1000+ Machine Design MCQ for LSAT [Solved]

1. In the calculation of induced shear stress in helical springs, the Wahl's stress factor is used to take care of
A. Combined effect of transverse shear stress and bending stress in the wire
B. Combined effect of bending stress and curvature of the wire
C. Combined effect of transverse shear stress and curvature of wire
D. Combined effect of torsional shear stress and transverse shear stress in the wire
Answer : B

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

3. The notch angle of the Izod impact test specimen is
A. 10°
B. 20°
C. 30°
D. 45°
Answer : D

4. Stress concentration is caused due to
A. Variation in properties of material from point to point in a member
B. Pitting at points or areas at which loads on a member are applied
C. Abrupt change of section
D. All of the above
Answer : D

5. In static loading, stress concentration is more serious in
A. Brittle materials
B. Ductile materials
C. Brittle as well as ductile materials
D. Elastic materials
Answer : A

6. When compared to the rod of the same diameter and material, a wire rope
A. Is less flexible
B. Has a much smaller load carrying capacity
C. Does not provide much warning before failure
D. Provides much greater time for remedial action before failure
Answer : B

7. 18/8 steel contains
A. 18% nickel and 8% chromium
B. 18% chromium and 8% nickel
C. 18% nickel and 8% vanadium
D. 18% vanadium and 8% nickel
Answer : B

8. A connecting rod is designed as a
A. Long column
B. Short column
C. Strut
D. All of these
Answer : C

9. In worm gears, the pressure angle is ________ the angle between two inclined faces in axial plane.
A. Half
B. Twice
C. Thrice
D. None of these
Answer : A

10. Which of the following pipe joints would be suitable for pipes carrying steam?
A. Flanged
B. Threaded
C. Bell and spigot
D. Expansion
Answer : D

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

12. The circumferential and longitudinal strains in a cylindrical boiler under internal steam pressure are ?c and ?l respectively. The change in volume of the boiler cylinder per unit volume will be
A. ?_c + 2?_l
B. 2?_c + ?_l
C. ?_c + ?_l²
D. ?_c² + ?_l
Answer : B

13. In designing a sleeve coupling, length of the sleeve is taken as (where d = Diameter of the shaft)
A. d + 17 mm
B. 2d + 13 mm
C. 2d + 20 mm
D. 3.5d
Answer : D

14. Which of the following is a permanent fastening?
A. Bolts
B. Keys
C. Cotters
D. Rivets
Answer : D

15. The belt slip occurs due to
A. Heavy load
B. Loose belt
C. Driving pulley too small
D. Any one of the above
Answer : D

16. Resistance to fatigue of a material is measured by
A. Young's modulus
B. Coefficient of elasticity
C. Elastic limit
D. Endurance limit
Answer : D

17. The dedendum circle diameter is equal to (where ? = Pressure angle)
A. Pitch circle diameter × cos?
B. Addendum circle diameter × cos?
C. Clearance circle diameter × cos?
D. Pitch circle diameter × sin?
Answer : A

18. In block brakes, the ratio of shoe width to wheel diameter is taken between
A. 0.1 and 0.25
B. 0.25 and 0.50
C. 0.50 and 0.75
D. 0.75 and 1
Answer : B

19. 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

20. In nitrated parts, the origins of the fatigue cracks will occur at
A. Surface
B. Just below the surface
C. Within the core
D. None of the above
Answer : D

21. In a multiple V-belt drive, when a single belt is damaged, it is preferable to change the complete set in order to
A. Reduce vibration
B. Reduce slip
C. Ensure uniform loading
D. Ensure proper alignment
Answer : C

22. Lewis equation in gears is used to find the
A. Tensile stress in bending
B. Shear stress
C. Compressive stress in bending
D. Fatigue stress
Answer : C

23. A sliding bearing which can support steady loads without any relative motion between the journal and the bearing, is called
A. Hydrostatic lubricated bearing
B. Hydrodynamic lubricated bearing
C. Boundary lubricated bearing
D. Zero film bearing
Answer : A

