1000+ Machine Design MCQ for SSC GD [Solved]

1. The modulus of elasticity for mild steel is approximately equal to
A. 80 kN/mm²
B. 100 kN/mm²
C. 110 kN/mm²
D. 210 kN/mm²
Answer : D

2. The maximum stress due to stress concentration in a bar having circular transverse hole, as compared to its static stress without hole will be
A. Same in both cases
B. 2 times more
C. 3 times more
D. 4 times more
Answer : C

3. When two springs are in series (having stiffness K), the equivalent stiffness will be
A. K
B. K/2
C. 2K
D. K/4
Answer : B

4. Which of the following is not correct procedure to increase the fatigue limit?
A. Cold working
B. Shot peening
C. Surface decarburisation
D. Under stressing
Answer : C

5. According to maximum shear stress theory, the maximum shear stress in the shaft is
A. (1/2) × ?(?² + 4?²)
B. ?(?² + 4?²)
C. (1/2) × [? + ?(?² + 4?²)]
D. ? + ?(?² + 4?²)
Answer : A

6. According to Indian standards, total numbers of fundamental deviations are
A. 10
B. 15
C. 20
D. 25
Answer : D

7. According to Unwin's formula, the relation between the diameter of rivet hole (d) and the thickness of plate (t) is given by (where d and t are in mm)
A. d = t
B. d = 1.6 t
C. d = 2t
D. d = 6t
Answer : D

8. A bench vice has following type of threads
A. Metric
B. Square
C. Buttress
D. Acme
Answer : D

9. The shock absorbing capacity of a bolt can be increased by
A. Tightening it properly
B. Increasing shank diameter
C. Grinding the shank
D. Making shank diameter equal to core diameter of thread.
Answer : D

10. The acme threads are usually found on
A. Spindles of bench vices
B. Railway carriage couplings
C. Feed mechanism of machine tools
D. Screw cutting lathes
Answer : D

11. In most machine members, the damping capacity of the material should be
A. Low
B. Zero
C. High
D. Could be anything
Answer : C

12. Set screws are
A. Similar to small size tap bolts except that a greater variety of shapes of heads are available
B. Slotted for a screw driver and generally used with a nut
C. Used to prevent relative motion between parts
D. Similar to stud
Answer : C

13. The period during which the cam follower remains at rest, when cam moves, is known as
A. Constant period
B. Fixed period
C. Dwell period
D. Idle period
Answer : C

14. Idler pulley is used for
A. Increasing velocity ratio
B. For applying tension
C. Changing the direction of motion of belt
D. All of these
Answer : B

15. Basic hole is one
A. Whose upper deviation is zero
B. Whose lower deviation is zero
C. Whose lower as well as upper deviations are zero
D. Does not exist
Answer : B

16. Which one of the following is a positive drive?
A. V-belt drive
B. Rope drive
C. Crossed flat belt drive
D. Chain drive
Answer : D

17. Spring stiffness is
A. Ratio of coil diameter to wire diameter
B. Load required to produce unit deflection
C. Its capability of storing energy
D. Its ability to absorb shocks
Answer : B

18. The ratio of endurance limit in shear to the endurance limit in flexure is
A. 0.33
B. 0.4
C. 0.5
D. 0.55
Answer : D

19. In a multiple V-belt drive, if one of the belts break, then
A. Only the broken belt is replaced
B. The entire set of belts is replaced
C. The broken belt and the belt on either side of it, is replaced
D. The broken belt need not to be replaced
Answer : B

20. The groove angle of pulleys for V-belt is
A. 340 to 360
B. 420 to 450
C. More than 400
D. 300 to 320
Answer : A

21. Jam nut is a locking device in which
A. One smaller nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming
B. A slot is cut partly in middle of nut and then slot reduced by tightening a screw
C. A hard fibre or nylon cotter is recessed in the nut and becomes threaded as the nut is screwed on the bolt causing a tight grip
D. Through slots are made at top and a cotter pin is passed through these and a hole in the bolt, and cotter spitted and bent in reverse direction at other end
Answer : A

22. The taper on cotter varies from
A. 1 in 24 to 1 in 20
B. 1 in 15 to 1 in 10
C. 1 in 32 to 1 in 24
D. 1 in 48 to 1 in 24
Answer : D

23. Spring index is
A. Ratio of coil diameter to wire diameter
B. Load required to produce unit deflection
C. Its capability of storing energy
D. Indication of quality of spring
Answer : A

24. The process which improves the machinability of steels, but lowers the hardness and tensile strength is
A. Normalising
B. Full annealing
C. Process annealing
D. Spheroidising
Answer : D

25. Auto frettage is the method of
A. Joining thick cylinders
B. Calculating stresses in thick cylinders
C. Pre-stressing thick cylinders
D. Increasing the life of thick cylinders
Answer : C

