JNTU
JNTU B.Tech II KINEMATICS OF MACHINERY Previous Question Paper (September/October - 2023 - R15)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
Define mechanism-machine-structure.
Answer
A mechanism is a combination of rigid or resistant bodies connected to transmit motion. A machine is a mechanism or combination of mechanisms that transmits and modifies motion to perform useful work. A structure is an assembly of resistant bodies connected to support loads without transmitting motion.
What is the significance of single slider crank chain?
Answer
The single slider crank chain is significant as it serves as the fundamental basis for converting reciprocating motion into rotary motion (or vice versa). It is widely used in internal combustion engines, reciprocating compressors, and pumps, and its inversions provide various practical mechanisms like the oscillating cylinder engine and the rotary engine.
Outline velocity and acceleration.
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List the applications of relative velocity method.
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Label the applications of Hooke’s joint.
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List conditions for correct steering.
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Outline the uses of cam and followers.
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List the types of followers.
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Define law of gearing.
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Outline the types of gear trains.
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Part B
Explain classification of links in detail.
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Discuss the types of constrained motions.
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Analyze inversions of double slider crank chain with neat sketches.
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In the mechanism shown in Figure 1. The crank OA rotates at 50 rpm and the lengths of the links are OA= 125 mm, AC= 600 mm, QC= 150 mm, QD= 150 mm, CD= 130 mm, BD= 550 mm and OQ= 625 mm. When the angle AOQ= 45 degrees, determine:
a) The linear acceleration of the slider at B.
b) The angular acceleration of the links AC, CQD and BD.
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The crank and connecting rod of a reciprocating engine are 150 mm and 600 mm long respectively. The crank makes an angle of 60° with the inner dead centre, and revolves at a uniform speed of 300 rpm. Find the velocity of the mid-point of the connecting rod by Klein’s construction method. Assume any other data.
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Explain significance of kliens construction.
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Explain the Scott-Russel mechanism and show that it generates straight-line motion.
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Analyze Davis steering gear mechanism.
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Two shaft P & Q connected together by Hooke’s joint have their axes inclined at 20°. The shaft P revolves at uniform speed of 1500 r.p.m and the shaft Q carries a fly wheel of weight 150 N, radius of gyration 100 mm. Find the maximum torque in shaft Q, if it is assumed that the shafts are torsionally rigid.
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A radial translating flat - face follower has a lift of 3 cm. The rise takes place with SHM for 180° of cam rotation, followed by dwell of 30° and simple harmonic return for 120° followed by another dwell. The base circle radius of the cam is 3 cm. Find the cam profile and the minimum length of the follower face with a clearance of 0.3 cm at both the ends. Assume anticlockwise rotation of the cam. What are the maximum velocity and accelerations values during the follower rise when cam rotates at 50 r.p.m?
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A disc cam is to give uniform motion to a knife edge follower during out stroke of 50mm during first half of the cam revolution. The follower again returns to its original position with uniform motion during the next half of the revolution. The minimum radius of the cam is 50mm and the diameter of the cam shaft is 35mm. Draw the profile of the cam when a) The axes of the follower passes through the axes of the cam shaft, and b) The axes of the follower is offset by 20mm from the axes of the cam shaft.
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Establish a relation for the number of teeth in contact for a pair of gear wheels with involute teeth, in terms of pressure angle, the number of teeth on each of the wheels and the addendum. The number of teeth in the wheels are 20 and 31 with a pressure angle of 20°, module pitch = 2.5 mm and standard addendum of one module. Calculate the length of patch and arc of contact and angle turned by each wheel while any one pair of teeth is in contact.
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Figure 2 shows an epicyclic gear in which arm A is fixed to the shafts S, B is free to rotate on S and F is separately driven. A receives 7.5kW at 200 r.p.m and F is driven in the same direction at 100 r.p.m. Determine the speed of B and the torque on its shaft.
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