Bharathidasan University 2007 B.Tech Mechatronics Engineering KINEMATICS OF MACHINERY - Question Paper

B.Tech I Semester Regular Examinations, November 2006

KINEMATICS OF MACHINERY

( Common to Mechanical Engineering, Mechatronics and Production
Engineering)
Time: three hours Max Marks: 80
ans any 5 ques.
All ques. carry equal marks

1. (a) How can the mechanism of higher pair be changed by the mechanism of lower pair?

(b) Write notes on complete and incomplete constraints in lower and higher pairs, illustrating your ans with neat sketches. [6+10]

2. 2 points P and Q, four cm apart are to be connected by a pantograph. The motion of P to the motion of P Q is 13 : 7. Fine the distance of Q from the fixed point O of the pantograph such that the point P moves at lowest 12.7 cm in either direction of live O Q P when it is horizontal. obtain also the main dimensions of the pantograph.[16]

3. A quick return mechanism Link two rotates uniformly at 20rad/sec. Draw the acceleration polygon. obtain the absolute acceleration of point B.

4. An engine mechanism ABC has a crank AB of length four cm rotating about A. The connecting rod BC is 12 cm long and the piston C has a mass of 100 gm. C moves along the line AC. Draw the velocity diagram and the acceleration diagram for a uniform crank speed of 150 rad/sec in clockwise direction when the angle BAC is 450. What is torque needed at the crank to accelerate the piston C at this position? [16]

5. The angle ranging from the axes of 2 horizontal shafts to be connected by Hook’s joint is 1500. The speed of driving shaft is 150rpm. The driven shaft carries a flywheel weighing 10 Kg and having a radius of gyration of 10 Cm. If the forked end of the
driving shaft rotates 300 from horizontal plane, obtain the torque needed to drive the shaft to overcome the inertial of the flywheel. [16]

6. A flat ended valve tappet is operated by a symmetrical cam with circular arcs for flank and nose profiles. The total angle of action is 1500 base circle diameter 125 mm and the lift 25 mm. During the lift, the period of acceleration is half that of the retardation. Speed of cam shaft is 1250 r.p.m. The straight line path of the tapper passes through the cam axis. obtain (a) Radii of the nose and flank, and (b) Maximum acceleration and retardation during the lift. [16]

7. (a) What do you mea by conjugate gears? discuss how do the involute profile gear teeth satisfy it?
(b) A pair of gears having 40 and 20 teeth respectively, are rotating in mesh, the speed of the smaller being 2000 rpm. Determine
i. the speed of sliding ranging from the gear teeth faces at the point of engagement, at the pitch point and at the point of disengagement, if the smaller
wheel is the driver. presume that the gear teeth are of the 200 involute forms that the addendum length is five mm and module pitch is five mm.

ii. Also obtain the angle through which pinion turns while any 1 pair teeth are in contact. [8+8]

8. In an epicyclic train an annular wheel A having 54 teeth meshes with a planet wheel B
which gears with a sun wheel C, the wheels A and C being coaxial. The wheel B is carried on a pin fixed on 1 end of arm P which rotates about the axis of the
wheels A and C. If the wheel A makes 20 rpm in a clockwise direction and the arm P rotates at 100 rpm in the anticlockwise direction and the wheel C has 24 teeth, determine the speed and sense of rotation of arm P

Earning:   Approval pending.