2005 Punjab Technical University B.Tech Mechanical Engineering THEORY OF MACHINES (New) ME 203 Question paper

Course: B.Tech Mechanical Engineering

University: Punjab Technical University

THEORY OF MACHINES (New) ME 203 3rd Sem May 2k5

Max Marks 60

Note: Section A is compulsory. Attempt any Four questions from Section B and any two questions from section C..

Section A Marks 2 each

1.
(a) Define Turning pair and Screw pair. Give examples.
(b) What is SLIP in a belt drive?
(c) List some applications of CAMS.
(d) What is the difference between a DYNAMOMETER and BRAKE?
(e) Why balancing is required in rotating machinery?
(f) Define Lift, Effort and Power as applied to Governors.
(g) Discuss merits and demerits of CHAIN DRIVE.
(h) Compare flat belt drive and Vee belt drive.
(i) What is HOOKE’s joint?
(j) How are chains classified?

Section B Marks 5 each

2. Sketch mechanism of OLDHAM COUPLING and explain how the motion is transmitted from one shaft to another which are parallel but not co-axial.

3. Derive the equation (T1 – Tc) / (T2 – Tc) = exp (mu x theta) for belt drive.

4. A reciprocating engine has a stroke of 36 cm and connecting rod four times the crank. At the instant, the crank has turned through an angle of 30 degree from the inner dead centre. The crank rotates at 200 rpm clockwise and has an acceleration of 1140 cm/sec/sec. Determine:
(a) Velocity and acceleration of piston.
(b) The angular velocity and angular acceleration of the connecting rod.

5. A shaft which rotates at a constant speed of 150 rpm is connected by belting to a parallel shaft 120 cm apart which has to run at 60, 80 and 100 rpm. The smallest pulley on the driver shaft is 30 cm. Determine the remaining diameters of the two stepped pulleys for cross belt and open belt.

6. Derive an equation for the friction moment of a collar thrust bearing.

Section C Marks 10 each

7. Draw the profile of a cam with a flat faced follower as per following specification: Cam to rotate in an anticlockwise direction. Follower to move outward through a distance of 3 cm during 120 degree of cam rotation. Follower to dwell for 60 degree of cam rotation; follower to return to its initial position during 120 deg. Of cam rotation; follower to dwell for the remaining period of cam rotation.
The minimum radius of the cam is 1.75 cm and the flat face of the follower is at right angle to the line of stroke of follower. The outward and return stroke are to take place with modified uniform velocity and SHM respectively.

8. A shaft carries four masses A, B, C and D weighing 200, 300, 240 and 260 kg and revolving at radii 9, 7, 10 and 12 cm n planes measured from A at 27, 42 and 72 cm. The angle between the cranks are A to B 45 degree; B to C 75 degree; C to d 135 degree. The balancing weights are to be placed in planes at 12 cm and 10 cm from A and D respectively, the distance between them being 50 cm. Find the balancing weight and angular position.

9. A Hartnell type spring loaded Governor rotates about a vertical axis. The two rotating masses weigh 1.2 kg each and move at a radius of 12 cm when the speed is 550 rpm. At this speed the arms 10 cm and 7.5 cm effective length are respectively, vertical and horizontal. The equilibrium speed is 575 rpm when the rotating masses are at their maximum radius of 14.4 cm.
Determine the stiffness, the compression of the spring at 550 rpm and the radius at which the weights rotate when the equilibrium speed is 525 rpm.

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2005 Punjab Technical University B.Tech Mechanical Engineering THEORY OF MACHINES II (New) ME 206 Question paper

Course: B.Tech Mechanical Engineering

University: Punjab Technical University

THEORY OF MACHINES II (New) ME 206 4TH Sem May 2k5

Max Marks 60

Note: Section A is compulsory. Attempt any Four questions from Section B and any two questions from section C.

Section A Marks 2 each

1.
(a) Differentiate between static force analysis and dynamic force analysis.
(b) Define inertia force and inertia torque.
(c) Explain briefly why only a part of the unbalanced force due to reciprocating mass is balanced by revolving mass.
(d) In a locomotive, the ratio of the connecting rod length to the crank radius is kept very large. Why?
(e) Explain the terms:
(i) Module
(j) Pressure angle
(f) State the law of gearing
(g) What are the functions of a differential gear of an automobile?
(h) Explain in brief the working f ‘Sun and Planet Wheel’.
(i) What do you understand by gyroscopic couple?
(j) In the design of four-link mechanism, what do you understand by Dead Centre Position.

Section B Marks 5 each

2. The connecting rod of a vertical reciprocating engine is 2 m long between centres and it weighs 250 kg. The mass centre if 800 mm from the big end bearing. When suspended as a pendulum from the gudgeon pin axis, it makes 8 complete oscillations in 22 seconds. Calculate the radius of gyration of the rod about an axis through its mass centre. The crank is 400 mm long and rotates at 200 rpm.

3. Explain briefly the difference between simple, compound and epicyclic gear trains. What are the special advantages of epicyclic gear trains?

4. Two involute ge4ars of 20 degree pressure angle are in mech. The number of teeth on pinion is 20 and the gear ratio is 2. In the pitch expressed in module is 5 mm and the pitch line speed is 1.2 m/s, assuming addendum as standard and equal to one module, find;
(a) the angle turned through by pinion when one pair of teeth is in mesh, and
(b) the maximum velocity of sliding.

5. Find the angle of inclination with respect to the vertical of a two-wheeler negotiating a turn. Given combined mass of the vehicle with its rider 250 kg; moment of inertia of the engine fly-wheel 0.3 kg-m2; speed of engine fly-wheel 5 times that of road wheels and in the same direction; height of centre of gravity of rider with vehicle 0.6 m; two-wheeler speed 90 km/hr; wheel radius 360 mm; radius of turn 50m.

6. Explain the term ‘Interference’ as applied to gears.

Section C Marks 10 each

7. (a) Explain the terms:
(i) Swaying couple
(ii) Hammer blow.
(b) The firing order in a 6 cylinder vertical four-strike in-line engine is 1-4-2-6-3-5. The piston stroke is 100 mm and the length of each connecting rod is 200 mm. The pitch distances between the cylinder centre lines are 100 mm, 100 mm, 150 mm, 100 mm and 100 mm respectively. The reciprocating mass per cylinder is 1 kg and the engine runs at 3000 rpm.
Determine the out-of-balance primary and secondary forces and couples on this engine taking a plane midway between the cylinder 3 and 4 as the reference plane.

8. (a) Explain the different stages of Kinematic synthesis.
(b) Explain the advantages of involute teeth over cycloidal teeth.

9. Fig. 1 (please see the attachment) shows a four bar mechanism. Calculate the required value of T2 and various forces on the links for equilibrium of the system.



Given AB= 20 cm; BC = 37 cm; CD = 25 cm; CE = 10 cm; AD = 21.5 cm.