short answers questions dme

8/20/2019 Short Answers Questions Dme

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Questions with Short Answer

for

DESIGN OF MACHINE ELEMENTS

(Third Edition)

V. B. Bhandari

Retired Professor & Head

Department of Mechanical Engineering

Vishwakarma Institute of TechnologyPune.

Tata McGraw-Hill Publishing Company Limited

New Delhi


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CHAPTER 1

1.1 What are the steps in machine design process?

1.2 How will you select a mechanism for the product?

1.3 Prepare a block diagram showing the general layout of electrically operated

overhead (EOT) traveling crane and give names for various sub-assemblies.

1.4 What type of information is given on the final drawings of product?

1.5 What is ‘design by craft evolution’?

1.6 Name the products produced by craft evolution.

1.7 What are the steps in ‘design by craft evolution’?

1.8 Why is ‘design by craft evolution’ become obsolete?

1.9 What is ‘design by drawing’ method?

1.10 What are the advantages of ‘design by drawing method’ over ‘design by craft

evolution’?

1.11 Give examples of Indian standards for engineering materials.

1.12 Give examples of Indian standards for dimensions of machine elements.

1.13 Give examples of Indian standards for fits and tolerances.

1.14 Give examples of Indian standards for testing of machine elements.

1.15 Give examples of Indian standards for engineering drawings.

1.16 What are the advantages of standardization?

1.17 What is R5 series? Develop R5 series from 1 to 10.


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1.21 What is R 10/3 ( …,8,….) designation of derived series?

1.22 What is R 20/4 (1, …….1000) designation of derived series?

1.23 What is R 20/3 (200, …….) designation of derived series?

1.24 What is R 20/3 (…….,200) designation of derived series?

1.25 What are the five basic forms for the shape of product?

1.26 What is the relationship between functional requirement and external

appearance of the product?

1.27 Explain the meaning of different colours as per Morgan’ code.

1.28 What is the scope of ergonomics in product design?

1.29 What are the types of controls?

1.30 What are the ergonomic considerations in design of controls?

1.31 What are the types of displays?

1.32 What are the ergonomic considerations in design of displays?


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CHAPTER 2

2.1Why is the tensile strength of cast iron decreases as the thickness of part

increases?

2.2 How will you classify cast irons?

2.3 What is FG 200 designation of cast iron?

2.4 How will you designate grey cast iron with minimum tensile strength of 300

N/mm2?

2.5 What are BM 350 and PM 600 designations of cast iron?

2.6 How will you designate blackheart malleable cast iron with minimum tensile

strength of 350 N/mm2?

2.7 How will you designate whiteheart malleable cast iron with minimum tensile


2.8 How will you designate pearlitic malleable cast iron with minimum tensile


2.9 How will you designate spheroidal graphite cast iron with minimum tensile

strength of 900 N/mm

2

and elongation of 2%?2.10 How will you designate spheroidal graphite cast iron?

2.11 What is SG 800/2 designation of cast iron?

2.12 Name the components made of spheroidal graphite cast iron.

2.13 How will you designate steels on the basis of tensile strength?

2.14 What are Fe 360 and FeE 250 designations of steels?

2.15 How will you designate plain carbon steel with minimum tensile strength of

320 N/mm2

?

2.16 How will you designate plain carbon steel with minimum yield stress of

200 N/mm2?

2.17 How will you designate plain carbon steel with 0.4 % carbon and 0.8%

manganese?


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2.18 How will you designate free cutting steels?

2.19 What is 25C12S12 designation of steel?

2.20 What is 15Cr3 designation of steel?

2.21

What is 16Ni3Cr2 designation of steel?2.22 What are important components made of plain carbon steels?

2.23 What is the effect of addition of sulphur in carbon steels?

2.24 What are the advantages of plain carbon steel?

2.25 What are the disadvantages of plain carbon steel?

2.26 How will you designate alloy steel with following composition?

carbon = 0.35% to 0.45%

chromium = 0.90% to 1.1%

2.27 How will you designate alloy steel with following composition?

carbon = 0.12 to 0.20%

nickel = 0.80 to 1.2%

chromium = 0.60 to 1.0%

2.28 What is the effect of addition of silicon in alloy steels?

2.29 What is the effect of addition of manganese in alloy steels?

2.30

What is the effect of addition of nickel in alloy steels?

2.31 What is the effect of addition of chromium in alloy steels?

2.32 What is the effect of addition of molybdenum in alloy steels?

2.33 What is ASTM Class No.20 designation of cast iron?

2.34 What is GG-12 designation of cast iron?

2.35 What are the four basic heat treatment processes?

2.36 What is annealing? What is its objective?

2.37

What is normalising? What is its objective?

2.38 What is quenching? What is its objective?

2.39 What is tempering? What is its objective?

2.40 What is case hardening? How is it achieved?

2.41 What is flame hardening? Where do you recommend it?


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2.42 What is induction hardening? Where do you recommend it?

2.43 What is case carbursing? Where do you recommend it?

2.44 What is carbo-nitriding? Where do you recommend it?

2.45

What is nitriding? Where do you recommend it?2.46 How will you designate carbon steel castings?

2.47 What is Grade 200-400 designation of carbon steel castings?

2.48 How will you designate high tensile steel castings?

2.49 What is CS 640 designation of high tensile steel castings?

2.50 How will you designate carbon steel casting with ultimate tensile strength

of 400 N/mm2 and yield stress of 200 N/mm

2?

2.51

How will you designate high tensile steel casting with ultimate tensile


2.52 How will you designate aluminum alloy castings?

2.53 What is 2585 designation of aluminum alloy castings?

2.54 How will you designate wrought aluminum alloy?

2.55 What is 24345 designation of wrought aluminum alloy?

2.56 What are the advantages and disadvantages of brass form design

considerations?

