A E192003 Pages:3

4 a) Define the following terms as applied to a cam with a neat sketch (5)
i) Prime circle
ii) Pressure angle

b) Derive the expression for velocity and acceleration when the follower moves with (5)
simple harmonic motion
PART ‏تا‎
‎Answer any three full questions, each carries 10marks.

5 A cam drives a flat reciprocating follower in the following manner. During first (10 )
120° rotation of the cam, follower moves outwards through a distance of 20mm
with simple harmonic motion. The follower dwells during next 30° of cam
rotation. During next 120° of cam rotation, the follower moves inwards with
simple harmonic motion. The follower dwells for the next 90° of cam rotation. The
minimum radius of the cam is 25mm.Draw the profile of the cam.

6 A symmetrical circular cam operating a flat faced follower has the following (10)
particulars:
Minimum radius=30mm, Lift h=20mm, Angle of ascent B=75°, Nose radius=S5mm,

Speed=600 rpm

Find
i) the principal dimensions of the cam
ii) the acceleration of the follower at the beginning of the lift, at the end of
contact with circular flank, at the beginning of contact with nose and at
the apex of the nose
7 A pair of 20° full depth involute spur gears having 30 and 50 teeth respectively of (19)

module 4mm in mesh. The smaller gear rotates at 1000rpm. Take addendum = 1
module. Find
i) Sliding velocity at engagement and at disengagement of pair of a teeth

ii) Contact ratio.

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