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Unread 08-09-2003, 13:58
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Paul Copioli Paul Copioli is offline
President, VEX Robotics, Inc.
FRC #3310 (Black Hawk Robotics)
Team Role: Engineer
 
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217's CCT

I sent a private message to Tytus, if he wishes to share it with the group I have no objections. Basically, I agree will Mr. Beatty regarding the differential. It is unnecessary in this design. Remember that the differential is meant to allow torque transfer to 2 axles from one input and also allowing the axles to travel at different rotating speeds. Its major design limitation is that it will transfer torque to the path of least resistance (one tire on pavement and one tire on snow.. snow wins and car goes nowhere).

There are other uses for a differential (redundancy in helicoptors, etc.), but speed matching is not one of them.

Regarding the CCT , it uses a planetary gearset with one motor coupled to the input (sun) gear and one to the ring gear. When selected correctly, you can get a very wide speed range with the SAME output torque. We had a worm gear because we cheated on our gear selection to get more speed. The result was backdriving of the ring gear. If we had used a different gear ratio, the back driving would not have occured (we have experiments to prove it), but we decided we needed the speed.

It took a sacrifice of 2 regionals (Chicago included) to get it right, but we all thought it was worth it. It was working by the 2002 Nationals (ask team 27 ... sorry Kyle, I had to add that). We have our patent application in and our pending approval from the U.S. patent office.

If you need further details regarding the CCT, please look in the whitepapers section.

-Paul
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