Compound Machines
1. Determine the instructor-assigned task in detail, including all required operations and time constraints.
2. Investigate available equipment components and possible configurations.
3. Brainstorm ideas for accomplishing the assigned task, and record at least three ideas in your engineering notebook.
4. Using isometric grid paper or 3D modeling software, sketch and annotate a preliminary design solution including the individual mechanism’s mechanical advantage and the drive ratios.
5. Build, test, and modify your compound machine design.
2. Investigate available equipment components and possible configurations.
3. Brainstorm ideas for accomplishing the assigned task, and record at least three ideas in your engineering notebook.
4. Using isometric grid paper or 3D modeling software, sketch and annotate a preliminary design solution including the individual mechanism’s mechanical advantage and the drive ratios.
5. Build, test, and modify your compound machine design.
The Simple Machines of the Compound Machine
Gear TrainBefore:
IMA (Ideal Mechanical Advantage) = 6.86:1 AMA (Actual Mechanical Advantage) = 6.5:1 *After making sure with our instructor that we got everything right, it turns out that we had a lot of torque. After we discovered our mistake, we realized that we had the ratios swapped around. After: IMA = 1:6.86 AMA = 1:6.5 |
LeverIMA = 1.37:1
AMA = 1.21:1 |
Fixed PulleyIMA = 1:1
AMA = 1:1 |
Wheel and AxleIMA = 1:1
AMA = 1:1 |
Summary
The entire mechanism works by turning the wheel and axle, shown on the far left. Which activates the gear train, shown middle left, that pulls a string. In sequence, turns the fixed pulley, that changes the direction of the string, shown middle right. And finally the string pulls down the lever which is weighted by 200 grams on the other side, shown on far right. Before instructor examination we had our IMA = 9.4:1 and our AMA = 7.865:1 with an effeciency of 83.7% but afterwards we had our IMA = 0.1997:1 and our AMA = 0.186:1 with an effeciency 93%.
All in all, this mechanism was designed to lift a weight up to 500 grams.
All in all, this mechanism was designed to lift a weight up to 500 grams.