IBPS RRB - Theory of Machines 1000+ MCQ [Solved] PDF Download

1. The number of links in pantograph mechanism is equal to
A. 2
B. 3
C. 4
D. 5
Answer : C

2. V-belts are usually used for
A. Long drives
B. Short drives
C. Long and short drives
D. None of these
Answer : B

3. In a Hartnell governor, the lift of the sleeve is given by (where r? and r? = Max. and min. radii of rotation, x = Length of ball arm of the lever, and y = Length of sleeve arm of the lever)
A. (r? + r?) (y/x)
B. (r? + r?) (x/y)
C. (r? - r?) (y/x)
D. (r? - r?) (x/y)
Answer : C

4. Which of the following governor is used to drive a gramophone?
A. Watt governor
B. Porter governor
C. Pickering governor
D. Hartnell governor
Answer : C

5. The inversion of a mechanism is
A. Changing of a higher pair to a lower pair
B. Turning its upside down
C. Obtained by fixing different links in a kinematic chain
D. Obtained by reversing the input and output motion
Answer : C

6. Which of the following is an inversion of a single slider crank chain?
A. Pendulum pump
B. Oscillating cylinder engine
C. Rotary internal combustion engine
D. All of these
Answer : D

7. The balancing weights are introduced in planes parallel to the plane of rotation of the disturbing mass. To obtain complete dynamic balance, the minimum number of balancing weights to be introduced in different planes is
A. 1
B. 2
C. 3
D. 4
Answer : B

8. Throw of a cam is the maximum distance of the follower from
A. Base circle
B. Pitch circle
C. Root circle
D. Prime circle
Answer : A

9. The centre of gravity of a coupler link in a four bar mechanism will experience
A. No acceleration
B. Only linear acceleration
C. Only angular acceleration
D. Both linear and angular acceleration
Answer : D

10. In order to give a complete secondary balance of a multi-cylinder inline engine,
A. The algebraic sum of the secondary forces must be equal to zero
B. The algebraic sum of the couples about any point in the plane of the secondary forces must be equal to zero
C. Both (A) and (B)
D. None of these
Answer : C

11. Angle of dwell of cam is defined as the angle
A. During which the follower returns to its initial position
B. Of rotation of the cam for definite displacement of the follower
C. Through which the cam rotates during the period in which the follower remains in the highest position
D. Moved by the cam from the instant the follower begins to rise, till it reaches its highest position
Answer : C

12. The power from the engine to the rear axle of an automobile is transmitted by means of
A. Worm and worm wheel
B. Spur gears
C. Bevel gears
D. Hooke's joint
Answer : D

13. When the crank is at the inner dead centre, in a reciprocating steam engine, then the velocity of the piston will be
A. Minimum
B. Zero
C. Maximum
D. None of these
Answer : B

14. With usual notations for different parameters involved, the maximum fluctuations of energy for a flywheel is given by
A. 2EC_S
B. EC_S/2
C. 2EC_S²
D. 2E²C_S
Answer : A

15. When the nature of contact between the elements of a pair is such that one element can turn about the other by screw threads, the pair is known as a
A. Screw pair
B. Spherical pair
C. Turning pair
D. Sliding pair
Answer : A

16. When a point at the end of a link moves with constant angular velocity, its acceleration will have
A. Radial component only
B. Tangential component only
C. Coriolis component only
D. Radial and tangential components both
Answer : A

17. The frictional torque transmitted in a flat pivot bearing with assumption of uniform pressure is _________ as compared to uniform wear.
A. Less
B. More
C. Same
D. None of these
Answer : B

18. Which of the following is an open pair?
A. Ball and socket joint
B. Journal bearing
C. Lead screw and nut
D. Cam and follower
Answer : A

19. The equation of motion for a single degree of freedom system with viscous damping is 4(dx²/dt²) + 9(dx/dt) + 16x. The damping ratio of the system is
A. 9/8
B. 9/82
C. 9/16
D. 9/128
Answer : C

20. In order to facilitate starting of locomotive in any position, the cranks of a locomotive with two cylinders, are placed at
A. 45° to each other
B. 90° to each other
C. 120° to each other
D. 180° to each other
Answer : B

21. When two pulleys are connected by means of a cross belt drive, then both the pulleys will rotate in __________ directions.
A. Same
B. Opposite
C. Perpendicular
D. None of these
Answer : B

22. For dynamic balancing of a shaft
A. The net dynamic force acting on the shaft is equal to zero
B. The net couple due to the dynamic forces acting on the shaft is equal to zero
C. Both (A) and (B)
D. None of the above
Answer : C

23. The size of cam depends upon
A. Base circle
B. Pitch circle
C. Prime circle
D. Pitch curve
Answer : A

24. The frictional torque transmitted in a conical pivot bearing, considering uniform pressure, is (where R = Radius of shaft, and ? = Semi-angle of the cone)
A. (1/2) ? W R cosec?
B. (2/3) ? W R cosec?
C. (3/4) ? W R cosec?
D. ? W R cosec?
Answer : B

25. A body of weight W is required to move up the rough inclined plane whose angle of inclination with the horizontal is ?. The effort applied parallel to the plane is given by (where ? = tan ? = Coefficient of friction between the plane and the body)
A. P = W tan ?
B. P = W tan (? + ?)
C. P = W (sin ? + ? cos ?)
D. P = W (cos ? + ? sin ?)
Answer : C

