Differentiate between planar linkage and spatial linkage Exp

Differentiate between planar linkage and spatial linkage. Explain with illustration. Define Frame, Link, and Kinematic pair. Explain with illustration. Differentiate between double pin Joint and triple pin Joint. Explain with illustration.

Solution

(d) ans-

unconstrained rigid body (spatial)- 6

cylindrical joint- 2

spherical joint- 3

unconstrained rigid body (planer)- 3

cam pair- 2

revolute joint- 1

2. (a) ans-

A mechanical linkage is an assembly of bodies connected to manage forces and movement.

It is common practice to design the linkage system so that the movement of all of the bodies are constrained to lie on parallel planes, to form what is known as a planar linkage. It is also possible to construct the linkage system so that all of the bodies move on concentric spheres, forming a spherical linkage. In both cases, the degrees of freedom of the link is now three rather than six, and the constraints imposed by joints are now c=3-f.

(b) ans:-

A link is defined as a rigid body having two or more pairing elements which connect it to other bodies for the purpose of transmitting force or motion..

In every machine, at least one link either occupies a fixed position relative to the earth or carries the machine as a whole along with it during motion. This link is the frame of the machine and is called the fixed link.

The combination of links and pairs without a fixed link is not a mechanism but a kinematic chain.

(c) Ans:-

When two members are jointed together such that no transfer of moment is allowed between members, connection is called pin connection (provided relative axial movement is also restricted),type of joint is called pin joint.

In two pin joints the body is constrained by two pins which are usually placed opposite to each other wheres in triple pin joints three pins are there which are usually spaced by 120 degrees.