ME6503 - DESIGN OF MACHINE ELEMENTS TWO MARKS QUESTIONS WITH ANSWERS

R.M.K COLLEGE OF ENGINEERING
AND TECHNOLOGY
RSM NAGAR, PUDUVOYAL-601206
DEPARTMENT OF MECHANICAL ENGINEERING
ME6503 – DESIGN OF MACHINE ELEMENTS
V SEM MECHANICAL ENGINEERING
Regulation 2013
ANNA UNIVERSITY
2 MARKS QUESTIONS & ANSWERS
PREPARED BY
R.ASHOK KUMAR M.E, (Ph.D), M.I.S.T.E

R.M.K COLLEGE OF ENGG AND TECH / AQ / R2013/ ME6503 / V / MECH / JUNE 2017 – NOV 2017
ME6503 – DESIGN OF MACHINE ELEMENTS QUESTION BANK by ASHOK KUMAR.R (AP / Mech) 2
UNIT – I – STEADY STRESSES AND VARIABLE STRESSES IN
MACHINE ELEMENTS
PART - A
1.1) What are the factors to be considered in the selection of materials for a
machine element?
The factors to be considered in the selection of materials are
 Strength
 Durability
 Ductility
 Resistance to heat and corrosion
 Ability to cast
 Machinability
 Electrical conductivity
1.2) What are the mechanical properties of metals? List any four mechanical
properties. [Au, May / Jun - 2012]
 Strength
 Durability
 Ductility
 Resistance to heat and corrosion
 Ability to cast
 Machinability
 Electrical conductivity
1.3) What are the common materials used in mechanical engineering design?
[AU, Nov / Dec – 2015]
 Steel & steel based alloys
 Aluminium & aluminium based alloys
 Nickel based alloys
 Copper based alloys
1.4) How the machine design may be classified? [AU, Nov / Dec – 2016]
The machine design may be classified as follows:
 Adaptive design
 Development design

 New design
 Rational design
 Empirical design
 Industrial design
 Optimum design
 System design
 Element design
 Computer aided design
1.5) What is an adaptive design? [AU, Apr / May – 2015, May / Jun – 2016]
It is a design process where the new product is developed just making a small
changes to the existing product. It is used where limited scope is available to go for
an entirely new design.
Examples: Geared Bicycle, Die Design
1.6) What is adaptive design? Where it is used? Give examples.
[Au, Nov / Dec –2012]
It is a design process where the new product is developed just making a small
changes to the existing product. It is used where limited scope is available to go for
an entirely new design.
Examples: Geared Bicycle, Die Design
1.7) What do you mean by Optimum design? [Au, Nov / Dec –2011]
Optimum design is the best design for the given objective function under the
specified constraints. It may be achieved by minimizing the undesireable effects.
1.8) What are the steps in machine design process? [AU, Apr / May – 2010]
 Recognition of need
 Definition of problem
 Synthesis
 Analysis and optimization
 Evaluation and presentation
1.9) Define nominal, basic and actual size.
Nominal Size – The nominal size is the designation which is used for the
purpose of general identification of a component.

Basic Size – It is the design size of the component from which the limits are
delivered by the application of tolerance.
Actual Size – The size of a finished component which is actually measurable
with instruments is known as the actual size of the component.
1.10) What is meant by tolerance?
The difference between the maximum and minimum limits of dimension is
known as tolerance.
1.11) Define limits.
Limits are the two extreme permissible dimension of any part. There are two
extreme permissible sizes for a dimension. The largest permissible size is called as
upper limit or high limit (H) whereas the smallest permissible size is called as lower
limit (L).
1.12) Define limits and fits. [AU, Apr / May – 2015, May / Jun – 2016]
Limits are the two extreme permissible dimension of any part. There are two
extreme permissible sizes for a dimension. The largest permissible size is called as
upper limit or high limit (H) whereas the smallest permissible size is called as lower
limit (L).
Fit is defined as the degree of tightness or looseness between two mating
parts. The type of fit depends upon the amount of clearance and interference.
1.13) What are the types of fits? [Au, Nov / Dec– 2008]
 Clearance fit
 Interference fit
 Transition fit
1.14) Define clearance and interference fit.
Clearance Fit is defined as the fit established when a positive clearance
exists between the hole and the shaft. It is obtained by selecting the maximum and
minimum limits of the shaft and the hole so that the clearance due to the difference
between the dimensions of the smallest possible hole and the largest possible shaft
is always positive.
Interference Fit is defined as the fit established when a negative clearance
exist between the sizes of the hole and the shaft. It is obtained by selecting the
maximum and minimum limits of the shaft and the hole so that there is an

interference of the surfaces and the clearance due to the difference between the
dimensions of the largest possible and the smallest possible shaft is always negative.
1.15) What are unilateral and bilateral tolerances?
[Au, May / Jun – 2013, Nov / Dec – 2016]
The tolerance allowed on one side of nominal size then it is said to be
unilateral tolerance
The tolerance allowed on both side of nominal size then it is said to be
bilateral tolerance
1.16) What is hole basis system?
The nominal size of hole is taken same as the design size. The tolerance
zone of hole is taken as constant, while the tolerance zone of the shaft is varied above
or below the zero –line according to the required fits as shown in figure.
1.17) What is shaft basis system?
A nominal size is taken as a design size. The tolerance zone of a shaft is
adopted as constant while a tolerance zone of the hole is changed above or below
zero – line according to the fits as shown in figure

1.18) What is meant by interchangeability?
It is a principle employed to mating components. The components are picked
random, complying with the stipulated specifications and functional requirements of the
assembly. When one components assembles properly with any mating component, both
being chosen random, then it is interchangeable manufacture. It is the uniformity of size
of the components produced which ensures interchangeability
1.19) Define preferred numbers.
The preferred numbers are the conventionally rounded off values derived
from geometric series including the integral powers of 10 having as common ratio
of the following factors
√10
5
, √10
10
, √10
20
𝑎𝑛𝑑 √10
40
1.20) Mention some standard codes of specification of steels. [Au, Nov / Dec– 2008]
Designation of Plain Carbon steels: These are denoted like x . C. y, where
x – number 100 times the average percent of carbon, y – number 100 times the
average percent of manganese
Designation of Alloy Steel: Alloy steels are denoted by arranging elements
in the descending order of their proportion. And the average %of each element is
shown with its symbol before that number.
1.21) Define load. What are the different types of loads that can act on machine
components?
It is defined as any external force acting upon the machine part. The different
types of loads are
 Steady load
 Variable load
 Shock load

 Impact load
1.22) What are the factors that govern selection of materials while designing a
machine component? [Au, Nov / Dec– 2010]
 Strength & Stiffness
 Surface finish & Tolerances
 Manufacturability
 Ergonomics & aesthetics
 Working atmosphere
1.23) What is steady and variable load?
Steady Load: A load is said to be a dead or steady load, when it does not
change in magnitude or direction.
Variable Load: A load is said to be a live or variable load, when it changes
continually.
1.24) What is an impact load? Give example. [Au, May / Jun - 2012]
A load is said to be an impact load, when it is applied with some initial
velocity. Examples are load applied in punching machine and in impact testing
machine.
1.25) What is impact load? [AU, Nov / Dec – 2015]
A load is said to be an impact load, when it is applied with some initial
velocity. Examples are load applied in punching machine and in impact testing
machine.
1.26) What is meant by shock and impact load?
Shock Load: A load is said to be a suddenly applied or shock load, when it
is suddenly applied or removed.
Impact Load: A load is said to be an impact load, when it is applied with
some initial velocity
1.27) What are the methods used to improve fatigue strength?
[Au, Nov / Dec –2013]
 Cold working like shot peening, burnishing
 Heat treatments like induction hardening, case hardening, nitrating and
pre stressing

1.28) List at least two methods to improve the fatigue strength.
[Au, Nov / Dec –2014]
 Cold working like shot peening, burnishing
 Heat treatments like induction hardening, case hardening, nitrating and
pre stressing
1.29) Define stress and strain.
Stress: The internal resisting force per unit area is called as stress
Strain: The ratio of change in length to original length is called strain
1.30) Define Poisson’s ratio. [AU, Apr / May – 2011]
When a body is stressed within its elastic limit, the ratio of lateral strain to
the longitudinal strain is constant for the given material
µ =
Lateral strain
Longitudinal strain
1.31) Explain the normal stress theory and its limitations [AU, Apr / May – 2010]
The normal stress theory states that the failure or yielding occurs when
maximum normal stress reaches the limiting strength of the material in simple
tension test.
Limitations:
 It is suitable not suitable for ductile materials
 Theory takes only the effect of tensile and compressive stress only
1.32) Explain factor of safety. [AU, Apr / May – 2010]
It is defined as the ratio of maximum stress to the working stress
Factor of safety =
Maximum stress
Working stress
In case of ductile materials
Factor of safety =
Yeild point stress
Working stress
In case of brittle materials
Factor of safety =
Ultimate stress
Working stress
1.33) Define factor of safety. [Au, Nov / Dec –2012, 2015]
It is defined as the ratio of maximum stress to the working stress

