Lecture - 11 (Transmission angle in four bar mechanism)

The angle between coupler link and output link in four bar mechanism is known as transmission angle. It is represented as 'μ'. 
In the given figure Let us consider angle between link AO and link OC (fixed link) is represented by 'θ'. 
Let us consider length of link OC is 'a', length of link OA is 'b', length of AB is 'c' and length of BC is 'd'. 

 According to law of cosine we get - 
Now μ will be different for different values of θ.
μ will be maximum for θ = 180 degrees & minimum for θ = 0 degrees. 

 Problem 1- Calculate maximum and minimum value of transmission angle for the following mechanism. Length of link OC is 5cm, length of link AO is 1cm, length of link AB is 4cm and length of link BC is 3cm.


Solution 1 - 
To calculate minimum value of transmission angle observe the mechanism when θ = 0 degrees 


 To calculate maximum value of transmission angle observe the mechanism when θ = 180 degrees 

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