MCQs onSliding Contact Bearings: 1. Which of the following are included in the finishing operations for porous bearing? [IES-2005 1. Infiltration 2.Si!ing ".#eat treat$ent %.&oining Select the correct answer using the code gi'en below( )a* 1 and 2 )b* 2 and " )c* 2 and % )d* 1 and % +ns. )a*
Basic Modes of Lubrication: 2. In sliding contact bearings, a positi'e pressure can be built up and a load supported b a fluid onl b the use of a( [IES-2005 )a* i'erging fil$ )b* &on'erging-di'erging &on'erging-di'erging fil$ )c* &on'erging fil$ )d* /lat fil$ +ns. )c* ". Which one of the following is correct? [IES-200 + hdrodna$ic hdrodna$ic slider bearing de'elops load bearing capacit $ainl because of)a* Slider 'elocit )b* wedge shaped oil fil$ )c* il co$pressibilit )d* oil 'iscosit +ns. )b* + hdrodna$ic slider bearing de'elops load bearing capacit $ainl because of wedge shaped oil fil$. %. +ssert +ssertion ion )+*( )+*( In stead stead rotati rotating ng condit condition ion the ourna ournall inside inside a hdro hdrod dna$ na$ic ic ourna ournall bearing re$ains floating on the oil fil$. [IES-200 3eason )3*( 4he hdrodna$ic pressure de'eloped in stead rotating conditions in ournal bearings balances the load on the ournal. )a* oth + and and 3 are true and 3 is the correct e6planation of + )b* oth + and 3 are true but 3 is 74 the correct e6planation of + )c* + is true but 3 is false )d* + is false but 3 is true +ns. )a* 4he fil$ pressure created b the $o'ing surface itself pulling the lubricant into a wedge shaped shaped !one at a 'eloci 'elocit t suffic sufficien ientl tl high high to create create the necessar necessar pressu pressure re re8uir re8uired ed to separate the surface against the load on the bearings. #drodna$ic lubrication is also called as full fil$ lubrication or fluid lubrication. So, +ssertion and 3eason both are correct and + is the correct e6planation of 3. 5. Increase in 'alues of which of the following results in an increase of the coefficient of friction in a hdrodna$ic hdrodna$ic bearing? [IES 2009 1. :iscosit :iscosit of the oil. 2. &learance between shaft and bearing. ". Shaft speed.
Select the correct answer using the code gi'en below( )a* 1 and 2 onl )b* 1 and " onl )c* 2 and " onl )d* 1, 2 and " +ns. )b* 2 is false ;etroff 7s@; A)r@c* f B if )i* C B D )ii* c D )iii* 7s B F. + ournal bearing with hdrodna$ic lubrication is running steadil with a certain a$ount of $ini$u$ fil$ thicGness. When the load and speed are doubled, how does the $ini$u$ fil$ thicGness 'ar? [IES-200 )a* 3e$ains unchanged )b* Hets doubled )c* Hets reduced to one-fourth of original 'alue )d* Hets reduced to half of original 'alue +ns. )a* When the load and speed is doubled, the $ini$u$ fil$ thicGness re$ains unchanged. Since, S = )7s@p* )r@c*2 Since S re$ains the sa$e e'en after doubling the speed as well as load and fil$ 4hicGness depends on the So$$erfield nu$ber. 9. What is the $ain ad'antage of hdrodna$ic bearing o'er roller bearing? )a* Eas to asse$ble [IES-2005 )b* 3elati'el low price )c* Superior load carring capacit at higher speeds )d* ess frictional resistance +ns. )c* . &onsider tile following state$ents( [IES-1JJ"D 2002D 200F 3adius of friction circle for a ournal bearing depends upon 1. &oefficient of friction 2. 3adius of the ournal ". +ngular speed of rotation of the shaft Which of the state$ents gi'en abo'e are correct? )a* 1,2 and " )b* nl 1 and 2 )c* nl 2 and " )d* nl 1 and " +ns. )b* radius of friction circle = f A r
J. In a ournal bearings, the radius of the friction circle increases with the increase in[IES-1JJ9 )a* oad )b* 3adius of the ournal )c* Speed of the ournal )d* :iscosit of the lubricant +ns. )b*
