Important improvements on Rubber band attachment with a flywheel Pro Preview

"The devil is in the details". We are improving the Rubber band attachment with a Flywheel by introducing a few small, but important modifications that make the whole robot attachment more stable and reliable. With the conclusion of the series this attachment could be used as a basis for some very interesting STEM demonstrations on energy accumulation and conservation.

  • #108
  • 16 Oct 2015
  • 3:28

Challenge at the FIRST LEGO League (FLL) competition:

With this video tutorial we conclude this series on whole to complete the World Class Search Engine mission without using any of the LEGO Mindstorms EV3 sets and using a rubber band with a flywheel. 

The goal was to give you an idea how you could accumulate energy and use this energy at a later moment to complete a robot competition task. 

The attachment

Pinless, of course. Discussed in previous tutorials, but you should also check out these videos for more on pinless attachments and different robot constructions

  1. Pinless attachment added below the robot
  2. Quick Pinless Attachments for LEGO EV3 Competition Robots (Part 2)
  3. Quick Pinless Attachments for LEGO EV3 Competition Robots (Part 1)

Previous videos tutorials

  1. Rubber band attachment with a flywheel - solving FLL 2014 Search Engine (part 1)

  2. Rubber band attachment with a flywheel - solving FLL 2014 Search Engine (part 2)

  3. Rubber band attachment with a flywheel - solving FLL 2014 Search Engine (part 3). Two tasks at once

  4. Rubber band attachment with a flywheel - solving FLL 2014 Search Engine (part 4). Two tasks at once


While recording the videos for this rubber band attachment, we noticed that it could be improved in a number of ways and today we are going to discuss 2 of the improvements. Just let me remind you how the attachment works. It's a rubber band attachment, we reach the mission model, we push on this lever here and we can see that it move the rack here and we can solve different challenges with this.

One thing we noticed is that every time we load the attachment and then we can trigger it, at the end the rack might fall. It's a good decision to have some kind of a stopper and we'll add a small pin right here that will do this for us and now the attachment is loaded we push to the border

and we stop the rack. Another modification, another improvement to this attachment that is also very important is the following. There is some friction between the black gear wheel here, the small and the large gear wheels and the beams. Because of this friction, sometimes when we are at a competition and for example we have pushed on one of the beams and this friction occurs then it's difficult for the whole attachment to work, for example we release here with the push of the axle, but the attachment doesn't work, because there's a friction right here, the gear wheel. How do we solve this? We must add additional parts right here that are supporting the frame and the beams. That won't allow any friction between the beams and the gear wheel.

I've chosen to use this part but you can also use other parts.

Here they are.

Now because of this 2 parts there's no friction between the gear wheel and the beams. Now if I release with the push of the axle the attachment works. These are 2 very small interesting modifications that are a must if you want this attachment to work a 100% of the time. We welcome any comments on this. Try to use it, try to construct it and see if you can modify it in other ways so that it works even better.