2.57 Name the components made of brass.

2.58 What are the advantages and disadvantages of phosphor bronze form design

considerations?

2.59 Name the components made of phosphor bronze.

2.60 What are the advantages and disadvantages of gunmetal from design

considerations?

2.61

Name the components made of gunmetal.

2.62 What are the advantages and drawbacks of die casting process?

2.63 What are the die casting alloys?

2.64 Distinguish between thermoplastic and thermosetting plastic.

2.65 What are the advantages of plastics?


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2.66 What are the disadvantages of plastics?

2.67 What are filler, plasticizer, flame retardant and pigment? What is their

purpose in plastic materials?

2.68

Where do use Polyamide?2.69 Where do use Polyurethane?

2.70 What types of fibres are used in fibre reinforced plastic?

2.71 What are the advantages of glass reinforced plastics?

2.72 What are the disadvantages of glass reinforced plastics?

2.73 What are the advantages of carbon reinforced plastics?

2.74 What are the disadvantages of carbon reinforced plastics?

2.75

Distinguish between natural and synthetic rubbers.

2.76 What are the applications of synthetic rubber?

2.77 What is creep strength?

2.78 What is creep rapture strength?

2.79 Explain the three stages of creep curve.

Answers:

2.4 FG 300 2.6 BM 350 2.7 WM 400

2.8 PM 600 2.9 SG 900/2 2.15 Fe 320

2.16 FeE 200 2.17 40C8 2.26 40Cr4

2.27 16Ni4Cr3 2.50 200-400 2.51 CS 1030


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CHAPTER 3

3.1 What is manufacturing?

3.2

What are the three categories of manufacturing processes? Give their

examples.

3.3 What are the factors to be considered while selecting optimum manufacturing

method for a component?

3.4 Name various casting processes.

3.5 What is forging?

3.6 Name various forging processes.

3.7

Name various metal removal processes.

3.8 What are the metal removal processes for machining flat surfaces?

3.9 What are the metal removal processes for machining external cylindrical

surfaces?

3.10 What are the metal removal processes for machining internal cylindrical

surfaces?

3.11 Why are cast iron components placed in compression?

3.12 Why are cast iron components rounded at corners?

3.13 Why are cast iron components made of uniform thickness?

3.14 Why is concentration of metal avoided at the junction in cast iron

components?

3.15 Where do you use forged components? Give practical examples.

3.16 Why is draft provided for forged components?

3.17 Why is draft angle more for inner surface of forged components?

3.18 Why is draft angle less for outer surface of forged components?

3.19 What is parting line of forged component?

3.20 What is forging plane of forged component?

3.21 How will you decide the location of parting line of forged component?


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3.22 Why are thin sections avoided in forged components?

3.23 What is recrystallization temperature of metal?

3.24 What is hot working process?

3.25

Name various hot working processes.3.26 What is cold working process?

3.27 Name various cold working processes.

3.28 Why are fasteners avoided in assemblies?

3.29 Where do you use shaft-basis system?

3.30 Where do you use hole-basis system?

3.31 Draw a sketch showing fundamental deviation and magnitude of tolerance

with respect to zero line.

3.32 What do you understand by (50 H8-g7)?

3.33 Recommend a suitable class of fit between idler gear and spindle,

3.34 Recommend a suitable class of fit between camshaft and bearing,

3.35 Recommend a suitable class of fit between gear shaft and bearing,

3.36 Recommend a suitable class of fit between pin and eye in knuckle joint,

3.37 Recommend a suitable class of fit between belt pulley and shaft,

3.38

Recommend a suitable class of fit between worm wheel and shaft,

3.39 Recommend a suitable class of fit between hand wheel and spindle,

3.40 Recommend a suitable class of fit between pump impeller and shaft.

3.41 Explain the relationship between the grade of tolerance and corresponding

manufacturing method.

3.42 What is the effect of surface roughness on performance of machine parts?

3.43 What are the units for measurement of surface roughness?

3.44

What is c.l.a. value of surface roughness?

3.45 What is r.m.s. value of surface roughness?

Answers:

(3.33) H7-d8 (3.34) H6-e7 (3.35) H7-f7


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(3.36) H7-g6 (3.37) H7-h6 (3.38) H7-j6

(3.39) H7-k6 (3.40) H7-r6


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CHAPTER 4

4.1 What is the dividing line between ductile and brittle materials?

4.2 Distinguish between stress-strain diagrams for ductile and brittle materials?

4.3 What are the factors to be considered for deciding the magnitude of factor of

safety?

4.4 What is stress?

4.5 What is strain?

4.6 What is Hooke’s law?

4.7 What is tensile stress?

4.8 What is compressive stress?

4.9 What is shear stress?

4.10 What is the difference between modulus of elasticity and modulus of

rigidity?

4.11 What is the relationship between modulus of elasticity, modulus of rigidity

and Poisson’s ratio?

4.12

What is Poisson’s ratio?4.13 What is parallel axis theorem for moment of inertia?

4.14 Explain the construction of cotter joint with the help of neat sketch.

4.15 Explain the principle of wedge action used in cotter joint.

4.16 What is the magnitude of taper on the cotter?

4.17 Explain the construction of knuckle joint with the help of neat sketch.

4.18 What is the difference between normal stress and shear stress?

4.19

Explain the construction of Mohr’s circle diagram to find out principal

stresses.

4.20 What is lever? Explain the principle on which it works.

4.21 What is mechanical advantage?

4.22 What is leverage?


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4.23 What is first type of lever? Give its examples.

