Punjab Technical University 2005 M.E THEORY OF MACHINES - Question Paper

THEORY OF MACHINES (New) ME 203 third Sem May

Note: part A is compulsory. Attempt any 4 ques. from part B and any 2 ques. from part C..

part A Marks two every

1.
(a) describe Turning pair and Screw pair. provide examples.
(b) What is SLIP in a belt drive?
(c) List a few applications of CAMS.
(d) What is the difference ranging from a DYNAMOMETER and BRAKE?
(e) Why balancing is needed in rotating machinery?
(f) describe Lift, Effort and Power as applied to Governors.
(g) explain 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?

part B Marks five every

2. Sketch mechanism of OLDHAM COUPLING and discuss how the motion is transmitted from 1 shaft to a different which are parallel but not co-axial.

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

4. A reciprocating engine has a stroke of 36 cm and connecting rod 4 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 2 stepped pulleys for cross belt and open belt.

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

part C Marks 10 every

7. Draw the profile of a cam with a flat faced follower as per subsequent specification: Cam to rotate in an anticlockwise direction. Follower to move outward through a distance of three 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 replaced uniform velocity and SHM respectively.

8. A shaft carries 4 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 ranging from 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 ranging from them being 50 cm. obtain the balancing weight and angular position.

9. A Hartnell kind spring loaded Governor rotates about a vertical axis. The 2 rotating masses weigh 1.2 kg every 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

Earning:   Approval pending.