SSC JHT - Machine Design 1000+ MCQ [Solved] PDF Download

1. According to I.B.R., the efficiency of a double riveted butt joint with double cover straps of equal width should be
A. 45 to 60 %
B. 63 to 70 %
C. 70 to 83 %
D. 80 to 90 %
Answer : C

2. The centre to centre distance between two consecutive rivets in a row, is called
A. Margin
B. Pitch
C. Back pitch
D. Diagonal pitch
Answer : B

3. The strength of a riveted joint is equal to
A. Tearing strength of plate (P_t)
B. Shearing strength of rivet (P_s)
C. Crushing strength of rivet (P_c)
D. Least value of P_t P_s and P_c
Answer : D

4. The value of Lewis form factor used in design of gears is
A. Dependent on number of teeth of a gear
B. Dependent on system of teeth
C. Independent of size of teeth
D. All of these
Answer : D

5. The design of pin of a rocker arm of an I.C. engine is based on
A. Bearing failure
B. Shearing failure
C. Bending failure
D. All of these
Answer : D

6. The permissible stress in the fillet weld is 100 N/mm². The fillet weld has equal leg lengths of 15 mm each. The allowable shearing load on the weldment per cm length of the weld is
A. 7.5 kN
B. 10.6 kN
C. 15 kN
D. 22.5 kN
Answer : B

7. When the bolt is very yielding as compared to the connected members, then the resultant load on the bolt will be equal to the
A. Initial tension
B. External load applied
C. Sum of the initial tension and external load applied
D. Initial tension or external load, whichever is greater
Answer : D

8. I.S. specifies following total number of grades of tolerances
A. 18
B. 16
C. 20
D. 22
Answer : A

9. A feather key is generally
A. Loose in shaft and tight in hub
B. Tight in shaft and loose in hub
C. Tight in both shaft and hub
D. Loose in both shaft and hub
Answer : B

10. The constant factor in case of R10 series of preferred numbers is
A. 1.06
B. 1.12
C. 1.26
D. 1.58
Answer : C

11. The resultant axial load on a bolt depends upon
A. External load applied
B. Initial tension due to tightening of the bolt
C. Relative elastic yielding of the bolt and the connected members
D. All of the above
Answer : D

12. Aircraft body is usually fabricated by
A. Welding
B. Pre-casting
C. Riveting
D. Casting
Answer : C

13. A bolt
A. Has a head on one end and a nut fitted to the other
B. Has head at one end and other end fits into a tapped hole in the other part to be joined
C. Has both the ends threaded
D. Is provided with pointed threads
Answer : A

14. The application of third type levers is found in
A. Handle of a hand pump
B. Hand wheel of a punching press
C. Lever of a loaded safety valve
D. A pair of tongs
Answer : D

15. When spring index increases, the value of Wahl's stress factor
A. Increases linearly
B. Decreases linearly
C. Remains same
D. Increases exponentially
Answer : D

16. In an oil lubricated journal bearing, the coefficient of friction between the journal and the bearing
A. Remains constant at all speeds
B. Is minimum at zero speed and increases monotonically with increase in speed
C. Is maximum at zero speed and decreases monotonically with increase in speed
D. Becomes minimum at an optimum speed and then increases with further increase in speed
Answer : D

17. The face of the tooth is the
A. Surface of the top of the tooth
B. Surface of the tooth above the pitch surface
C. Surface of the tooth below the pitch surface
D. Width of the tooth measured along the pitch circle
Answer : B

18. The cold working of metals is carried out __________ the recrystallisation temperature.
A. Above
B. Below
C. At
D. None of these
Answer : B

19. A special case of ductility which permits materials to be rolled or hammered into thin sheets, is called
A. Plasticity
B. Elasticity
C. Ductility
D. Malleability
Answer : D

20. Which is correct statement? Stress concentration in static loading is
A. Very serious in brittle materials and less serious in ductile materials
B. Very serious in ductile materials and less serious in brittle materials
C. Equally serious in both types of materials
D. Seriousness would depend on other factors
Answer : A

21. The rolling contact bearings are known as
A. Thick lubricated bearings
B. Plastic bearings
C. Antifriction bearings
D. Thin lubricated bearings
Answer : C

22. A fast and loose pulley drive is used when
A. Shafts are arranged parallel and rotate in the opposite directions
B. Shafts are arranged parallel and rotate in the same directions
C. Shafts are arranged at right angles and rotate in one definite direction
D. Driven shaft is to be started or stopped whenever desired without interfering with the driving shaft
Answer : D

23. When a helical compression spring is cut into halves, the stiffness of the resulting spring will be
A. Same
B. Double
C. One-half
D. One-fourth
Answer : B

24. In standard taper roller bearings, the angle of taper of outer raceway is
A. 5°
B. 8°
C. 15°
D. 25°
Answer : D

25. In worm gears, the angle between the tangent to the pitch helix and an element of the cylinder, is known as
A. Helix angle
B. Pressure angle
C. Pitch lead angle
D. None of these
Answer : A