4.24 What is second type of lever? Give its examples.

4.25 What is third type of lever? Give its examples.

4.26

What type of stress is induced in the cross-section of lever?4.27 Why are levers usually tapered?

4.28 What is the difference between stress intensity factor and fracture

toughness in fracture mechanics?

4.29 What are the three modes of crack propagation in fracture mechanics?

4.30 What are the components where thermal stresses are considered?

4.31 What are residual stresses?

4.32

What are the causes of residual stresses?

4.33 When are residual stresses beneficial?

4.34 When are residual stresses harmful?


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CHAPTER 5

5.1 What is the effect of stress concentration on ductile components?

5.2

What is the effect of stress concentration on brittle components?

5.3 How will you reduce stress concentration in keyway?

5.4 How will you reduce stress concentration in threaded parts?

5.5 Explain the principle of rotating beam fatigue testing machine.

5.6 What is the difference between S-N curves for ferrous and non-ferrous

components?

5.7 What is the physical significance of notch sensitivity factor being ‘one’ and

‘zero’?

5.8 What is the approximate method to find out endurance limit?

5.9 What is impact?

5.10 Give examples of impact force?


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CHAPTER 6

6.1 Why are square threads preferred to V threads in power screws?

6.2 What are the advantages of trapezoidal threads over square threads?

6.3 What are the disadvantages of trapezoidal threads compared with square

threads?

6.4 What is acme thread? What is the difference between acme and trapezoidal

threads?

6.5 What are the advantages of buttress threads?

6.6 What is the disadvantage of buttress threads?

6.7 What are the applications of buttress threads?

6.8 What are multiple start screws?

6.9 What is the pitch of screw?

6.10 What is the lead of screw?

6.11 What is the nominal diameter of screw?

6.12 What is the helix angle of thread?

6.13

Write down the relationship between lead, pitch and number of starts in power screw.

6.14 Write down the relationship between helix angle, mean diameter and lead

of screw.

6.15 Write down the relationship between load being raised, the effort applied,

helix and friction angles in power screw.

6.16 Write down the relationship between load being lowered, the effort applied,

helix and friction angles in power screw.

6.17 Write down the expression for efficiency of square threaded screw.

6.18 What is the effect of helix angle on efficiency of square threaded screw?

6.19 What is the effect of lead on efficiency of square threaded screw?

6.20 What is the ‘effective’ coefficient of friction in trapezoidal threads?


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6.21 Write down the expression for efficiency of trapezoidal threaded screw.

6.22 What are the factors upon which the coefficient of friction in power screw

depends?

6.23

Name the materials for power screw components.6.24 What are the types of stresses induced in power screw?

6.25 Why are thrust ball bearings used at the collar in power screws?

6.26 In hand operated fly presses overhauling screw is used. Why?

6.27 What are the applications of high efficiency power screws?

6.28 What are the applications of low efficiency power screws?

6.29 What are the factors upon which the thread bearing pressure in power screw

depends?

6.30 Why is separate nut preferred to integral nut with body of screw jack?


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CHAPTER 7

7.1 When do you use through bolts?

7.2

What are the types of through bolts?

7.3 What is eyebolt?

7.4 Why are through bolts not preferred in assembly operations?

7.5 Distinguish between tap bolt and through bolt.

7.6 Distinguish between cap screw and tap bolt.

7.7 When do you use stud?

7.8 What are the advantages of cap screws with heads engaged internally and from

the end face compared with usual cap screws?

7.9 What is the difference between setscrew and cap screw?

7.10 What are the two methods to make bolt of uniform strength?

7.11 What is locking device?

7.12 Name various locking devices.

7.13 How is locking of threads obtained in split nut?

7.14 How is locking of threads obtained by setscrew and elastic piece?

7.15 How does spring washer obtain locking of threads?

7.16 What are the advantages of vee threads?

7.17 Why the roots and crests are rounded in vee threads?

7.18 What are the materials for bolts and screws?

7.19 What are the methods to make bolts and screws?

7.20 Why thread rolling is superior to thread cutting?

7.21 The threads are equally strong in failure by shear and failure by tension if

the height of nut is 0.4 times of nominal diameter. Why?

7.22 What is turnbuckle?

7.23 What are the applications of turnbuckle?


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7.24 Why are connecting rod bolts tightened with initial tension greater than

external load?

7.25 Which of two should be more- initial tightening load or external load, in

bolted joint?7.26 What are the practical applications of uniform strength bolts?

7.27 What are the advantages of pre loading of bolts?

7.28 What is the function of plain washer in bolted joint?

7.29 Why usually bolts are subjected to tensile loading and rivets to shear

loading?

7.30 What are the different types of stresses to which a bolt is subjected?

7.31

What is the effect of gasket on bolt load?

7.32 What are the methods of increasing the fatigue strength of bolted joint?

7.33 What are the methods of increasing the shock absorbing capacity of bolt?


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8.21 What is the transverse pitch of rivet?

8.22 What is the diagonal pitch of rivet?

8.23 What is Lozenge joint?

8.24

What is economical joint? Where does it used?8.25 What are the materials for rivet?

8.26 What are the types of failure in riveted joint?

8.27 What is longitudinal butt joint in boiler shell? What is its objective?

8.28 What is circumferential lap joint in boiler shell? What is its objective?

8.29 What is Unwin’s formula? What is its limitation?

8.30 ‘Butt joint is used for the longitudinal joint of a boiler shell’. Why?