Factor of safety =
Maximum stress
Working stress
1.34) What is factor of safety for brittle materials? [AU, Apr / May – 2011]
It is defined as the ratio of ultimate stress to the working stress
Factor of safety =
Ultimate stress
Working stress
1.35) List the important factors that influence the magnitude of factor of safety.
[Au, Nov / Dec –2011]
 Material properties
 Nature of load
 Presence of localized stresses
 Presence of initial stress
 Mode of failure
1.36) Differentiate the stress distribution in a bar subjected to an axial force and
beam subjected to bending [AU, Apr / May – 2010]
In axial case, the stress distribution is uniform across the section. In bending
the stress is tensile on one side of the neutral axis and compressive on the other.
1.37) Determine the force required to punch a hole of 20mm diameter in a 5mm
thick plate with ultimate shear strength of 250 MPa? [Au, Nov / Dec –2014]
Given:
d = 20mm t = 5mm τ = 250N/mm2
Solution
𝝉 =
𝑭
𝑨
𝝉 =
𝑭
𝝅 ∗ 𝒅 ∗ 𝒕

250 =
𝐹
𝜋 ∗ 20 ∗ 5
𝑭 = 𝟕𝟖. 𝟓𝟑𝟗 ∗ 𝟏𝟎 𝟑
𝑵
1.38) What are the various theories of failure?
[Au, May / Jun – 2013, Nov / Dec – 2016]
 Maximum principle stress theory
 Maximum shear stress theory
 Maximum principle strain theory
 Maximum strain energy theory
 Maximum distortion energy theory
1.39) Which theory of failure is suitable for the design of brittle materials?
[AU, Nov / Dec – 2015]
Maximum Principle Stress or Rankine theory
1.40) What is the maximum principal strain theory (Saint Vennant's theory)?
[Au, Nov / Dec – 2009]
The maximum principal strain theory states that the failure occurs at a point
in a member when the maximum principal strain reaches the limiting value of
strain
1.41) What are the types of variable stresses?
 Completely reversed or cyclic stresses
 Fluctuating stresses
 Repeated stresses
1.42) State the difference between straight beams and curved beams.
[Au, Nov / Dec –2012]
STRAIGHT BEAMS CURVED BEAMS
 Centroidal axis and neutral axis
coincident each other
 Centroidal axis and neutral axis
will not coincide each other.
Neutral axis is shifted towards
the center of curvature

 Stress developed are same
throughout the section
 Stress developed at inner and
outer radii of the section
1.43) Why nonsymmetrical I and T sections are preferred in design of curved
beams? [AU, April / May – 2017]
To achieve better stress distribution, section where the centroidal axis is
shifted towards the insides must be chosen, this tends to equalize the stress
variation on the inside and outside fibers for a curved beam. Such sections are
trapeziums, nonsymmetrical I and T sections.
1.44) What is eccentric loading?
An external load, whose line of action is parallel but does not coincide with
the centroidal axis of the machine component, is known as eccentric loading
1.45) Define stress concentration. [Au, May / Jun - 2012]
Whenever a machine component changes the shape of its cross section, the
simple stress distribution no longer holds good and the neighbourhood of the
discontinuity is different. This irregularity in the stress distribution caused by
abrupt changes form is called stress concentration.
1.46) What is meant by stress concentration?
[Au, May / Jun - 2009, Nov / Dec –2011]
Whenever a machine component changes the shape of its cross section, the
simple stress distribution no longer holds good and the neighbourhood of the
discontinuity is different. This irregularity in the stress distribution caused by
abrupt changes form is called stress concentration.
1.47) Give one method of reducing stress concentration in key slots.
[Au, May / Jun - 2012]
Stress concentration in key slots will be reduced by drilling holes around the
slot.
1.48) Define stress concentration and stress concentration factor.
[Au, May / Jun – 2014]
Stress concentration is the increase in the local stresses at points of rapid
changes in cross section and discontinuities

Stress concentration factor is defined as the ratio between the maximum
stresses in a member to the nominal stress at the same section based upon the net
area.
𝑆𝑡𝑟𝑒𝑠𝑠 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 =
𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝑠𝑡𝑟𝑒𝑠𝑠
𝑁𝑜𝑚𝑖𝑛𝑎𝑙 𝑠𝑡𝑟𝑒𝑠𝑠
1.49) How to avoid stress concentration? [Au, Nov / Dec –2012]
 Avoid sharp corners
 Providing fillets
 Use multiple holes instead of single hole
 Undercutting the shoulder parts
1.50) What are the methods of reducing stress concentration?
[Au, May / Jun - 2009]
1.51) How will you account for stress concentration in design of the machine parts.
[AU, Apr / May – 2010]
 Surface finish
 Size change
 Sharp corners
1.52) What are the methods to reduce stress concentration? [Au, Nov / Dec –2008]
1.53) What are the types of fracture?
Ductile fracture
Brittle fracture
1.54) Distinguish between brittle fracture and ductile fracture.
In brittle fracture, crack growth is up to a small depth of the material. In
ductile fracture large amount of plastic deformation is present to a higher depth.

1.55) What are the modes of fracture?
 Mode I (Opening mode) – Displacement is normal to crack surface.
 Mode II (Sliding mode) – Displacement is in the plane of the plate.
 Mode III (Tearing mode) – Out of plane shear.
1.56) Define (a) stiffness and (b) resilience [Au, May / Jun - 2009]
The ability of material to resist deformation under stress is known as
stiffness
The ability of material to absorb energy to resist shock and impact loads is
known as resilience
1.57) Define resilience [Au, Nov / Dec –2009, April / May – 2017]
known as resilience
1.58) Define proof resilience and modulus of resilience. [AU, April / May – 2017]
The maximum strain energy that can be stored in a material within the elastic
limit is known as proof resilience
Modulus of resilience is the proof resilience of the material per unit volume
Modulus of resilience =
Proof resilience
Volume of the body
1.59) Describe the material properties of hardness, stiffness and resilience.
[Au, Nov / Dec –2013, May / Jun – 2016]
The ability of material to resist wear, scratches, deformation and
machinability is known as Hardness
The ability of material to resist deformation under stress is known as
stiffness
known as resilience
1.60) Differentiate between hardness and toughness of materials.
[Au, May / Jun – 2014]
The ability of material to resist wear, scratches, deformation and machinability
is known as Hardness
The ability of material to resist fracture due to high impact loads is known as
Toughness

1.61) Define endurance limit. [Au, May / Jun – 2015]
Endurance limit is the maximum value of completely reversed stress that the
standard specimen can sustain an infinite number (106
) of cycles without failure.
1.62) What are the factors affecting endurance strength.
Factors affecting endurance strength are
 Load
 Surface finish
 Size
 Temperature
 Impact
 Reliability
1.63) What is an S-N curve? [AU, Nov / Dec – 2016]
An S-N Curve is a plot of the magnitude of an alternating stress versus the
number of cycles to failure for a given material. Typically both the stress and number
of cycles are displayed on logarithmic scales. The actual S-N line representing the
mean of the data from several tests. It is used to find the fatigue stress value
corresponding to a given number of cycles.
1.64) What is Geber theory [Au, Nov / Dec – 2009]
Gerber parabola joins endurance stress and ultimate stress (like Goodman
line). According to Gerber method, the relationship between σm , σa ,σu and σ-1is given
by

1.65) Write Soderberg equation for a machine component subjected to
(a)Combination of mean and variable torques
(b) Combination of mean and variable bending moments
[Au, Nov / Dec – 2010]
𝜏 𝑒𝑞 =
𝜏 𝑦
𝑛
= 𝜏 𝑚 + 𝐾𝑓 .
𝜏 𝑎 . 𝜏 𝑦
𝜏−1
𝜎𝑒𝑞 =
𝜎 𝑦
𝑛
= 𝜎 𝑚 + 𝐾𝑓 .
𝜎 𝑎 . 𝜎 𝑦
𝜎−1

UNIT – II – SHAFTS AND COUPLINGS
Part – A
2.1) What is meant by a shaft?
A shaft is a rotating machine element which is used to transmit power from
place to another.
2.2) What are the types of the shaft?
 Transmission Shaft: These shaft transmit power between the source and
the machines absorbing power. The counter shafts, line shafts, overhead
shafts and all factory shafts are transmission shaft.
 Machine Shaft: These shafts are from an integral part of machine itself.
The crank shaft is an example for machine shaft
2.3) What are the materials used in shafts? [AU, Nov / Dec – 2015]
 Hot-rolled plain carbon steel
 Cold-drawn plain carbon/alloy composition
 Alloy steels
2.4) Distinguish between shaft, axle and spindle from the design point of view.
A shaft is a rotating machine element which is used to transmit power from
place to another.
An axle, though similar in shape to the shaft, is a stationary machine element
and is used for transmission of bending moment only. It simply acts as a support
for some rotating body.
A spindle is a short shaft that imparts motion either to a cutting tool or to a
work piece.
2.5) What is the difference between spindle and axle?
[AU, Apr / May – 2015, Nov / Dec – 2016]
An axle, though similar in shape to the shaft, is a stationary machine element
and is used for transmission of bending moment only. It simply acts as a support
for some rotating body.
A spindle is a short shaft that imparts motion either to a cutting tool or to a
work piece.