26. The spring mostly used in gramophones is
A. Helical spring
B. Conical spring
C. Flat spiral spring
D. Volute spring
Answer : C

27. A localised compressive stress at the area of contact between two members is known as
A. Tensile stress
B. Bending stress
C. Bearing stress
D. Shear stress
Answer : C

28. When a close coiled helical spring is compressed, its wire is subjected to
A. Tension
B. Shear
C. Compression
D. All of the above
Answer : A

29. The ratio of the ultimate stress to the design stress is known as
A. Elastic limit
B. Strain
C. Factor of safety
D. Bulk modulus
Answer : C

30. In testing a material for endurance strength, it is subjected to
A. Static load
B. Dynamic load
C. Impact load
D. Completely reversed load
Answer : D

31. If an application calls for stresses on screw threads in one direction only, then the following type of thread would be best suited
A. Square
B. Acme
C. Buttress
D. BSW
Answer : C

32. Elastic nut is a locking device in which
A. One small nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming
B. A slot is cut partly in middle of nut and then slot reduced by tightening a screw
C. Hard fibre or nylon cotter is recessed in the nut and becomes threaded as the nut is stewed on the bolt causing a tight grip
D. Through slots are made at top and a cotter pin is passed through these and a hole in the bolt, and cotter pin splitted and bent in reverse direction at other end
Answer : C

33. Wire ropes as compared to cotton ropes
A. Are lighter in weight
B. Offer silent operation
C. Can withstand shock loads
D. All of these
Answer : D

34. A locking device extensively used in marine type connecting rod ends is a
A. Jam nut
B. Castle nut
C. Sawn nut
D. Ring nut
Answer : D

35. The piston pin bearings in heavy duty diesel engines are
A. Needle roller bearings
B. Tapered roller bearings
C. Spherical roller bearings
D. Cylindrical roller bearings
Answer : A

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

37. Factor of safety for fatigue loading is the ratio of
A. Elastic limit to the working stress
B. Elastic limit to the yield point
C. Endurance limit to the working stress
D. Young's modulus to the ultimate tensile strength
Answer : C

38. Split nut is a locking device in which
A. One smaller nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming
B. A slot is cut partly in middle of nut and then slot reduced by tightening screw
C. A hard fibre or nylon cotter is recessed in the nut and becomes threaded as the nut is screwed on the bolt causing a tight grip
D. Through slots are made at top and a cotter pin is passed through these and a hole in the bolt, and cotter pin splitted and bent in reverse direction at the other end
Answer : B

39. In a butt welded joint, the size of weld is __________ the throat of weld.
A. 0.5 times
B. Equal to
C. 2 times
D. Double
Answer : B

40. An elastic bar is fixed at the upper end and loaded at the lower end by a falling weight. The shock load produced can be reduced by
A. Increasing the length of bar
B. Decreasing the cross-sectional area of the bar
C. Decreasing the modulus of elasticity of the bar
D. All of the above
Answer : D

41. 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

42. In order to avoid tearing of the plate at an edge, the distance from the centre line of the rivet hole to the nearest edge of the plate should be equal to (where d = Diameter of rivet hole)
A. d
B. 1.5 d
C. 2.5 d
D. 2 d
Answer : B

43. 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

44. A compound cylinder with inner radius 50 mm and outer radius 70 mm is made by shrinking one cylinder on to the other cylinder, the junction radius is 60 mm and the junction pressure is 1.1 N/mm². The maximum hoop stress developed in the inner cylinder is
A. 3.6 N/mm² compression
B. 3.6 N/mm² tension
C. 7.2 N/mm² compression
D. 7.2 N/mm² tension
Answer : C

45. The deflection of a cantilever beam under load W is 8. If its width is halved, then the deflection under load W will be
A. 2/8
B. 8/2
C. 4/8
D. 8/4
Answer : C

46. When a circular beam of diameter d is subjected to a shear force F, the maximum shear stress induced will be
A. 4F/ ?d²
B. 6F/ ?d²
C. 8F/ ?d²
D. 16F/ 3?d²
Answer : D

47. The shear plane in case of bolts should
A. Be across threaded portion of shank
B. Be parallel to axis of bolt
C. Be normal to threaded portion of shank
D. Never be across the threaded portion
Answer : D

48. When a belt drive is transmitting maximum power,
A. Effective tension is equal to centrifugal tension
B. Effective tension is half of centrifugal tension
C. Driving tension on slack side is equal to centrifugal tension
D. Driving tension on tight side is twice the centrifugal tension
Answer : D

49. The number of slots in a 25 mm castle nut is
A. 8
B. 4
C. 2
D. 6
Answer : D

50. A column of length l is fixed at both ends. The equivalent length of the column is
A. l/2
B. l/?2
C. l
D. 2 l
Answer : A