Machine Design 1000+ MCQ with answer for SSC CGL

1. 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

2. In a boundary lubricated bearing, there is a __________ of lubricant between the journal and the bearing.
A. Thick film
B. Thin film
C. Either A or B
D. None of these
Answer : B

3. The property of a bearing material which has the ability to accomodate shaft deflections and bearing inaccuracies by plastic deformation without excessive wear and heating, is known as
A. Bondability
B. Embeddability
C. Comformability
D. Fatigue strength
Answer : C

4. 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

5. The metal suitable for bearings subjected to heavy loads is
A. White metal
B. Silicon bronze
C. Monel metal
D. Phosphor bronze
Answer : A

6. For a bevel gear having the pitch angle ?, the ratio of formative number of teeth (TE) to actual number of teeth (T) is
A. 1/sin?
B. 1/cos?
C. 1/tan?
D. sin? cos?
Answer : B

7. The building up of worn and undersized parts, subjected to repeated loads by electroplating is
A. Best method
B. Extremely hazardous
C. Has no effect as regards fatigue strength
D. Cheapest method
Answer : A

8. The design of shafts made of brittle materials is based on
A. Guest's theory
B. Rankine's theory
C. St Venant's theory
D. Von Mises theory
Answer : B

9. The draw of cotter should not be more than
A. 3 mm
B. 6 mm
C. 8 mm
D. 12 mm
Answer : A

10. 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
Answer : A

11. A backing ring is used inside the pipe joint when making a
A. Butt weld
B. Fillet weld
C. Sleeve weld
D. Socket weld
Answer : A

12. A double strap butt joint (with equal straps) is
A. Always in single shear
B. Always in double shear
C. Either in single shear or double shear
D. Any one of these
Answer : B

13. When the speed of belt increases,
A. The coefficient of friction between the belt and pulley decreases
B. The coefficient of friction between the belt and pulley increases
C. The power transmitted will decrease
D. The power transmitted will increase
Answer : C

14. 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

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

16. In unilateral system of tolerance, the tolerance is allowed on
A. Both sides of the actual size
B. One side of the actual size
C. One side of the nominal size
D. Both sides of the nominal size
Answer : C

17. Cast iron pipes are mainly used
A. For conveying steam
B. In water and sewage systems
C. In pressure lubrication systems on prime movers
D. All of the above
Answer : B

18. The backlash for spur gears depends upon
A. Module
B. Tooth profile
C. Both module and pitch line velocity
D. Pitch line velocity
Answer : C

19. A chain drive transmits __________ power as compared to belt drive.
A. More
B. Less
C. Same
D. None of these
Answer : A

20. The shock resistance of steel is increased by adding
A. Nickel
B. Chromium
C. Nickel and chromium
D. Cobalt and molybdenum
Answer : C

21. Residual stress in materials
A. Acts when external load is applied
B. Becomes zero when external load is removed
C. Is independent of external loads
D. Is always harmful
Answer : C

22. A leaf spring in automobiles is used
A. To apply forces
B. To measure forces
C. To absorb shocks
D. To store strain energy
Answer : C

23. Stress concentration factor is defined as the ratio of
A. Maximum stress to the endurance limit
B. Nominal stress to the endurance limit
C. Maximum stress to the nminal stress
D. Nominal stress to the maximum stress
Answer : C

24. Eulers formula for a mild steel column is not valid if the slenderness ratio is
A. 90
B. 60
C. 120
D. 100
Answer : B

25. The helix angle for single helical gears ranges from
A. 10° to 15°
B. 15° to 20°
C. 20° to 35°
D. 35° to 50°
Answer : C

26. The stiffness of a closely coiled helical spring subjected to an axial load W is equal to (where G = Modulus of rigidity, and n = Number of active coils)
A. Gd?/ 8D³n
B. Gd³/ 8D³n
C. Gd?/ 4D³n
D. Gd?/ 8D²n
Answer : A

27. The property of a material which enables it to resist fracture due to high impact loads is known as
A. Elasticity
B. Endurance
C. Strength
D. Toughness
Answer : D

28. Which of the following material has the maximum ductility?
A. Copper
B. Mild steel
C. Aluminium
D. Zinc
Answer : B

29. The yield point in static loading is __________ as compared to fatigue loading.
A. Higher
B. Lower
C. Same
D. None of these
Answer : A

30. The creep in the belt is due to
A. Effect of temperature on belt
B. Material of belt
C. Unequal extensions in the belt due to tight and slack side tensions
D. Stresses beyond elastic limit of belt material
Answer : C

31. 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

32. 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

33. 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

34. When two nonintersecting and non-coplanar shafts are connected by gears, the arrangement is known as
A. Spur gearing
B. Helical gearing
C. Bevel gearing
D. Spiral gearing
Answer : D

35. The material generally used for aircraft components is
A. Mild steel
B. High speed steel
C. Stainless steel
D. Aluminium
Answer : D

36. A spring is used to
A. Measure forces
B. Apply forces
C. Store energy
D. All of these
Answer : D

37. The effective stress in wire ropes during normal working is equal to the stress due to
A. Axial load plus stress due to bending
B. Acceleration/retardation of masses plus stress due to bending
C. Axial load plus stress due to acceleration/retardation
D. Bending plus stress due to acceleration/retardation
Answer : A

38. Ball bearing type screws are found in following application
A. Screw jack
B. Aeroplane engines
C. Crane
D. Steering mechanism
Answer : D

39. The shock absorbing capacity of a bolt may be increased by
A. Increasing its shank diameter
B. Decreasing its shank diameter
C. Tightening the bolt properly
D. Making the shank diameter equal to core diameter of thread
Answer : B

40. 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

41. When a nut is tightened by placing a washer below it, the bolt will be subjected to following type of loads
A. Compression
B. Tension
C. Shear
D. Combined loads
Answer : B

42. 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

43. The minimum number of teeth on the pinion which will mesh with any gear without interference for 20° full depth involute teeth will be
A. 12
B. 14
C. 18
D. 24
Answer : C

44. The bending stress in a curved beam is
A. Zero at the centroidal axis
B. Zero at the point other than centroidal axis
C. Maximum at the neutral axis
D. None of these
Answer : B

45. The stress in the threaded part of the bolt will be __________ as compared to the shank.
A. Same
B. Higher
C. Lower
D. None of these
Answer : B

46. The power transmitted by belt drive depends upon
A. Belt velocity br>B. Initial belt tension
C. Arc of contact
D. All of the above
Answer : D

47. The bearings of medium series have capacity __________ over the light series.
A. 10 to 20 %
B. 20 to 30 %
C. 30 to 40 %
D. 40 to 50 %
Answer : C

48. Stress concentration in cyclic loading is more serious in
A. Ductile materials
B. Brittle materials
C. Equally serious in both cases
D. Depends on other factors
Answer : A

49. If d is the normal diameter of a bolt in mm, then the initial tension in kg in a bolt used for making a fluid tight joint as for steam engine cover joint is calculated by the relation
A. 124 d
B. 138 d
C. 151 d
D. 168 d
Answer : D

50. When a bolt is subjected to shock loading, the resilience of the bolt should be considered in order to prevent breakage at the
A. Thread
B. Middle
C. Shank
D. Head
Answer : A