2.6) What is meant by Jack shaft? [AU, April / May – 2010]
It is a short shaft connected to pulley, gears that transmits motion from a
motor to a machine. It is also called as counter shaft.
2.7) What are the factors to be considered for the selection of shaft materials?
The material used for shaft should have the following properties
 It should have high strength.
 It should have good machinability.
 It should have low notch sensitivity factor.
 It should have good heat treatment properties.
 It should have high wear resistant properties.
2.8) What are the types of stresses induced in shafts? [Au, Nov / Dec –2011]
The following stresses are induced in the shafts:
 Shear stresses due to the transmission of torque (i.e. due to torsional
load).
 Bending stresses (tensile or compressive) due to the forces acting upon
machine elements like gears, pulleys etc. as well as due to the weight of
the shaft itself.
 Stresses due to combined torsional and bending loads.
2.9) Name the stresses induced in the shaft. [AU, April / May – 2011]
load).
the shaft itself.
2.10) What are the various stresses induced in the shafts? [Au, May / Jun – 2014]
load).

the shaft itself.
2.11) What is the significance of slenderness ratio in shaft design?
[AU, Nov / Dec - 2008]
If slenderness ratio is increased the shaft deviates from its stub behavior and it
is essential to consider buckling while designing the shaft
2.12) What is meant by design of a shaft based on rigidity? [AU, Nov / Dec – 2015]
There are two types of rigidity base designing in shaft
Torsional Rigidity: The torsional rigidity is important in the case of camshaft
of an I.C. engine where the timing of the valves would be effected. The permissible
amount of twist should not exceed 0.25° per metre length of such shafts. For line
shafts or transmission shafts, deflections 2.5 to 3 degree per metre length may be
used as limiting value. The widely used deflection for the shafts is limited to 1 degree
in a length equal to twenty times the diameter of the shaft.
𝑇
𝐽
=
𝐶𝜃
𝐿
Lateral Rigidity: It is important in case of transmission shafting and
shafts running at high speed, where small lateral deflection would cause huge out-
of-balance forces. The lateral rigidity is also important for maintaining proper
bearing clearances and for correct gear teeth alignment. If the shaft is of uniform
cross-section, then the lateral deflection of a shaft may be obtained by using the
deflection formulae as in Strength of Materials. But when the shaft is of variable
cross-section, then the lateral deflection may be determined from the fundamental
equation for the elastic curve of a beam, i.e.
𝑑2
𝑦
𝑑𝑥2
=
𝑀
𝐸𝐼
2.13) State the reasons for preferring hollow shaft over solid shaft.
For same weight of shaft, hollow shaft can transmit 1.5 times the torque
transmitted by solid shaft.

For a particular power transmission, hollow shaft requires minimum
weight.
2.14) What are the advantage of hollow shafts? [AU, April / May – 2017]
The advantages of hollow shaft are:
Light weight: for the same power to be transmitted and same material of
both shafts, a hollow shaft is lighter than the solid shaft.
Stiffness: for the same weight, stiffness of hollow shaft is more than solid
shaft.
Strength: for the same weight, strength of hollow shaft is more than solid
shaft.
Natural Frequency: Natural frequency of hollow shaft is more than that of
solid shaft with same weight
2.15) Why a hollow shaft has greater strength and stiffness than solid shaft of
equal weight? [AU, April / May – 2011, Nov / Dec –2012, May / Jun – 2016]
Stresses are maximum at the outer surface of shaft. A hollow shaft has almost
all the material concentrated at the outer circumference and so has a better strength
and stiffness for equal weight.
2.16) What do you mean by stiffness and rigidity with reference to shafts?
[AU, Nov / Dec - 2010]
Stiffness is the resistance offered by the shaft for twisting and rigidity is the
resistance offered by the shaft for lateral bending.
2.17) The material of a shaft is changed from C40 steel to alloy steel to increase the
rigidity. Give your comment. [AU, April / May – 2017]
C40 is carbon steel which has less rigidity due to carbon content and alloy steel
has less carbon content thus exhibiting high rigidity.
2.18) Why is maximum shear stress theory is been used for shaft?
[AU, Nov / Dec - 2009]
Since, the shaft is made up of ductile material, thus the maximum shear stress
theory is been used.
2.19) Define variable load? [AU, April / May – 2010]
A load is said to be a live or variable load, when it changes continually.

2.20) What are the theories of failure used in design of shafts?
[Au, Nov / Dec –2012]
 Maximum Shear Stress Theory (Guest’s or Tresca’s Theory)
 Maximum Normal stress Theory (Rankine’s Theory)
 Maximum Strain Energy Theory (Haigh’s Theory)
 Maximum Distortion Energy Theory (Hencky and Von Mises Theory)
2.21) What is meant by critical speed of shaft? [AU, April / May – 2010]
The speed, at which the shaft runs so that the additional deflection of the shaft
from the axis of rotation becomes infinite, is known as critical or whirling speed.
2.22) Define the term critical speed of the shaft. [AU, Nov / Dec – 2016]
The speed, at which the shaft runs so that the additional deflection of the shaft
from the axis of rotation becomes infinite, is known as critical or whirling speed.
2.23) How the length and diameter of a shaft affects its critical speed?
[AU, Apr / May – 2015, Nov / Dec – 2016]
Increase in length decreases the critical speed and increase in diameter
increases the critical speed.
2.24) What is meant by equivalent bending moment [Au, May / Jun - 2012]
The equivalent bending moment may be defined as that the moment which
alone produces the same tensile or compressive stress (σb) as actual bending moment.
𝑀𝑒 =
1
2
[𝑀 + √ 𝑀2 + 𝑇2] =
𝜋
32
∗ 𝜎𝑏 ∗ 𝑑3
2.25) Define equivalent torsional moment of a shaft [AU, April / May – 2017]
The equivalent torsional moment is defined as that the moment which acting
alone produces the same torsional shear stress in the shaft as combined bending and
torsional moment
𝑇𝑒 = √ 𝑀2 + 𝑇2 =
𝜋
16
∗ 𝜏 ∗ 𝑑3

2.26) Sketch the cross section of a splined shaft. [Au, May / Jun - 2012]
d – Diameter of shaft
b – Width of keyway
h – Height or thickness of keyway
2.27) A shaft of 70mm long is subjected to shear stress of 40 MPa and has an angle
of twist equal to 0.017 radian. Determine the diameter of the shaft. Take G=80
GPa. [Au, Nov / Dec –2013]
Given:
𝑙 = 70𝑚𝑚
𝜏 = 40 𝑁
𝑚𝑚2⁄
𝜃 = 0.017 𝑟𝑎𝑑𝑠
𝐺 = 80 ∗ 103 𝑁
𝑚𝑚2⁄
Solution:
𝑇
𝐽
=
𝐺𝜃
𝐿
𝜋
16
∗ 𝜏 ∗ 𝑑3
𝜋
32
∗ 𝑑4
=
𝐺𝜃
𝐿
𝜋
16
∗ 40 ∗ 𝑑3
𝜋
32
∗ 𝑑4
=
80 ∗ 103
∗ 0.017
70
d = 4.11mm

2.28) Shaft A has diameter which is double the diameter of shaft B of same
material and transmit 80 kW if both shafts rotate at same speed, what is the
power transmitted by shaft B [Au, Nov / Dec –2014]
𝑷𝒐𝒘𝒆𝒓 𝑃 =
2𝜋𝑁𝑇
60
𝑃𝑜𝑤𝑒𝑟 𝑇𝑟𝑎𝑛𝑠𝑚𝑖𝑡𝑡𝑒𝑑 𝑏𝑦 𝐴 𝑃𝐴 =
2𝜋𝑁 𝐴 𝑇 𝐴
60
𝑃𝑜𝑤𝑒𝑟 𝑇𝑟𝑎𝑛𝑠𝑚𝑖𝑡𝑡𝑒𝑑 𝑏𝑦 𝐵 𝑃𝐵 =
2𝜋𝑁 𝐵 𝑇 𝐵
60
𝑃𝑜𝑤𝑒𝑟 𝑅𝑎𝑡𝑖𝑜
𝑃𝐴
𝑃𝐵
=
2𝜋𝑁 𝐴 𝑇 𝐴
60
2𝜋𝑁 𝐵 𝑇 𝐵
60
𝑆𝑖𝑛𝑐𝑒 𝑁𝐴 = 𝑁 𝐵
𝑃𝑜𝑤𝑒𝑟 𝑅𝑎𝑡𝑖𝑜
𝑃𝐴
𝑃𝐵
=
𝑇𝐴
𝑇𝐵
𝑃𝐴
𝑃𝐵
=
𝜋
16
∗ 𝜏 ∗ 𝑑 𝐴
3
𝜋
16
∗ 𝜏 ∗ 𝑑 𝐵
3
80 ∗ 103
𝑃𝐵
=
𝜋
16
∗ 𝜏 ∗ 23
𝜋
16
∗ 𝜏 ∗ 13
𝑃𝐵 = 10000𝑊
𝑃𝐵 = 10𝑘𝑊
2.29) What is a key? Where is it used? On what basis is it selected?
Key is a type of a fastener which is used to connect gears, pulleys, sprockets,
cam, flywheels etc, to the shaft. It is used with shaft to transmit the power from one
member to another member.
Keys are selected based on the magnitude of torque transmitted, type of
lading such as steady, variable or oscillatory, fit required, limited shaft stress and
cost etc.
2.30) What is key? State its functions. [Au, Nov / Dec –2011]

2.31) What is the function of key? [AU, April / May – 2011]
2.32) What is the function of keys? List types of keys [Au, Nov / Dec –2012]
cam, flywheels etc. to the shaft. It is used with shaft to transmit the power from one
 Sunk key
 Saddle key
 Tangent key
 Round key
 Splines
2.33) How are keys classified?
 Sunk key
 Saddle key
 Tangent key
 Round key
 Splines
2.34) Discuss forces on keys. [Au, Nov / Dec –2014]
 Force due to fit of the key in keyway (Tighten force). These force
produce compressive stress in key.
 Force due to torque transmitted by the shaft. These force produce
shearing and compressive stresses in the key.
2.35) What is the main use of woodruff keys? [Au, May / Jun, Nov / Dec –2013]
The woodruff key is used to transmit small value of toque in automotive and
machine tool industries. The keyway in the shaft is milled in a curved shape where
the keyway in the hub is usually straight.

2.36) What is the effect of key ways cut into the shaft? [AU, May / Jun – 2016]
 Reduces the strength and load carrying capacity of shaft because of
material removal
 It increases stress concentration factor near the corners of key way and
reduction in cross section area of shaft
2.37) Differentiate between keys and splines.
[Au, May / June – 2009, 2012, Nov / Dec –2011]
Keys Splines
 Keys are used in shaft with
single keyway
 Keys are used as fastener to
connect shaft and other elements
like gears, pulleys etc.
 Keys may dismantle during the
operation
 Splines are used in shaft with
multiple keyway
 Splines are special types of keys
which are made integral with
shaft.
 Splines will not dismantle during
the operation
2.38) What is coupling? [AU, May / June - 2009]
Coupling is a machine member employed to connect two power transmitting
shafts through keys.
2.39) What are the different types of couplings?
 Rigid couplings
 Muff or Sleeve coupling
 Clamp or Split Muff coupling
 Flange coupling
 Flexible couplings
 Bush pin type coupling
 Universal coupling
 Oldham coupling
2.40) What are the types of flexible coupling and rigid couplings?
[AU, Nov / Dec – 2016]
 Rigid couplings

 Flange coupling
 Oldham coupling
2.41) Name any two of the rigid and flexible couplings. [Au, May / Jun - 2013]
 Rigid couplings
 Flange coupling
 Oldham coupling
2.42) What are the different types of rigid couplings? [AU, April / May – 2011]
 Muff or Sleeve coupling
 Clamp or Split Muff coupling
 Flange coupling
2.43) Name any two of the rigid coupling. [Au, May / Jun – 2014]
 Muff or Sleeve coupling
 Clamp or Split Muff coupling
 Flange coupling
2.44) In what situation is flexible coupling is used?
[AU, Nov / Dec – 2008, 2009, 2015]
 Flexible couplings are preferred in order to reduce the effect of shock
and impact loads between the power transmitting shafts.
 They are used to permit an axial misalignment between the shafts
without absorption of power.
2.45) Under what circumstances flexible couplings are used?
[Au, Nov / Dec –2012, May / Jun – 2016]
 Flexible couplings are preferred in order to reduce the effect of shock
and impact loads between the power transmitting shafts.

 They are used to permit an axial misalignment between the shafts
without absorption of power.
2.46) Differentiate between rigid coupling and flexible coupling.
[AU, May / Jun – 2016]
RIGID COUPLING FLEXIBLE COUPLING
 Rigid coupling cannot tolerate
misalignment between the axis of
shafts
 Rigid coupling cannot absorb
shocks and vibrations
 Inexpensive
 Flexible coupling allows
misalignment between the axis of
shaft to 5◦
 Flexible coupling absorb shocks
and vibrations
 Expensive compared to rigid
coupling
2.47) State the reasons for which the couplings are located near the bearings.
[AU, April / May – 2017]
Couplings are located near the bearings due to the following two reasons:
 It reduces the bending moment and lateral deflection of shaft
 It reduces the angle of twist due to torsional moment
2.48) What are the possible modes of failure of the pin (bolt) in a flexible coupling?
[AU, Nov / Dec – 2015]
 Bearing failure
 Shear failure
 Bending failure
 Tensile failure due to combined bending and shear stress
2.49) Suggest suitable couplings for
(a) Shaft with parallel misalignment
(b) Shafts with angular misalignment of 10°
(c) Shafts in perfect alignment [AU, Nov / Dec - 2010]
 Bush pin type coupling or Oldham coupling is used for shafts with
parallel misalignment.
 Universal coupling used for shafts with angular misalignment of
10°.
 Rigid couplings used for Shafts in perfect alignment.

UNIT – III – TEMPORARY AND PERMANENT JOINTS
PART – A
3.1) Define screwed joints. What are its basic elements?
A screwed joint is mainly composed with two elements bolt and nut. The
screwed joints are widely used where the machine parts are required readily connected
or disconnected without any damage to the machine.
3.2) List the types of commonly used thread forms.
 British standard whitworth (B.S.W) thread
 British association (B.A) thread
 American national standard thread
 Unified standard thread
 Square thread
 Acme thread
 Knuckle thread
 Buttress thread
 Metric thread
3.3) What are the different applications of screwed fasteners?
[AU, Nov / Dec – 2016]
It is widely used where the machine parts are needed to be readily
connected or disconnected without damaging the machine.
The parts may be rigidly connected or provisions may be made for
predetermined relative motion.
 It is also used for transmitting power and energy.
3.4) What is a stud? [AU, Nov / Dec - 2009]
A stud is a round bar threaded at both ends. One end of the screwed into a
tapped hole of one of the parts to be fasted without nut. Studs are used instead of tap
bolts for securing various kinds of covers. Examples covers of engine and pump
cylinders, valves etc.

3.5) Sketch a stud [AU, Nov / Dec - 2008]
3.6) How is a bolt designated? Give examples. [AU, May / June – 2009]
A bolt is designated by a letter M followed by nominal diameter and pitch
in mm.
It is given by Md*p
If coarse pitches are used the ‘p’ is omitted. M10*3
Nominal diameter = 20mm
Pitch = 3mm
3.7) What are the materials for bolts and screws [AU, April / May – 2011]
Low Carbon steel
Medium Carbon steel
Aluminium
Nickel
Copper

3.8) What is preloading of bolts? [AU, Nov / Dec – 2015, 2016]
Preload is the tension created in a fastener when it is tightened. This tensile
force in the bolt creates a compressive force in the bolted joint known as clamp force
3.9) What is known as proof strength of the bolts? [AU, Apr / May – 2015]
The proof strength is the quotient of the proof load and the tensile-stress area.
The proof load is the maximum load (force) that a bolt can withstand without acquiring
a permanent set.
3.10) What is meant by single start and double start thread? [Au, Nov / Dec –2012]
If the thread is having only one helical groove, then it is called as single –
start thread. When the thread having more than one helical grooves, (up to four grooves)
is called as multi – start threads. If the number of starts is two, then it is known as double
start thread.
3.11) What do you understand by the single start and double start threads?
[Au, Nov / Dec –2011]
If the thread is having only one helical groove, then it is called as single –
start thread. When the thread having more than one helical grooves, (up to four grooves)
is called as multi – start threads. If the number of starts is two, then it is known as double
start thread.
3.12) Define the term self-locking of power screws.
[Au, Nov / Dec –2012, May / Jun - 2013]
If the friction angle (ϕ) is greater than helix angle (α) of the power screw,
the torque required to lower the load will be positive, indicating that an effort is applied
to lower the load. This type of screw is known as Self Locking screw. The efficiency
of the self locking screw is less than 50%.
3.13) What is threaded joint? [AU, April / May – 2010]
Threaded joints are detachable joints of two or more component parts
either directly connected with each other or by standardized fasteners, i.e. bolts, nuts
and screws.

3.14) Determine the safe tensile load for a bolt of M20, assuming a safe tensile
stress of 40 MPa. [Au, May / Jun - 2012]
Given:
Bolt size : M20 σ = 40N/mm2
Solution:
From PSGDDB at 5.42, for M20 bolt size
Shear area Ac = 245mm2
𝜎 =
𝑃
𝐴 𝑐
40 =
𝑃
245
P = 9800N
3.15) State the advantages of threaded joints. [Au, May / Jun - 2012]
Threaded joints are highly reliable in operation.
Threaded joints are convenient to assemble and disassemble.
A wide range of threaded joints in may be adopted to various operating
conditions.
Screws are relatively cheap to produce due to standardization and highly
efficient manufacturing processes.
3.16) What is the meaning of M14 * 2 threaded? [AU, April / May – 2010]
Nominal diameter of bolt d = 14 mm
Pitch p = 2mm
3.17) Why are ACME treads preferred over square thread for power screw?
[Au, Nov / Dec –2014]
 It is easy to manufacture by using dies.
 It is stronger than square threads.

 It is thicker and wider and the work in better environments with dirt and
debris.
3.18) List out the factors that influence the amount of initial tension.
[Au, May / Jun - 2012]
 Tensile stresses due to stretching of the bolt
 Torsional shear stress due to frictional resistance at the threads
 Shear stress across threads
 Compressive or crushing stress on the threads
 Bending stress if the surfaces under the bolt head or nut are not perfectly
normal to the bolt axis
3.19) What are the stresses induced in screwed fastening due to static loading?
[AU, May / Jun – 2016]
The following stresses in screwed fastening due to static loading are
 Internal stresses due to screwing up forces,
 Stresses due to external forces, and
 Stress due to combination of stresses due to screwing up forces &
external forces
3.20) What is a gib? Why is it provided in a cotter joint?
[Au, Nov / Dec –2013, May / Jun – 2016]
Gib is an element made up of mild steel with thickness equal to cotter. A gib
is used in combination with cotter to provide the following advantages
 Reduce bending of socket end
 Increase the bending area of contact between the mating surfaces
3.21) What is a cotter joint?
A cotter joint is temporary fastening and is used to connect rigidly two co
axial rods or bars which are subjected to axial tensile or compressive forces.
3.22) What is the purpose of cotter joint? [AU, April / May – 2010]
The purpose of cotter joint is to connect rigidly two co axial rods or bars
which are subjected to axial tensile or compressive forces.
3.23) What are the types of cotter joints?
 Socket and spigot cotter joint
 Sleeve and cotter joint

 Gib and cotter joint
3.24) What are different types of cotter joints? [Au, May / Jun – 2014]
 Socket and spigot cotter joint
 Sleeve and cotter joint
 Gib and cotter joint
3.25) List the advantages of cotter joint over threaded joints.
 Small axial adjustment is possible with cotter joints
 Speed in connections and disconnections of rods.
3.26) What is meant by knuckle joint?
A knuckle joint is used to connect two rods which are under the action of
tensile loads. If the joints are guided, the rods may support compressive loads.
3.27) Where are knuckle joints used? [AU, April / May – 2011]
 Link of a cycle chain
 Tie rod joint for roof truss
 Valve joint with eccentric rod
 Pump rod joint
 Tension link in bridge structure
 Lever and rod connections
3.28) Mention the various methods of failure of knuckle joint.
 Failure of the solid rod in tension
 Failure of the knuckle pin in shear
 Failure of the single eye or rod end in tension
 Failure of the single eye or rod end in shearing
 Failure of the single eye or rod end in crushing
 Failure of the forked end in tension
 Failure of the forked end in shearing
 Failure of the forked end in crushing
3.29) Mention the assumptions made in riveted joint design.
The assumptions made in riveted joint design are
 The load on the joint is equally shared by all the rivets

 The tensile stress is equally distributed over the section of metal between
the rivets
 The shear stress and crushing stress in all the rivets is uniform
 There is no bending stress in rivets
 The holes onto which the rivets are driven do not weaken the member
 The rivets fills the hole after it is driven
 The friction between the surfaces of the plate is negeleted
3.30) State any two advantages of welded joints over riveted joints.
 The welded structure are usually lighter than the riveted structures.
 The welded joints provide maximum efficiency than riveted joints.
 Alteration can be easily done existing structures.
 Welded joints have great strength.
 The process time of welding is less than the riveting
 It is possible to weld any part of a structure at any point.
3.31) Classify the rivet heads according to IS specifications. [Au, Nov / Dec –2011]
 Rivet heads for general purposes (below 12mm diameter) according to
IS 2155 – 1982 (Reaffirmed 1996).
 Rivet heads for general purposes (below 12mm to 48mm diameter)
according to IS 1929 – 1982 (Reaffirmed 1996)
 Rivet heads for boiler works (below 12mm to 48mm diameter) according
to IS 1928 – 1961 (Reaffirmed 1996)
3.32) What is bearing failure in rivets? [AU, Apr / May – 2015]
The rivets do not actually shear off under the tensile stress, but crushed as
shown in figure. Due to this the rivet hole becomes of an oval shape and hence the joint
becomes loose. The failure of rivets in such a manner is known as bearing failure.

3.33) What is caulking?
In boilers and hydraulic tanks containing pressurized fluids, there are
possibilities of leak at the joints between the two overlapping plates, or between the
bearing plate and underneath of the rivet head. Therefore the riveted joints of the boilers
and tile hydraulic tanks have to be made leak – proof. This is accomplished by burring
down or forcing down the edges of the rivet heads and the plates. This will force the
edge of the plate or the rivet head to bite into the bearing plate which makes the joint
leak – proof. The burring down of the edges of the rivet head or the plates is
accomplished by hammering down by a blunt chisel like tool of about 5mm thick and
50 mm in breadth with the edge ground at an angle of 80°, known as caulking tool as
shown in Figure, along the edges of the plates and all-round the rivet head. This
operation is called caulking.
3.34) What is fullering?
The burring down the edges of the plates is by the use of fullering tool,
similar to the caulking tool but the thickness of the tool is equal to that of the plates as
shown in the Figure. To facilitate the fullering operation the edges of the plates will be
previously chamfered or bevelled to an angle of 80° before the joint is made. The
fullering operation increases this angle to 80°.

3.35) List the four ways by which a riveted joint may fail. [Au, May / Jun - 2012]
 Tearing of the plate at an edge
 Tearing of the plate across a row of rivets
 Shearing of rivets
 Crushing of plate or rivets
3.36) Name the possible modes of failure on riveted joint
[AU, Nov / Dec – 2008, 2012]
3.37) What are the different modes of failure of a riveted joint?
3.38) Write any two advantages and disadvantages of welded joints over riveted
joints. [Au, May / Jun - 2013]
Advantages:

Disadvantages:
 High skilled labour required
 Possibility of crack developing
 Uneven heating and cooling during fabrication so additional stress are
developed
 The inspection of welding is difficult
 Welding reduces the fatigue strength
3.39) What is the total shear in a double strap butt joint with equal length of
straps? [AU, Nov / Dec – 2015]
Total shear in a double strap butt joint will be equal length of strap = 2 times
on single
3.40) Define welding. [AU, Nov / Dec - 2008]
Welding is a process of joining two similar or dissimilar metals with or
without application of pressure along with or without addition of filler materials
3.41) What are the reasons of replacing riveted joint by welded joint in modern
equipment? [AU, Nov / Dec - 2010]
 Material is saved in welded joints.
 Leak proof joints are easily obtained.

3.42) What is a welded joint?
A welded joint is a permanent joint which is obtained by the fusion of the
edges of the two parts to be joined together with or without application of pressure along
with or without addition of filler materials
3.43) Why are welded joints preferred over riveted joints? [AU, May / June – 2009]
 Material is saved in welded joints.
 Leak proof joints are easily obtained.
3.44) What are the advantages of weld joints compared with riveted joints
3.45) State the advantages of the welded joints. [AU, Nov / Dec – 2015]
 The process time of welding is less
3.46) What are the disadvantages of welding? [Au, Nov / Dec –2014]
 High skilled labour required
 Possibility of crack developing
 Uneven heating and cooling during fabrication so additional stress are
developed
 The inspection of welding is difficult
 Welding reduces the fatigue strength
3.47) State the two types of eccentric welded connections.
[Au, Nov / Dec –2013, 2016 May / Jun – 2016]
 Welded connections subjected to moment in a plane of the weld

 Welded connections subjected to moment in a plane normal to the plane
of the weld.
3.48) What are the two types of stresses are induced in eccentric loading of loaded
joint?
 Direct shear stress.
 Bending or torsional shear stress.
3.49) What are the two types of fillet weld? [AU, May / Jun – 2016]
 Single transverse fillet weld
 Double transverse fillet weld
3.50) Transverse fillet weld are preferred to parallel fillet welds. Why?
Transverse fillet can resist shear load along with longitudinal load.
3.51) Differentiate with a neat sketch the fillet welds subjected to parallel loading
and transverse loading. [Au, May / Jun – 2014]
3.52) Why throat is considered while calculating stresses in fillet welds?
The transverse fillet welds are subjected to tensile stress. The minimum cross
section of the weld is at the throat. Therefore the failure due to tensile stress will
occur at the throat section.
3.53) Write down the expression for strength of parallel fillet weld in terms of
permissible shear stress, length of welded joint. [AU, Nov / Dec - 2009]
𝑃 = 2 ∗ 0.707 ∗ ℎ ∗ 𝑙 ∗ 𝜏

3.54) What is the bending stress induced in the weld when a circular rod of
diameter d, welded to a rigid plate by a circular fillet weld of size 't', which is
subjected to a bending moment M? [AU, Nov / Dec – 2015]
From PSGDDB at 11.3 from the table 4th
row and 4th
column
𝜎 =
5.66𝑀
𝑡𝑑2 𝜋
3.55) What is an eccentric loaded welded joint? [Au, May / Jun – 2013, 2014]
The external load applied may not pass through the geometric center in
structural joints called as eccentric loaded weld joint.
3.56) When will the edge preparation need?
If the two plates to be welded have more than 6mm thickness, the edge
preparation should be carried out.

