Roll No. ......................
Total Pages : 4
BT-3/D-21 43155
THEORY OF MACHINE
Paper–MEC-201A / MTC-205A
Time : Three Hours] [Maximum Marks : 75
Note : Attempt five questions in all selecting at least one question
from each unit.
UNIT–I
1. In a quick return motion mechanism of a crank and slotted
lever type, the ratio of maximum velocities is 2. If the length
of stroke is 25 cm, find (i) the length of the slotted lever,
(ii) the ratio of times of cutting and return strokes, and
(iii) the maximum cutting velocity per second if the crank
rotates at 30 r.p.m. 15
2. In the mechanism shown in fig., the crank O2A makes 300
r.p.m in the conte clock wise direction as shown. Find
(i) Angular velocity of link O1A. (ii) Velocity of slider at B.
15
B
A (on crank)
C O1
(on link O1B)
O2 30°
O2 A = 6 cm, O1B = 30 cm
(a) Configuration diagram
43155//KD/39 [P.T.O.
UNIT–II
3. Fig shows a mechanism in which the hydraulic actuator O2A
is expanding at a constant rate of 10 cm / sec. Determine
the directions and magnitudes of angular velocity and
acceleration of link O4A. 15
A
Q on
link O2A 35 cm
P
60° 90°
O2 O4
20 cm
4. A reciprocating roller follower has cycloidal motion and its
stroke of 30 mm is completed in 90°of the cam rotation.
The follower is offset against the direction of rotation by
6.25 mm and radius of the roller is 12.5 mm. determine the
base circle radius which would limit the pressure angle to
30°. 15
UNIT–III
5. For a static equilibrium of the quick return mechanism shown
in fig. find the required input torque T2 for a force of 3500 N
on the slider. Angle of EB with the vertical is 70°. The
impending motion of the slider is to the left. 15
43155//KD/39 2
D 6 F = 3500 N
C 30 cm
5
m
40 c
99
50 cm
BC =
70° A
20 cm
B
2
E
3
50 cm
1
A
6. A V-twin engine has the cylinder axes at right angle and
connecting rods operate a common crank. The reciprocating
mass per cylinder is 10 kg. The crank is 7.5 cm long and
each connecting rod is 35 cm long. Show that the engine
may be balanced for primary effects by means of a revolving
balance mass. If the speed of crank is 500 r.p.m., what is
the maximum value of the resultant secondary force and in
which direction does it act. 15
UNIT–IV
7. A rope pulley is designed to transmit 30 kW. Diameter of
pulley = 360 mm. Speed = 120 rpm. Angle of groove = 45°.
Angle of lap on smaller pulley = 170°. Coefficient of friction
= 0.27. Number of ropes = 10. Mass of the rope 55 C2 kg/m.
Working tension of rope is limited to 125 C2 kN, Where C is
43155//KD/39 3 [P.T.O.
the circumference of rope in meter. Find (i) the initial tenston,
(ii) diameter of each rope. 15
8. An epicyclic gear consists of bevel wheels as shown in fig.
The driving pinion A has 20 teeth and meshes with wheel B
which has 25 teeth. The wheel B and C are fixed together
and turn freely on shaft F. The shaft F can freely rotate about
the main axis XX. Wheel C has 50 teeth and meshes with
wheels D and E, each of which has 60 teeth. Find the speed
and direction E when A rotates at 200 rpm. If (i) D is fixed,
(ii) D rotates at 100 rpm in the same direction as A.
In both the cases, find the ratio of torque transmitted by the
shafts of wheels A and E, the friction being neglected. 15
C
F
E
B
D
x
x
A
43155//KD/39 4
