Yashwantrao Chavan Maharashtra Open University 2006 Certification TML Theory of Machines - Question Paper

TML074/EE/20070819
Theory of Machines
Time : 180 minutes Marks : 100
Instructions for the students :
1. All ques. are compulsory.
2. “Long ans kind ques. (LAQ)” is a supply kind ques. of 20 marks,
which require typical ans of about 60-80 lines in about 32-40 minutes.
3. “Short ans kind ques. (SAQ)” is a supply kind ques. of five marks,
which require typical ans of about 15-20 lines in about 08-10 minutes.
4. Use of non-programmable kind of scientific calculator is allowed.
5. Draw neat diagrams wherever necessary.
6. presume suitable data if necessary.

Long ans kind ques. (LAQ’s)

1. In a slider crank mechanism, the crank is 480 mm long and
rotates at 20 rad/s in the counter clockwise direction. The length
of connecting rod is 1.6 m. When crank turns 600 from inner
dead centre, determine
i) Velocity of slider
ii) Velocity of point ‘E’ located at a distance 450 mm on
connected rod extended.
iii) The position and velocity of point F on the connecting rod
having the lowest absolute velocity.
iv) Angular velocity of connecting rod.
v) Velocities of rubbing of pins of crankshaft, crank and
crosshead having diameters 80, 60 and 100 mm
respectively.

2. In the toggle mechanism shown in figure the crank OA rotates at
210 rpm counter – clockwise increasing at the rate of 60 rad/s2.
For provided configuration determine :
i) Velocity of slider D and the angular velocity of link BD.
ii) Acceleration of slider D and the angular acceleration of link
BD.

3. (a) The subsequent data relate to a screw jack : Pitch of threaded
screw = eight mm, diameter of threaded screw = 40 mm, coefficient
of friction ranging from screw and nut = 0.1, Load = 20
kN.
Assuming that load rotates with screw, determine
i) Ratio of torque needed to raise and lower the load
ii) The efficiency of machine.
(b) discuss the classification of follower.
10
10
4 2.5 kW of power is transmitted by an open belt. Drive. The linear
velocity of belt is 2.5 m/s. The angle of lap on the smaller pulley
is 1650. The co-efficient of friction is 0.3. Determine the effect
on power transmission in the subsequent cases :
i) Initial tension in belt is increased by 8%.
ii) Initial tension in the belt is reduced by 8%.
iii) Angle of lap is increased by 8% by use of idler pulley for
the identical speed and tension of tight side.
iv) Co-efficient of friction is increased by 8% by suitable
dressing to friction surface of the belt.

Short ans kind ques. (SAQ’s)
5. discuss with examples – a) Lower pair b) Higher pair 5
6. discuss Pantograph mechanism. 5
7. discuss the laws of Friction. 5
8. Classify the chains.

Earning:   Approval pending.