UNIT – IV – ENERGY STORING ELEMENTS AND ENGINE
COMPONENTS
PART – A
4.1) What is a spring?
A spring is an elastic member, which deflects, or distorts under the action of
load and regains its original shape after the load is removed.
4.2) What is the use of springs? [AU, Nov / Dec - 2008]
 To cushion, absorb or control energy due to either shock or vibration as
in car springs, railway buffers, air – craft landing gears, shock absorbers
and vibration dampers.
 To apply forces as in brakes, clutches and spring – loaded valves.
 To control motion by maintain contact between two elements as in cams
and followers.
 To store energy as in watches, toys etc.
4.3) State any two functions of springs. [AU, Nov / Dec – 2016]
 To store energy for part of a functional cycle.
 To force a component to bear against, to maintain contact with, to
engage, to disengage or to remain clear of some another component.
 To return a component to its original position after displacement.
 To permit some freedom of movement between aligned components
without disengaging them.
4.4) Give some of materials used for spring [AU, Nov / Dec - 2008]
 Carbon steel
 Oil tempered carbon steel
 Stainless steel
 Hard drawn steel wire
 Monel metal
 Phosphor bronze
 Brass
4.5) Give a list of the different types of springs
 Helical springs
 Torsional springs

 Leaf or Laminated springs
 Disc spring or Belleville springs
4.6) Mention any four types of springs. [Au, May / Jun - 2012]
 Helical springs
 Torsional springs
 Leaf or Laminated springs
 Disc spring or Belleville springs
4.7) Distinguish between close coiled and open coiled springs.
[Au, Nov / Dec –2014]
Open coiled spring Closed coil spring
 The wires are coiled such that
there is a gap between the two
consecutive turns.
 Helix angle is greater than 10º
 Both torsional and bending stress
are significant
 The wires are very closely coiled
such that there is no gap between
the two consecutive turns.
 Helix angle is less than 10º
 Only torsional stress are
predominant
4.8) Sketch the stresses induced in the cross section of a helical spring,
considering Wahl's effect. [AU, April / May – 2017]

4.9) Explain the following terms of the spring. (a) Free length (b) Spring index
Free length of the spring is the length of the spring when it is free or
unloaded condition. It is equal to the solid length plus the maximum deflection or
compression of the spring and clearance between the adjacent coils.
Lf = solid length + Ymax + 0.15 YMax
Spring index (C) is defined as the ratio of the mean diameter of the coil to
the diameter of the wire.
𝑪 =
𝑫
𝒅
4.10) Define (a) Spring Index (b) Spring rate. [Au, Nov / Dec –2011]
𝑪 =
𝑫
𝒅
The spring rate (stiffness) or spring constant is defined as the load required
per unit deflection of the spring.
𝒌 =
𝑷
𝒚
4.11) Define spring rate. [AU, May / Jun – 2016]
The spring rate (stiffness) or spring constant is defined as the load required
𝒌 =
𝑷
𝒚
4.12) Define spring index and spring constant. [Au, Nov / Dec –2012]
𝑪 =
𝑫
𝒅
The spring constant (stiffness) or spring rate is defined as the load required
𝒌 =
𝑷
𝒚

4.13) What is stiffness of spring? [AU, Nov / Dec – 2015, May / Jun – 2016]
The Stiffness (spring rate) or spring constant is defined as the load
required per unit deflection of the spring.
𝒌 =
𝑷
𝒚
4.14) When a helical compression spring is cut into two halves, what is the stiffness
of the resulting half spring? [AU, April / May – 2017]
The Stiffness of the spring will be doubled.
4.15) Write the formula for natural frequency of spring.
[Au, Nov / Dec –2012, 2016]
𝑓𝑛 =
𝑑
2𝜋𝐷2 𝑛
√
6𝐺𝑔
𝜌
𝑐𝑦𝑐𝑙𝑒𝑠/ 𝑠𝑒𝑐
d – Diameter of wire
D – Mean coil diameter of spring
n – Number of active turns
G – Modulus of rigidity
g – Acceleration due to gravity
ρ – Density of the spring material
4.16) Obtain the expression for stiffness of helical spring. [Au, May / Jun - 2012]
The spring constant (stiffness) or spring rate is defined as the load required
𝑲 =
𝑷
𝒚
4.17) Two springs of stiffness K1 and K2 are connected in series. What is the
stiffness of the connection [AU, April / May – 2010]
1
𝑘
=
1
𝑘1
+
1
𝑘2
4.18) For a springs in series, the spring rate ( stiffness) add reciprocally prove
The total deflection of the springs,

𝑦 = 𝑦1 + 𝑦2
𝑘 =
𝑃
𝑦
𝑦 =
𝑃
𝑘
𝑃
𝑘
=
𝑃
𝑘1
+
𝑃
𝑘2
1
𝑘
=
1
𝑘1
+
1
𝑘2
4.19) What is Whal’s factor? [AU, April / May – 2011]
In order to take into account the effect of direct shear and change in coil
curvature a stress factor is defined, which is known as Wahl's factor
𝐾𝑠 =
4𝐶 − 1
4𝐶 − 4
+
0.615
𝐶
C – Spring index
4.20) Why is Wahl’s factor to be considered in the design of helical compression
springs? [AU, April / May – 2010]
When a wire is wounded in the form of helix, the length of inner fiber of
wire is reduced in comparison to the length of outer fiber. It results in stress
concentration at the inner fiber In order to take into account the effect of direct shear
and change in coil curvature a stress correction factor.
𝐾𝑠 =
4𝐶 − 1
4𝐶 − 4
+
0.615
𝐶
C – Spring index
4.21) What are the different styles of end for helical compression spring?
[AU, Nov / Dec - 2009]
 Plain ends
 Ground ends
 Squared ends
 Squared and ground ends

4.22) What is the effect of increase in wire diameter on the allowable stress value?
[AU, Nov / Dec - 2010]
Increase in wire diameter will increase the spring rate but it will reduces the
spring index (C).
4.23) What type of spring is used to maintain an effective contact between a cam
and a reciprocating roller or flat faced follower? [AU, Nov / Dec – 2015]
An open coil helical compression spring is used to maintain an effective
contact between a cam and a reciprocating roller or flat faced follower.
4.24) A helical spring of rate 12 N/mm is mounted on the top of another spring of
rate 8 N/mm. Find the force required to give a deflection of 50mm.
[Au, Nov / Dec –2013]
Given:
k1 = 12 N/mm k2 = 8 N/mm y = 50mm
Solution:
1
𝑘
=
1
𝑘1
+
1
𝑘2
1
𝑘
=
1
12
+
1
8
𝒌 = 𝟒. 𝟖𝒎𝒎
𝑘 =
𝑃
𝑦
4.8 =
𝑃
50
𝑷 = 𝟐𝟒𝟎𝑵
4.25) What is meant by surge in springs? [Au, Nov / Dec – 2008, 2012]
The material is subjected to higher stresses, which may cause early fatigue
failure. This effect is called as spring surge
4.26) What is surge in springs? [Au, May / Jun - 2013]
The material is subjected to higher stresses, which may cause early fatigue
failure. This effect is called as spring surge

4.27) What is buckling of springs?
The helical compression spring behaves like a column and buckles at a
comparative small load when the length of the spring is more than 4 times the mean
coil diameter.
4.28) What are the points to be taken into consideration while selecting the pitch
of the spring?
The points taken into consideration of selecting the pitch of the springs are
 The pitch of the coil should be such that if the spring is accidentally
compressed the stress does not increase the yield point stress in torsion.
 The spring should not be close up before the maximum service load is
reached.
4.29) Define active turns.
Active turns of the spring are defined as the number of turns, which impart
spring action while loaded. As load increases the no of active coils decreases.
4.30) Define inactive turns.
Inactive turns of the spring are defined as the number of turns which does
not contribute to the spring action while loaded. As load increases number of inactive
coils increases from 0.5 to 1 turn.
4.31) Write about the eccentric loading of springs?
If the load acting on the spring does not coincide with the axis of the spring,
then spring is said to be have eccentric load. In eccentric loading the safe load of the
spring decreases and the stiffness of the spring are also affected.
4.32) What are the methods used for eliminating surge in springs?
The methods used for eliminating surge are
 By using dampers on the center coil so that the wave propagation dies
out
 By using springs having high natural frequency.
4.33) What are the disadvantages of using helical spring of non-circular wires?
 The quality of the spring is not good
The shape of the wire does not remain constant while forming the helix.
It reduces the energy absorbing capacity of the spring.

