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Old 2010-01-22, 06:04 PM   #29
Coasts Too Much
justtysen's Avatar
Join Date: May 2009
Location: Westchester, NY USA
Age: 35
Posts: 458
Originally Posted by juggleaddict View Post
Originally Posted by justtysen View Post
Yes, in fact most three speed hubs have a reduction gear as it is simply the inverse of the higher gear. In high gear, the sun gear is the input (cranks) and the ring gear is the output (hub) if you switched the bindings around so that the cranks turned the ring gear and the hub was turned by the sun gear than you would have a lower than 1:1 gearing.
That's way more complicated than it needs to be, you really just need to make the gears on surrounding the main gear larger, and make the main gear smaller. that way all you're changing is the diameter, not the construction of the entire hub assembly.
Considering that I made two significant errors, such that my gears were operating in reverse and that my "high gear" was really a low gear and vice versa, I'd certainly say it was more complicated than I expected.

Still though, I don't think making the planet gears larger than the sun gear will have the desired result. You still have to take into account the ring gear. In the Schlumpf set up, if all you did was make the planet gears larger than the sun gear, they would rotate less than once for a rotation of the planet carrier, but that <1 rotation would be added to the full rotation of the carrier, thereby turning the ring gear (Schlumpf's output) 1+<1 rotations.

Originally Posted by joemarshall View Post
...but it is hard to describe how the shifty rod bits go across.
It looks like the shifter slides a dual ringed clutch along the crank spindle, and that the pegged teeth on either side of that clutch are spring loaded against each other. Their engagement being staggered on each side, so that when shifting one side is disengaged, and the other side's pegs are compressed, after enough of a rotation (that small coasting section) these pegs reach their corresponding notches and pop out, engaging the new side. The spring tension in the shifter itself would have to be greater than that in the combined pegs to prevent them from shifting the clutch back.
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