Ratcheting Mechanism

Hey everyone. I was hoping that everyone would share any issues they’ve had with ratcheting mechanisms. I was also curious to see how many people have implemented ratchet and pawls in their design.

We took out our ratchet because we are just fine without it. Plus if it is on the wheel it takes a couple seconds to switch motor powers. We might put it back not definitely not on the wheel.

If you want a really compact flywheel design, you might not be able to fit it in. I’ve tried on my flywheel but it doesn’t fit :frowning:

So do you mean a ratchet on a flywheel or just a ratchet in general? My experience with the ratchet was fooling around with it to try and get it to work with a catapult, which we determined to be impossible without making a massive system.

I have a ratchet on my robot which is directly driven by the motors. It is quite compact and works very well. I’ve never had any problems with it, and when using it, I have never overheated the motors, or even had them stall. I would recommend putting a ratchet on your robot if you are able to.

Depending on your flywheel, I think ratchets are indispensable. The only real alternative being a deceleration program.
We have gone through several designs. Apparently its a really bad idea to use standoffs as pawls because they completely destroy the ratchet. Which really sucks as I’m not a big fan of getting massive loads of pulleys and string.
http://i.imgur.com/Bx4vG3os.jpg

I hate it when I think we came up with a brilliant unique design, and then someone posts a reveal video with an almost identical but slightly better design.:confused:

I think the ratchet has to be on the motor end of the gearbox, as otherwise it takes forever for the flywheel to slow down. Unless that’s your goal of course.

My team has been using the same ratcheting mechanism for… 2 months (don’t quote me on that :p). The pawl is a 1x3 aluminum piece held by rubber bands into the ratchet. We probably won’t have to replace it for a while more because we don’t see any type of wear on it. We probably would change it if we (rather, when we) go through a design change and before major competitions.

The ratchet only takes up about the width of about 1.5 high strength gears if used on a regular gear, so if you have enough space for it, I’d say go for it.

We have experimented with both ratcheted and un-ratcheted flywheels, honestly in the configurations we are using we have seen little to no advantage to using a ratcheted flywheel.

What do you mean, we came up with that design in the middle of the summer

I use 2 ratchet and pawls to allow one motor to control two separate intake systems. When the motor turns one direction, it rotates a chain that feeds balls into the shooter. When it rotates the other direction, it rotates a chain that pulls balls up from the field. This allows us to intake balls from the field at any time without accidentally forcing one into the shooter. All with 1 motor.

Very cool. Nice design. One of my teams experimented with something very similar. When the motor turned one way it would rotate the intake. When it turned the other way it would turn a mechanism to deploy their ramp at the end of a match. The ratchet allowed them to turn independently. They aren’t currently using it, but we may find a use for it later.

Thanks! There are a lot of mechanisms that really only need to rotate in one direction. The realization that the intake only ever needed to, well, intake, is what led me to come up with this solution.

Really Nice!

We have found no need for ratchets or deceleration algorithms on flywheels and have had no problems for the past 4 months.

Halfway through our last competition we deactivated our ratcheting system because it needed fixing. We experienced no issues with current feedback due to the momentum of the wheels, so for simplicity’s sake we’re removing the system for our next competition. While I’m sure that there are better systems than ours, we did find that our ratcheting system would deteriorate over extended periods of use.

We will switch to a deceleration program for next competition.

The pawls rubbing the gear causes a lot of friction when not engaged.

With a lot of fine tuning this can actually be made almost insignificant, but after a match or two the friction would either return or our pawls would become so loose they wouldn’t work. ¯_(ツ)_/¯

I see ratchets being more necessary for single flywheels (faster speeds). Our team is using a very compact dual flywheel design and have found no advantage to them.

So what is the point of having a ratcheting system for deceleration. I have just been setting the motor power to 0 which puts the motors in idle, allowing the wheel to slowly decelerate. Is this bad for the motors?

I apologize for not being more descriptive, we made a ratchet that we designed independently, prior to seeing yours. Our design was almost identical except that instead of screws it used axles, and instead of cut pillow bearings it used stand-offs. Unfortunately, we had an endless supply of problems, one being that the standoffs stripped the ratchet. (Yes we had to get another ENTIRE set of pulleys, which really was annoying X-D) Another being that the axles were almost always escaping. (something to do with flywheel vibrations) Eventually I tried the full size bearing blocks, but that really didn’t work. So with one week left, I stumbled across your video, and after realizing our design was not as unique as I thought and yours was so much better, I gave up and used the pillow bearing technique. than felt kind of silly for copying someone else’s idea, so I made it a bit different. (double reverse ratcheting central hub) I thought I had linked your video in the post, but evidently not.
Anyway, I think ratchets are especially useful when using a velocity control, because if the motors run backwards it doesn’t effect the flywheel. I’m now working on a design for a thinner ratchet.

Oh, I see what you mean :P. And how do you plan on making a thinner ratchet? I would be really interested in seeing that. In the picture it shows what looks like two 84-tooth gears on the ratchet, unless those are two individual ratchet mechanisms. If those are two 84 tooth gears, just take off the other side, and it will work fine.