Catapult Ratchet Mechanism

We did build a choo-choo catapult this year, and it’s fine when it’s down. Anyway, the amount of force required will probably wreck your pawl.

I am dealing with a very similar gear slipping problem for the vex turning point game. Every time I stop at the bottom to load a ball, the catapult simply slips back up. Did this 12 tooth pawl fix it?

you could use a gear ratio so that your ratchet spins faster then the catapult, this way you both get more precision, and the ratchet has much less strain on it. you can pm me if you want more info on how I did mine.

It’s not that that ratchet slips, but it’s the gears slipping. So like at the bottom, the ratchet stops the driven gear from moving, but the catapult simply slips back up.

there’s something wrong with either where you placed the ratchet or your build.

Well meshed gears should never slip past each other

A picture would make your problem much easier to diagnose

Here are some pictures of my ratcheting system and gear box:

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.