View Full Version : Chalupa Motor

02-06-2002, 02:46 PM
This is the very first post from myself, and here's hoping that it returns a lot of information.

I, personally, have looked everywhere from FIRST Robotics Competition (http://www.usfirst.org/robotics/index.html) to CCL Industrial Machinery (http://home.cclmotors.com/) to Small Parts (http://www.smallparts.com/) and I have yet to get any strong solutions for my team's problem. Being the driving force of our launcher, we need to find a coupling or mating gear that will allow us to interface with it more efficiently.

Any help would be greatly appreciated.

. Cameron Loranger 652
. Team Webmaster & Robot Programmer

Lloyd Burns
02-07-2002, 07:26 AM
I only posted a reply because the board said replies = 0, which shouldn't happen to a request for information.

The information you are after has already been posted in this forum earlier. You can search (use the feature at the bottom right of the page, here) for items about motors in general, Chiaphua or Atwood Motors, gears, etc. You might also peruse the 'back pages' at the bottom left - only the most recently 'posted' or 'posted to' threads are on page one, and the old ones are kept on the highter numbered pages.

Basically, you were given a gear cluster, a little mushroom, the top of which runs well with the motor shaft, which has a non-standard pressure angle, and won't run with commonly available gears. The stem of the mushroom, the narrow part, has a atandard pressure angle, so you can drive available gears with it.

The mounting of the gear cluster has also been talked about, and a picture of a mounting has already been posted. People have discussed how hard it is to machine the gear cluster, too.

Sources for standard gears is another subject which has been covered.

I wish you well in your research. Sorry this is so general.

Ken Leung
02-07-2002, 08:20 AM
Here is what people talked about earlier about the chiaphua mating gear:

About Chiaphua mating gear...

You will notice that the output shaft of chiaphua motor have some non standard teeth. It is a 36 Diametral Pitch, 9 tooth, enlarged, 25 degree pressure angle gear AND it is enlarged. The kit came with a gear cluster that can mate with the shaft. It’s a 44 tooth with a 16 tooth next to it, and a ¼” hole in the center. You want to use the 44 tooth side to mesh with Chiaphua’s output shaft, and the 16 tooth side has a 32 DP and a 20 degree pressure angle.

You can buy gears from a lot of places that will mate with the 16 tooth side.

The material of the gear cluster is a pretty good material, so you can just put it on a ¼” shaft and it will spin fine. Although, just to be save, you can mount the ¼” shaft in bearings and lubricate the gear
“The gear has some brass content (copper, etc) and is a pretty good bearing.” -Paul Copioli
“The metal of the gear that mates with the Chiaphua gear is
"FX-2008-90HT copper infiltrated steel heat treated to Ra 68"
A friend looked up the spec. It has a Min Ultimate of 90,000psi.” -Joe J.

A picture of a quick gearbox for the chiaphua, take a look at how the mating gear go with the chiaphua motor output shaft. It is recommended that you support the gear cluster on both side of the shaft.
“Motor mount screws are 10-32, spaced exactly 2.00" apart
The center "bulge" is .75" in diameter
The centers of each gear (shaft, big gear) is .740" apart.” –Larry Barello

As for buying a replacement mating gear for chiaphua… The only suggestion so far is to spend around $240 to buy the whole assembly from Atwood. Any better suggestion?


All these can be found in the newsletter in the "Bulletins and Newsletters" sub-forum, inside the "Feature Announcements & Forum Help" forum @ http://www.chiefdelphi.com/forums/showthread.php?s=&threadid=2108

02-07-2002, 09:30 AM
thanks a lot for the info. We will put it to good use.

Joe Johnson
02-07-2002, 11:30 AM

From McMaster part number: 61005K51

It has a 3/8 bore on one side and a 1/4 inch bore on the other.

I would clamp the coupling to the 3/8 diameter drill rod and then chuck the drill rod in a lathe.

I would gradually open up the 1/4 inch hole until the Chiaphua gear just pressed inside the coupling.

Then I would tighten down the clamp on the 1/4 inch side and viola... ... you've got a nice 3/8 inch diameter shaft to work with.

By the way, I am NOT doing this, so I can only judge what I think I would like to do. Any other folks think this is a good idea or not?

Joe J.

P.S. I am assuming that you want to mate to the 9 tooth gear cut into the motor shaft and not one of the gears on the cluster. Did I assume correctly? JJ

02-07-2002, 11:37 PM
I pressed a 40 tooth PIC stainless gear directly onto the output shaft of the Atwood motor. I opened up the bore on the PIC gear to .2950, made an arbor to hold everybody straight, then pressed it onto the shaft. The output was hard enough to actually broach serations into the PIC gear to help keep it in place. I then tighten the set screw as an additional place holder. I think with a 50 ton press you could reduce the bore to .285 and press the gear on without damaging the Atwood shaft.:cool:

03-30-2002, 09:09 PM
If our team put in the Atwood Powerjack Gear box ( that came w/ the big huge box that trailers and such use), would that be considered legal? We did take out the clutch, drilled a few holes here and there etc. At the Chatsworth Scrimmage, a inspector was not sure whether or not it was legal. Anyone else have any ideas???

Nate Smith
03-30-2002, 10:43 PM
I'm saying no on using the Atwood gearbox...see my other post for the details...

03-31-2002, 04:56 PM
Originally posted by Genome17
If our team put in the Atwood Powerjack Gear box ( that came w/ the big huge box that trailers and such use), would that be considered legal? We did take out the clutch, drilled a few holes here and there etc. At the Chatsworth Scrimmage, a inspector was not sure whether or not it was legal. Anyone else have any ideas???

No, this would not be legal.

Try this simplified logic flow, which is fully documented in the rules (once again, please READ APPENDIX A, SECTION K of the rules!):

1 - Did it come in the kit of parts?
- yes -> OK, it's legal
- no -> go to question 2

2 - Did the team get it from SPI?
- yes -> OK, it's legal
- no -> go to question 3

3 - Is the material listed in the "Additional Hardware List" in Appendix C of the rules?
- yes -> OK, it's legal
- no -> can't use it. Replace with alternate material and return to step 1.

The Atwood Powerjack Gearbox did not come with the FIRST kit, is not available from SPI, and is not included on the Additional Hardware List. If the inspector at the Chatsworth Scrimmage didn't call you on it, you got lucky. Don't count on that happening at the L.A. Regional.



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