ME 6401 Kinematics of Machinery, Second year, Department of Mechanical Sandwich, Model Exam Questions
Answer All
questions
PART A – (10×2=20
marks)
1.
Differentiate
between a machine and a structure.
2.
Define
transmission angle of a four-bar mechanism. What is the worst value of
transmission angle.
3.
Define
rubbing velocity at a pin joint. What will be the rubbing velocity at pin joint
when the two links move in the same and opposite directions?
4.
State
the condition for a link to experience coriolis acceleration or for what kind
of relation motion the coriolis component of acceleration occurs.
5.
What
is the classification of cam based on contact surfaces?
6.
What
are the different types of motion with which a follower can move?
7.
Define:
a) Normal pitch and b) axial pitch relation to helical gears.
8.
State
the law of gearing.
9.
Briefly
write about reverted gear train with suitable sketch.
10. What is the
minimum force required to slide a body on a rough horizontal plane.
PART
B– (5×13=65 marks)
11. a ) i. Explain
Whitworth Quick-Return mechanism. (7)
ii. Explain Crank and slotted lever
Quick-Return motion mechanism(8)
or
b) Explain Inversion of single slider-crank
chain.(13)
12. a) In a four – link mechanism,
the crank AB rotates at 36 rad/s. The lengths of links are AB = 200 mm , BC =
400 mm , CD = 450 mm and AD = 600mm. AD is the fixed link. At the instant when
AB is at right angle to AD, Determine the velocity of i) The mid-point of link BC. ii) A point on link
CD,100mm from the points connecting the link CD and AD.(13)
Or
b) Ina slider-crank mechanism, the
crank is 480mm long and rotates at 20rad/s in the counter clock wise direction.
The length of the connection rod is 1600mm. When the crank runs 60o
from the inner – dead center, determine.
i) The velocity of the
slider.
ii) The velocity of a
point E located at a distance 450mm on the connection rod
extended.
iii) The position and
velocity of a point F on the connection rod having least absolute
velocity.
iv) The angular velocity
of the connecting rod.
v) The velocity of rubbing at the pins of the
crank shaft, crank and the cross-head having diameter 80,60 and 100mm
respectively. (13)
13.
A cam is to be designed for a knife-edge follower with the following data:
i) Follower lift is 40mm with SHM,
during 90o of cam rotation.
ii) Dwell for the next 300.
iii) Follower return to its original
position with SHM, during the next 600 of cam rotation.
iv) Dwell for the remaining cam
rotation.
The line of stroke of the follower passes through the
axis of the camshaft. Radius of the base circle of the cam is 40mm.
(i)
Draw
the displacement diagram
(ii)
Draw
the profile of the cam
(iii)
Determine
the maximum velocioty and acceleration of the follower during forward and
return strokes, if the cam rotates at 200 rpm in clockwise direction.(13)
(or)
(b)
A cam rotating clockwise at a uniform speed of 100rpm is required to give
motion to knife- edge follower as below
(a) Follower to move outward through
25mm during 1200 of cam rotation.
(b) Follower to dwell for the next
600 of the cam rotation.
(c) Follower to return to its
starting position during next 900 of cam rotation.
(d) Follower to dwell for the
remaining 900 of cam rotation.
The minimum radius of cam is 50mm.
Draw the profile of the cam when the line of Stroke of the follower passes
through the axis of the camshaft. If the
displacement of the follower takes place with uniform and equal acceleration
and retardation on both the outward and return strokes find the maximum
velocity and acceleration during its outstroke and return stroke.
Also draw the displacement velocity
and acceleration diagram for one complete revolution of the cam.(13)
14.
a) With the help of a neatly draw sketch of a spur gear, explain elaboratery
the nomenclature of gears.
(or)
(or)
b)
Two mating involute spur gear of 200 pressure angle have a gear
ratio of 2. The number of teeth on pinion is 20 and its speed is 250
revolutions per minute. The module pitch of
the teeth is 12mm.
If the addendum of each wheel is
such that the path of approach and path of recess on each side are half the
maximum possible length find: i) addendum for pinion and gear wheel ii) the
length of arc of contact , and iii) the maximum velocity of sliding during
approach and recess. Assume pinion to be driver. (13)
15.
a) A single dry plate clutch transmits 7.5Kw at 900rpm. The axial pressure is
limited to 0.07 N/mm2. If the coefficient of friction is 0.25, find
i) mean radius and face width of the friction lining assuming the ratio of the
mean radius to the face width as 4 and ii) outer and inner radii of the clutch
plate.
(13)
OR
b) An open belt drive connected two pulleys of
1.2 m and 0.5 m diameters and parallel shafts 4m apart the maximum tension in
the belt is 1800m th coffiecit of friction is 0.3. the driven pulley of dia
1.2m runs at 250rpm. Calculate i) the length of the belt required ii) the power
transmitted iii) the torque on each of the two shafts. (13)
16.
A cam rotating clockwise with a uniform speed is to given the roller follower
of 20mm diameter with the following motion
i)
follower to move outward through a distance of 30mm during 1200 of
cam rotation
ii)
follower to dwell for 600 of cam rotation
iii)
follower to return to its during 900 of cam rotation
iv)
follower to dwell for the remaining 900
of cam rotation.
The
maximum radius of the cam is 45mm and the displacement of the follower to takes
place with simple harmonic motion and both the outward and return stroke. Draw
the cam profile when
i)
The
line of stroke of the follower passes through the axis of the cam shaft. (13)
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