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CHAPTER 9

9.1 What is transmission shaft?

9.2 What is axle? Give examples.

9.3 What is spindle? Give examples.

9.4 What is countershaft?

9.5 What is jackshaft?

9.6 What is line shaft?

9.7 What are the materials for making transmission shaft?

9.8 Why is maximum principal stress theory not applicable to shafts?

9.9 Why is maximum shear stress theory used for shafts?

9.10 When the shaft is subjected to fluctuating loads, what will be the equivalent

torsional moment and equivalent bending moment.

9.11 How will you design shaft on the basis of torsional rigidity?

9.12 How will you design shaft as per ASME Code?

9.13 ‘A hollow shaft has greater strength and stiffness than solid shaft of equal

weight’. Explain the statement.9.14 Explain under what circumstances are hollow shafts preferred over solid

shafts.

9.15 What is key?

9.16 What are the elements of keyed joint?

9.17 What are the types of key?

9.18 What are the factors to be considered while selecting the types of key?

9.19

What are the materials for making key?

9.20 Why is saddle key suitable only for light duty?

9.21 What are the standard proportions of square key?

9.22 What are the standard proportions of flat key?

9.23 What are the types of failure in flat key?


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9.24 What are the two types of stresses in flat key?

9.25 What are the types of spline?

9.26 What are the advantages and disadvantages of involute splines over

straight-sided splines?9.27 Why are flexible couplings popular?

9.28 What are the requirements of a good coupling?

9.29 What is the construction of rigid flange coupling?

9.30 Sketch a protective type of rigid flange coupling and indicate major

dimensions in terms of shaft diameter d.

9.31 In what situation flexible coupling is used?

9.32

What is the construction of bushed-pin flexible coupling?

9.33 In bushed flexible coupling why is there a clearance between flanges?

9.34 ‘For connecting shafts of a particular diameter, bushed pin type coupling

either has greater number of bolts or larger bolt diameter than rigid coupling’.

Why?

9.35 ‘The most satisfactory location of coupling is one, which is very close to a

bearing on shaft’. Why?

9.36

Where do you design the shafts on the basis of lateral rigidity?

9.37 What is the permissible deflection for transmission shafts?

9.38 What is the permissible shaft deflection at the gears?

9.39 What are the methods of improving lateral rigidity of shafts?

9.40 ‘It is not advisable to use expensive alloy steels in place of plain carbon

steels where lateral rigidity is the design criterion’. Why?

9.41 What are the methods of determining the lateral deflection of shaft?

9.42

Explain the principle of area moment method.

9.43 Explain the principle of graphical integration method.

9.44 How is resonance avoided in shafts?


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10.21 ‘Permissible torsional shear stress is 30% of ultimate tensile strength of

spring wire’. Why?

10.22 How will you design buckle-proof spring?

10.23

Explain fatigue diagram for spring design.10.24 How will you avoid surge in spring?

10.25 What are the materials used for making leaves of multi-leaf spring?

10.26 What is Belleville (coned disk) spring?

10.27 What are the advantages of Belleville spring?

10.28 What are the applications of Belleville spring?

10.29 What is shot peening of spring?

10.30

What is the objective of shot peening of spring?


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CHAPTER 11

11.1 What is a clutch?

11.2

Specify the types of clutch?

11.3 What is positive clutch?

11.4 Why a positive clutch is used?

11.5 By what means power is transmitted by clutches?

11.6 What factors should be considered in designing friction clutch?

11.7 Why splines are used in mechanical clutches?

11.8 What are the advantages of multi-plate clutch over single plate clutch?

11.9

What is the assumption of uniform pressure theory?

11.10 What is the assumption of uniform wear theory?

11.11 What are the phases of wear mechanism in friction lining?

11.12 In case of multi-plate clutch if ( 1n ) is number of disks on driving shaft and

( 2n ) is the number of disks on driven shaft, then what is the number of pairs of

contacting surfaces?

11.13 Give practical applications of single plate clutch?

11.14 Give practical applications of multi-plate clutch?

11.15 Distinguish between dry and wet operations of clutch.

11.16 What is woven asbestos friction material?

11.17 What is moulded asbestos friction material?

11.18 Compare woven and moulded asbestos friction materials.

11.19 Why are asbestos friction materials prohibited in number of countries?

11.20

What are the four ingredients of modern friction lining?11.21 What is the recommended semi-cone angle of cone clutch?

11.22 The coefficient of friction between the contacting surfaces of a cone clutch

is 0.2. What is the minimum value of semi-cone angle? (Ans. 11.30)

11.23 Plot a graph of temperature of clutch assembly against time.


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11.24 What are the factors on which the coefficient of friction between contacting

surfaces depends?

11.25 Why a service factor is used for calculating the design capacity of a clutch?


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CHAPTER 12

12.1 What is a brake?

12.2

How will you classify brakes?

12.3 Write down the relationship between the energy absorbed by brake, braking

torque and the angle through which the brake drum rotates during braking.

12.4 In block brakes, two blocks diametrically opposite to each other are used.

Why?

12.5 What is the difference between block brakes with short and long shoes?

12.6 What is the magnitude of pedal force in case of automotive type internal

expanding shoe brake? Why?

12.7 What is simple band brake?

12.8 Distinguish between simple and differential band brakes?

12.9 What is the effect of temperature rise at the braking surface?

12.10 What is the significance of (pv) factor?

where, p = intensity of normal pressure (N/mm2 )

v = rubbing speed (m/mim)

12.11 What is the relationship between temperature rise of brake drum assembly,

energy absorbed by brake, mass of brake drum assembly and its specific heat?

12.12 What is the specific advantage of differential band brake over other types of

band brake?

12.13 What are the factors upon which the braking capacity of brake depends?

12.14 Compare block and band brakes. State their relative advantages and

disadvantages.

12.15 What type of brake is used in passenger vehicles?

12.16 Why in automobiles, braking action when traveling in reverse is not as

effective as when moving forward?


