chapter 01 kinematic link & pairs
TRANSCRIPT
![Page 1: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/1.jpg)
KINEMATIC LINK & PAIRS
CHAPTER 01
![Page 2: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/2.jpg)
KINEMATIC LINK:
It is defined as the part of machine which has
a relative motion with respect to some other
part of same machine is called Kinematic link
or element.
![Page 3: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/3.jpg)
KINEMATIC LINKS CAN BE DIVIDED INTO THREE
TYPES.
1. Rigid link- In this type of link there is no deformation while transmitting the motion. Motion between the piston and crank can be considered as a rigid link.
2. Flexible link- In this type of link there is partial deformation while transmitting the motion. Belt drive is an example of flexible link.
3. Fluid link- In this type of link the motion is transmitted with the help of fluid pressure. Hydraulic brake is an example of fluid link.
![Page 4: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/4.jpg)
KINEMATIC PAIRS
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. Let us discuss the various types
of constrained motions.
![Page 5: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/5.jpg)
CONSTRAINED MOTIONS
Types of Constrained Motions
• Completely constrained motion • Incompletely constrained motion
• Successfully constrained motion
![Page 6: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/6.jpg)
1. COMPLETELY CONSTRAINED MOTION
![Page 7: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/7.jpg)
2. INCOMPLETELY CONSTRAINED MOTION
![Page 8: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/8.jpg)
3. SUCCESSFULLY CONSTRAINED MOTION
![Page 9: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/9.jpg)
TYPES OF KINEMATIC PAIRS
1. According to the type of relative motion between the elements
Sliding pair
•Turning pair
•Cylindrical pair
![Page 10: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/10.jpg)
CONTDD…
Rolling pair
•Spherical pair
•Helical pair or screw pair
![Page 11: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/11.jpg)
(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.
![Page 12: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/12.jpg)
(A) SLIDING PAIR [DOF = 1]
![Page 13: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/13.jpg)
(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
![Page 14: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/14.jpg)
(B) TURNING PAIR (REVOLUTE PAIR) [DOF = 1]
![Page 15: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/15.jpg)
(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.
![Page 16: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/16.jpg)
(C) ROLLING PAIR [DOF = 1]
![Page 17: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/17.jpg)
(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
![Page 18: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/18.jpg)
(D) HELICAL PAIR OR SCREW PAIR [DOF = 1]
![Page 19: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/19.jpg)
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
![Page 20: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/20.jpg)
(E) SPHERICAL PAIR [DOF = 3]
EG. BALL AND SOCKET JOINT
![Page 21: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/21.jpg)
2. ACCORDING TO THE TYPE OF CONTACT
BETWEEN THE ELEMENTS
Lower pair
Higher pair
![Page 22: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/22.jpg)
LOWER PAIR
When the two kinematic links are connected
such that they have a surface contact between
the two links it is called as lower pair.
Or
The joint by which two members are connected
has surface contact.
![Page 23: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/23.jpg)
![Page 24: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/24.jpg)
HIGHER PAIR
When the two kinematic links are connected
such that they have a line or point contact
between the two links it is called as higher pair
![Page 25: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/25.jpg)
1. BALL BEARING 2. CAM AND FOLLOWER
![Page 26: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/26.jpg)
3. ACCORDING TO THE TYPE OF CLOSURE OR
MECHANICAL CONNECTIONS
(A) Self closed pair. When the two elements of
a pair are connected together mechanically in
such away that only required kind of relative
motion occurs, it is then known as self closed
pair. The lower pairs are self closed pair
![Page 27: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/27.jpg)
(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
![Page 28: CHAPTER 01 KINEMATIC LINK & PAIRS](https://reader031.vdocuments.us/reader031/viewer/2022012507/618393a01402597a854de3c4/html5/thumbnails/28.jpg)
KINEMATIC CHAIN
When the kinematic pairs are coupled in such a
way that the last link is joined to the first
link to transmit definite motion (i.e. completely
or successfully constrained motion), it is called
a kinematic chain.