B.E/ B.TECH DEGREE EXAMINATION NOV/DEC 2011
FOURTH SEMESTER
MECHANICAL ENGINEERING
U07ME402 – KINEMATICS OF MACHINERY
Time:Three Hours Maximum
Marks:100
Answer ALL Questions
PART-A (10X 1=10Marks)
1.Cam and follower is type of pair.
a.Closed pair b.Turning pair c.Higher pair d.Lower
pair
2.Quick return motoin mechanism is the inversion
of chain
a.Four bar chain
mechanism b.Single slider chain mechanism c.Double slider chain mechanism d.All
the above
3. How many instantaneous centres are possible in a
four bar chain mechanism.
a.8 b.6 c.4 d.10
4. In a four bar chain mechanism ,number of binary
joints
a.Four b.Six c.Eight d.Ten
5.In a radial cam,the follower moves in a dirction
to the axis.
a.
Parallel b.Perpendicular c.Inclined d.All
the above
6.For high speed engines, the cam follower should
move with
a.
Reciprocating motion b.Ocillating
motion c.Cycloidal motion d.None of the above
7.Two intersecting and coplanar shafts are connected
by gears.
a.Spur
gear b.Helical gear c.Bevel gear d.Worm and worm wheel
8.In watch mechanism wich type of gear train is
used.
a.Reverted
gear train. b.Simple gear train c.Compound gear train d.Epicyclic gear train
9.What is the S.I unit for frictional moment?
a.N/m b.N-m/S c.N-m/s2 d.N-m
10.Function of dynamometer is
a.To measure
displacement b. To measure
velocity.
c.To measure
acceleration. d.To measure driving forcr
(Answer ALL the questions)
PART B (10X 2=20Marks)
1. Define ‘degree
of freedom’.
2. Compare machine and
structure.
3. Define
instantaneous centre and instantaneous axis.
4. What are the
properties of instantaneous centre?
5. Compare Roller
and mushroom follower of a cam.
6. Define
undercutting in cam.
7. What are the
methods to avoid interference?
8. What are the
types of gear trains?
9. Compare laws of
static friction and dynamic friction.
10. Compare slip and
creep in belt drive.
PART B (5
X 14=70Marks)
11.(a) Sketch four bar chain mechanism and explain its various
inversions.
(or)
(b). Explain
with various inversions of double slider crank chain mechanism.
12.(a)
In a four bar chain ABCD, AD is fixed and is 120mm long. The crank
AB
is 30mm long rotates at 100r.p.m clockwise. While the link CD=60mm oscillates
about D, BC and AD are equal length. Find the angular velocity and angular
acceleration of link BC when angle BAD=600.
(or)
(b).
In a slider crank mechanism, the length of crank OB and connecting rod AB are
125mm and 500mm respectively. The centre of gravity of the connecting rod is
250mm from the slider A. The crank speed is 600r.p.m clockwise. When the crank
has turned 450from the inner dead centre position, determine: (1)
Linear velocity and acceleration of the mind point of the connecting rod and
(2) Angular velocity and angular acceleration of the connecting rod.
13.(a) A cam rotating
clockwise with a uniform speed is to give the roller
follower
of 20mm diameter with the following motion.
(a)
Follower to move outwords through a distance of 30mm
during 1200 of cam rotation;
(b)
Follower to dwell for
600 of cam rotation;
(c)
Follower to return to
its initial position during 900 of cam rotation and
(d)
Follower to dwell for
the remaining 900 of cam rotation.
The minimum radius of the cam is 45mm and the displacement of
the follower is to take place with simple harmonic motion on both the outward
and return strokes. Draw the cam profile when
The line of stroke of the follower is offset by 15mm from the axis of the
cam.
(or)
(b) It is required to set out the
profile of a cam to give the following motion to
the reciprocating follower with a flat
mushroom contact face :
(i)
Follower to have a stroke of 20mm during 1200
of cam rotation,
(ii) Follower to
dwell for 300 of cam rotation,
(iii) Follower to
return to its initial position during 1200 of cam rotation, and
(iv) Follower to
dwell for remaining 900 of cam rotation.
The minimum radius of the cam is
25mm. The outstroke of the follower is performed with SHM and the return stroke
with equal uniform acceleration and retardation.
14.(a) A
pinion having 20 teeth engages with an internal gear having 80 teeth. If the
gears have in volute profiled teeth with 200 pressure angle, module
of 10 mm and addendum of 10 mm, Find the path of contact, arc of contact and
the contact ratio.
(or)
(b). In
an epicyclic gear train, the internal wheels A and B and compound wheels C and
D rotate independently about axis O. The wheels E and F rotate on pins fixed to
the arm G. E gears with A and C. Wheel F gears with B and D. All the wheels
have the same module and the number of the teeth are: Tc=28;TD=26;
TE=TF=18.
1. Sketch the arrangement.
2.
Find thenumber of teeth on A and B.
3.If
the arm G makes 100r.p.m.clockwise and A is fixed, find
the speed of B.
4.If the arm G makes
100r.p.m. clockwise and wheel A makes 10r.p.m. counter clockwise ; find the
speed of wheel B.
15.(a) A single plate friction clutch, with
both sides of the plate being effective, is used to transmit power at 1440r.p.m
It has outer and inner radii 80mm and 60mm respectively. The maximum intensity of
pressure is limited to 10
x 104N/m2. If the coefficient of friction is 0.3,
determine:
(i)
Total
pressure exerted on the plate and
(ii) Power transmitted.
(or)
(b).
The
block brake is set by a spring that produces a force S on each arch equal to
3500 N. The wheel diameter is 350mm and the angle of contact for each block is
1200. Take coefficient of friction as 0.35, determine the maximum
torque that the brake is capable of absorbing.
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