Miscellaneous Machine Elements
1. An unfired pressure vessel is used to carry stem, gases or fluids at pressure
A. Less than atmospheric pressure
B. Greater than atmospheric pressure
C. Equal to atmospheric pressure
D. None of the mentioned
.
Answer: B:
Explanation: Terminology.
2. Class 1 pressure vessels are used to contain
A. Lethal substances
B. Light duties applications
C. None of the listed
D. LPG
.
Answer: A:
Explanation: Class 1 pressure vessels are used exclusively for lethal substances. LPG doesn’t fall in the category of lethal substances.
3. An oil seal is a mechanical device made of elastic material which is used to prevent leakage of fluid between two machine components.
A. True
B. False
.
Answer: B:
Explanation: It is made of elastomer material.
4. Does oil seal consist of any spring in its structure?
A. Yes
B. No
.
Answer: A:
Explanation: It consist of garter spring which exerts a radial pressure on the rotating shaft and prevents leakage.
5. Which of the following isn’t true about oil seals?
A. Cheap
B. Can be used over a wide range of lubricating oils
C. Can’t tolerate misalignment
D. All of the mentioned
.
Answer: C:
Explanation: Oil seals can tolerate the misalignment to some extent.
6. If magnitude of contact pressure between sealing lip and rotating shaft is very high then
A. There is excessive friction
B. High temperature
C. Rapid wear
D. All of the listed
.
Answer: D:
Explanation: With high pressure, friction increases leading to high temperatures and increasing wear.
7. Wire ropes have
A. High strength to weight ratio
B. Solent operation even at high velocities
C. Greater reliability
D. All of the mentioned
.
Answer: D:
Explanation: All of the listed are true for wire ropes.
8. Wire rope specified as 8×10. Calculate the number of strands.
A. 8
B. 10
C. 16
D. 20
.
Answer: A:
Explanation: First number indicates number of strands.
9. Wire rope is specified as 8×10. Calculate the number of steel wires in each strand.
A. 10
B. 20
C. 5
D. 8
.
Answer: A:
Explanation: Second number represents the number of steel wires in each strand.
10. If the wires in the strand are twisted in the same direction as the strands, then rope is called a _____ lay rope.
A. Lang
B. Regular Lay
C. Ordinary
D. None of the listed
.
Answer: A:
Explanation: The lay of the rope tells the manner in which the wires are helically laid into strands and strands into rope. Same direction is indicated by Lang’s lay.
11. Which among regular lay and Lang lay are popular?
A. Regular Lay
B. Lang Lay
C. Both are equally used
D. Can’t be stated
.
Answer: A:
Explanation: In regular lay ropes, there is a balance resulting from opposite direction of twisting the strands to that of the wires.
12. In Lang lay ropes, both inner and outer wires are bent on same arc of radius.
A. True
B. False
.
Answer: B:
Explanation: Due to same direction of rotation, outer wires are bent on an arc of larger radius.
13. The wire rope is subjected to
A. Tensile Stress
B. Bending Stress
C. Both bending and tensile stress
D. None of the listed
.
Answer: C:
Explanation: There is direct tensile stress due to load being raised as well as bending stress.
14. In design of wire ropes, bending stress is converted into an equivalent bending load which is given by [d= diameter of individual wire and D= diameter of sheave].
A. AEd/D
B. 2AEd/D
C. AEd/2D
D. None of the listed
.
Answer: A:
Explanation: P=σA and σ=Ed/D.
15. An elevator is assembled to raise equipment to a height of 22m. It is estimated that maximum weight of the material to be raised is 4.9kN. It is observed acceleration in such cases is 1.2m/s².10mm diameter wire ropes with fibre core are used. The tensile designation of the wire is 1500. Number of wire ropes can be taken 2. Calculate the weight of material raised by each load.
A. None of the listed
B. 2450N
C. 4900N
D. 9800N
.
Answer: B:
Explanation: Weight of material raised by each rope= 4.9/2.
16. An elevator is assembled to raise equipment to a height of 22m. It is estimated that maximum weight of the material to be raised is 4.9kN. It is observed acceleration in such cases is 1.2m/s².10mm diameter wire ropes with fibre core are used. The tensile designation of the wire is 1500.Number of rope wires is assumed to be 2. Calculate the weight of wire if weight of 50m wire is 18kg.
A. 19.36N
B. 90.25N
C. 77.70N
D. 56.66N
.
Answer: C:
Explanation: W=mass per unit length x length x g.
