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



This is an Inventor rendering of a potential two speed ball-shifting gearbox, designed by Newport Robotics Group. If anyone wants to try to build it, PM me and I can give you the specs!

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

Looks familar! :wink:

I would be interested in the drawings and would check them out for you.

Coming from an experienced Ball Lock transmission team; this type of transmission is a winner! Shift any transmission once your hooked; shift a Ball Lock twice and you will never turn back!

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

Now that you have the hard work done, get those machines running!

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

looks great! congrats. I was curious from both you and anyone from 222 that reads this.

  1. how do you cut the grooves for the balls? do you just use an end mill or do you get them wire EDMed.

  2. What kind of tolerance do you need to hold on the shafts and gear cuts to make the system sloppy (reduced torque transmission)?

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 :slight_smile: 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

that looks awesome!

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.

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’’

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!!!

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.

Who said this was for the shooter? :confused:

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!

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?

So, just to make sure I understand the concept–the piston moves the larger piece inside the output shaft, which forces the balls out into the gears, engaging the gear?

Thats exactly right. In this one I am assuming there is going to be springs as the shaft and the plunge are two separate pieces.

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?

Yes, that is true about the model. The model is not quite correct in that the larger end piece of the inner shaft (the one attached to the cylinder) will be removable. The reason the shaft is two pieces is so that the larger spool will be centered with springs on the smaller inner shaft, which will allow it to lag a little when it pushes the balls outwards which make shifting easier.

Has anybody run into major problems so far with their ball-lock shifters?

Ok. Thaks for explaining.

We used a 2 speed ball lock shifter last season and thought it worked out great. Assembly was a little annoying until we figured out that using grease to hold the balls in place while sliding the parts together works very well!

We also just built the plunger as 1 piece instead of using springs. This seemed to work pretty well because the air in the cylinder basically acts as your spring. I had the rookie kids this year pull apart the gearboxes to “get their feet wet” plus I wanted to see what they looked after a full season. The insides held up even better than I would have thought. The plunger definitely showed lots of tiny “dings” but is far from failure. We put it all back together and it still works great.

–Antoine

Three years strong and I don’t think we’ll go to anything else…at least not in the near future. The concern Sanddrag has expressed about shaft wear and such is NOT a problem at all. We do measure sizes before and after season when looking at what we could improve and we have not discovered wear. This is simply because we harden the pieces we need to and keep a good amount of lubrication. So rather than posting something you DON’T know about from experience, maybe you should let the people who have built these talk about the down sides. I don’t mean to start a fight with anyone, but I just can’t understand how people who have not used these transmissions can discuss any problems with them. :mad: The biggest negative we’ve seen is these transmissions take time to machine with our team capabilities. You can make them with just a lathe and a mill. They are that simple, but having access to a wire EDM or a water jet would greatly help reduce the amount of machine time.

Great to see 948 investigating this design. Hope to see it on your robot this season! Good luck

Very interesting, indeed.
I am not familiar with the concept of ball lockup shifting gearboxes, indeed this is the first I have ever seem of them. I am in charge of developing a godd two-speed gearbox for '07, so here are my questions (more will follow after this) Your expertise and help is greatly appreciated.
I understand how the balls are pushed into slots in the gears, but what is it that causes the thus engaged gears to turn the output shaft? In a dog shifter gearbox, the dog is positively engaged on the shaft (still allowed to slide) and so whatever gear the dog is locked into thus turns the shaft. I cannot find any such mechanism in this drawing. Perhaps I am missing something, but I think this is an important consideration.
And, following that, what happens to the gear (with its ball slots) when it is disengaged and must freewheel on the output shaft? My understanding of the design at present leads me to believe that it would bounce and chatter considerably, possibly even locking the entire gearbox up if it doesn’t properly disengage.
Just my thoughts, if someone can answer them, I would greatly appreciate it. Thank you in advance. -JH