In the previous post Chains were discussed, continuing with Chains:
A Mechanism: is a kinematic-Chain having one Link fixed. The above Fig.c, shows a Chain-Mechanism having 5 links, suppose you have 'N' links, you can use them to get N number of mechanisms by making each link fixed in sequence, for example the Chain of a cycle. These N mechanism are are called inversions of a Chain. The concept of inversions is very useful, which will be discussed after you are ready for the same, at a later stage.
A Few more points to be kept in mind which studying kinematics are:
Plane Motion: A body is said to have a plane motion when all its points move parallel to a fixed plane. Thus the motion, whether it is translational or rotational or combination of both.
Plane Rotation: A body is said to be in plane rotation if its plane motion is such that each point in it (the body) remains at a constant distance from a fixed axis perpendicular to the plane of motion.
Plane Translation: A body is said to be in plane translation if the motion is such that a line connecting any two points on a plane, parallel to the plane of motion, remains parallel to all the previous positions. There are two conditions which fit the criteria (a) rectilinear & (b) curvilinear. By and large it is rectilinear motion.
Helical motion: Is a combination of rotation and translation along the axis of rotation such as the rotation of a Nut on a bolt.
Nut and the bolt, shown in the diagram below, is an example of helical motion, when the nut is rotated it goes through a rotational motion along with a motion in a linear path.
Spherical motion: If each point on the body remains at a constant distance from a fixed point, when in rotation, it is said to be in spherical motion, for example a Governor, shown in the diagram below.
This brings us to the end of the basic definitions of motions of various types covered under kinematics. The next step will be to show you how these various types of motions are put into use for designing a kinematic mechanism so as to exploit these concepts to make useful machines or machine elements.
Plane Rotation: A body is said to be in plane rotation if its plane motion is such that each point in it (the body) remains at a constant distance from a fixed axis perpendicular to the plane of motion.
Plane Translation: A body is said to be in plane translation if the motion is such that a line connecting any two points on a plane, parallel to the plane of motion, remains parallel to all the previous positions. There are two conditions which fit the criteria (a) rectilinear & (b) curvilinear. By and large it is rectilinear motion.
Helical motion: Is a combination of rotation and translation along the axis of rotation such as the rotation of a Nut on a bolt.
Nut and the bolt, shown in the diagram below, is an example of helical motion, when the nut is rotated it goes through a rotational motion along with a motion in a linear path.
Spherical motion: If each point on the body remains at a constant distance from a fixed point, when in rotation, it is said to be in spherical motion, for example a Governor, shown in the diagram below.
This brings us to the end of the basic definitions of motions of various types covered under kinematics. The next step will be to show you how these various types of motions are put into use for designing a kinematic mechanism so as to exploit these concepts to make useful machines or machine elements.
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