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12.17 Why an equivalent coefficient of friction is used when designing long shoe

drum brake?

12.18 What is ‘backstop’ in an inclined conveyor?


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CHAPTER 13

13.1 What are the three basic elements of a belt drive?

13.2 What are the types of belts?

13.3 Flat belt drives are not popular. Why?

13.4 Where do you use round belt?

13.5 What are the advantages of round belts?

13.6 What are the disadvantages of round belts?

13.7 What are the materials by which flat belts are made?

13.8 What are the disadvantages of fabric rubber belts?

13.9 How are the ends of flat belt joined?

13.10 What is meant by ply of belt?

13.11 What are the three basic parts of the cross-section of V belt?

13.12 What is the optimum belt velocity for maximum power transmission?

13.13 What is the effect of centrifugal tension on power transmitted by a belt

drive?

13.14

What conditions should be followed while flat belt drive is installed?13.15 In open belt drive, which side of the belt is tight, whether upper side or

lower side? Why?

13.16 What data is required for selecting a flat belt from manufacturer’s

catalogue?

13.17 What is load correction factor for flat belt?

13.18 What is arc of contact factor for flat belt?

13.19

What are the materials by which pulleys of flat belts are made?

13.20 What is ‘crowning’ of belt pulleys?

13.21 What is the basis on which the minimum diameter of the pulley is selected?

13.22 What are the losses in belt drives?

13.23 What is pitch width of V belt?


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13.24 What is nominal height of V belt?

13.25 What is pitch length of V belt?

13.26 How will you classify the cross-section of V belt?

13.27

What is B 4430 Lp designation of V belt?13.28 Name the two factors that decide the cross-section of V belt?

13.29 How will you find out the number of V belts required for a given

application?

13.30 What is correction factor for service in case of V belt?

13.31 What data is required for selecting a V belt from manufacturer’s catalogue?

13.32 What is timing belt?

13.33

In what way timing belts are superior to ordinary V belts?

13.34 Why belts are provided with initial tension?

13.35 Name the belt tensioning devices.

13.36 What is the function of an idler pulley in belt drives?

13.37 When do you prefer V belt to a flat belt?

13.38 Why V belts are more powerful than flat belts?

13.39 Why slip is less in V belt compared with flat belts?


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CHAPTER 14

14.1 What are the three basic elements of chain drive?

14.2 What are the types of chain?

14.3 What are the applications of hauling chains?

14.4 What are the materials for the parts of roller chain?

14.5 Define the pitch of roller chain.

14.6 Define the pitch circle diameter of the sprocket in chain drive.

14.7 What is the relationship between pitch circle diameter of the sprocket, pitch

of the chain and number of teeth on sprocket?

14.8 How do you express the length of a roller chain?

14.9 What is the effect of increasing and decreasing the number of teeth on

sprocket in chain drive?

14.10 What is the reason for selecting even number of pitches or links for roller

chain?

14.11 Define breaking load of roller chain.

14.12

What is service factor for roller chain?14.13 What is multiple strand factor for roller chain?

14.14 What is tooth correction factor for roller chain?

14.15 What is the recommended centre distance in roller chain drive?

14.16 What are the materials for sprocket in roller chain drive?

14.17 What are the guidelines for selecting the number of teeth for sprocket in

roller chain drive?

14.18

What is idler sprocket in roller chain drive?

14.19 What are the methods of chain tensioning?

14.20 Why is horizontal chain drive preferred?

14.21 What are the methods of lubrication in roller chain drive?

14.22 What is silent chain?


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14.23 Distinguish between gear and chain-sprocket.

14.24 In motorcycles, chains are used and not belts. Why?


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CHAPTER 15

15.1 What is a bearing?

15.2 How bearings are classified?

15.3 What are the four parts of a ball bearing?

15.4 Enumerate two ways of classifying rolling contact bearings.

15.5 Draw a neat and labeled sketch of deep groove ball bearing.

15.6 Draw a neat and labeled sketch of cylindrical roller bearing.

15.7 Why the radial load carrying capacity of roller bearing is more than ball

bearing?

15.8 Why the rigidity of roller bearing is more than ball bearing?

15.9 Why roller bearing generates more noise than ball bearing?

15.10 Draw a neat and labeled sketch of angular contact bearing.

15.11 Draw a neat and labeled sketch of self-aligning ball bearing.

15.12 Draw a neat and labeled sketch of spherical roller bearing.

15.13 What types of bearing are used in applications where misalignment is likely

to be present?15.14 Draw a neat and labeled sketch of taper roller bearing.

15.15 Why taper roller bearing takes thrust and radial load?

15.16 Draw a neat and labeled sketch of thrust ball bearing.

15.17 State any two advantages of thrust ball bearing.

15.18 What is the material of balls and races in rolling contact bearings?

15.19 What is the material of cages in rolling contact bearings?

15.20

What is the material of the rollers in antifriction bearings?

15.21 What is the heat treatment for balls in rolling contact bearings?

15.22 What is the heat treatment for rollers in rolling contact bearings?

15.23 Suggest any two types of bearing to take up combined heavy axial and

heavy radial loads.


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15.24 What is an antifriction bearing?

15.25 Define static load.

15.26 Name three factors on which static load carrying capacity depends.

15.27

What do you mean by failure of a rolling contact bearing?15.28 What is the life of an individual ball bearing?

15.29 What is median or average life of rolling contact bearings?

15.30 What is equivalent dynamic load in rolling contact bearing?

15.31 Write down the relationship between dynamic load carrying capacity, the

equivalent dynamic load and bearing life.

