Compound Machine Project
The purpose of this project was to design a Compound machine using 3 simple machines. The final product should be able to lift 500 grams with 300 grams of input force.
This was one of my original ideas. It involved the effort resistance sliding down an inclined plane. A string attached to the resistance would turn a small input gear, one of two gears in a simple gear train. A string attached to the larger of two gears, the output, would pull down on a first class lever. The resistance force, which would be on the other side of the fulcrum, would rise.
In this sketch, another of my original ideas, the effort force is once again applied to an inclined plane. The string attached to the effort force is applied to a pulley. On the other side of the pulley, the same string turns a small input gear, this gear, in turn, applies force to and turns a larger output gear. The resistance force hangs directly on the output gear and rises when that gear turns.
In this machine the effort force is applied to the long end of a first class lever. On the other side of the fulcrum, the the lever rises. A string is attached to that end of the lever and to a small input gear. When the string rises, the gear spins and turns the output gear(the larger gear) in this simple gear train. A string attached to this gear pulls the resistance force up an inclined plane.
Here is the sketch of the final design. As you can see it is similar to the above sketch in every way but one. We decided to use a gear and sprocket instead of a gear train. The advantage of this was simply due to the fact that with the materials provided in our vex kits we were able to get a more favorable gear ratio using this method.
The result of our efforts:
We had to add a third gear to this part of the machine whose only function tighten the chain.
With our design we were able to lift 1000 grams with a mere 125 grams. That is an AMA (Actual Mechanical Advantage) of 5:40, much higher than our target of 3:5
Conclusion:
I believe that we did very well on the project. We were able to achieve a very high mechanical advantage (5:40). The only things that i believe could have improved our machine were these: a different material for the inclined plane, something that provided less residence. We also could have increased the length of our lever on the effort side of the fulcrum. We also could have increased the mechanical advantage of our gear and sprocket by decreasing the size of the input gear and increasing the size of the output gear. Finally, we could have increased the length and decreased the angle of the inclined plane