17. An elevator is assembled to raise equipment to a height of 22m. It is estimated that maximum weight of the material to be raised is 4.9kN. It is observed acceleration in such cases is 1.2m/s².10mm diameter wire ropes with fibre core are used. The tensile designation of the wire is 1500.Number of rope wires is assumed to be 2. Number of rope wires is assumed to be 2. Calculate the weight of wire if weight of 50m wire is 18kg. Calculate the force due to acceleration.
A. 1000N
B. 309.144N
C. 504.225N
D. 102.225N
.
Answer: B:
Explanation: Mass of material raised by each wire rope= 2450/9.81 = 249.7kg. Mass of each wire rope= 77.7/9.81 =7.92kg. Force due to acceleration= [249.7+7.92] x 1.2.
18. An elevator is assembled to raise equipment to a height of 22m. It is estimated that maximum weight of the material to be raised is 4.9kN. It is observed acceleration in such cases is 1.2m/s².10mm diameter wire ropes with fibre core are used. The tensile designation of the wire is 1500.Number of rope wires is assumed to be 2. Number of rope wires is assumed to be 2. Calculate the total load on wire rope neglecting the bending load if weight of 50m wire is 18kg.
A. 1054.55N
B. 3504.55N
C. 2836.84N
D. 5678.6N
.
Answer: C:
Explanation: F=4900/2 + 77.7 + 249.7×1.2 + 7.92×1.2.
19. Small sheaves are preferred over large sheaves on what parameters?
A. Increasingly centrifugal force in large sheaves
B. Higher cost of small sheaves
C. Preferring centrifugal force reduction even for more money
D. None of the listed
.
Answer: A:
Explanation: Larger sheaves have higher centrifugal forces and higher cost because more material is used in their construction.
20. Rope operating over steel sheaves wear slowly than those used in conjunction with cast iron sheaves.
A. True
B. False
.
Answer: B:
Explanation: Rope operating over steel sheaves wear faster. If wear on cast iron sheave is 100, than wear on steel sheave is 110.
21. Which type of rope drum is preferred?
A. Drums with helical grooves
B. Plain cylindrical drums
C. Both are equally preferred
D. None of the listed
.
Answer: A:
Explanation: They have more bearing surface of the drum and prevent friction between adjacent turns of the rope.
22. If nominal diameter of the rope is 20mm, then pitch of the groove is around?
A. 2mm
B. 22mm
C. 40mm
D. 10mm
.
Answer: B:
Explanation: p= d + 2 mm.
23. Piston rod is an example of column.
A. True
B. False
.
Answer: A:
Explanation: An slender machine component having its length considerable in proportion to its width qualifies for a column criterion.
24. Bucking of column means
A. Lateral deflection
B. Axial deflection
C. Torsional deflection
D. None of the listed
.
Answer: D:
Explanation: Buckling is characterised by lateral deflection but it is different from lateral deflection as there is sudden lateral deflection in buckling unlike lateral deflection where there is gradual deflection.
25. Slenderness ratio is [l= length of column and k= least radius of gyration of cross section about its axis].
A. l/k
B. k/l
C. l/2k
D. k/2l
.
Answer: A:
Explanation: It is a ratio of length to least radius of gyration.
26. Columns with what slenderness ratio are not designed with respect to buckling but are designed for compressive stresses.
A. >1
B. <1 C. >30
D. <30
.
Answer: D:
Explanation: When slenderness ratio is <30, there is no effect of buckling.
27. If slenderness ratio=45, which mode of failure will dominate?
A. Buckling
B. Compressive Stresses
C. Both buckling and compressive stress
D. Can’t be stated
.
Answer: A:
Explanation: If slenderness ratio>30, column shall be more prone to buckling.
28. Short column and long column are classified on the basis of
A. Slenderness ratio
B. Diameter
C. Length
D. None of the listed
.
Answer: A:
Explanation: Slenderness ratio takes into consideration length and radius of gyration and thus is preferred.
29. Cast iron column with a slenderness ratio of 75 are
A. Short Columns
B. Long Columns
C. Very short columns
D. None of the listed
.
Answer: A:
Explanation: Cast iron column with a slenderness ratio <80are short columns.
30. Steel columns with a slenderness ratio of 95 are
A. Short Columns
B. Long columns
C. Very long columns
D. None of the listed
.
Answer: A:
Explanation: Steel columns with slenderness ratio <100 are classified in short columns.
31. Which of the following are true for End fixity coefficient
A. Dimensionless number
B. Used in Euler’s equation
C. Provides condition of restraint at two ends
D. All of the listed
.
Answer: D:
Explanation: It is a dimensionless number used in Euler’s equation to take into account the restraints at the two ends.
32. Value of end fixity coefficient for both hands fixed is
A. 1
B. 4
C. 2
D. 0.25
.
Answer: B:
Explanation: Lower the mobility higher is the end fixity component.
