Mechanisms

As an assignment, I needed to find a mechanism that converts rotational motion to linear-ish motion. I chose a mechanism called a multiple straight line drive or a hypocycloid gear straight line mechanism. It looks like this.

Any point on the circumference of the inner gear will form a straight line when the smaller gear moves around in the outer gear ring. This is because the inner gear's diameter is half the length of the outer gear's diameter. Therefore, as the inner gear moves around the outer gear the piston will move up and down in accordance to the position of the inner gear. Thus rotational motion of the inner gear is translated into linear motion of the piston. This mechanism does not allow for much force to be exerted on the piston, however.

I initially chose this mechanism because it reminded me of a piston in a car's engine. I thought it was applicable to something I have used a lot. I think it can be useful in the engines of cars, though I am not sure if it would provide enough force. I was also interested in this mechanism because the linear motion of the piston is very fluid. As I was watching the video of the mechanism and thought about how it worked, I concluded that it would not be convenient to use this mechanism if the piston needed to move a large distance. This is because the height the piston moves is exactly the diameter of the larger gear. In order for the piston to move a large distance, the diameter of the larger gear would need to be that large distance, which would take up a lot of space.