# Machine Design MCQ (Multiple Choice Questions)

1. In machine design, which of the following joins two rotating shafts to each other?
a) Key
b) Coupling
c) Gear
d) Belt drive

Explanation: Key is a device which joins a machine element to a shaft. Gears and belt drives are devices which are used to transfer power from one shaft to another. Couplings are used to join two rotating shafts.

2. Which of the following is true with respect to hollow and solid shafts in machine design?
a) Hollow shafts are costlier than solid shafts
b) Stiffness of a solid shaft is more than hollow shaft
c) Strength of hollow shaft is less than solid shaft
d) Hollow shafts are cheaper than solid shafts

Explanation: Hollow and solid shafts are two types of shafts that are commonly used. The space required by a hollow shaft is more than solid ones. Stiffness of a hollow shaft is more as compared with solid shaft. Also, strength of hollow shafts are more than solid shafts.

3. which of the following coupling is used to connect two parallel shafts when they are at a small distance apart?
a) Hooke’s coupling
b) Rigid coupling
c) Muff coupling
d) Oldham’s coupling

Explanation: Hooke’s or universal coupling is used to connect two shafts with intersecting axes, rigid couplings for collinear shafts and oldham’s coupling for shafts which are placed at a small distance apart. Muff coupling is a type of rigid coupling.

4. Which of the following expression is not correct for designing a shaft according to rigidity?
a) T = GθJ / L
b) J = TL / Gθ
c) θ = TL / GJ
d) L = GθT / J

Explanation: According to shaft design on rigidity basis, the following expression is used: T / J = Gθ / L, where J: polar moment of inertia, T: torsional moment, θ: angle of twist, L: length of shaft, G: modulus of rigidity.

5. What are the two types of rigid flange couplings in machine design?
a) Stable and unstable
b) Flexible and non-flexible
c) Protected and unprotected
d) Deformable and non-deformable

Explanation: Rigid flange coupling have flanges and a nut bolt arrangement and cannot tolerate any mis-alignment between shafts and are used to transmit high torques. They are of two types: protected and unprotected type.

6. What will be the diameter of a bolt (in mm), if the total number of bolts is 4 and shaft has a diameter of 10 mm in a flexible coupling?
a) 2
b) 2.5
c) 5
d) 1.25

Explanation: To calculate the diameter of bolt in a flexible coupling, we have, db=0.5 d / sqrt N, where, db :bolt diameter (mm), N: number of bolts, d: shaft diameter (mm).

7. What will be the Wahl factor, if coil and wire diameters are 60 and 12 mm, respectively?
a) 0.998
b) 1.064
c) 0.752
d) 1.310

Explanation: The spring index is calculated by C = 60 / 12 = 5. Further, the Wahl factor is given by K= (4C-1 / 4C-4) + (0.615 / C), which gives K= 1.310.

8. Which of the following is not the function of a spring in machine design?
a) They are used for the measurement of force and to control motion
b) They are used to absorb shocks and vibrations
c) They are used to store energy
d) They are used to measure displacement

Explanation: Spring is a mechanical device which changes its size under deflection due to the application of force and regains its original size when the load is removed. The functions of a spring are to measure forces such as in spring balance, absorb shocks , and are also used to store energy.

9. Which of the following is not true for rigid and flexible couplings?
a) Rigid couplings are expensive than flexible couplings
b) Flexible couplings can tolerate any slight misalignment between axes of shafts
c) Flexible couplings can absorb shocks and vibrations
d) Rigid couplings cannot tolerate slight misalignment between axes of shafts

Explanation: Rigid couplings are inexpensive as compared to flexible couplings. Flexible couplings are provided with additional safety parts such as bushes to absorb shock and vibrations. Rigid couplings cannot tolerate any misalignment between the axes of shafts.

10. Which of the following materials are subjected to most severe stress concentration?
a) Ductile materials under fluctuating load
b) Brittle materials under static and fluctuating load
c) Brittle materials under fluctuating load
d) Ductile materials under static load

Explanation: The stress concentration effects is most severe in brittle materials due to their inability for plastic deformation. However, in ductile materials, until the material do not reach yield point, there is no stress concentration.

11. In machine design, which of the following is not true for a good coupling?
a) It should be capable for transmitting power from one shaft to another
b) It should keep shafts in proper alignment
c) It should be easy to assemble and disassemble for repair and maintenance
d) If there is small misalignment between the shafts, the coupling cannot transmit power

Explanation: A coupling is a device which is used to connect two shafts rigidly and transmit power from one shaft to another shaft. The requirements of a good coupling is to transmit power even if there is small misalignment, a coupling should be easy to assemble and disassemble for maintenance purpose.

12. Which of the following line is the most economical in machine design?
a) Goodman line
b) Soderberg line
c) Gerber parabola
d) Lagrange line

Explanation: As soderberg line is the most safest line, the cost required to design according to this criteria will be more, followed by goodman line and gerber parabola.

13. Which type of failures does modified goodman line combines?
a) Fatigue and yield
b) Bending and fatigue
c) Yield and bending
d) Fatigue, bending and yield

Explanation: Modified goodman line is a modified version of goodman line. The failure point ‘Sut’ on mean stress axis is shifted to ‘Syt’ for the safety of the component with the help of Lagrange’s line which joins ‘Syt’ on both y and x axes.

14. In machine design, which of the following mechanical device transfers or multiplies load with an application of small effort?
a) Gears
b) Shafts
c) Levers
d) Bearings

Explanation: Levers are mechanical devices in the form a rigid bar which multiplies or transfer the force with a small effort with the help of a fulcrum.

15. Which of the following coupling consists of only sleeve and a key?
a) Muff coupling
b) Flexible coupling
c) Rigid coupling
d) Universal coupling

Explanation: Rigid couplings or flexible coupling have flanges and a nut bolt arrangement. Universal couplings have two intersecting forks, collars, centre block, pins and are used to connect two intersecting shafts. Muff coupling have a sleeve and a key arrangement.

a) Taper roller bearing
b) Thrust ball bearing
c) Angular contact bearing
d) Deep groove ball bearing

Explanation: Taper roller bearing, angular contact bearing and deep grove ball bearing can take loads in both the directions, axial as well as in radial. Thrust ball bearing can take only axial loads.

17. Which theory of failure is mostly used for ductile materials in machine design?
a) Maximum principal stress theory
b) Maximum shear stress theory
c) Distortion energy theory
d) Haigh’s theory

Explanation: For brittle materials, maximum principal stress theory is used as brittle components fail by fracture instead of yielding. Further, Haigh’s theory is related with maximum strain energy. For ductile materials, maximum shear stress theory is used as yielding is the failure criterion. Distortion energy theory is also used for ductile materials, only if the components require close dimensional accuracy.

18. Which of the following forms of thread can transmit power in only one direction?

Explanation: Buttress threads have a thread angle of 45 degrees, which are only inclined in one given direction, so the power is transmitted in that direction only. Acme, trapezoidal and square threads can transmit power in either directions.

19. Which of the following line is the safest in machine design?
a) Goodman line
b) Soderberg line
c) Gerber parabola
d) Lagrange line

Explanation: As gerber parabola represents the average of all failure points, the region below and above the parabola is not safe. The region below the goodman line is safe, but the region above it consists of some failure points.There are no failure points below and above the soderberg line, so, it is the safest.

20. In machine design, suppose if load applied ‘P’ becomes zero while lowering the load ‘W’ in the case of a power screw, which of the condition should be correct so that the load applied does not becomes zero ( θ: Angle of inclination of load with respect to horizontal, ϕ: friction angle)?
a) θ > ϕ
b) θ < ϕ
c) θ = ϕ
d) θ ≤ ϕ

Explanation: For lowering the load, we have, P= W tan (θ – ϕ). If load applied becomes zero, then, W ≠ 0 and θ = ϕ. For P ≠ 0, θ > ϕ. If, θ < ϕ, then ‘P’ becomes negative, which is absurd.

21. In machine design, if in a helical spring, load ‘P’ is applied, such that there is total compression, then the corresponding length is known as ?
a) Free length
b) Solid length
c) Compressed length
d) Combined free and solid length

Explanation: If a load is applied such that spring is totally compressed, then there will be negligible distance between corresponding coils. Hence, the length is referred to be as solid length. Free length is the length when no load acts on a spring.

22. Which of the following terms are involved for calculating equivalent torsional moment when a shaft is subjected to fluctuating loads?
a) kb Mb and Mt kt
b) Only kb Mb
c) Only kt Mt
d) Mb and Mt

Explanation: When a shaft is subjected with fluctuating loads, then the equivalent torsional moment , is given by: sqrt (kb Mb)2 + (kt Mt)2, where kb and kt are combined shock and fatigue factor for bending and torsional moments, respectively and Mb and Mt are bending and torsional moments, respectively.

23. In machine design, while calculating the diameter of shaft according to maximum shear stress theory, which of the following diagrams will be mostly needed?
a) Bending moment diagram only
b) Shear force and bending moment diagrams
c) Bending moment and load diagrams
d) Bending moment, shear force and load diagrams

Explanation: To calculate the diameter of shaft according to maximum shear stress theory, the expression is given by, d3 = 16 T / π ζmax $$\sqrt{(k_b M_b)^2 + (k_t M_t)^2 }$$, ζmax is mostly known or given, Mt can be directly calculated according to shaft design by rigidity, Mb which is bending moment needs to be calculated according to different loads applied on the system, so, in most cases bending moment and load diagrams are only needed.

24. What will be the value for the equivalent stiffness (Keq) of a spring system, if two springs are connected in parallel and stiffnesses are 50 and 40 N/m, respectively?
a) 22.22 N/m
b) 90 N/m
c) 10 N/m
d) 5.71 N/m

Explanation: If two springs are in parallel, then, equivalent stiffness, is given by, Keq = K1 + K2, which gives K = 90 N/m.

25. Which of the following elements transfers torque and is only subjected with bending moment?
a) Brake
b) Clutch
c) Axle
d) Belt drive

Explanation: An axle is a machine element which supports rotating elements such as wheels, and is subjected to bending moments due to transverse loads applied on them and transmits torque. An axle can be simply seen in the rear part of a vehicle, supporting rear wheels.

26. Which of the following is a disadvantage of welding?
a) Lighter structures
b) Very rigid joints
c) Greater strength
d) Inspection is easier

Explanation: Welding is simply a process of joining two or more metals by the application of heat and a filler material. They are lighter structures, the strength produced by them is very strong. Inspection is difficult and it requires skilled labour.

27. Which of the following in power screws is the correct equation for torque if the load is lowered ? ( W: Weight in N, θ: Angle of inclination, ϕ: Friction angle)
a) W tan (θ / ϕ)
b) W tan (θ x ϕ)
c) W tan (θ + ϕ)
d) W tan (θ – ϕ)

Explanation: When a torque is applied, the load moves down on the helical path of screw, which is the hypotenuse of triangle, lead the perpendicular distance and circumference the base of the triangle. By resolving the forces acting on the weight, we get, W tan (θ – ϕ).

28. Which of the following designation of bearing is correct for “6004” in machine design?
a) Deep grove medium bearing with a bore diameter of 4 mm
b) Double row angular bearing with a bore diameter of 20 mm
c) Deep grove extra light bearing with a bore diameter of 20 mm
d) Deep grove light bearing with a bore diameter of 4 mm

Explanation: The number “6” signifies the bearing must be a deep grove ball bearing. Further, the second number “0” designates an extra light bearing. According to the rule, if the last two numbers are 04 and above, the corresponding number must be multiplied by 5 to get the required bore diameter.

29. Which is not a possible type of failure in a riveted joint?
a) Crushing failure of the plate
b) Shear failure of rivet
c) Tensile failure of the plate between rivets
d) Shear failure of plate

Explanation: A riveted joint is a type of joint used to join two components or plates with the help of a rivet. The possible failures in the analysis of a riveted joint are mainly shear failure of rivet, crushing failure of the plate, and tensile failure of the plate between rivets.

30. What are the assumptions made by Stribeck to calculate the static load of a bearing?
a) Balls must be flexible
b) Balls may not be equally spaced
c) Balls in upper half do not support any load
d) Balls in upper half support the load

Explanation: For the calculation of static load for a ball and a roller bearing, the assumptions made by Stribeck were: Balls must be rigid and should be equally spaced. Further, the balls should not support any load.

31. What is the requirement to weld a butt joint?
a) The components must lie in the same plane
b) The components may not necessarily lie in the same plane
c) Bevelling is not required for components with a thickness less than 5 mm
d) There is no requirement to weld a butt joint

Explanation: Butt joint is a type of welded joint which is used when the components are placed by their ends are then welded and the two of them must lie in the same plane. Further, bevelling is required if the thickness of a component is less than 5 mm.

32. In machine design, which of the following is true about the roller bearing in comparison with ball bearing?
a) Power lost in friction is more
b) Axial dimensions are less
d) They have point contact

Explanation: Roller bearing is a bearing which uses cylindrical roller in most of the cases. Practically, the area of contact of roller is more as compared to ball, so, the heat lost in friction is more as compared to ball bearing.

33. Which of the following correctly symbolizes a fillet joint?
a) A right angled triangle
b) Two parallel lines with an arc above them
c) A triangle with an arc above it
d) A triangle

Explanation: A square butt designates, two parallel lines with an arc above them. A single V butt designates, a triangle with an arc above it. A simple triangle means a projection and a right angled triangle means a fillet joint.

34. In machine design, what is the number of teeths of worm gear in the following designation “2/20/10/8/150”?
a) 10
b) 20
c) 150
d) 2

Explanation: The number “2” designates the number of teeths of worm, “150” is the center distance between the worm and worm gear, “10” is the diametral quotient and “20” is the required number of teeths of a worm gear.

35. Which of the following is not a type of welding joint?
a) Lap joint
b) Butt joint
c) Tee joint
d) Single strap joint

Explanation: Lap joint is a joint in which welding is done by overlapping two components or plates. It may be of parallel or transverse type. Butt joint is done when two components are placed by their ends and welded. Tee joint is also a type of joint where components are placed perpendicular to each other and then welded at their intersections. Single strap joint is a type of rivet joint.

36. Which of the following is the function of rebound clips in a multi-leaf spring?
a) Helps to share the load from master leaf to graduated leaves
b) Hold all the leaves of the spring
c) Engage the bolts to clamp the leaves
d) Attach a member or component to

Explanation: Bolt holes are used to engage all the bolts for clamping. A central clamp is required to hold all the leaves, an eye for attaching a member and rebound clips to share the load from master to graduated leaves.

37. In machine design, how can be leverage calculated?
a) Load arm / Effort arm
d) Effort arm / Load arm

Explanation: In levers, mainly three terms are used: fulcrum, load and effort. The perpendicular distance from the line of action of load to fulcrum is known as load arm and distance from the line of action of effort to fulcrum is called effort arm. Further, the ratio of load to effort is known as Mechanical advantage and the ratio of effort arm to load arm is called Leverage.

38. In machine design, if the effort is located between the load and fulcrum, which type of lever it is?
a) First type
b) Second type
c) Third type
d) Fourth type

Explanation: If the fulcrum is located between load and effort, it is called first type of lever. If load is located between the fulcrum and effort, then it is of second type and for third class of lever, the effort must be between load and fulcrum.

39. Which of the following is not the cause of stress concentration?
a) Abrupt changes in cross-section
b) Discontinuity in the component
c) Machining scratches
d) Point load applied on the component

Explanation: Stress concentration is the development of high stresses due to changes in cross-section, irregularities and discontinuities in the component, machining scratches, etc which causes the separation of flow lines.

40. In machine design, which of the following straight line joins endurance limit(Se) on the stress amplitude axis and yield strength (Syt) on the mean stress axis?
a) Soderberg line
b) Modified goodman line
c) Gerber line
d) Goodman line

Explanation: Gerber line is a parabola joining Se on stress amplitude (y-axis) and Sut on mean stress (x-axis). A goodman line is a straight line which joins Se on y-axis and Sut on x-axis. A soderberg line is a straight line which joins Se on y-axis and Syt on x-axis. A modified goodman line is a combination of lagrange and goodman lines.

41. Which of the following shaft are the integrals or equally spaced lines made on a shaft?
a) Stepped shaft
b) Spline shaft
c) Cam shaft
d) Crankshaft

Explanation: Splines are a type of shaft in which there are equally spaced grooves mainly used to transmit high torque and due to the presence of grooves, the load is shared equally.

42. What is the thickness of components required to weld a V or U joint?
a) Less than 5 mm
b) 5 to 12 mm
c) 12.5 mm
d) Greater than 12.5 mm

Explanation: To weld square butt joint, components must be less than 5 mm thick. For double V or U joint, a thickness greater than 12.5 mm is required and for V or U joint thickness requirement is 5 to 12 mm.

43. Which of the following is a dominance of power screw?
b) High efficiency
c) Wear of screw is reduced

Explanation: A power screw is a mechanical device which can be used to lift or lower the heavy loads with the aid of a small effort and also for the transmission of power. It has a large load carrying capacity, simple to design, provides noiseless service. But, it has poor efficiency due to the power lost in friction. Further, due to friction, wear becomes a serious problem and mechanical advantage is increased as the effort applied is less.

44. In machine design, if in an eccentrically loaded bolted joint, there are nine bolts and a load ‘P’ is acting with an eccentricity ‘e’, then the primary shear force is given by?
a) P / 4
b) P
c) P / 9
d) P /18

Explanation: An eccentrically loaded bolted joint is an arrangement where a bracket and a load is applied vertically to the far end of bracket. Further, the bracket is connected to a support or wall with the help of bolts. In an eccentrically loaded bolted joint, the primary shear force is calculated by the ratio of load acting to the number of bolts given.

45. Which type of welding uses an oxygen-acetlyene gas?
a) Thermit welding
b) Electric arc welding
c) Gas welding
d) Forge welding

Explanation: In thermit welding, a mould is prepared and then thermit is placed to join the metals. In electric arc, an arc is used to heat and join the parts of metal. Forge welding uses an impact force for joining of metals. In gas welding, oxy-acetylene gas is burned in the presence of a torch to create a pointed flame.

46. Which of the following is not a type of transmission shaft?
a) Crankshaft
b) Countershaft
c) Transmission shaft
d) Line shaft

Explanation: Transmission shaft is a shaft used for the transmission of power from source to an application (eg: a machine). Line shaft and countershaft are the types of transmission shaft. A machine shaft is an integral part of itself. Eg: crankshaft.

47. In machine design, what is the maximum shear stress for a material of ultimate tensile strength (Sut) with keyway effect according to ASME code?
a) 0.18 Sut
b) 0.135 Sut
c) 0.30 Sut
d) 0.225 Sut

Explanation: According to ASME code for shaft design, the maximum shear stress for a material of ultimate tensile strength (Sut) is 0.18 Sut. Further, with keyway effect, the value is to be reduced by 25 % which gives, 0.18 x 0.75 x Sut.

48. In machine design, how can the term “Lead” be defined ?
b) Largest diameter of a screw thread
c) Smallest diameter of a screw thread
d) Distance travelled by the nut when the nut is given motion measured parallel to axis

Explanation: Largest and smallest diameters of a screw thread is known as major and minor diameters, respectively. Pitch is defined as the distance between two adjacent threads measured parallel to the axis of screw thread and lead is the distance travelled by a nut when the nut is given one turn, measured parallel to axis.

49. Which of the following is not the method to reduce stress concentration?
a) Usage of additional notches and holes
d) Usage of sharp corners

Explanation: For the reduction of stress concentration, several methods are used like using multiple notches, using additional discontinuities, drilling additional holes. Using fillet radius, to avoid sharp corners. These methods will ultimately smoothen the flow and flow lines will be less deviated.

