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Note for Kinematic and Kinetics Of Machines - KKM By Mr. Hema Mahesh Komma

• Kinematic and Kinetics Of Machines - KKM
• Note
• Jawaharlal Nehru Technological University Anantapur (JNTU) College of Engineering (CEP), Pulivendula, Pulivendula, Andhra Pradesh, India - JNTUACEP
• Mechanical Engineering
• 4 Topics
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Mr. Hema Mahesh Komma
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Siddharth Institute of Engineering & Technology, Puttur K. Hema Mahesh, Assistant Professor SIDDHARTH INSTITUTE OF ENGINEERING & TECHNOLOGY:: PUTTUR (Approved by AICTE, New Delhi & Affiliated to JNTUA, Anantapuramu) (Accredited by NBA & Accredited by NAAC with ‘A’ Grade) (An ISO 9001:2008 Certified Institution) Siddharth Nagar, Narayanavanam Road, PUTTUR-517 583 QUESTION BANK with ANSWERS Subject with Code: Kinematic of Machinery (16ME304) Year &Sem : II-B. Tech & I-Sem Course & Branch: B. Tech - ME Regulation: R16 UNIT - I 1 Explain the classification of the kinematics pairs in detail with neat sketch. The two links or elements of a machine, when in contact with each other, are said to form a pair. If the relative motion between them is completely or successfully constrained (i.e. in a definite direction), the pair is known as kinematic pair. The kinematic pairs may be classified according to the following considerations : 1. 2. 3. According to the type of relative motion between the elements. According to the type of contact between the elements. According to the type of closure 1. According to the type of relative motion between the elements. The kinematic pairs according to type of relative motion between the elements may be classified as discussed below: (a) Sliding pair. When the two elements of a pair are connected in such a way that one can only slide relative to the other, the pair is known as a sliding pair. The piston and cylinder, cross-head and guides of a reciprocating steam engine, ram and its guides in shaper, tail stock on the lathe bed etc. are the examples of a sliding pair. A little consideration will show, that a sliding pair has a completely constrained motion. (b) Turning pair. When the two elements of a pair are connected in such a way that one can only turn or revolve about a fixed axis of another link, the pair is known as turning pair. A shaft with collars at both ends fitted into a circular hole, the crankshaft in a journal bearing in an engine, lathe spindle supported in head stock, cycle wheels turning over their axles etc. are the examples of a turning pair. A turning pair also has a completely constrained motion. (c) Rolling pair. When the two elements of a pair are connected in such a way that one rolls over another fixed link, the pair is known as rolling pair. Ball and roller bearings are examples of rolling pair. Dept. of Mechanical Engineering Kinematic of Machinery Page 1

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Siddharth Institute of Engineering & Technology, Puttur K. Hema Mahesh, Assistant Professor (d) Screw pair. When the two elements of a pair are connected in such a way that one element can turn about the other by screw threads, the pair is known as screw pair. The lead screw of a lathe with nut, and bolt with a nut are examples of a screw pair. (e) Spherical pair. When the two elements of a pair are connected in such a way that one element (with spherical shape) turns or swivels about the other fixed element, the pair formed is called a spherical pair. The ball and socket joint, attachment of a car mirror, pen stand etc., are the examples of a spherical pair. 2. According to the type of contact between the elements. The kinematic pairs according to the type of contact between the elements may be classified as discussed below : (a) Lower pair. When the two elements of a pair have a surface contact when relative motion takes place and the surface of one element slides over the surface of the other, the pair formed is known as lower pair. It will be seen that sliding pairs, turning pairs and screw pairs form lower pairs. Dept. of Mechanical Engineering Kinematic of Machinery Page 2

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Siddharth Institute of Engineering & Technology, Puttur K. Hema Mahesh, Assistant Professor (b) Higher pair. When the two elements of a pair have a line or point contact when relative motion takes place and the motion between the two elements is partly turning and partly sliding, then the pair is known as higher pair. A pair of friction discs, toothed gearing, belt and rope drives, ball and roller bearings and cam and follower are the examples of higher pairs. 3. According to the type of closure. The kinematic pairs according to the type of closure between the elements may be classified as discussed below : (a) Self closed pair. When the two elements of a pair are connected together mechanically in such a way that only required kind of relative motion occurs, it is then known as self closed pair. The lower pairs are self-closed pair. (b) Force - closed pair. When the two elements of a pair are not connected mechanically but are kept in contact by the action of external forces, the pair is said to be a force-closed pair. The cam and follower is an example of force closed pair, as it is kept in contact by the forces exerted by spring and gravity. 2 Explain the inversions of double slider crank chain with neat sketch and list out the practical applications of inversions. Dept. of Mechanical Engineering Kinematic of Machinery Page 3

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Siddharth Institute of Engineering & Technology, Puttur Dept. of Mechanical Engineering K. Hema Mahesh, Assistant Professor Kinematic of Machinery Page 4