15.32 What is the relationship between L50 and L10 life?

15.33

Enumerate the steps for selection of rolling contact bearings for a particular

application.

15.34 State the data required for selection of rolling contact bearings.

15.35 State the types of failures in rolling contact bearings.

15.36 How are rolling contact bearings designated?

15.37 State any two advantages of using oil as lubricant compared with grease for

rolling contact bearings.

15.38

State any two advantages of using grease as lubricant compared with oil for

rolling contact bearings.

15.39 Why the coefficient of friction in needle roller bearing is higher than roller

bearing?


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CHAPTER 16

16.1 Define lubrication.

16.2

Name any two liquid lubricants.

16.3 Name any one semi-solid lubricant.

16.4 Name any two solid lubricants.

16.5 Enumerate the factors that form and maintain thick oil film in

hydrodynamic journal bearings?

16.6 Draw a sketch showing the pressure distribution around the periphery of a

hydrodynamic journal bearing.

16.7

What does journal-bearing mean?

16.8 What is footstep bearing?

16.9 What is collar bearing?

16.10 What is elastohydrodynamic lubrication?

16.11 Distinguish between full and partial bearings.

16.12 What is the preferred angle of contact for partial journal bearings?

16.13 What will happen when the viscosity of the lubricant is very low in a

bearing?

16.14 Name three types of viscometers.

16.15 What is the meaning of viscosity in Saybolt Universal Seconds (SUS)?

16.16 What is the meaning of viscosity in Redwood Seconds?

16.17 What is the meaning of viscosity in Engler degrees( 0 E) ?

16.18 State the relationship between kinematic viscosity and viscosity in Saybolt

Universal Seconds?

16.19 State the relationship between kinematic viscosity, absolute viscosity and

density of lubricant.

16.20 What are the two assumptions of Petroff’s equation?


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16.21 State the two dimensionless performance parameters in Petroff’s equation

that govern the coefficient of friction.

16.22 State four important assumptions of Reynold’s equation.

16.23

What are the two Sommerfeld’s solutions of Reynold’s equation?16.24 Define eccentricity ratio in hydrodynamic journal bearing.

16.25 Define radial clearance.

16.26 Define minimum film thickness.

16.27 What is the ideal value of length to diameter ratio?

16.28 What are the advantages and disadvantages of short bearings over long

bearings?

16.29

Define unit bearing pressure.

16.30 When (l/d) ratio is 1, what is optimum value of ( ho/c) for maximum load

carrying capacity?

16.31 When (l/d) ratio is 1, what is optimum value of ( ho/c) for minimum

frictional loss?

16.32 Draw a neat and labeled sketch of solid bushing for journal bearing.

16.33 Draw a neat and labeled sketch of lined bushing for journal bearing.

16.34

Explain the principle of oil-ring bearing.

16.35 Give a list of materials for sliding contact bearing.

16.36 What is babbitt?

16.37 Why babbitt is called white metal?

16.38 What are the two varieties of babbitt?

16.39 Give a typical composition of tin based babbitt.

16.40 Give a typical composition of lead based babbitt.

16.41

Compare bronze with babbitt as bearing material.

16.42 What are sintered metal bearings? What are their two varieties?

16.43 Compare iron-base and copper-base sintered metal bearings.

16.44 Give a typical composition of copper lead bearings. Where do you use

them?


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16.45 What are the commonly used non-metallic bearing materials?

16.46 What is paraffinic oil?

16.47 What is naphthenic oil?

16.48

What is the approximate relationship between SAE number and viscosity oflubricating oil?

16.49 State any four advantages of mineral oil over vegetable oil.

16.50 State any two advantages of vegetable oil over mineral oil.

16.51 What is the purpose of oxidation inhibitor?

16.52 What is ‘detergent’ additive?

16.53 What is VI improver?

16.54

What is pour point depressant?

16.55 What are anti-foam additives?

16.56 What is ‘oilness’?

16.57 Why SAE 80, SAE 90 and SAE 140 oils are used for the lubrication of

gears?

16.58 How do you classify grease?

16.59 State the types of bearing failure?


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CHAPTER 17

17.1 What is a mechanical drive?

17.2

Where do you use mechanical drives?

17.3 How do you classify mechanical drives?

17.4 State the guidelines for the selection of mechanical drives.

17.5 What are the important parameters necessary for the selection of a

particular drive for power transmission?

17.6 Define gear.

17.7 Specify machine tools for making gears.

17.8

What is a gear drive?

17.9 Why are gear drives superior to belt or chain drives?

17.10 What are the functions of a gearbox?

17.11 What are the four main types of gears?

17.12 Which types of gear are used when the shafts are parallel?

17.13 Which type of gear is used when the shafts are perpendicular to each other?

17.14 Which type of gear is used when the axes of shafts do not intersect and are

perpendicular to each other?

17.15 Which type of gear is used for high velocity ratio?

17.16 What is meant by spur gear?

17.17 What conditions must be satisfied for a pair of gears to have constant

velocity ratio?

17.18 State the fundamental law of gearing.

17.19 What are the conditions required for interchangeability in toothed gearing?

17.20 Which curves satisfy fundamental law of gearing?

17.21 Define involute curve.

17.22 Define cycloidal curve.

17.23 What is pitch circle?


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17.24 What is base circle?

17.25 What is addendum circle?

17.26 What is dedendum circle?

17.27

What is addendum?17.28 What is dedendum?

17.29 Why dedendum is more than addendum?

17.30 What is circular pitch?

17.31 What is diametral pitch?

17.32 What is module?

17.33 How do you specify the size of gear tooth?

17.34

What is the relationship between number of teeth on pinion and gear,

module and centre distance?

