1000+ Machine Design Multiple Choice Question Answer [Solved]

1. 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

2. In a flange coupling, the flanges are coupled together by means of
A. Bolts and nuts
B. Studs
C. Headless taper bolts
D. None of these
Answer : A

3. A sliding bearing which operates without any lubricant present, is called
A. Zero film bearing
B. Boundary lubricated bearing
C. Hydrodynamic lubricated bearing
D. Hydrostatic lubricated bearing
Answer : A

4. 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

5. If threads on a bolt are left hand, threads on nut will be
A. Right hand with same pitch
B. Left hand with same pitch
C. Could be left or right hand
D. Right hand with fine pitch
Answer : B

6. Two shafts A and B are made of the same material. The diameter of shaft A is twice as that of shaft B. The power transmitted by the shaft A will be __________ of shaft B.
A. Twice
B. Four times
C. Eight times
D. Sixteen times
Answer : C

7. The most important dimension in the design of a nut is
A. Pitch diameter
B. Inside diameter
C. Outside diameter
D. Height
Answer : D

8. 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

9. 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

10. A triple riveted butt joint with double straps of unequal width is to be designed for a boiler shell. The pitch of the rivets in the outer row is double the pitch in the inner row and zigzag riveting is proposed. Which of the following statement is correct?
A. There are four rivets per pitch length, all in double shear
B. There are four rivets per pitch length, out of which two are in single shear and two are in double shear
C. There are five rivets per pitch length, all in double shear
D. There are five rivets per pitch length, out of which four are in double shear and one is in single shear
Answer : D

11. 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

12. When screw threads are to be used in a situation where power is being transmitted in one direction only, then the screw threads suitable for this will be
A. Knuckle threads
B. Square threads
C. Acme threads
D. Buttress threads
Answer : D

13. The initial tension (in newtons) in a bolt used for making a fluid tight joint like steam engine cover joints, is calculated by the relation (where d = Nominal diameter of bolt in mm)
A. 1420 d
B. 1680 d
C. 2080 d
D. 2840 d
Answer : D

14. In skew bevel gearing, the axes of shafts are
A. Intersecting and the teeth are curved
B. Non-intersecting and nonparallel and the teeth are curved
C. Non-intersecting and non-parallel and the teeth are straight
D. None of the above
Answer : C

15. The ball bearings are provided with a cage
A. To reduce friction
B. To facilitate slipping of balls
C. To prevent the lubricant from flowing out
D. To maintain the balls at a fixed distance apart
Answer : D

16. The arms of the pulleys for flat belt drive have
A. Elliptical cross-section
B. Major axis in plane of rotation
C. Major axis twice the minor axis
D. All the three characteristics
Answer : D

17. A shaft is subjected to fluctuating loads for which the normal torque (T) and bending moment (M) are 1000 N-m and 500 N-m respectively. If the combined shock and fatigue factor for bending is 1.5 and combined shock and fatigue factor for torsion is 2, then the equivalent twisting moment for the shaft is
A. 2000 N-m
B. 2050 N-m
C. 2100 N-m
D. 2136 N-m
Answer : D

18. 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

19. 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

20. The fatigue life of a part can be improved by
A. Electroplating
B. Polishing
C. Coating
D. Shot peening
Answer : D

21. Taper usually provided on cotter is
A. 1 in 5
B. 1 in 10
C. 1 in 24
D. 1 in 40
Answer : C

22. An Involute pinion and gear are in mesh. If both have the same size of addendum, then there will be interference between the
A. Tip of the pinion and flank of gear
B. Tip of the gear and flank of pinion
C. Flanks of both gear and pinion
D. Tip of both gear and pinion
Answer : B

23. In case of pressure vessels having closed ends, the fluid pressure induces
A. Longitudinal stress
B. Shear stress
C. Circumferential stress
D. None of these
Answer : D

24. 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

25. 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

26. 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

27. 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

28. In order to ensure self locking in a screw jack, it is essential that helix angle is __________ friction angle.
A. Larger than
B. Smaller than
C. Equal to
D. None of these
Answer : B

29. 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

30. 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

31. 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

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

33. The cam follower extensively used in aircraft engines is
A. Knife edge follower
B. Flat faced follower
C. Spherical faced follower
D. Roller follower
Answer : D

34. 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

35. 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

36. If T? and T? are the tensions on the tight and slack sides of the belt respectively, and Tc is the centrifugal tension, then initial tension in the belt is equal to
A. T? - T? + Tc
B. T? + T? + Tc
C. (T? - T? + Tc)/2
D. (T? + T? + Tc)/2
Answer : D

37. For same pulley diameters, center distance, belt speed and belt and pulley materials,
A. Open belt drive transmits more power than crossed belt drive
B. Crossed belt drive transmits more power than open belt drive
C. Open and crossed belt drives transmit same power
D. Power transmission does not depend upon open and crossed types of constructions
Answer : B

38. 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

39. The included angle in unified of American National threads is
A. 60°
B. 55°
C. 47°
D. 29°
Answer : A

40. Screws used for power transmission should have
A. Very fine threads
B. High efficiency
C. Low efficiency
D. Strong teeth
Answer : B

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

42. For hardening alloy steels and high speed steels, they are heated to
A. 1100 to 1300°C
B. 1300 to 1500°C
C. 500 to 600°C
D. 700 to 900°C
Answer : A

43. When a closely coiled helical spring is subjected to a couple about its axis, the stress induced in the wire material of the spring is
A. Bending stress only
B. A combination of torsional shear stress and bending
C. Direct shear stress only
D. A combination of bending stress and direct shear stress
Answer : A

44. 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

45. While designing a screw in a screw jack against buckling failure, the end conditions for the screw are taken as
A. Both the ends fixed
B. Both the ends hinged
C. One end fixed and the other end hinged
D. One end fixed and the other end free
Answer : D

46. The suitable material for belt in agricultural machinery is
A. Leather
B. Rubber
C. Cotton duck
D. Balata gum
Answer : B

47. 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

48. According to I.B.R., shearing resistance required to shear off the rivet per pitch length (in double shear) is (where n = Number of rivets per pitch length)
A. (?/4) d² × ? × n
B. 1.875 × (?/4) d² × ? × n
C. 2 × (?/4) d² × ? × n
D. 3 × (?/4) d² × ? × n
Answer : B

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

50. The static tooth load should be __________ the dynamic load.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : C