Gate Bits Unit 4 Cams Kom (2)

OBJECTIVE QUESTIONS from GATE / IES / IAS 1. In a plate cam mechanim !ith reciprocatin" roller follo!er# the follo!er ha a contant acceleration in the cae of (a) Cycloidal motion (b) Simple harmonic motion (c) Parabolic motion (d) 3-4-5 polynomial motion  An. )c*

+. ,or a prin"%loa-e- roller%follo!er -rien !ith a -ic cam#

$GATE%1&&'(

$GATE%+1( $GATE%+1(

(a) The pressure angle should be larger during rise than that during return for ease of transmitting transmitting motion. (b) The pressure angle should be smaller during rise than that during return for ease of transmitting transmitting motion. (c) The pressure angle should be large during rise as ell as during return for ease of transmitting motion. (d) The pressure angle does not affect the ease of transmitting motion.

 An. )c*

'. The profile of a cam in a partic0lar one i "ien 23 the cam profile at θ = 5 /6 i at an an"le )!ith repect to 7 a7i* a). ! "4 b) ! "# c) ! "3 d) $ An. )c*

an- 3 4in  θ. The normal to $GATE%1&&8(

6. In a cam%follo!er mechanim# the follo!er nee- to rie thro0"h + mm -0rin" 9 o of cam rotation# the firt ' o !ith a contant acceleration an- then !ith a -eceleration of the ame ma"nit0-e. The initial an- final pee- of the follo!er are ero. The cam rotate at a 0niform pee- of ' rpm. The ma7im0m pee- of the follo!er i $GATE%+:( $GATE%+:( (a) $.%$m"s (b) &.#$m"s (c) &.%'m"s (d) #.4$m"s An. )-*

:. In a in"le pin-le a0tomatic lathe t!o tool are mo0nte- on the t0rret# one form tool on the front li-e an- the other# a partin" tool on the rear li-e. The partin" tool operation i m0ch lon"er than form tool operation an- the3 operate im0ltaneo0l3 )oerlap*. The n0m2er of cam re;0irefor thi
9. Coni-er the follo!in" tatement= $IES%+9( Cam follo!er are "enerall3 claifie- accor-in" to= 1. the nat0re of it motion +. the nat0re of it 0rface in contact !ith the cam '. the pee- of the cam >hich of the tatement "ien a2oe are correct? (a) & # and 3 (b) nly & and # (c) nly # and 3 (d) nly & and 3 An. )2*

@. The choice of -iplacement -ia"ram -0rin" rie or ret0rn of a follo!er of a cam%follo!er mechanim i 2ae- on -3namic coni-eration. ,or hi"h pee- cam follo!er mechanim# the mot 0ita2le -iplacement for the follo!er i $IES%++( (a) Cycloidal motion (b) simple harmonic motion (c) parabolic or uniform acceleration motion (d) uniform motion or constant *elocity motion An. )a*

8. In a cam -rie# it i eential to off%et the a7i of a follo!er to (a) decrease the side thrust beteen the folloer and guide (b) decrease the ear beteen folloer and cam surface (c) ta+e care of space limitation (d) reduce the cost An. )2*

$IES%1&&8(

&. Coni-er the follo!in" follo!er motion in repect of a "ien lift# pee- of rotation an- an"le of troe of a cam= $IES +@( )1*. C3cloi-al motion. )+*. Simple harmonic motion. )'*. Uniform elocit3 motion. >hich one of the follo!in" i the correct e;0ence of the a2oe in the -ecen-in" or-er of ma7im0m elocit3?   (a) 3-#-& (b) &-#-3 (c) #-3-& (d) 3-&-# An. )2*

1. >hat i the ma7im0m acceleration of a cam follo!er 0n-er"oin" imple harmonic motion?

>here# h 4 Stroe of the follo!er )* 4 An"0lar elocit3 of the cam ɸ4 Cam rotation an"le for the ma7im0m follo!er -iplacement. An. )a*

 $IES%+9((

11. Coni-er the follo!in" tatement= $IAS%+@( )i*.,or a ra-ial%tranlatin" roller follo!er#para2olic motion of the follo!er i er3 0ita2le for  hi"h pee- cam. )ii*.Ditch point on pitch circle of a cam correpon- to the point of ma7im0m pre0re an"le. >hich of the tatement "ien a2oe i/are correct? (a) )i* only (b) )ii* only (c) ,oth )i* and )ii* (d) either )i* nor )ii* An. )2*

1+. >hich one of the follo!in" i an Open Dair? (a) ,all and soc+et oint (b) /ournal bearing (c) 0ead scre and nut (d) Cam and folloer  An. )-*

$IES%1&&9(

1'. >hich one of the follo!in" et of element are ;0ic actin" clampin" element for fi7t0re? (a) 1edge and Cam (b)Cam and Toggle $IES%+1( (c)Toggle and 1edge (d)1edge Cam and Toggle An. )a*

16. The fi"0re ho! a cam !ith a circ0lar profile# rotatin" !ith a 0niform an"0lar elocit3 of  ra-/. >hat i the nat0re of -iplacement of the follo!er? $IES%+:( (a) 2niform (b) Parabolic (c) Simple harmonic (d) Cycloidal

An. )c* 1:. In a circ0lar arc cam !ith roller follo!er#the acceleration in an3 poition of the lift !o0l-epen- onl3 0pon $IES%1&&6(  (a) total lift total angle of lift minimum radius of cam and cam speed. (b) radius of circular arc cam speed location of centre of circular arc and roller diameter. (c) eight of cam folloer lin+age spring stiffness and cam speed. (d) total lift centre of gra*ity of the cam and cam speed An. )2*

COOSE TE COFFECT ATEFNATIVE ) JNTU HEFABA *

For the knife edge follower, the cam prole and pitch curve [ B] A) are dierent B)are ame !)ma" #e ame or dierent $)none of the a#ove %. &he angle, which repreent the cam prole and i mot important in cam deign, i [B ] 1.

) Cam angle ,) pressure angle C) angle of dell ) angle of descent The Sie of a cam depends upon 6 A7

3.

'A) Bae circle 'B) (itch circle '!) (rime circle '$) (itch curve . &he cam follower generall" ued in automo#ile engine i [ C ] 'A) *nife edge follower 'B) Flat faced follower '!) +pherical faced follower '$) oller follower -. &he troke of the follower i eual to /////// [ B ] 'A) 0alf of the maimum travel of the follower from the lowet poition &o the top mot poition 'B) 2aimum travel of the follower from the lowet poition to the top mot poition (C) 8alf of the diameter of base circle () 8alf of the diameter of prime circle  radial folloer is one hich 6 A7 ( )translates along an a9is passing through the cam centre (,) reciprocates in guides (C) oscillates ith a simple harmonic motion () has an a9is of mo*ement displaced from the a9is of rotation of cam.

%.

$uring the dwell period of a cam, the follower move [ D]

3.

() 1ith uniform speed (,) 1ith Simple harmonic motion ( C) :n a straight line () ;emains at rest ,I IN TE BANS ) JNTU HEFABA * &.

The left of a flat-faced folloer hen it is in contact ith the flan+ of a circular arc camis e
2.  &he cam and follower i an eample of  lower pair 4. 5n a radial cam, the follower move in a direction Perpendicular to the cam

ai .  &he angle, which repreent the cam prole and i mot important in cam $eign i Pressureangle. -. &he period during which follower remain tationar" during ome nite rotation of the !am i Dwell Period . %. The cam sie depends upon Baecircle. @. =or lo and moderate speed engines the cam folloer should mo*e ith Simple harmonic motion 8. 1hen the folloer mo*es ith S8> the *elocity diagram is Sin0oi-al cur*e &. The sie of a cam depends on 2ae circle 1. The angle beteen the direction of the folloer motion and a normal to the pitch cur*e is called pre0re an"le 11. The retardation of a flat faced folloer hen it has contact at the ape9 of the nose of a + circular arc cam is gi*en by )co  LOQ* 1+. The displacement of a flat faced folloer hen it has contact ith the flan+ of a circular arc cam is gi*en by ))F%rl*)l%co**

&3. =or high speed engines the cam folloer should mo*e ith c3cloi-al motion 16. =or lo and moderate speed engines the cam folloer should mo*e ith imple harmonic motion 1-.////////////////////////////////////////////////////////////// ffset is pro*ided to a cam folloer mechanism to minimie the i-e thr0t