17.35 What is pressure angle of gear tooth?

17.36 What are the effects of increasing or decreasing the pressure angle in gear

design?

17.37 Sketch base circles and pitch circles of two meshing gears and mark

pressure angle on it.

17.38

What is crowning of gear tooth?

17.39 What are the advantages and disadvantages of stub tooth?

17.40 What is gear ratio?

17.41 What is backlash in gear teeth?

17.42 What factors influence backlash in gear teeth?

17.43 What are the parameters required to specify spur gear?

17.44 How will you decide the directions of tangential and radial components of

gear tooth force?

17.45 What are the basic modes of gear tooth failures?

17.46 What are the types of gear tooth wear?

17.47 State the desirable properties of gear materials?

17.48 Name gear materials.


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17.49 What are non-metallic gears? Where do you use them?

17.50 Where do you make gear integral with shaft?

17.51 What are the advantages of forged gears?

17.52

What is a ‘rimmed’ gear? What is its advantage?17.53 What is interference in gears?

17.54 How will you eliminate interference in gear teeth?

17.55 What do you understand by ‘corrected’ gear?

17.56 What do you understand by ‘uncorrected’ gear?

17.57 What is the optimum value of face width in terms of module?

17.58 What stresses are induced in gear tooth?

17.59

State the assumptions of Lewis equation.

17.60 What is beam strength?

17.61 What is Lewis form factor?

17.62 When pinion and gear are made of same material, which component is to be

designed? Why?

17.63 When pinion and gear are made of different materials, which component is

to be designed? Why?

17.64

Why permissible bending stress for gear tooth is taken as one third of

ultimate tensile strength?

17.65 What is service factor for gear tooth load?

17.66 What is velocity factor for gear tooth load?

17.67 What is dynamic load? What are its causes?

17.68 What is wear strength of gear tooth?

17.69 What is ratio factor in wear strength of gear tooth?

17.70

What is load stress factor in wear strength of gear tooth?

17.71 What is internal and external gearing?

17.72 In internal gear drives, the meshing external pinion alone is designed.

Why?

17.73 What are the methods of lubrication in gear drives?


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CHAPTER 18

18.1 What is a helical gear?

18.2 What is helix angle?

18.3 What is the normal range of helix angle?

18.4

What hands of helix are used for parallel helical gears?

18.5 What is transverse circular pitch?

18.6 What is normal circular pitch?

18.7 What is transverse diametral pitch?

18.8 What is normal diametral pitch?

18.9 What is transverse module?

18.10 What is normal module?

18.11 What is axial pitch?

18.12 What is transverse pressure angle?

18.13 What is normal pressure angle?

18.14 What is the relationship between transverse and normal pressure angles and

the helix angle?

18.15 What is virtual number of teeth in helical gear?

18.16 Write down the expressions for three components of resultant tooth force in

helical gears.

18.17 How will you decide the directions of three components of resultant tooth

force in helical gears?

18.18 What is the velocity factor for helical gears?


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18.19 How is the axial thrust in helical gears overcome?

18.20 What is the range of helix angle in herringbone and double helical gears?


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CHAPTER 19

19.1 What is a bevel gear?

19.2

Compare straight and spiral bevel gears.

19.3 What are the advantages of spiral bevel gears over straight bevel gears?

19.4 What are the disadvantages of spiral bevel gears over straight bevel gears?

19.5 How will you classify bevel gears on the basis of pitch angle?

19.6 What is cone distance in bevel gear?

19.7 What is pitch angle in bevel gear?

19.8 What is addendum angle?

19.9

What is dedendum angle?

19.10 What is pitch cone angle?

19.11 What is root angle?

19.12 What is face angle?

19.13 What is the relationship between pitch angles of pinion and gear and shaft

angle in case of bevel gear?

19.14 Where do you specify the dimensions such as module, addendum,

dedendum in case of bevel gears?

19.15 What is Tredgold’s approximation about formative number of teeth on

bevel gears?

19.16 What is back cone in case of bevel gear?

19.17 What is virtual number of teeth in bevel gear?

19.18 Write down the expressions for three components of resultant tooth force in

bevel gears.

19.19 How will you decide the directions of three components of resultant tooth

force in bevel gears?

19.20 What is the velocity factor for bevel gears?

19.21 What is the usual magnitude of spiral angle in spiral bevel gears?


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19.22 What is the usual magnitude of pressure angle in spiral bevel gears?

19.23 What is face contact ratio in spiral bevel gears? What is its magnitude?

19.24 How will you select the hand of spiral in spiral bevel gears?


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CHAPTER 20

20.1 What is a worm gear?

20.2 What is diametral quotient?

20.3 What is the axial pitch of worm?

20.4 What is the lead of worm?

20.5 What is the relationship between axial pitch of worm and module in worm

gear drive?

20.6 What is the lead angle of worm?

20.7 What is the relationship between number of starts on worm, diametral

quotient and lead angle of worm?

20.8 What is the relationship between number of starts on worm, number of

teeth on worm wheel and speed ratio of worm gear drive?

20.9 What is the relationship between number of teeth on worm wheel, diametral

quotient, module and centre distance?

20.10 Write down the expressions for three components of resultant tooth force

on worm and worm wheel?20.11 How will you decide the directions of three components of resultant tooth

force in worm gear drive?

20.12 In which type of gear drives, self-locking is available?

20.13 Why worm and worm wheel operate inside an oil reservoir?

20.14 Why heat dissipation is important consideration in worm gear drive?

20.15 What is the significance of using heterogeneous materials for worm and

worm wheel?

20.16 What is irreversibility in worm gear drives? How is it achieved?

20.17 What is the overall heat transfer coefficient for a worm gear box with

natural air circulation?