10. &onsider the following state$ents( [IES 2009 /or a ournal rotating in a bearing under fil$ lubrication conditions, the frictional resistance is1. ;roportional to the area of contact 2. ;roportional to the 'iscosit of lubricant ". ;roportional to the speed of rotation %. Independent of the pressure Which of the state$ents gi'en abo'e are correct? )a* 1, 2, " and % )b* 1 and % onl )c* 2, " and % onl )d* 2 and " onl +ns. )a* :iscous resistance )/* = 4 A+rea = )>7@F0t* A > = > 22 7@F0t
11. 4he bearing characteristic nu$ber in a hdrodna$ic bearing depends on)a* ength, width and load )b* length, width and speed. [IES-1JJF )c* :iscosit, speed and load )d* 'iscosit, speed and bearing pressure. +ns. )d*
12. It is seen fro$ the cur'e that there is a $ini$u$ 'alue of the coefficient of friction )C* for a particular 'alue of the earing &haracteristic 7u$ber denoted b K. What is this 'alue of the earing &haracteristic 7u$ber called? [IES-200% )a* LcMee 7u$ber )b* 3enolds 7u$ber )c* earing Lodulus )d* So$erfield 7u$ber +ns. )c*
1". +ssertion )+*( In e8uilibriu$ position, the ournal inside a ournal bearing re$ains floating on the oil fil$. [IES-1JJ5 3eason )3*( In a ournal bearing, the load on the bearing is perpendicular to the a6is of the ournal. )a* oth + and 3 are indi'iduall true and 3 is the correct e6planation of + )b* oth + and 3 are indi'iduall true but 3 is not the correct e6planation of + )c* + is true but 3 is false )d* + is false but 3 is true +ns. )b* oth + and 3 are true but 3 is not correct e6planation for +.
1%. + full ournal bearing ha'ing clearance to radius ratio of 1@100, using a lubricant with C=2A10-" ;a s supports the shaft ournal running at 7 = 2%00 rp$ If bearing pressure is 1.% L;a, the So$erfield nu$ber is [IES-2001 )a* A10-" )b* A10-5 )c* 0.% )d* 0.%A10 +ns. )a* S = )7s@p* )r@c*2
15. + sliding contact bearing is operating under stable condition. 4he pressure de'eloped in oil fil$ is p when the ournal rotates at 7 rp$. 4he dna$ic 'iscosit of lubricant is C and effecti'e coefficient of friction between bearing and ournal of dia$eter is f. Which one of the following state$ents is correct for the bearing? [IES-2001 )a* f is directl proportional to C and p )b* f is directl proportional to C and 7 )c* f is in'ersel proportional to p and f* )d* f is directl proportional to C and in'ersel proportional to 7 +ns. )b* ;etroff 2ns@p )r@c* N G ---O 0.002 1F. Which one of the following sets of para$eters should be $onitored for deter$ining safe operation of ournal bearing? [IES-2000 )a* il pressure, bearing $etal te$perature and bearing 'ibration )b* earing 'ibration, oil pressure and speed of shaft )c* earing $etal te$perature and oil pressure )d* il pressure and bearing 'ibration +ns. )a*
19. &onsider the following pairs of tpes of bearings and applications( 1. ;artial Pournal bearingQQQQQQ. 3ail wagon a6les 2. /ull ournal bearing QQQQQQQ.iesel engine cranG-shaft ". 3adial bearing QQQQQQQQQ.&o$bined radial and a6ial loads Which of these pairs is@are correctl $atched? [IES-2000 )a* 1 alone )b* 1 and 2 )c* 2 and " )d* 1, 2 and " +ns. )b* 1. Latch ist I with ist II and select the correct answer using the code gi'en below the lists( [IES-1JJ5 ist I )3e8uire$ent*
ist II )4pe*
+. #igh te$perature ser'ice 1. 4eflon bearing . #igh load
2. &arbon bearing
&. 7o lubrication
". #drodna$ic bearing
. ushings
%. Slee'e bearing
&odes( + & )a* 1 2 " % )b* % 1 2 " )c* 2 1 " % )d* 2 " 1 % +ns. )d*
