pic: Version 1.1

[Arefin Bari]

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[Tom Bottiglieri]

Looks good Arefin.

Now keep improving and between you and Greg Perkins, I believe we will have 2 great new transmission innovators in FIRST

[David Guzman]

Hey Arefin,

It looks very good, I can tell you have worked hard in it and it would be interisting to see every modification that you make to improve it.

Good Luck

[Michael Leicht]

Arefin nice job on the gear box. now how is inventor? just so proud of you. first you could not get inventor now you can, good job.

[Tytus Gerrish]

okay. awesome arefin. great job working with inventor.

now for the Critiquing...

i question the sheer size of this gearbox and the long skinny standoffs holding the plates together. the CIM is a 300 watt motor Perfectly capable of bending, breaking and shearing aluminum with its torque. secondly i suggest some machining to remove material from those gears, i say this not from a weight standpoint but rather from an inertial standpoint. a robot traveling in one direction at full throttle having to slam it into reverse or turn would benefit from less inerta in its gear train simply because its easier, more efficient and takes less time and energy to reverse the direction of a 4oz gear then an 16oz gear. the mass of your gears along with the skimpiness of your standoffs is a deadly combination. also removing the hubs making speed holes and using key ways, or if you don't have a broach witch is most of us try using one of the various locktite products for binding rotational parts together. the stuff works great and it doesn't take much work to use it. i would also suggest that instead of using the clevis's for mounting the cylender i would suggest you drill a hole in your plate and use the threads of the cylender as a bolt and lock it on with some 5/8-18 nuts that would also then act like an extra standoff for you. On the happy side, i like how simple your shifting is. just slide the gear easy right? well, make shure you chamfer the edges of the gears that are meshing into each other to keep them from grinding when you shift. Well, thats my twoCents.

[Arefin Bari]

thanks everyone...

thanks tytus for your input... i will consider all of your suggestions. i did think about the sheering problem. but seems to be i solved it (Thanks to JVN). Also thanks to greg for giving me his inputs for this transmission... this is only version 1.1, this transmission will be modified a lot of times.

and tom... greg is way smarter than i am. i have to learn a lot to get there...

[Kyle Love]

Hey man, it looks great!

[Jeff Waegelin]

Arefin,

Have you considered the problem of the center gear grinding against the bottom gear? It seems to me that if you're sliding two moving gears along each other, you could potentially have a problem with grinding of the teeth.

EDIT: I saw you referred to the "sheering problem". Is this what you meant?

[Arefin Bari]

Yes jeff.. thats exactly what i meant... thanks for your input...

[Jeff Waegelin]

Originally Posted by Arefin Bari

Yes jeff.. thats exactly what i meant... thanks for your input...

So what did you do to solve said problem? I'm just curious.

[Arefin Bari]

Originally Posted by Jeff Waegelin

So what did you do to solve said problem? I'm just curious.

Using 20 dp gears and space each shafts out with the pitch diameter also added another space of .003...

[Max Lobovsky]

There is probably room in the gearbox to shift ratios so that the shifting gears are spinning faster with less torque. Specifically, increase the size of the CIM pinion, then increase the final stage ratio.

I assume this is all 20 pitch? As I'm sure you know, make sure to buy the strongest material that you can find the shifting gears in.

A good question that I can't answer is wether extra backlash is a good idea for the shifting gears. More backlash means they will be able to shift faster (less friction, more time to do so), but more backlash also means they are slightly weaker. I'd guess a few thousandths extra is a good idea, but this is definitley a question to ask someone who has built a sliding gear shifting gear box.

Also, where are you purchasing that long gear in the final stage?

[Cory]

Originally Posted by Max Lobovsky

Also, where are you purchasing that long gear in the final stage?

Spur gear stock... available from SDP-SI, McMaster, etc

[Alex Golec]

Structurally, the position of the CIM motor just sticking out on a sheet of (I'm guessing) about 1/4 aluminum just seems like a hazard to me... but then again I have little engineering knowledge to judge this by. Also, as Tytus mentioned, I think the extra material from the gears needs to be removed and the pieces holding the plates together should be a little bit thicker.

Arefin, Great job on the drawing; it looks great!

_Alex

[jimfortytwo]

If I'm looking at this right, it seems that in the transition period between high gear and low gear the motor shaft is locked, because both gears are engaged at the same time. Is this actually what is desired? It seems needlessly cruel to the motor, and I would think actually makes slipping into the new mesh more difficult.

By all means lighten the gears if it is easy for you to do, but I suspect that the inertia of those disks is negligable in comparison to the momentum of the 130 pound robot, or even just the wheel attatched to this gearbox.