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Unread 27-11-2006, 18:10
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Joe Johnson Joe Johnson is offline
Engineer at Medrobotics
AKA: Dr. Joe
FRC #0088 (TJ2)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1996
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Re: DeWalt Transmission questions

Quote:
Originally Posted by StevenB
Attached is a drawing of what we were planning. This should eliminate drilling the sun gear completely, but we will have to push the CIM back by the height of the sun/carrier.
We did some rough calculations, and it seems that even with the CIM being slower, leaving the first stage in would mostly eliminate the need for a large external sprocket ratio. Was it simply for speed that the first stage was taken out, or are there other problems?
As to your mod to eliminate the machining of the sun/carrier, I think I like it! The only issue is the length of the whole assembly, but other than that, it is a nice solution.

As to taking out the 1st stage or leaving it in. The main reason I recommend taking it out involves chain force. In theory, if you leave the 1st stage in and then reduce the chain stage by the same ratio, all is the same, but.... ...not really. By putting the stage in the tention in the chain goes up by a factor of about 3. This make a huge difference because that means the side loading on the gearbox is 3X and as well as the side loading on the wheels from the chain.

If you are really brave, you may consider leaving in the gearstage and eliminating the chain stage entirely by going direct drive right to the wheel. I've made prototypes chassis this way, but I was never a competition robot.

Joe J.
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