50. Which of the following is not a type of sunk key?
b) Woodruff key
c) Square key

Explanation: A sunk key is a type of key which fits halfway in the shaft and the other half lies in the hub. Further, the main types of sunk keys are square key, rectangular key, gib headed key, woodruff key, parallel sunk key. Hollow saddle key is a type of saddle key.

## Chapterwise Multiple Choice Questions on Machine Design

Our 1000+ MCQs focus on all topics of the Machine Design subject, covering 100+ topics. This will help you to prepare for exams, contests, online tests, quizzes, viva-voce, interviews, and certifications. You can practice these MCQs chapter by chapter starting from the 1st chapter or you can jump to any chapter of your choice.

## 1. Machine Design MCQ on Engineering Materials

The section contains Machine Design multiple choice questions and answers on Engineering Material Properties, Stress and Strain diagrams, carbon steels, steel case hardening, steel and aluminium alloys, ceramics, plastics and die casting alloys.

## 2. Multiple Choice Question on Manufacturing Considerations in Machine Design

The section contains Design of Machines questions and answers on design considerations and hot and cold working of metals.

## 3. Design Against Static Load MCQ

The section contains Machine Design MCQs on failure modes and stresses, cotter and knuckle joints, principal and thermal stresses, levers and fracture mechanics.

## 4. Design Against Fluctuating Load Multiple Choice Question

The section contains Design of Machine multiple choice questions and answers on stress concentration, fluctuating stresses, fatigue failures and its factors.

## 5. Machine Design MCQ on Power Screws

The section contains Machine Design questions and answers on concepts of power screws, self locking screws and screw efficiency.

## 6. MCQ on Threaded Joints in Machine Design

The section contains Design of Machine MCQs on power screws, screw jack, threaded joints, uniform bolt strength, and loads based on the principle of eccentricity.

## 7. Machine Design Multiple Choice Question on Welded and Riveted Joints

The section contains Machine Design multiple choice questions and answers on various concepts which include welded joints, butt joints, fillet joints, riveted joints, various joints terminology and lap joints based on eccentricity principle.

 Welded Joints Butt Joints&FIllet Joins Unsymmetrically Loaded Welded Joints Welded Joints Subjected to Bending Moments Riveted Joints Rivet Heads & Terminology Failures in Rivets Longitudinal Butt & Circumferential Lap Joints Eccentrically Loaded Riveted Joints

## 8. MCQ on Shafts, Keys and Couplings in Machine Design

The section contains Design of Machine questions and answers on transmission shafts, shaft design and keys, couplings and pin flexible coupling.

## 9. Machine Design Multiple Choice Question on Springs

The section contains Machine Design MCQs on spring design, helical springs, spiral springs, concentric springs and multi leaf springs.

## 10. Machine Design MCQ on Friction Clutches, Brakes, Belt Drives and Chain Drives

The section contains Design of Machine multiple choice questions and answers on friction clutches, cone clutches, centrifugal clutches, brakes, block brakes, expanding brakes, belt drives and constructions, chain drives and its design.

## 11. Multiple Choice Question on Rolling Contact Bearings, Spur Gears and Helical Gears in Machine Design

The section contains Machine Design questions and answers on bearings and its types, load carrying capacities, sliding contact bearings, viscosity, spur gears and its terminology, gear trains and helical gears.

## 12. MCQ on Bevel Gears, Worm Gears and FlyWheel in Machine Design

The section contains Design of Machine MCQs on bevel gears and its terminology, bevel gear strength, worm gears and flywheel coefficient.

## 13. Multiple Choice Question on Cylinders and Pressure Vessels and Design of IC Engine Components

The section contains Machine Design multiple choice questions and answers on compound cylinder, pressure vessels, gaskets and IC engine component design.

## 14. MCQ on Miscellaneous Machine Elements

The section contains Design of Machine questions and answers on miscellaneous machine elements like pressure vessels, oil seals, wire ropes and its stresses and column bucking.

If you would like to learn "Machine Design" thoroughly, you should attempt to work on the complete set of 1000+ MCQs - multiple choice questions and answers mentioned above. It will immensely help anyone trying to crack an exam or an interview.

Wish you the best in your endeavor to learn and master Machine Design!