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Unread 18-09-2003, 15:13
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P.J. Baker P.J. Baker is offline
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FRC #0177 (Bobcat Robotics)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1999
Location: Hebron, CT
Posts: 110
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Not quite...

Tytus' tranny is not "merely a planetary gearset with the carrier fixed." Think about it. He has two inputs and one output. Holding the carrier fixed in a planetary gear set leaves you with only one input and one output. As I see it, the design is more like a special (and physically impossible) case of a planetary set where one input bevel is the sun and the other is the ring:

The output speed of Tytus' differential will ALWAYS be the average of the speeds of the two inputs. The output speed of a planetary gear set (i.e. the rotational velocity of the planet carrier) will only be equal to the average of the sun gear speed and the ring gear speed if the sun gear and the ring gear happen to be spinning at the same speed (when this happens the planet gears stop spinning and the sun, ring, and carrier all have the same speed).

Looking at the equations that relate the speeds of the sun, ring, planets, and carrier to each other, the only way that the carrier speed is the average of the ring speed and the sun speed is if the sun and ring gears have the same radii – which is not possible. So, like Paul C. has said before, the bevel differential is a close cousin of the planetary gear set, but it is not the same thing. As far as his claim that the CCT is not a differential, I’m not so sure, but I think that is more a matter of semantics than physics.

P.J.