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Complex Mechanisms Project
Problem/Constraints
Create a complex mechanism that uses at least 3 mechanisms including a gear train or a sprocket. The applied effort force must be no more than 300g. The machine must lift at least 500g. You must use the VEX kits to build the machine.
Brainstorming
We decide that a first class lever would be best for the beginning mechanism since you can get good amounts of MA out of them. We then added a simple gear train which consisted of a small gear input to a large gear output. A rope was attached to the resistance weight which was pulled up an inclined plane.
Final Plan
In our final plane, we did use the lever, although we made it extremely long. It was 19 inches long instead of 9. We switched out the gear train and made it into a sprocket instead in order to meet the constraints because a simple gear train must have at least 3 gears. The chain and sprocket consisted of two small gears and a large gear to lift the resistance weight. The inclined plane idea worked rather well and we ended up lifting 1000g with 100g. The system was very efficient and smooth operating.
Calculations
Each mechanism has its own mechanical advantage. We calculated the mechanical advantage of each mechanism: The Lever was found by dividing the effort distance by the resistance distance(19.5in/4in=4.875 MA) and the mechanical advantage of the sprocket and chain was found by dividing the diameter of each sprocket by the axles(3.5in/.5in=7)(.5in/.5in=1)then the large sprocket is multiplied by the small sprocket which gives you mechanical advantage(7x1=7 MA). The inclined plane mechanical advantage was found by dividing the length of the plane by the height it covered(12in/3in=4 MA). AFter you have the mechanical advantage for each mechanism, you mutliply the mechanical advantages across(4.875x7x4=136.5 Total Mechanical Advantage.
Reflection
After doing this project, I now understand how mechanical advantage works and why simple machines are important. Many tasks and work items can be made easier using simple machines. I also learned that when you combine mechanisms, it can even more greatly decrease the amount of effort you need. If I could go back and redesign my machine, I would add more mechanisms if I had time.
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