Subject Code: 2131906
GUJARAT TECHNOLOGICAL UNIVERSITY
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BE - SEMESTER-III (NEW) EXAMINATION — SUMMER 2019
Subject Name: Kinematics of Machines
Time: 02:30 PM TO 05:00 PM
Instructions:
- Attempt all questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
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Q.1 (a) Explain the terms: MARKS
- Machine
- Structure
- Mechanism
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03
(b) Sketch and explain inversions of four bar chain mechanism (any two) 04
(c) What are the types of inversions? Explain crank and slotted lever type quick return mechanism. 07
Q.2 (a) Classify straight line generating mechanisms. 03
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(b) State and prove ‘Aronhold Kennedy’s Theorem’ of three instantaneous centres. 04
(c) Explain the Freudenstein’s method of three-point synthesis of mechanisms. 07
OR
(c) Explain chebyshev spacing method for location precision point position in four bar chain mechanism. 07
Q.3 (a) Define linear and angular velocity. 03
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(b) Write a short note on velocity and acceleration diagram. 04
(c) PQRS is a four bar chain mechanism. The length of the links are PQ = 62.5mm; QR = 175mm; RS = 112.5mm; and PS = 200 mm. the link PS is a fixed link. The crank PQ rotates at 10 rad/s clockwise and makes 60° with l.d.c. Draw the velocity and acceleration diagram. Q and R lie on the same side of PS. Find the angular velocity and angular acceleration of links QR and RS. 07
OR
Q.3 (a) Explain function generation 03
(b) Define Type synthesis and Number synthesis. 04
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(c) Synthesize a four bar mechanism to meet the following instantaneous conditions for input output links: 07
?1=60° ?1 =3rad/sec a1 =-1rad/sec’
?2=90° ?2 =2rad/sec a2 =0
Q.4 (a) What is speed ratio and velocity ration in gear trains. 03
(b) Write a complete classification of gear trains. 04
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(c) Explain the working of Epicyclic gear train with sketch. Also give its applications. what are the advantages of Epicyclic gear train? 07
Date: 18/06/2019
Total Marks: 70
Q.4 (a) What are the standard tooth profiles? 03
(b) What is interference and undercutting in gear? 04
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(c) Two involute gears of pressure angle are rotating in mesh. The speed of smallest gear is 1400 rpm. The number of teeth on pinion is 20 and gear ratio is 2. If the addendum of pinion and wheel is standard and equal to one module and module is 5mm. Consider pressure angle as 20. 07
Find:
- length of arc of contact.
- velocity of sliding at the point of contact.
Q.5 (a) What is cam and follower? 03
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(b) Roller follower is more preferable to that of knife edged follower .why? 04
(c) Define the following terms as applied to cam with neat figure. (i) Base circle (ii) Pitch circle, (iii) Pressure angle, (iv) stroke of the follower. (v) Prime circle. 07
OR
Q.5 (a) What are the types of motion of the follower? 03
(b) With the help of neat sketches explain the types of cams and followers 04
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(c) Draw a cam profile for a given data: 07
- Outstroke during 60° of cam rotation
- Dwell for the next 45 ° of cam rotation
- Return stroke during next 60° of cam rotation and
- Dwell for the remaining of cam rotation
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The stroke of follower is 50mm and the minimum radius of the cam is 40mm. The follower moves with uniform velocity during both the outstroke and return strokes. The follower is of knife edge type. Draw the profile of the cam when the axis of the follower is passes through the axis of cam shaft.
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