This document provides instructions for a machine elements exam consisting of 3 parts: 1) Fill in the blanks for 10 terms 2) State whether 10 statements are true or false 3) Answer 5 questions choosing at least one from each of 3 groups (A, B, C). The first part must be completed in 45 minutes then submitted, after which a new answer sheet will be provided to complete the remaining parts in the allotted 3 hours. Early submission of part 1 earns an earlier start on the remaining parts.

1. May 2018 604(s)
DESIGNOF MACHINE ELEMENT
Time Allowed:3 Hours FullMarks:70
Answer to question No. 1 is compulsory and to be answered first.
This answer to be made in separate loose script(s) provided for the purpose.
Maximum time allowed is 45 minute, after which the loose answer script will be collected and
fresh answer script for answering the remaining part of the question will be provided.
On early submission of answer script of question No. 1,
a student will get the remaining script earlier.
Answerany five questionfromGroup-A,B & C, taking at leastone from each group.
1. A. Fill inthe blanks (any ten): 10X1
i) Factor of safety=
ii) Stressconcentrationinstaticloadingismore serious in------------
iii) Cotter jointisusedtoconnect----------
iv) The cast ironwhichhas self lubricatingpropertyis --------
v) RelationbetweenYoung’smodulus andBulkmodulusis-------
vi) In case of pure torsionbendingmomentof ashaftis--------
vii) The numberof principal stressesforapointina machine part subjectedtotwoforcesat
rightangle to eachother is----
viii) Hoopstressis ----------- the longitudinal stress.
ix) A rivetisspecifiedby-------
x) In longitudinal jointof aboiler,the type of jointusedis--------
xi) Infilletweld,nature of stresssetup inweldmetal is------
xii) Aneye boltisusedto----
xiii) Forcast ironcolumn,Rankine’sconstantis----
xiv) Keyjointis ------- joint
B. State whether the followingstatementsare True or False. 10X1
i) Shaftare alwaysmade of M.S
ii) Ball and rollerbearingare calledanti-frictionbearing.
iii) Flatspiral springare usedinclock.

2. iv) Module of a gearis the reciprocal of diametral pitch.
v) Worm gearingisusedas speedreducer.
vi) Poisson’sratioof steel variesfrom0.25to 0.33.
vii) Neutral axispassesthroughthe centroidof the section.
viii) Notchsensitivityisdirectlyproportional tonotchradius.
ix) Powertransmissionisbestdone bysquare thread.
x) Knuckle jointisa hingedjoint.
xi) Sunktaperkeysare alwayssquare incross-section.
xii) Sleeve couplingisthe same asMuff coupling.
xiii) Jackshaftisthat shaftwhichisdirectly connectedtothe source of power.
xiv) Idlerpulleyisusedinopenbeltdrive.
Group-A
2. a) What is factor of safety.Whatare the differentfactoruponwhichfactorof safetydepends.
b) State the differentfactortobe consideredbefore designingaforgedpart. (5+5)
3. a) A mildsteel rodissubjectedtoapull of 0.1MN. The ultimate stressof mildsteel is400 N/mm2
.
Assumingfactorof safetyas 4, calculate the diameterof the rod.
b) Name the varioustheoriesof failure,if amachine partissubjectedtostressesatmutually
perpendiculardirection. (5+5)
4. a) Designa cotter jointtowithstand areciprocatingloadof 50 KN on the basisof the following
data: Material--- mildsteel
Allowable tensilestress----80N/ mm2
Allowablecompressivestress---100N/mm2
Allowable shearstress---45N/ mm2
Draw twoviewsof the cotter joint.
b) A vertical leverACis25 mm thickand is attached bya fulcrumpinat C and toa horizontal tie bar
at B. If P=300 N, l1=1000 mm, andl2=250 mm, find:
i) reactionat B andC.
ii) tensilestresssetupinthe tie bar at B, if its diameteris20 mm.
iii) shearstresssetupin20 mm diameterpinsatA, B and C,and
iv) the bearingpressure onthe leveratB. (5+5)

3. Group-B
5. a) Determine the widthof apulleywhichistotransmit18.3875 KW at 250 r.p.m.Diameterof the
pulleyis90 cm. The beltwas puton witha tensionof 147.15 N percm widthof the belt. The maximum
tensionpercmwidthof beltisnotto exceed196.2 N.
b) A sunkkey20 mm wide x 15 mm thickx 100 mm lengthtransmita torque of 176580 Ncm froma
shaft80 mm in diameter.Determine the shearingstressandcrushingstressinducedin the key. (5+5)
6. Designa C.I.protectedtype flange couplingfora M.S shaftto transmit73.55 KW at 200 r.p.m.The
allowable shearstressinthe shaftandkeymaterial is3924 N/cm2
and that inthe material of the
couplingboltsis2943 N/cm2
.The angle of twistisnot to be exceedone degreeinalengthof 15 times
the diameter.The maximumtorque is20% greaterthan the average torque.ForM.S, take G=7.848X106
(10)
7. A horizontal shaftsupportedintwobearingcarriesapulleyata distant400 mmfrom the righthand
bearing,the distance of the pulleyfromthe lefthandbearingbeing600 mm.The shafttransmit7.355
KW at 250 r.p.m.The diameterof the pulleyis 200 mm and itsweightis98.1 N .The tensiononthe tight
side of the beltis2943 N. Finda suitable diameterforthe shaft.Assume allowable shearstressinthe
shaftmaterial as4905 N/ cm2
. Use equivalenttorque formula. (10)
8. A bracketplate is attachedto a vertical columnbyfive numberof rivetsplacedsymmetrically.The
distancesS1=300 mm, S2=600mm ande=600mm. The plate is10mm thickand 16mm diameterrivetsare
used.If the allowable shearingandcrushingstressesinthe materialof the rivetbe 650 N/cm2
and 1200
N/cm2
, findthe safe value of eccentricloadP. (10)
9. a) What are the advantagesanddisadvantagesof geardrive overothersystemof drive.
b) Designthe teethof a gear having14
1
2
degree involuteteethotransmit7.355 KW at 500 r.p.m.The
P.C.Dof the gear is240mm and module is4mm.Assume safe staticstress forthe material of the gear as
5866 N/cm2
.Service factormaybe takenas 0.60. (3+7)
Group-C
10. a) What isestimatingandcosting.Write downthe difference betweenestimatingandcosting.
b) What are the mainelementsof cost.Explaineachelementindetailgivingsuitable example. (5+5)
11. a) Write downthe factorsuponwhichselection of the bearingmaterialdepends.
b) What are the desirable propertiesof alubricant. (5+5)