Summary and Reflection:
Drew and I knew that in theory, the more gears (to increase the ratio) that we attached to the motor, the more torque it would have, the more efficiently the racer would move. For this to happen, a gear having more teeth would be moved with a gear having less teeth.
Overall, it took a lot of time to figure out how to connect the gears together in a way that would allow all of the teeth to move freely enough to spin each other but not so far apart that they didn’t touch. If this wasn’t the case, then our torque was too great for the speed or vice versa for every single one of our iterations until the last. We worked a lot on making sure things would link up according to FLUs as the process went on and we tried to come up with gear trains that would fit together accordingly and allow the racer to have enough torque and speed to actually move.
Our second to last iteration (our other ones would fall apart due to a not sturdy structure )
I think that if we had more time to work on our lego racer, we would try to find a better ratio of speed to torque to make it go faster. I’d also try to figure out which sized gear was throwing off our proportions so much so that it could fit together more easily.
Our Final Lego Racer
Video Clip:
Engineering Analysis:
Our gear train was design to increase the torque of the motor and then connect it to the back wheels of our racer. Thus we used gears with less teeth to move gears with more teeth. We connected the latter gear to a gear with smaller teeth via a rod and continued this process. The idea was to use this gear train along with a lightweight yet sturdy lego structure. Our final ratio was 41:1. We ended here because after to many hours spent constructing new gear trains and racer structures to accompany them, we were so happy that one finally worked. It had enough speed and torque to move down the race course with the weight on top which was more than we could say for any of our other models. We tried the other ratios to try to get a sense of what point was too much torque and which point was too much speed in comparison (“Stall avoidance” vs Speed Tradeoff).
| Iteration # | Gear Ratio | Speed | Notes |
| 1 | 5:2 | 0 | A lot of our gears cancelled each other out and just created more friction, not actually moving the car |
| 2 | 125:1 | 0 | The torque was to great in comparison to the speed to move the gears |
| 3 | 25:3 | 0 | The gears didn’t match up enough |
| 4 | 51:1 | 26.8 seconds down the course | The torque and speed were such that the car was finally able to move, although not very fast |
I like the table you used to show the different gear ratios in your blog post. Moreover, I really liked the design of your racecar. I thought it was quite unique in its slender construction.