pic: 3 speed concept - 1st gear

[sanddrag]

Originally Posted by Arefin Bari

If I was to design this gearbox, I would make it much smaller as you did point out before. Maybe the output (sprockets) can be placed inside the gearbox. Now in order to do this design I would like inputs and ideas about how to shift (please share exactly how you would do it). Thanks in advance.

I'm not exactly sure how to make it smaller without going to smaller face width gears. The thing that takes up all the room is the fact that you need to get all the way out of one gear before you move into the next one. For making up for the bigness, I had thought of putting the motors within the width of the gearbox (on top of it or something). Also, there is definitely room for sprockets inside.

To shift, I was envisioning some sort of rigid piece that couples the threaded end of one cylinder to the body of another cylinder. Maybe the end that screws on to the threaded cylinder rod can also have a larger diameter tube that slides freely over the body of the same clylinder for more support, less wobble, etc. Anyway, you would get three possible positions both extended, one extended one retracted, and both retracted. Of course this would end up being a long assembly as well. I'm just not sure how else to do it. I don't really know anything about multipositioning but can it work? Maybe even lead screw but that doesn't seem fast enough or robust enough.

And of course you can go ahead and design it all up fancy. I'd really like to see what somebody can do with it.