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GUJARAT TECHNOLOGICAL UNIVERSITY
DIPLOMA ENGINEERING - SEMESTER–IV • EXAMINATION – WINTER - 2016
Subject Code: 3341903 Date: 22-11-2016
Subject Name: Theory of Machines
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make Suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Use of programmable & Communication aids are strictly prohibited.
5. Use of only simple calculator is permitted in Mathematics.
6. English version is authentic.
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1.Explain difference between Machine and Mechanism
2. Explain in brief the difference between kinetics and Kinematics.
3. List the Inversions of a double slider crank mechanism
4. Define cam and state the function of cam.
5. State the laws of friction
6.State advantages of Gear drive
7. Define the following terms.(1) Lower pair (2) Higher pair
8. Explain Damped vibration in brief.
9. State function of fly wheel in Automotive application.
10. Give name of any four types of follower.
Q.2 (a) Define linear and angular velocity. State relation between them 03
OR
(a) Give Classification of Kinematic pair 03
(b) Explain Constant Acceleration and retardation motion of the follower. 03
OR
(b) Explain Different types of Cam with neat sketch. 03
(c) In a four bar linkage ABCD, AD = 160 mm is fixed link., driving link AB = 60 mm, driven link CD = 75 mm. and link BC = 100 mm. Angle BAD = 900. Link AB rotates at 10 rad/s in clockwise direction, determine (i) Angular velocity of link BC 04
OR
(c) In a steam engine, the crank and connecting rod are 300mm and 1500 mm long respectively. Draw the velocity diagram when crank has rotated in clock wise direction for 500from I.D.C. Find the engine speed when the velocity of piston is 4.9 m/s. 04
(d) Draw the profile of a cam operating a knife-edge follower with the following data. Least radius of a cam = 25 mm. Lift of the follower = 50 mm. The cam lifts the follower for 1500with SHM followed by a dwell period of 300. Then follower lowers down during 1200 of cam rotation with uniform velocity followed by a remaining dwell period. Assume clockwise rotation of a cam.04
OR
(d) Draw the profile of the cam that gives a lift of 40 mm to a roller follower, dia.15 mm. The axis of the follower passes through the center of the cam. The cam rotates in clockwise direction. The minimum radius of the cam is 30 mm. The follower is to be lifted with simple harmonic motion during 1200of camrotation,dwells for 300of the cam rotation in the lifted position, returns to initial position during 900of cam rotation with uniform velocity motion, and dwells for remaining degree of cam rotation 04
Q.3 (a) List advantages and Dis advantages of Friction 03
OR
(a)List various types of thrust bearing and state their application. 03
(b) Define (1) Co efficient of friction (2) Angle of repose (3) Limiting angle of friction 03
OR
(b) Derive the expression for friction torque acting on a conical pivot bearing assuming uniform pressure with usual notations. 03
(c)Explain Cone clutch with neat Sketch. 04
OR
(c)Explain construction and working of single plate clutch. 04
(d) A Conical pivot bearing supports an axial load of 20KN. The cone angle is 600and shaft radius is 180 mm. Determine the power lost in friction at 100 rpm. µ =0.06. Assume both Uniform pressure and Uniform wear condition. 04
OR
(d) A multiple clutch is having 3 driving plates and 2 driven plates. The outer and inner radii of friction surfaces are 130 mm and 80 mm respectively. The intensity of pressure is not to exceed 0.13 N/mm2. Assume uniform wearcondition. Find the power transmitted by the clutch at 1200 rpm. µ =0.3 04
Q.4 (a) What is function of Flywheel? How it differ from that of governor? 03
OR
(a) Draw Turning moment diagram for (1) Four stroke cycle engine (2) Multi cylinder Engine (3) Press machine 03
(b) Two parallel shafts A and B are to be connected by two spur gear each having a module of 8 mm. The speed of gear A is 200 rpm and gear B is 600 rpm. Find the number of teeth on each gears and the exact distance between the shafts. 04
OR
(b) A flat belt 150 mm wide and 8 mm thick is used to transmit power from a motor pully running at 1440 rpm. The diameter of motor pully is 225 mm. The allowable stress in the belt is not exceed 2 N/mm2. The angle of contact of belt on the smaller pully is 1650and co efficient of friction for the leather belt is 0.27. Neglecting the centrifugal tension in the belt. Find the power transmitted by the belt. 04
(c) The Turning moment diagram of a multi cylinder petro engine is drawn to the following scale.Crank displacement : 1 cm =150Turning Moment : 1 cm = 500 NmThe intercepted areas between the output and mean resistance line taken in order are +5.2, -12, +9.2, -14, +8.5, -7.2 and 10 cm2. If the fluctuation of speed is not to exceed 2.5 % of mean speed, which is 360 rpm, Find
(1) Energy to be stored by flywheel in joules.
(2) Mass of flywheel if radius of gyration is 0.6 m
Q.5 (a)What is balancing? Explain need of balancing? 04
(b)Explain the Procedure of balancing several rotating masses in the same plane. 04
(c)Define vibration. Explain Mechanical system of vibration. 03
(d) Explain (1) Longitudinal vibration (2) Transverse vibration (3) Torsional vibration. 03
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