24. A bolt of M 24 × 2 means that
A. The pitch of the thread is 24 mm and depth is 2 mm
B. Cross-sectional area of the threads is 24 mm²
C. The nominal diameter of bolt is 24 mm and pitch is 2 mm
D. The effective diameter of bolt is 24 mm and there are 2 threads per cm
Answer : C

25. In cross or regular lay ropes
A. Direction of twist of wires in strands is opposite to the direction of twist of strands
B. Direction of twist of wires and strands are same
C. Wires in two adjacent strands are twisted in opposite direction
D. Wires are not twisted
Answer : A

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. Deep groove ball bearings are used for
A. Heavy thrust load only
B. Small angular displacement of shafts
C. Radial load at high speed
D. Combined thrust and radial loads at high speed
Answer : D

28. Which of the following statement is correct?
A. The cold rolled shafting is stronger than hot rolled shafting
B. The hot rolled shafting is stronger than cold rolled shafting
C. The cold rolled and hot rolled shaftings are equally strong
D. The shafts are not made by rolling process
Answer : A

29. The pitch diameter is the __________ diameter of an external or internal screw thread.
A. Effective
B. Smallest
C. Largest
D. None of these
Answer : A

30. The pipe joint mostly used for pipes carrying water at low pressures is
A. Socket joint
B. Nipple joint
C. Union joint
D. Spigot and socket joint
Answer : A

31. The permissible stress for carbon steel under static loading is generally taken as
A. 2000-3000 kg/m²
B. 3000-4000 kg/cm²
C. 4000-4500 kg/cm²
D. 7500-10,000 kg/cm²
Answer : C

32. 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

33. In a band and block brake, the ratio of tensions on the tight and slack sides of band is given by (where ? = Coefficient of friction between the blocks and the drum, ? = Semi-angle of each block subtending at the centre of drum, and n = Number of blocks)
A. T?/T? = ?? × n
B. T?/T? = (??)ⁿ
C. T?/T? = [(1 - ? tan?)/ (1 + ? tan?)]ⁿ
D. T?/T? = [(1 + ? tan?)/ (1 - ? tan?)]ⁿ
Answer : D

34. For circumferential joint in boilers, the type of joint used is
A. Butt joint with single cover plate
B. Butt joint with double cover plate
C. Lap joint with one ring overlapping the other
D. Any one of the above
Answer : C

35. In order to determine the stresses in a thin cylinder due to an internal pressure, it is assumed that
A. The effect of curvature of the cylinder wall is neglected
B. The tensile stresses are uniformly distributed over the section of the walls
C. The effect of the restraining action of the heads at the end of the pressure vessel is neglected
D. All of the above
Answer : D

36. 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

37. The difference between the tooth space and the tooth thickness as measured on the pitch circle, is called
A. Working depth
B. Clearance
C. Backlash
D. Face width
Answer : C

38. 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

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

40. Form coefficient of spring is
A. Ratio of coil diameter to wire diameter
B. Load required to produce unit deflection
C. Its capability of storing energy
D. Concerned with strength of wire of spring
Answer : C

41. For applications involving high stresses in one direction only the following type of thread would be best suited
A. ISO metric thread
B. Acme thread
C. Square thread
D. Buttress thread
Answer : D

42. 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

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 stress induced in the belt is,
A. Tensile stress
B. Compressive stress
C. Direct shear stress
D. Torsional shear stress
Answer : A

45. 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

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

47. The cracks in helical springs used in railway carriages usually start on the inner side of the coil because of the fact that
A. It is subjected to a higher cyclic loading than the outer side
B. It is subjected to a higher stress than the outer side
C. It is more stretched than the outer side during the manufacturing process
D. It has a lower curvature than the outer side
Answer : A

48. 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

49. In a steam engine, the piston rod is usually connected to the crosshead by means of a
A. Knuckle joint
B. Cotter joint
C. Oldham coupling
D. Universal joint
Answer : B

50. According to Indian standard specifications, 100 H6/g5 means that the
A. Basic size is 100 mm
B. Actual size is 100 mm
C. Difference between the actual size and basic size is 100 mm
D. None of the above
Answer : A