Ratchet

[SafetyFirst]

We are using a kicker mechanism, and we are hoping to use a ratchet system to crank back the kicker and quickly release it in order to kick the ball. Since this is the first time that our team is using this type of system, we are seeking assistance about how to implement this properly. Does anyone have experience with a ratchet system that can send us designs and/or CADs to help us?

[Joe G.]

This document has some good stuff. (http://ebooks.library.cornell.edu/k/kmoddl/pdf/002_008.pdf)

[Pi3th0n]

Our team was just planning on using one from a craftsman wrench until andymark made this (http://www.andymark.com/product-p/am-2774.htm).

[pfreivald]

You'll pay through the nose for them, but McMaster-Carr has a ratchet and pawl set in 3/8th stainless that's quite robust and attachable to your system in whatever way you find convenient. (We welded in a plug and then hex broached it.)

[jkessler_22]

Which is now unfortunately out of stock...

(The AndyMark solution, that is)

[Monochron]

You'll pay through the nose for them, but McMaster-Carr has a ratchet and pawl set in 3/8th stainless that's quite robust and attachable to your system in whatever way you find convenient. (We welded in a plug and then hex broached it.)

Would you mind posting a link to that? I haven't been able to find it with simple searching.

[m1506m]

Would you mind posting a link to that? I haven't been able to find it with simple searching.

http://www.mcmaster.com/#gear-pawls/=qj5c4s

[pfreivald]

Would you mind posting a link to that? I haven't been able to find it with simple searching.

http://www.mcmaster.com/#gear-ratchets/=qjbakp

[magnets]

Remember, you don't necessarily need a ratchet, you could use neutral and a gearbox that isn't backdrivable. It sounds a lot like a dewalt drill transmission to me :] !

[AdamHeard]

Mcmaster 5163A16

[Brian_R]

Also look for cheap off-the-shelf solutions. If your gearbox has (or can have) hex shaft, a ratchet from a socket set or a ratcheting combination wrench might have you covered:

An example from Lowes (http://www.lowes.com/pd_338392-25428-85671_4294707916__?productId=3387692&Ns=p_product_qty_sales_dollar|1&pl=1&currentURL=%3FNs%3Dp_product_qty_sales_dollar|1&facetInfo=)

There's already a couple of threads about converting COTS shifting gearboxes (Vex Ball shifter in particular) to one-speed-and-neutral, which you can do by removing one gear.

Hope this helps!

[pmangels17]

You could also consider a worm drive. They are generally not backdriveable depending on the number of starts on the worm.

[pmangels17]

They you could run the catapult the other way too if you need to simply by reversing the motor.

[Tem1514 Mentor]

Using an AndyMark shifter drive system with some simple changes might do what you want.

[pfreivald]

Using an AndyMark shifter drive system with some simple changes might do what you want.

How do the teeth hold up over time, shifting under strain?

[Tem1514 Mentor]

How do the teeth hold up over time, shifting under strain?

Only time will tell but I would expect that the drive shifter dog would be the first thing to fly apart.