26. Balancing of rotating and reciprocating parts of an engine is necessary when it runs at
A. Slow speed
B. Moderate speed
C. Highs peed
D. Any one of these
Answer : C

27. In a reciprocating steam engine, when the crank has turned from inner dead centre through an angle ?, the angular velocity of the connecting rod is given by
A. ? sin?/(n² - sin²?)^1/2
B. ? cos?/(n² - cos²?)^1/2
C. ? sin?/(n² - cos²?)^1/2
D. ? cos?/(n² - sin²?)^1/2
Answer : D

28. The amplitude of vibration is always __________ the radius of the circle.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : A

29. When a mass of a critically damped single degree of freedom system is deflected from its equilibrium position and released, then it will
A. Return to equilibrium position without oscillation
B. Oscillate with increasing time period
C. Oscillate with decreasing amplitude
D. Oscillate with constant amplitude
Answer : B

30. The primary unbalanced force is maximum when the angle of inclination of the crank with the line of stroke is
A. 0° and 90°
B. 0° and 180°
C. 90° and 180°
D. 180° and 360°
Answer : B

31. The relation l = (2/3).(j + 2) apply only to kinematic chains in which lower pairs are used. This may be used to kinematic chains in which higher pairs are used, but each higher pair may be taken as equivalent to
A. One lower pair and two additional links
B. Two lower pairs and one additional link
C. Two lower pairs and two additional links
D. Any one of these
Answer : B

32. In vibration isolation system, the transmissibility will be equal to unity, for all values of damping factor, if ?/?n is
A. Equal to 1
B. Equal to 2
C. Less than 2
D. Greater than 2
Answer : B

33. What is the number of instantaneous centres for an eight link mechanism?
A. 15
B. 28
C. 30
D. 8
Answer : B

34. Angle of descent of cam is defined as the angle
A. During which the follower returns to its initial position
B. Of rotation of the cam for a definite displacement of the follower
C. Through which the cam rotates during the period in which the follower remains in the highest position
D. Moved by the cam from the instant the follower begins to rise, till it reaches its highest position
Answer : A

35. The equation of motion for a vibrating system with viscous damping is (d²x/dt²) + (c/m).(dx/dt) + (s/m).x = 0, if the roots of the equation are __________ then the system will be under damped.
A. Equal
B. Real
C. Complex conjugate
D. None of these
Answer : C

36. The ratio of the number of teeth to the pitch circle diameter in millimetres, is called
A. Circular pitch
B. Diametral pitch
C. Module
D. None of these
Answer : B

37. When the pitching of a ship is upward, the effect of gyroscopic couple acting on it will be
A. To move the ship towards starboard
B. To move the ship towards port side
C. To raise the bow and lower the stern
D. To raise the stern and lower the bow
Answer : A

38. The displacement of the D-slide valve is __________ the steam lap by a distance known as lead of the valve.
A. Greater than
B. Less than
C. Equal to
D. None of these
Answer : A

39. Governor is used in automobile to
A. Decrease the variation of speed
B. Maximize the fuel economy
C. Limit the vehicle speed
D. Maintain constant engine speed
Answer : C

40. Sense of tangential acceleration of a link
A. Is same as that of velocity
B. Is opposite to that of velocity
C. Could be either same or opposite to velocity
D. Is perpendicular to that of velocity
Answer : C

41. In vibration isolation system, if ?/?n < 2, then for all values of damping factor, the transmissibility will be (where ? = Angular speed of the system, ?n = Natural frequency of vibration of the system)
A. Less than unity
B. Equal to unity
C. Greater than unity
D. Zero
Answer : C

42. A fixed gear having 200 teeth is in mesh with another gear having 50 teeth. The two gears are connected by an arm. The number of turns made by the smaller gear for one revolution of arm about the centre of bigger gear is
A. 2
B. 3
C. 4
D. 5
Answer : C

43. The mechanism forms a structure, when the number of degrees of freedom (n) is equal to
A. 0
B. 1
C. 2
D. -1
Answer : A

44. Cylindrical cams can be classified as
A. Circular
B. Tangent
C. Reciprocating
D. None of the above
Answer : D

45. A spring controlled governor is said to be isochronous when the controlling force
A. Increases as the radius of rotation decreases
B. Increases as the radius of rotation increases
C. Decreases as the radius of rotation increases
D. Remain constant for all radii of rotation
Answer : D

46. Minimum number of teeth for involute rack and pinion arrangement for pressure angle of 20° is
A. 18
B. 20
C. 30
D. 34
Answer : A

47. An eccentric sheave pivoted at one point rotates and transmits oscillatory motion to a link whose one end is pivoted and other end is connected to it. This mechanism has
A. 2 links
B. 3 links
C. 4 links
D. 5 links
Answer : C

48. The locus of a point on a thread unwound from a cylinder will be
A. A straight line
B. A circle
C. Involute
D. Cycloidal
Answer : C

49. The indicator using Watt mechanism is known as
A. Thompson indicator
B. Richard indicator
C. Simplex indicator
D. Thomson indicator
Answer : B

50. In a gear having involute teeth, the normal to the involute is a tangent to the
A. Pitch circle
B. Base circle
C. Addendum circle
D. Dedendum circle
Answer : B