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20.18 What is the overall heat transfer coefficient for a worm gear box with

forced air circulation?

20.19 What is the permissible temperature rise for the lubricant in worm gear

box?20.20 In a worm gear drive only wheel is designed. Why?

20.21 What are main types of failures in worm gear drives?


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CHAPTER 21

21.1 What is flywheel?

21.2

Explain the construction of solid one-piece flywheel.

21.3 What is the difference between the functioning of flywheel and that of

governor?

21.4 What do you understand by ‘ fluctuation of energy’ and ‘maximum

fluctuation of energy’?

21.5 What are the principal stresses in solid disk flywheel?

21.6 What are the materials used for making flywheel?

21.7

What is rimmed flywheel?

21.8 What types of stress are induced in the rim of a rimmed flywheel?

21.9 What type of stress is induced in the spokes of a rimmed flywheel?


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CHAPTER 22

22.1 ‘In case of thin cylinder subjected to internal pressure, the tendency to

burst lengthwise is twice as great as at transverse section.’ Why?

22.2 ‘In case of thin cylinder subjected to internal pressure, the tangential stress

should be the criterion for determining the cylinder wall thickness.’ Why?

22.3 What is the difference between stresses in thin and thick cylinders?

22.4 What are the advantages of pre-stressed cylinder?

22.5 What are the advantages and disadvantages of asbestos gasket?

22.6 What are the materials used for making gasket?

22.7

Where do you use vulcanized-rubber gasket?

22.8 Sketch different shapes for the cross-section of gasket.

22.9 What is effect of gasket on bolted assembly?

22.10 Explain the construction of welded pressure vessel.

22.11 What do you understand by ‘category’ of welded joint in pressure vessel?

22.12 How will you classify categories of welded joint in pressure vessel?

22.13 What do you understand by classes of pressure vessel?

22.14 How is pressure vessel tested?

22.15 What are the types of welded joint used in pressure vessel?

22.16 Explain the principle of area compensation method for openings in pressure

vessel.


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CHAPTER 23

23.1 What is an oil seal?

23.2

Explain the construction of oil seal.

23.3 What is the effect of contact pressure between sealing lip and shaft on the

performance of oil seal unit?

23.4 What are the rubber compounds used for making the lip of oil seal?

23.5 Explain the construction of 6x19 wire rope.

23.6 What are the types of stresses induced in wire rope?

23.7 What is effective modulus of elasticity of wire rope?

23.8

What type of failure occurs in wire rope?

23.9 What are the requirements of rope sheave and rope drum for wire rope?

23.10 Draw a neat sketch for the profile of groove on the sheave of wire rope.

23.11 Draw a neat sketch of the rope drum.

23.12 What do you understand by column or strut?

23.13 Distinguish between lateral deflection of beam and buckling of column.

23.14 What is the value of slenderness ratio to consider the effect of buckling?

23.15 Explain the various end conditions of column.

23.16 What is the borderline between Euler’s and Johnson’s equations?


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CHAPTER 24

24.1 What is statistics?

24.2

What are the objectives of statistical techniques?

24.3 What is population?

24.4 What is sample?

24.5 Distinguish between population and sample.

24.6 What is data?

24.7 What is frequency distribution?

24.8 What is class frequency?

24.9

What is class width?

24.10 What is histogram?

24.11 Draw a neat sketch of normal curve.

24.12 What is random variable?

24.13 Write down the equation of normal curve in terms of standard variable.

24.14 What do you understand by statistically controlled system?

24.15 What is the relationship between design and natural tolerances and

percentage rejection?

24.16 What is the relationship between reliability and quality of a product?


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CHAPTER 25

25.1 What is S.I. engine?

25.2

What is C.I. engine?

25.3 What are the advantages and disadvantages of diesel engine over petrol

engine?

25.4 What is two-stroke cycle engine?

25.5 What is four-stroke cycle engine?

25.6 State the applications of two-stroke cycle petrol engine.

25.7 State the applications of four-stroke cycle petrol engine.

25.8

State the applications of four-stroke cycle diesel engine.

25.9 What are the main components of I.C. engine?

25.10 What is mechanical efficiency?

25.11 What is reboring allowance?

25.12 Name the parts attached to cylinder head?

25.13 What is piston barrel?

25.14 What is piston skirt?

25.15 What is the function of piston skirt?

25.16 What is the function of piston pin?

25.17 Why hollow piston pin is preferred over solid one?

25.18 What is floating gudgeon pin?

25.19 What is piston seizure and piston slap? On what factor do they depend?

25.20 Why one end of connecting rod is made bigger than the other?

25.21 Which formula is used for buckling of connecting rod?

25.22 What is the difference between small and big ends of connecting rod?

25.23 What is the usual ratio of length of connecting rod to length of stroke? How

do you decide it?


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25.24 What is the effect of angularity of connecting rod upon the side pressure of

piston?

25.25 What are ‘shims’? What is their function? What is ‘crush’?

25.26

What are three main portions of crankshaft?25.27 State the minimum number of bearings for centre and overhung

crankshafts.

25.28 What is a multi-throw crankshaft?

25.29 State condition for maximum bending moment on crankshaft.

25.30 At what angle of crank, is the crankshaft subjected to maximum torque?

25.31 What types of stresses are induced in crankshaft?

25.32

What is the function of valve gear mechanism?

25.33 What are the main parts of valve gear mechanism?

25.34 What are the types of valves used in I.C. engines?

25.35 Name the materials for engine valves.

25.36 What is the interference angle between the valve seat and valve-seating

surface? Why is it provided?

25.37 What are the forces acting on rocker arm?

short answers questions dme

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