pic: Team 948 2-Speed Ball-Shifting Gearbox CAD Drawing

[jfelser]

The designs for the transmission can be found at http://www.nrg948.org/pr/2 Speed Ball Gearbox_0.2.zip, feel free to download them and look them over. They were made in Inventor 6, but I believe the newer versions shouldn't have too much of a problem opening the files...

Nice Inventor work! A+ for the gears and sprocket if you made them yourself?

Nope - many thanks to FIRST CAD library for their excellent work.

Looks familar!

Hehe, it's funny that you recognize it... I had your white paper on this type of transmission open for reference the entire time I was modeling Obviously your ideas are present all through the design.

Any idea how your side plates are going to look and what tooth count are your gears?

I modeled the side plates as well, but took them out in the rendering so that you could see the inner workings of the shifting better. The larger gears are 60T, the smaller ones 35T. The gears on the drive outputs are 14T.

One thing that could shed some wieght would be to get hubless gears or machine those hubs off.

We will definitely be doing this, at least for the keyed gears, in the actual transmission.

-Jake

[Dan Petrovic]

that looks awesome!

we've been discussing the idea of a ball-lock shifting transmission, and everything is just so great about it.

[sanddrag]

Originally Posted by InfernoX14

we've been discussing the idea of a ball-lock shifting transmission, and everything is just so great about it.

I tend to think the sliding friction and wear of the gears on the shaft isn't.

[team222badbrad]

Originally Posted by sanddrag

I tend to think the sliding friction and wear of the gears on the shaft isn't.

So your saying dogs don't wear on the gears either?

Milling the four slots into the gears with a mill bit is easy. Slap the bored out gear on the mill vise, dial indicate it on center, move the table to each slot, and your done. (If you have a digital readout lucky you!)

We do not have access to this wire EDM you speak of!

These transmission can be built with a mill and lathe.

The tolerance is usually about 4-5 thousands. In other words, if your shaft was 1.000'' you would bore the gear diameter out to 1.004'' I do believe we have made that gap as much as .01''

[Athleticgirl389]

I never would have thought of having a 2-speed for shooting. That is very creative!!! Great job on the inventor there! I am new to inventor myself... learning quite quickly... hopefully I can something that kool one day haha. But I am very impressed!!!

[David Guzman]

This looks good. Keep up the good work.

I have to agree with the weight issue.

Also once you have the hubs off you could put them a lot closer together making the box thiner.

I do not think there is more friction on ball bearing shifters than there is on a dog shifter. Also a ball bearing shifter can be made oil filled inside the shaft.

I also designed a Ball Bearing Shifter that is currently being manufactured. Once is done I will post pics along with a white paper. Thanks to Team 222 for the idea.

[Greg Needel]

Originally Posted by Athleticgirl389

I never would have thought of having a 2-speed for shooting. That is very creative!!! Great job on the inventor there! I am new to inventor myself... learning quite quickly... hopefully I can something that kool one day haha. But I am very impressed!!!

Who said this was for the shooter?

Be wary, you must machine everything perfectly, otherwise it will shred itself. 114 built one of these last year, and had far too much fun with it, until we realized we had no weight for the pneumatics. However, during the offseason, this is a great shifting system. I encourage you to keep playing with the design.

Another tip is on the shifting plunger, you may want to mount springs on the part that forces the balls out, to reduce wear on the part. This is due to the fact that it needs to be able to lag until the balls line up with the grooves in the gear.


Good luck, and I highly reccomend this type of drive system!

[David Guzman]

I was looking at the Inventor files and it shows the shaft that is connected to the piston and the piece that pushes the bearings as two separate pieces. However it shows that the shaft that goes to the piston has a recessed and the piece that pushes the bearings has an ID equal to the diameter of the recessed. I hope that is understandable.

Anyway my question is how are you going to insert one in the other?