1000+ Machine Design MCQ for XAT [Solved]

1. 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

2. 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

3. A coupling used to connect two perfectly aligned shafts, is
A. Muff coupling
B. Compression coupling
C. Flange coupling
D. All of these
Answer : D

4. If P1 and P2 are the tight and slack side tensions in the belt, then the initial tension Pi (according to Barth) will be equal to
A. [(?P1 + ?P2)/2]²
B. P1 + P2
C. ?2 × (P1 + P2)
D. [?2 × (P1 + P2)] + Pc Where Pc is centrifugal tension
Answer : A

5. Resilience of a material is important, when it is subjected to
A. Combined loading
B. Fatigue
C. Thermal stresses
D. Shock loading
Answer : D

6. The ratio of driving tensions in V-belt drives is __________ flat belt drives.
A. Equal to
B. sin? times more than
C. sin? times less than
D. cosec? times more than
Answer : D

7. 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

8. 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

9. 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

10. The temperature required for full annealing in hypereutectoid steel is
A. 50°C above upper critical temperature
B. 50°C below upper critical temperature
C. 50°C above lower critical temperature
D. 50°C below lower critical temperature
Answer : A

11. 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

12. 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

13. If the tearing efficiency of a riveted joint is 75%, then the ratio of diameter of rivet to the pitch is equal to
A. 0.2
B. 0.25
C. 0.50
D. 0.6
Answer : B

14. In the levers of third type, the mechanical advantage is __________ one.
A. Less than
B. Equal to
C. More than
D. None of these
Answer : A

15. When bevel gears having equal teeth and equal pitch angles connect two shafts whose axes intersect at right angle, then they are known as
A. Angular bevel gears
B. Crown bevel gears
C. Internal bevel gears
D. Mitre gears
Answer : D

16. Rankine Gordon formula for buckling is valid for
A. Long column
B. Short column
C. Short and long column
D. Very long column
Answer : C

17. The velocity of sliding ________ the distance of the point of contact from the pitch point.
A. Is directly proportional to
B. Is inversely proportional to
C. Is equal to cos ? multiplied by
D. Does not depend upon
Answer : A

18. 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

19. An imaginary circle which by pure rolling action gives the same motion as the actual gear, is called
A. Addendum circle
B. Dedendum circle
C. Pitch circle
D. Clearance circle
Answer : C

20. The included angle for the British Association thread is
A. 29°
B. 55°
C. 47.3°
D. 60°
Answer : B

21. A type of brake commonly used in motor cars is a
A. Shoe brake
B. Band and block brake
C. Band brake
D. Internal expanding brake
Answer : D

22. A taper key which fits half in the key way of the hub and half in the key way of shaft, is known as
A. Angular bevel gears
B. Mitre gears
C. Crown Bevel gears
D. Internal bevel gears
Answer : B

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

24. The fatigue stress concentration factor is defined as
A. The ratio of endurance limit with stress concentration to the endurance limit without stress concentration
B. The ratio of endurance limit without stress concentration to the endurance limit with stress concentration
C. The product of the endurance limits with and without stress concentration
D. All of the above
Answer : B

25. 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

26. A spring of stiffness 1000 N/m is stretched initially by 100 mm from the undeformed position. The work required to stretch it by another 100 mm is
A. 5 N-m
B. 7 N-m
C. 10 N-m
D. 15 N-m
Answer : D

27. 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

28. 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

29. 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

30. In thrust bearings, the load acts
A. Along the axis of rotation
B. Parallel to the axis of rotation
C. Perpendicular to the axis of rotation
D. In any direction
Answer : A

31. According to Indian standard specifications, a grey cast iron designated by 'FG 200' means that the
A. Carbon content is 2%
B. Maximum compressive strength is 200 N/mm²
C. Minimum tensile strength is 200 N/mm²
D. Maximum shear strength is 200 N/mm²
Answer : C

32. 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

33. The design calculations for members subject to fluctuating loads with the same factor of safety, yield the most conservative estimates when using
A. Gerber relation
B. Soderberg relation
C. Goodman relation
D. None of these
Answer : C

34. 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

35. 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
Answer : C

36. Which is positive drive?
A. Flat belt drive
B. V-belt drive
C. Crossed belt drive
D. Timing belt
Answer : D

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

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

39. The maximum efficiency of a square threaded screw is
A. (1 - sin?)/ (1 + sin?)
B. (1 + sin?)/ (1 - sin?)
C. (1 - sin?)/ (1 + cos?)
D. (1 + cos?)/ (1 - sin?)
Answer : A

40. A tapered key which fits in a key way in the hub and the bottom of which is shaped to fit the curved surface of the shaft, is known as,
A. Hollow saddle key
B. Hollow key
C. Soft key
D. None of these
Answer : A

41. In designing a key, it is assumed that the distribution of forces along the length of key
A. Varies linearly
B. Is uniform throughout
C. Varies exponentially, being more at the torque-input end
D. Varies exponentially, being less at the torque-input end
Answer : B

42. 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

43. Which of the following spring is used in mechanical wrist watch?
A. Helical compression spring
B. Spiral spring
C. Torsion spring
D. Belleville spring
Answer : C

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

45. Wahl's stress factor __________ very rapidly as the spring index decreases.
A. Increases
B. Decreases
C. Remain same
D. None of these
Answer : A

46. For tight leakage joints, following type of thread is best suited
A. Metric
B. Buttress
C. Square
D. NPT (national pipe threads)
Answer : D

47. 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

48. In designing a flange coupling, the pitch circle diameter of bolts is taken as (where d = Diameter of the shaft)
A. 2d
B. 3d
C. 4d
D. 5d
Answer : B

49. Basic shaft 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 : A

50. The process extensively used for making bolts and nuts is
A. Hot piercing
B. Extrusion
C. Cold peening
D. Cold heading
Answer : D