The stress distribution is not favorable as in circular wires. But this effect
is negligible where loading is of static nature.
4.34) Estimate the equivalent stiffness of springs in parallel and in series.
Series:
1
𝑘
=
1
𝑘1
+
1
𝑘2
Parallel:
𝑘 = 𝑘1 + 𝑘2
4.35) What are the purposes of using concentric springs? [AU, Apr / May – 2015]
 To obtain greater spring force within the given space.
 To ensure the operation of a mechanism in the event of failure of one of
the springs.
4.36) What are the applications of concentric springs? [AU, Apr / May – 2010]
 It is used in rail – road car suspension.
 It is used in automobile clutches, valve springs in aircraft, heavy duty
diesel engines.
4.37) When two concentric springs of stiffness 100 N/mm and 50 N/mm respectively
are subjected to an axial load of 750 N, what will be the deflection of each
spring? [AU, Nov / Dec – 2007]
Given:
k1 = 100 N/mm k2 = 50 N/mm P = 750N
Solution:
𝑘 = 𝑘1 + 𝑘2
𝑘 = 100 + 50
𝒌 = 𝟏𝟓𝟎 𝑵/𝒎𝒎
𝑘 =
𝑃
𝑦
150 =
750
𝑦
𝒚 = 𝟓 𝒎𝒎

4.38) What is a leaf spring. [AU, Nov / Dec - 2009]
Leaf spring is a spring made of a number of strips of metal curved slightly
upwards and clamped together one above the other.
4.39) What is meant by semi elliptical leaf springs? [Au, May / Jun – 2014]
The spring consists of number of leaves, which are held together by U- clips.
The long leaf fastened to the supported is called master leaf. Remaining leaves are
called as graduated leaves.
4.40) What is nipping of laminated leaf spring?
Prestressing of leaf springs is obtained by a difference of radii of curvature
known as nipping.
4.41) What is nipping of leaf spring? [AU, Nov / Dec – 2015, May / Jun – 2016]
Prestressing of leaf springs is obtained by a difference of radii of
curvature known as nipping.
4.42) What is the advantage of leaf spring over helical spring?
The advantage of leaf spring over helical spring is that the end of the spring
may be guided along a definite path as it deflects to act a structural member in
addition to energy absorbing device.
4.43) Write notes on the master leaf & graduated leaf?
The longest leaf of the spring is known as main leaf or master leaf has its
ends in the form of an eye through which bolts are passed to secure the spring. The
leaf of the spring other than master leaf is called the graduated leaves.
4.44) What is meant by nip in leaf springs?
By giving greater radius of curvature to the full length leaves than the
graduated leaves, before the leaves are assembled to form a spring thus a gap or
clearance will be left between the leaves. This initial gap is called nip.
4.45) What is a lever? [Au, Nov / Dec –2011]
Lever a rigid bar resting on a pivot, used to move a heavy or firmly fixed
load with one end when pressure is applied to the other.
4.46) What is the use of flywheel? [AU, Nov / Dec - 2008, May / Jun - 2012]
A flywheel is a heavy rotating mass which is placed between the power
source and the driven member to act as a reservoir of energy. The primary function
of Flywheel is to acts as an energy accumulator. A flywheel used in machine serves

as a reservoir which stores energy during the period when the supply of energy is
more than the requirement and releases it dulling the period when the requirement of
energy is more than the supply.
4.47) What is the function of a flywheel? [AU, Apr / May – 2011, Nov / Dec –2012]
of Flywheel is to acts as an energy accumulator. The function of the flywheel is to
serve as a reservoir which stores energy during the period when the supply of energy
is more than the requirement and releases it dulling the period when the requirement
of energy is more than the supply.
4.48) What is the purpose of the flywheel? [AU, Nov / Dec – 2015]
4.49) What is the main function of a flywheel in an engine? [Au, Nov / Dec –2011]
4.50) What is the purpose of flywheel that is used in an IC engine?
[Au, Nov / Dec –2013]

4.51) How does the function of flywheel differ from that of governor?
[Au, May / Jun – 2012, Nov / Dec –2012, 2016]
A governor regulates the mean speed of an engine when there are variations
in the mean loads. It automatically controls the supply of working fluid to the engine
with the varying load condition and keeps the mean speed within the limits. Flywheel
does not control the speed variation caused by the varying load and does not maintain
the constant speed. Flywheel reduces the fluctuation of speed. Flywheel controls the
speed variations caused by the fluctuation of engine turning moment during each
cycle of operation
4.52) Define co-efficient of fluctuation of speed. [Au, Nov / Dec –2011]
The ratio of maximum fluctuation of speed to the mean speed is called
coefficient of fluctuation of speed.
𝐶𝑠 =
𝑁1 − 𝑁2
𝑁
4.53) Define Co-efficient of fluctuation of speed in flywheel. [Au, May / Jun - 2013]
𝐶𝑠 =
𝑁1 − 𝑁2
𝑁
4.54) Define (a) Coefficient of fluctuation of speed (b) Coefficient of fluctuation of
energy. [Au, Nov / Dec –2014, May / Jun – 2016]
𝐶𝑠 =
𝑁1 − 𝑁2
𝑁
The ratio of maximum fluctuation of energy to the work done per cycle is
called coefficient of fluctuation of energy
𝐶 𝐸 =
Maximum fluctuation of energy
Work done per cycle
4.55) Define the term "fluctuation of energy". [Au, May / Jun – 2014]

𝐶 𝐸 =
Work done per cycle
4.56) Define co-efficient of fluctuation of energy. [AU, Nov / Dec - 2009]
𝐶 𝐸 =
Work done per cycle
4.57) Define the term co-efficient of steadiness. [AU, Nov / Dec – 2009, 2011]
The ratio of mean speed to the maximum fluctuation of speed is called
coefficient of steadiness
𝑚 =
𝑁
𝑁1 − 𝑁2
𝑚 =
1
𝐶𝑠
4.58) What type of stresses is produced in a disc flywheel? [AU, Nov / Dec - 2010]
 Tensile stress due to centrifugal force
 Tensile bending stress caused by the restraint of the arms and
 The shrinkage stresses due to unequal rate of cooling of casting.
4.59) State the type of stresses induced in a rim flywheel?
4.60) What are the types of stresses induced in a flywheel rim?
4.61) What are the stresses induced in flywheel arms?
 Tensile stress due to centrifugal force.
 Bending stress due to torque.
 Stress due to belt tension.

4.62) What is meant by connecting rod?
The connecting rod is the intermediate member between the piston and
crankshaft. Its primary function is to transmit the push and pull from the piston pin
to the crank pin and thus convert the reciprocating motion of the piston into the rotary
motion of the crank.
4.63) What are the forces acting on the connecting rod? [AU, April / May – 2017]
 Force on the piston due to gas pressure and inertia of the reciprocating
parts
 Force due to inertia of the connecting rod
 Force due to friction of the piston rings and of the piston
 Force due to friction of the piston pin bearing and the crank pin bearing
4.64) Why I section is chosen for the connecting rod of I.C engines?
[AU, Nov / Dec – 2015]
In connecting rod there is a chance for buckling about x – axis and y – axis.
Since the both the ends are assumed to be hinged about x – axis and fixed about y –
axis, the area moment of inertia about x – axis and y – axis is having a relationship
as Ixx = 4Iyy. Since the I Section satisfies condition Ixx = 4Iyy, so I section is
preferred.
4.65) What are the essential requirements in an end face seal?
[AU, Nov / Dec –2013, 2016]
High compressive stress and Hardness
4.66) At what angle of the crank the twisting moment is maximum in the
crankshaft? [Au, Nov / Dec –2011]
The crank angle for maximum twisting moment usually lies between 25º and
35º from top dead center for petrol engines and between 30º and 40º for diesel
engines.
4.67) What are the major failure in a crankshaft? What is it due to?
Major failure of the crank shaft is shear, because of Torsion.

