VEX Ball Shifting into Neutral

[Dr.Gusta]

Okay I know there is a big thread about this but I was a bit afraid that my post would get lost since there are so many posts, so I am posting here. My team and I had the idea of putting a ratchet on the low gear of the gear box so while in that gear it could not back drive without putting stress on the CIM motors. Then the high gear would be made a neutral gear as described in the other thread. This would make it so the pawl would not have to be pulled out just the sifter would shift to neutral. What my question is when the low gear has so much torque on it will the sifting mech be damaged or hurt in any way when it is pulled into neutral?

[Dr.Gusta]

I just cleaned up the CAD a bit and rendered out a few views for you guys to see what I am talking about.

[Aren_Hill]

Originally Posted by Dr.Gusta

Okay I know there is a big thread about this but I was a bit afraid that my post would get lost since there are so many posts, so I am posting here. My team and I had the idea of putting a ratchet on the low gear of the gear box so while in that gear it could not back drive without putting stress on the CIM motors. Then the high gear would be made a neutral gear as described in the other thread. This would make it so the pawl would not have to be pulled out just the sifter would shift to neutral. What my question is when the low gear has so much torque on it will the sifting mech be damaged or hurt in any way when it is pulled into neutral?

No, mechanically the Ballshifter construction is very well suited to releasing under high loads, due to the geometry of the shifting mechanism the shifter shaft sees a much smaller load and may be pulled free with much lower amounts of force than DOG shifters.

[Dr.Gusta]

Awesome thank you for the reply I really appreciate it.

[donkehote]

you can also use a 1/2" ratchet wrench on the output shaft to achieve the same non backdrive characteristic, but with much much less work.

[Dr.Gusta]

The only problem we ran into with that is that if we put it on the final output it will never be able to fire unless we could disengage the wrench some how.

[AndreaV]

Originally Posted by donkehote

you can also use a 1/2" ratchet wrench on the output shaft to achieve the same non backdrive characteristic, but with much much less work.

You need to put the rachet somewhere before the neutral, so an extended shaft is needed, which calls for the wcp gearbox, which has dogs (o noes, dogs!). Fabricating a custom longer shaft could also work, may need some new bearings.

[donkehote]

Originally Posted by Dr.Gusta

The only problem we ran into with that is that if we put it on the final output it will never be able to fire unless we could disengage the wrench some how.

very good point... didn't think about that.

looking at the cad, you could extend the first shaft (the 3/8 hex one with the gear the 3 cim pinions drive) using a 3/8 hex bearing on the case instead of a round one. then you could put the wrench on the outside of the case. would just need something to keep the shaft from walking out of the case.

other than that, the solution you have there should work, don't see why not.

[mman1506]

You could also try removing the gears for the low gear stage and put the wrench through a similar hole to what you have now replacing the smaller gear
.

[Kevin Ray]

We considered what you have and thought about making the cogs of the ratchet much less steep--almost perpendicular to the center. With a small pneumatic cylinder to activate the pawl you could easily control it.