26. In helical gears, the distance between similar faces of adjacent teeth along a helix on the pitch cylinders normal to the teeth, is called
A. Normal pitch
B. Axial pitch
C. Diametral pitch
D. Module
Answer : A

27. The dedendum is the radial distance from the
A. Pitch circle to the top of a tooth
B. Pitch circle to the bottom of a tooth
C. Top of a tooth to the bottom of a tooth
D. Addendum circle to the clearance circle
Answer : B

28. A transmission shaft includes
A. Over head shaft
B. Counter shaft
C. Line shaft
D. All of these
Answer : D

29. The condition for maximum power transmission is that the maximum tension in the flat belt should be equal to
A. 3 Pc
B. Pc
C. Pc/3
D. 2 Pc Where, Pc = tension in belt due to centrifugal force
Answer : A

30. In a gear, having Involute teeth, the normal to the Involute is a tangent to the
A. Base circle
B. Pitch circle
C. Addendum circle
D. Dedendum circle
Answer : A

31. The flank of the tooth is the
A. Surface of the top of the tooth
B. Surface of the tooth above the pitch surface
C. Width of the tooth measured along the pitch circle
D. Surface of the tooth below the pitch surface
Answer : D

32. Oldham coupling is used to connect two shafts
A. Which are perfectly aligned
B. Which are not in exact alignment
C. Which have lateral misalignment
D. Whose axes intersect at a small angle
Answer : C

33. If a spring is cut down into two springs, the stiffness of cut springs will be
A. Half
B. Same
C. Double
D. None of the above
Answer : C

34. Maximum principal stress theory is applicable for
A. Ductile materials
B. Brittle materials
C. Elastic materials
D. All of the above
Answer : B

35. If the centre distance of the mating gears having involute teeth is varied within limits, the velocity ratio.
A. Increases
B. Decreases
C. Remains unchanged
D. None of these
Answer : C

36. An alien bolt is
A. Self locking bolt
B. Same as stud
C. Provided with hexagonal depression in head
D. Used in high speed components
Answer : C

37. Three different weights fall from a certain height under vacuum. They will take
A. Same time to reach earth
B. Times proportional to weight to reach earth
C. Times inversely proportional to weight to reach earth
D. None of the above
Answer : A

38. In Vickers hardness testing, the pyramid indentor apex is
A. 40°
B. 122°
C. 136°
D. 152°
Answer : C

39. Applications in which stresses are encountered in one direction only uses following type of threads
A. Metric
B. Buttress
C. Acme
D. Square
Answer : B

40. The objective of caulking in a riveted joint is to make the joint
A. Free from corrosion
B. Stronger in tension
C. Free from stress
D. Leak-proof
Answer : D

41. In worm, gears, pitch lead angle is
A. Half the angle between two inclined faces in axial plane
B. The angle between the tangent to the pitch helix and the plane of rotation
C. The angle between the tangent to the pitch helix and an element of the cylinder
D. None of the above
Answer : B

42. When the connected members are very yielding (soft gasket) as compared to the bolt, then the resultant load on the bolt will be equal to the
A. Initial tension
B. External load applied
C. Sum of the initial tension and external load applied
D. Initial tension or external load, whichever is greater
Answer : C

43. Which of the following statement is wrong?
A. A key is used as a temporary fastening
B. A key is subjected to tensile stresses
C. A key is always inserted parallel to the axis of the shaft
D. A key prevents relative motion between the shaft and boss of the pulley
Answer : B

44. Gear box is used
A. To produce torque
B. For speed reduction
C. To obtain variable speeds
D. To increase efficiency of system
Answer : C

45. The property of a material which enables it to be drawn into wires with the application of a tensile force, is called
A. Plasticity
B. Elasticity
C. Ductility
D. Malleability
Answer : C

46. The draw of cotter need not exceed
A. 3 mm
B. 5 mm
C. 10 mm
D. 20 mm
Answer : A

47. A shaft is subjected to a maximum bending stress of 80 N/mm² and maximum shearing stress equal to 30 N/mm² at a particular section. If the yield point in tension of the material is 280 N/mm² and the maximum shear stress theory of failure is used, then the factor of safety obtained will be
A. 2.5
B. 2.8
C. 3.0
D. 3.5
Answer : B

48. In order to permit the thermal expansion/contraction of tubing, it should be
A. Crimped
B. Honed
C. Flared
D. Bent
Answer : D

49. A circular shaft can transmit a torque of 5 kN-m. If the torque is reduced to 4 kN-m, then the maximum value of bending moment that can be applied to the shaft is
A. 1 kN-m
B. 2 kN-m
C. 3 kN-m
D. 4 kN-m
Answer : C

50. A screw is said to be a self locking screw, if its efficiency is
A. Less than 50 %
B. More than 50 %
C. Equal to 50 %
D. None of these
Answer : A