Ratchet and Pawl mechanism

:)Hey guys my good friend Justin from Hawaii put up a good video showcasing this mechanism on a wheel
Here it is
https://www.youtube.com/watch?v=g_TFwXdik1s
The picture of the actual mechanism is also here
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enjoy
David_5839A:)
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this is some good stuff check it out

Hey guys its David again
I’m here to explain this mechanism.
Basically it is inspired by a bike wheel. A bike wheel has something like this so when the pawl gets stuck in the teeth of the gear the freewheel begins to spin. But when you stop peddling the wheel doesn’t just stop the wheel begins to coast until the momentum is used up. This will be especially beneficial in autonomous when the ref or judge ends autonomous with the switch. For the more unfortunate folks who do not see this thread or threads related to this one, this can cause breaking and snapping of chain, damage of gears, and/or the total breakage of the internal motor gears accompanied by the dreaded clicking noise. Instead of having a deceleration function or programing a slow down code this design allows the flywheel to use up all of its momentum instead of returning it right back into the motors. When the motors stop running, the pawl will be running across the teeth of the ratchet and that wont kill the motors. This will also be beneficial when you stop the flywheel in driver control and also when the ref/judge ends the match all together. You will have many more seconds to score rather than waste 3-6 seconds on a slowdown. Comment back if you have any questions.
Check out this video and don’t leave any hate comments on it.
peace David_5839A

so how do you like this design and will you be adopting it?

wow that’s nice. So simplistic. What parts did you use? Also did you drill a hole in the wheel? I would imagine so since the wheel would be constrained and not spin freely.

An 8/32 hole was drilled through the ratcheting piece
The center of the wheel was drilled and modified so that the wheel could freely spin.
The screw held the pawl to the spoke which was also drilled.

I would probably not adopt this idea at the moment because I would rather not drill into the wheel… I would prefer not to permanently modify the wheel. I will definitely think about this design though as I like how simple it is.

Thanks for sharing :slight_smile:

I finally got my account verified now I can post and reply :slight_smile:
I’m the one who built the ratchet and pawl mechanism in the picture. My friend David posted it for me because I couldn’t.
I changed the wheel inserts to the plastic circle one. I did not drill the wheel to fit my axel. I know that some of the wheels have the inserts glued in but in the one I had the wheel inserts was practically falling out haha. So replacing the inserts were fairly easy.
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Same here, I’d like to work with some more designs before defaulting to this. I wonder if a turntable would work in the same fashion. Although the freewheel would be a bit smaller, it does have the possibility of being heavier.

That was one of my hopes that you would have done. Can you put a picture up of what exactly you modified on the wheel? (where you actually drilled)

Thanks

Do you have any problem with vibration at high speeds because of the imbalance in weight?

I totally understand but it has advantages, but a disadvantage is that you’ll need to drill a hole through a spoke

I hope this helps. I’m sorry if it’s hard to read or see where the hole is.
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I’m not sure about how the wheel spins because I haven’t tested it.

Yea that helps thanks
Have you looked at some of the wheels like this…

I know it is not a 5 inch wheel but it could be something to think about
(of course you would have to see if one of the holes fits the distance that the gear and other piece)

Edit: it would also need the circular fitting

Sorry I had trouble getting the picture in…
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yeah Justin is right srry for the error

he just drilled into the spoke

you can defiantly make a mechanism like this without drilling holes, what we did for ours is we installed our rachet and paw onto the gear that powered the wheel, and used the holes that already exist in the gear

That’s really smart I never thought of doing it that way.