Catapult Ratchet Mechanism

so which gears are slipping? the catapult ones and the slipgears?


The small sprocket on the pinion axle is the make shift ratchet

well then there’s something wrong with the meshing of those gears. could be the shaft flexing, in which case I recommend using high strength shafts, that fixed a similar problem with my catapult.

also you should have bearings on all your shafts

My bearings are on the outside of the c-channel, so you can’t really see them. Also, I am using a screw for my catapult. So i put circular inserts in the gear, and just put a screw through it.

ah I see. it could be your slip gear shaft bending still. I highly recommend high strength shafts.

I took out the axle to check, and it wasn’t bent.

quite odd. I see no reason why those two gears might be slipping. can you wiggle them around at all?


the slipping doesn’t happen unless there is enough torque being supplied by the rubber bands. That really limits the amount of rubber bands I can use, and then I can’t shoot the flags.

quite unusual. can you manually force the gears to slip? try taking a slo motion video of the gears slipping to reveal the cause.

Yeah its pretty easy to make the gears slip. This is the rubber banding that I am using. It slips every time I move it. Its only 3 rubber bands on each side.

I took a sloko like you suggested and something caught my eye. My gears are perfectly meshed. I was wondering if there were any solutions to this, because they are a standard amount of vex holes apart.

How do you get it to the bottom to load in the first place if it slips there? It should be slipping whether it’s the motor putting it there or the ratchet holding it there. If it slips in one case and not the other, that indicates something.

No, it’s skipping everywhere. As the image shows, the gears aren’t completely meshed. There is still some space between the teeth. I don’t know how to solve that, because, since it’s on standard vex metal, they are the proper amount of holes apart.

When you mention the screw, it makes me wonder. You say it as though you did not put the screw through bearing flats. The screws have some wiggle room in the square holes. If that screw does not go through bearing flats, I would change that.

Also, examine the slipping gears. Make sure they haven’t worn down from all the slipping. If they have, even if you fix the original problem, they may well keep slipping anyway.

The screw does go through the bearing, and there is no wiggle room. I have tried to shake the gears around, but they would not budge.

I saw in another thread and @Xenon already recommended that putting in a high strength axle would help. Can someone explain why exactly.

They’re less likely to bend. Even if the bending is temporary so you don’t see it on inspection, it doesn’t mean an axle isn’t bending. Could be worth trying.

You’ve got two sets of gears instead of one, which really ought to solve most slipping problems. Clearly that hasn’t solved it here. (It also helps prevent the catapult from twisting, which is really good for separate reasons.) I still wonder if some of the teeth on the gears are worn down.