Lecture - 13 ( single slider crank mechanism (part-2))

Third inversion 

In 3rd inversion of single slider crank mechanism connecting rod is fixed.
Examples - crank & slotted Lever quick return motion mechanism, oscillating cylinder engine mechanism.

  • CRANK AND SLOTTED LEVER QUICK RETURN MOTION MECHANISM- 

In this mechanism input is in the form of rotation and output is in the form of oscillation. Brief diagram of mechanism is shown below
According to figure link1 (CA) is connecting rod of mechanism which is fixed. Link 2 is crank which is in rotation motion. Link 3 is slider which is placed inside slotted bar. Link 4 of mechanism is slotted bar.

Let us consider'β' is the cutting stroke angle and 'α' is return stroke angle. Time required in cutting stroke angle will be more than time required in return stroke angle, therefore it is quick return motion mechanism .As shown in figure value of 'α' is less than value of 'β' because of quick return motion mechanism.
Quick return ratio is defined as the ratio of time required in cutting stroke to the time required in return stroke. Its value is always greater than 1.


  • OSCILLATING CYLINDER ENGINE MECHANISM 

In this mechanism rotation of crank is converted to oscillation of cylinder and vice versa. Here first turning pair is between connecting rod and Crank, second turning pair is between crank and Piston rod and third turning pair is between cylinder and connecting rod.

Fourth inversion

When slider of the mechanism is fixed then it become 4th inversion of single slider crank mechanism. 
Example is pendulum pump or Bull engine
In this mechanism piston (link1) is Hollow and also fixed. Link 3 is plunger and plunger Rod, because they both are single body. Link 3 moves up and down. A brief diagram is shown below- 

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