Download PTU B.Tech 2020 March Automation-And-Robotics Question Paper 3rd Sem BTAR 305 18 Kinematics And Theory Of Machines

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Roll No. HEEEEEEEEE Total No. of Pages : 03
Total No. of Questions : 09

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B.Tech. (Automation & Robotics) (2018 Batch) (Sem.-3)
KINEMATICS AND THEORY OF MACHINES
Subject Code : BTAR-305-18
M.Code : 76504
Time : 3 Hrs. Max. Marks : 60

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INSTRUCTIONS TO CANDIDATES :

1. SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks each.
2. SECTION-B contains FIVE questions carrying FIVE marks each and students have to attempt any FOUR questions.
3. SECTION-C contains THREE questions carrying TEN marks each and students have to attempt any TWO questions.

SECTION-A

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1. Write briefly :

1. What do you understand by resistant bodies?
2. Define kinematic pair.
3. Explain types of joints in a chain.
4. Write Grubler’s criterion equation for plane mechanisms with constrained motion.

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5. What do you understand by the instantaneous centre of rotation (centro) in kinematic of machines?
6. Define Centrode:
7. What are the different types of motion with which a follower can move?
8. Explain the terms :
   1. Circular pitch and
   2. Backlash.

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9. Differentiate between Involute and Cycloidal Gears.
10. What do you understand by limiting angle of friction?

SECTION-B

2. In a crank and slotted lever quick return mechanism, as shown in Fig. 1, the driving crank length is 75 mm. The distance between the fixed centres is 200 mm and the length of the slotted lever is 500 mm. Find the ratio of the times taken on the cutting and idle strokes. Determine the effective stroke also.

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Fig.1

3. In a four bar mechanism ABCD, AD is fixed and is 120 mm long. The crank AB is 30 mm long and rotates at 100 r.p.m. clockwise, while the link CD =60 mm oscillates about D. BC and AD are of equal length. Find the angular velocity of link CD when angle BD = 60°.

4. State and prove the law of gearing, Show that involute profile satisfies the conditions for correct gearing.

5. A single plate clutch, with-both sides effective, has outer and inner diameters 300 mm and 200 mm respectively. The maximum intensity of pressure at any point in the contact surface is not to exceed 0.1 N/mm’. If the coefficient of friction is 0.3, determine the power transmitted by a clutch at a speed 2500 r.p.m.

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6. State the laws of (a) Dynamic friction, and (b) Fluid friction.

SECTION-C

7. Write notes on :

1. Mechanical advantage and transmission angle of mechanism.
2. Grashof’s law

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8. A cam is to be designed for a knife edge follower with the following data :

1. Cam lift = 40 mm during 90° of cam rotation with simple harmonic motion.
2. Dwell for the next 30°.
3. During the next 60° of cam rotation, the follower returns to its original position with Simple harmonic motion.
4. Dwell during the remaining 180°. Draw the profile of the cam when
   1. The line of stroke of the follower passes through the axis of the cam shaft,

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   2. The line of stroke is offset 20 mm from the axis of the cam shaft.

The radius of the base circle of the cam is 40 mm. Determine the maximum velocity and acceleration of the follower during its ascent and descent, if the cam rotates at 240 r.p.m.

9. An epicyclic gear train, as shown in Fig.2, is composed of a fixed annular wheel A having 150 teeth. The wheel A is meshing with wheel B which drives wheel D through an idle wheel C, D being concentric with A. The wheels B and C are carried on an arm which revolves clockwise at 100 r.p.m. about the axis of A and D. If the wheels B and D have 25 teeth and 40 teeth respectively, find the number of teeth on C and the speed and sense of rotation of C.

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Fig.2

NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any page of Answer Sheet will lead to UMC against the Student.

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