Simple Slider Crank Mechanism
The simple slider crank mechanism is a basic mechanical system that converts rotary motion into reciprocating motion. It consists of three main components: a crank, a connecting rod, and a slider. The crank is a rotating arm that converts the input rotary motion into a reciprocating motion. The connecting rod connects the crank to the slider, which moves back and forth along a straight line.

Inversion
In mechanical engineering, the term "inversion" refers to the rearrangement of the components of a mechanism while keeping the input and output motions the same. It allows engineers to modify or adapt existing mechanisms for specific applications.

Scotch Yoke Mechanism
The scotch yoke mechanism is an inversion of the simple slider crank mechanism. It is commonly used in reciprocating engines and pumps. In this mechanism, the connecting rod is replaced by a yoke, and the slider is replaced by a yoke pin or a roller that moves in a straight line. The input rotary motion is converted into a reciprocating motion by the yoke pin or roller.

Comparison
To understand why the scotch yoke mechanism is an inversion of the simple slider crank mechanism, let's compare the two mechanisms:

Components:
- Simple Slider Crank Mechanism:
- Crank
- Connecting rod
- Slider

- Scotch Yoke Mechanism:
- Crank
- Yoke
- Yoke pin or roller

Motion:
- Simple Slider Crank Mechanism:
- Rotary motion of the crank is converted into reciprocating motion of the slider.

- Scotch Yoke Mechanism:
- Rotary motion of the crank is converted into reciprocating motion of the yoke pin or roller.

Inversion:
The scotch yoke mechanism is considered an inversion of the simple slider crank mechanism because it replaces the connecting rod and slider with a yoke and yoke pin or roller. The basic concept of converting rotary motion to reciprocating motion remains the same, but the arrangement of the components is different.

Applications:
The scotch yoke mechanism is commonly used in reciprocating engines, pumps, and other mechanical systems where a straight-line reciprocating motion is required. It provides a simple and efficient solution for converting rotary motion into linear motion.

Conclusion
In summary, the scotch yoke mechanism is an inversion of the simple slider crank mechanism. It replaces the connecting rod and slider with a yoke and yoke pin or roller, while still achieving the same conversion of rotary motion to reciprocating motion. This inversion allows for different applications and variations of the basic mechanism, providing engineers with more flexibility in designing mechanical systems.