Sunday, September 8, 2013


Through tinkering with the Lego design a bit more we decided it was the best course of action for our car. Although the weighted objectives table stated that the build would take 2-5 days which was a fair estimate we decided that we had the budget to spend that time developing the pull back car design. With that in mind and no longer an issue the pull back design definitely has a lot more strengths than mouse trap design. 

In order to experiment with this design we tried a bunch of different configurations which was very easy having the entire car except the spring being build out of lego's. After thorough investigation our first prototype had served it's purpose and we figured out what issues were holding back the design from its full potential. The major issues were the limited gearing ratio which needs to be increased to get the travel that we need. Also in order to increase travel distance we also need a bigger wheel/tire radius. Also we learned that the farther the spring is would the more the chassis would torque and twist so we need to compensate for that too. In addition the axle that hold the spring and it's gear also need to be held tighter so that the gear stays straight and doesn't skip teeth when in high tension.

Mark 1 Top
Mark 1 Side 
Mark 1 Bottom

So from all this information we decided that nothing more can be done with the prototype and it was now time to refine the design. Unfortunately the gears and wheels haven't come in yet so for now I used the same gearing and wheels but the chassis was entirely redone.
Mark 2
With these changes that car now work really well, barring that I don't have the resources yet for the correct gear ratio, or wheels. I'm sure once those come in we will have a fully functional car that meets all the customer needs and as well as the challenge.

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