1J. +ssertion )+*( In anti-friction bearings, the frictional resistance is 'er low as the shaft held b it re$ains in floating condition b the hdrodna$ic pressure de'eloped b the lubricant. [IES-200F 3eason )3*( In hdrodna$ic ournal bearings, hdrodna$ic pressure is de'eloped because of flow of lubricant in a con'erging -di'erging channel )a* oth + and 3 are indi'iduall true and 3 is the correct e6planation of + )b* oth + and 3 are indi'iduall true but 3 is not the correct e6planation of + )c* + is true but 3 is false )d* + is false but 3 is true +ns. )d*
20. Satisfactor hdrodna$ic fil$ in a ournal bearing is for$ed when )a* Pournal speed is lowD unit pressure on the bearing is high and 'iscosit of lubricant used is low [IES-200F )b* Pournal speed is lowD unit pressure on the bearing is low and 'iscosit of lubricant used is low )c* Pournal speed is highD unit pressure on the bearing is high and 'iscosit of lubricant used is high )d* +ppropriate co$bination of ournal speed, unit pressure on bearing and lubricant 'iscosit e6ists resulting in low coefficient of friction +ns. )c*
21. In an oil-lubricated ournal bearing, coefficient of friction between the ournal and the bearing. [IES-1JJ5 )a* 3e$ains constant at all speeds. )b* is $ini$u$ at !ero speed and increases $onotonicall with increase in speed. )c* is $a6i$u$ at !ero speed and decreases $onotonicall with increase in speed. )d* beco$es $ini$u$ at an opti$u$ speed and then increases with further increase in speed. +ns. )d*
22. Latch ist I with ist II and select the correct answer( [IES-2002 ist I )earings*
ist II )oad tpe*
+. #drodna$ic Pournal bearing
1. #igh radial and thrust load co$bined
. 3ectangular #drostatic bearing 2. 3adial load onl &. 4aper 3oller bearing
". 4hrust load onl
. +ngular contact ball bearing
%. Lediu$ to low radial and thrust co$bined
+ &
+ &
)a* 2 " 1 % )b* % 1 " 2 )c* 2 1 " % )d* % " 1 2 +ns. )a*
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2F. Which one of the following tpes of bearings is e$ploed in shafts of gearbo6es of auto$obiles? [IES-1JJJ )a* #drodna$ic ournal bearings )b* Lulti-lobed ournal bearings )c* +ntifriction bearings )d* #brid ournal bearings +ns. )c*
29. +ssertion )+*( In hdrodna$ic ournal bearings, the rotating ournal is held in floating condition b the hdrodna$ic pressure de'eloped in the lubricant. 3eason )3*( ubricant flows in a con'erging-di'erging channel. [IES-1JJ% )a* oth + and 3 are indi'iduall true and 3 is the correct e6planation of + )b* oth + and 3 are indi'iduall true but 3 is not the correct e6planation of + )c* + is true but 3 is false )d* + is false but 3 is true +ns. )a* oth + and 3 are true and 3 pro'ides correct e6planation for +
Hydrostatic Step Bearing 2. +ssertion )+*( #drostatic lubrication is $ore ad'antageous when co$pared to hdrodna$ic lubrication during starting and stopping the ournal in its bearing. 3eason )3*( In hdrodna$ic lubrication, the fluid fil$ pressure is generated b the rotation of the ournal. [IES-1JJ )a* oth + and 3 are indi'iduall true and 3 is the correct e6planation of + )b* oth + and 3 are indi'iduall true but 3 is not the correct e6planation of + )c* + is true but 3 is false )d* + is false but 3 is true +ns. )b* 2J. 4he $ost suitable bearing for carring 'er hea' loads with slow speed is )a* #drodna$ic bearing )b* ball bearing [I+S 1JJ% )c* 3oller bearing )d* hdrostatic bearing +ns. )d*
Comparison of Rolling and Sliding Contact bearings "0. Latch ist -I )earings* with ist-II )+pplications* and select the correct answer using the codes gi'en below the lists( [I+S-1JJ ist TI
ist-II
+. Pournal bearing
1. Electric $otors
. 4hrust bearing
2. Watches
&. &onical pi'ot bearing ". Larine engines . all bearing +&
+ &
)a* " % 1 2 )b* % 2 1 " )c* " % 2 1 )d* % 2 " 1 +ns. )c*
%. Swi'elling chairs
