test: Question Set - 11

1. When the bearing is subjected to large fluctuations of load and heavy impacts, the bearing characteristic number should be _________ the bearing modulus.
(A) 10 times
(B) 5 times
(C) 15 times
(D) 20 times

2. Which is positive drive?
(A) Flat belt drive
(B) V belt drive
(C) Crossed belt drive
(D) Timing belt

3. If two springs are in parallel then their overall stiffness will be
(A) Half
(B) Same
(C) Double
(D) None of the above

4. In hydrodynamic bearings
(A) The oil film pressure is generated only by the rotation of the journal
(B) The oil film is maintained by supplying oil under pressure
(C) Do not require external supply of lubricant
(D) Grease is used for lubrication

5. A sliding bearing which operates without any lubricant present, is called
(A) Zero film bearing
(B) Boundary lubricated bearing
(C) Hydrodynamic lubricated bearing
(D) Hydrostatic lubricated bearing

6. The bearings of heavy series have capacity __________ over the medium series.
(A) 20 to 30%
(B) 10 to 20%
(C) 30 to 40%
(D) 40 to 50%

7. Antifriction bearings are
(A) Sleeve bearings
(B) Hydrodynamic bearings
(C) Thin lubricated bearings
(D) None of the above

8. If p = bearing pressure on projected bearing area, z = absolute viscosity of lubricant, and N = speed of journal, then the bearing characteristic number is given by
(A) ZN/p
(B) p/ZN
(C) Z/pN
(D) N/Zp

9. Euler’s formula for a mild steel column is not valid if the slenderness ratio is
(A) 90
(B) 60
(C) 120
(D) 100

10. A screw is said to be over hauling screw, if its efficiency is
(A) More than 50%
(B) Less than 50%
(C) Equal to 50%
(D) None of these

11. The usual clearance provided in hydrodynamic bearing per mm of diameter of shaft is
(A) 0.01 micron
(B) 0.1 micron
(C) 1 micron
(D) 10 microns

12. In hydrostatic bearings
(A) The Oil film pressure is generated only by the rotation of the journal
(B) The oil film is maintained by supplying oil under pressure
(C) Do not require external supply of lubricant
(D) Grease is used for lubrication

13. For hardening alloy steels and high speed steels, they are heated to
(A) 1100 to 1300°C
(B) 1300 to 1500°C
(C) 500 to 600°C
(D) 700 to 900°C

14. Oil in journal bearing should be applied at the point where load is
(A) Nil or lightest
(B) Maximum
(C) Average
(D) Any one of the above

15. The rated life of a bearing varies