4.68) Why is piston end of a connecting rod kept smaller than the crank pin end?
[AU, Nov / Dec - 2010]
The piston end of the connecting rod experiences less bending moment than
the crank end. Hence, on the basis of beam of uniform strength, the piston end of the
connecting rod is smaller.
4.69) Under what force, the big end bolts and caps are designed?
[Au, Nov / Dec –2011]
parts
 Inertia of the reciprocating parts
4.70) What type of external forces act on connecting rod? [Au, Nov / Dec –2012]
parts
 Inertia of the reciprocating parts

UNIT – V – BEARINGS
PART – A
5.1) What is bearing?
A bearing is a machine element which support another moving machine
element. It permits relative motion between the contact surfaces of the members
while carting the load.
5.2) Classify the types of bearings. [Au, May / Jun – 2014, Nov / Dec – 2016]
 Depending upon the direction of load
 Radial bearings
 Thrust bearings
 Depending upon the nature of contact
 Sliding contact bearings
 Rolling contact bearing
5.3) What are the required properties of bearing materials?
 High compressive strength
 Low coefficient of friction
 High thermal conductivity
 High resistance to corrosion
 Sufficient fatigue strength
5.4) Name few materials for sliding contact bearings.
 Aluminium alloys
 Copper allots
 Babbit alloys
 steel
5.5) What is meant by journal bearing? [Au, May / Jun – 2013, 2014, 2016]
The sliding contact bearings in which sliding action along the circumference
of a circle or an arc of a circle and carrying radial loads are known as Journal or
Sleeve bearings
5.6) What is meant by hydrodynamic lubrication? [AU, May / Jun – 2016]
In hydrodynamic lubrication hydro means (liquid) and dynamic means
(relative motion) it is the combination of both liquid and relative motion to reduce

the friction. In hydrodynamic, a thick film of lubricant is formed between the journal
and the bearing.
5.7) What is full journal bearing? [AU, Nov / Dec – 2015]
When the angle of contact of the bearing with the journal is 360° as shown
in Figure, then the bearing is called a full journal bearing.
5.8) For a journal bearing the maximum operating temperature must be less than
80°C. Why? [AU, Nov / Dec - 2010]
Temperature rise in journal bearing affects the viscosity of the oil. If
temperature increase the viscosity of oil is reduced. Which would lead to metal to
metal contact and cause wear between moving parts.
5.9) What is meant by square journal bearing? [AU, Nov / Dec – 2015]
When the length of the journal bearing is equal to diameter of the bearing
then the journal bearing is known as square journal bearing.
5.10) Differentiate clearly between sliding contact and rolling contact bearing.
[Au, Nov / Dec –2012]
Sliding Contact Bearing Rolling Contact Bearing
 Integral part with machine
 More axial space required
 High maintenance cost due to
specialized lubrication oil
 Assembled with the machine
whenever needed
 Less axial space required
 Less maintenance cost due to
simple lubrication system
5.11) Define anti friction bearings. [Au, May / Jun - 2012]
A bearing in which the friction developed between the relative rotating
members such as shaft and sleeve is very low is termed as anti – friction bearing. In

rolling contact bearings the friction developed is very low, they are called as anti –
friction bearings
5.12) What are anti - friction bearings? [AU, April / May – 2017]
rolling contact bearings the friction developed is very low, they are called as anti –
friction bearings
5.13) Give an example for anti-friction bearing. [AU, Nov / Dec – 2015]
 Ball bearing
 Roller bearing
5.14) What do you mean by life of an individual bearing?
[Au, May / Jun – 2013, 2016]
The life of individual rolling bearing, the number of revolution’s which the
bearing runs before the first evidence of fatigue develops in the material of one of
the ring or any rolling elements.
5.15) What is meant by life of anti-friction bearings?
[Au, Nov / Dec – 2008, 2013, 2016]
The life of individual rolling bearing, the number of revolution’s which the
bearing runs before the first evidence of fatigue develops in the material of one of
the ring or any rolling elements.
5.16) Why ball bearings are called antifriction bearing? [AU, April / May – 2011]
ball bearings the friction developed is very low, they are called as anti –friction
bearings
5.17) Name the materials used for sliding contact bearings [AU, April / May – 2011]
 Aluminium alloys
 Copper alloys
 Babbit alloys
 Steel
5.18) What are the commonly used non – metallic bearing materials
 Graphite

 Wood
 Plastic (nylon, teflon)
5.19) Classify the sliding contact bearings according to the thickness of layer of the
lubrication between the bearing and the journal. [Au, May / Jun - 2012]
Thick film bearing
Thin film bearing
Zero film bearing
Hydrostatic or externally pressurized lubricated bearing
5.20) What are the types of journal bearings depending upon the nature of
contact?
 Full journal bearing
 Partial bearing
 Fitted bearing
5.21) Explain the term dynamic load carrying capacities of rolling contact bearing.
[Au, Nov / Dec –2012]
The dynamic load may be defined as the constant stationary radial load or
axial load which is applied to a bearing with rotating inner ring and stationary outer
ring, would give the same life of the bearing carried for a minimum life of one million
revolutions.
5.22) What is Sommerfield number? State its importance in the design of journal
bearing? [AU, Apr / May – 2015]
It is a dimensionless parameter used in design of journal bearing.
𝑆 =
𝑍𝑛′
𝑝
(
𝐷
𝐶
)
2
In Raimondi and Body graph using Sommerfield number the minimum oil
film thickness (ho) can be found.
5.23) Define static Capacity of Bearing [Au, Nov / Dec –2014]
The static capacity of bearing is defined as the static radial load or axial load
which is applied would cause the same total permanent deformation at the most
heavily stressed ball and race contact as that which occurs under the actual loading
conditions

5.24) What are the various types of radial ball bearings? [Au, May / Jun - 2012]
 Single row deep groove bearing
 Filling notch bearing
 Angular contact bearing
 Double row bearing
 Self – aligning bearing
5.25) State the advantage of thrust ball bearing. [AU, Nov / Dec - 2009]
 Low starting and running friction
 Low cost maintenance
 Easy to mount and erect
 Accuracy in shaft alignment
5.26) State the disadvantage of thrust ball bearing. [AU, Nov / Dec - 2009]
 Initial cost is high
 Complicated in design
 Less capacity to withstand shock
 Noisy operation at very high speed
5.27) State some of the components of rolling contact bearings
 Inner race
 Outer race
 Rolling element
 Retaining cage or separator
5.28) What is self-aligning ball bearing? Statue its unique feature.
[AU, Apr / May – 2015]
The bearings permits shaft defection within 2 – 3 degrees. The normal
clearance in a ball bearing are too small to accommodate any appreciable
misalignment of the shaft relative to the housing.
5.29) Define the term Reliability of a bearing. [AU, Nov / Dec – 2016]
Reliability of the bearing is the ability of the bearing to serve in million
revolutions under stated dynamic load.
5.30) What is quill bearing [AU, April / May – 2010]
A quill bearing is a bearing that instead of having roller bearings, it has long
thin rollers shaped like a toothpick. They are commonly used in transmissions and

power machinery. It is basically a "needle bearing". The bearing has a hard outer
shell which is considered the outer race, a series of needle bearings inside the shell
that usually ride directly on a hardened shaft, therefore not need in inner race as a
typical roller bearing.
5.31) What is the situations demand the use of needle roller bearings?
High speed and high load carrying requires needle bearing.
5.32) List any 4 advantages of rolling contact over sliding contact bearing.
[AU, May / June – 2009]
 Reliability of service
5.33) What are the advantages of Rolling Contact Bearings over Sliding Contact
Bearings? [AU, May / Jun – 2016]
 Reliability of service
5.34) What are the factors should be considered when selecting rolling bearings?
 Space availability
 Type amount of load
 Speed
 Alignment
 Environmental conditions
5.35) What are the modes of failure of rolling contact bearing?
[Au, Nov / Dec –2010]
Surface fatigue
Peeling
Scoring
Fretting

creep
5.36) In hydrodynamic bearing, what are factors which influence the formation of
wedge fluid film? [Au, Nov / Dec –2014]
 A continuous supply of oil
 A relative motion between the two surfaces in a direction
approximately tangential to the surfaces
 The ability of one of the surfaces to take up a small inclination to the
other surface in the direction of relative motion
 The line of action of resultant oil pressure must coincide with the line
of action of external load between the surfaces
5.37) List the basic assumptions used in the theory of hydrodynamic lubrication.
[Au, Nov / Dec –2011]
The lubricant obeys Newton’s law of viscous flow
The pressure is assumed to be constant throughout the film thickness
The lubricant is assumed to be incompressible
The viscosity is assumed to be constant throughout the film
The flow is one dimensional
5.38) Define minimum oil film thickness.
The minimum distance between the bearing and journal under complete
lubricating conditions.
5.39) What is the limitation of Mckee’s equation? [AU, April / May – 2017]
The limitation of Mckee’s equation is its validity beyond certain bearing
modulus number.
5.40) Plot the friction induced in various bearings based on shaft speed.

ME6503 - DESIGN OF MACHINE ELEMENTS TWO MARKS QUESTIONS WITH ANSWERS

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