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How does the Schlumpf hub work?

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  • curbrider
    replied
    Nice animation of all 3 planetary configurations here.
    http://science.howstuffworks.com/gear7.htm

    Then scroll down one page.
    Last edited by curbrider; 2010-01-22, 08:35 AM. Reason: WILL link direct to item

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  • skrobo
    replied
    darkoman drive system solves all problems, put it on an 09 torker and you have what you all are looking for!!

    a unicycle hub has to be simpler than a bicycle hub w/ the same amount of gears considering that neither can really slip either direction w/ the exception of a ratchet system for the chain cog on a bicycle.

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  • juggleaddict
    replied
    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.

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  • hugo
    replied
    Originally posted by johnfoss View Post
    Ouch! I'm no expert at shifting, but I use the side of the heel of my shoe, not my ankle.

    Judging by the images above, it looks like possibly this shifts the "drive cog" over to the flat-toothed gear and away from the planetary gears to give you the 1:1 gear. Something like that?
    I do not want to get into a "heels or ankles" discussion, but I started with using the heels, until I recently found out that it is easier to shift with the padding of the shoe which is just below the ankle.

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  • johnfoss
    replied
    Originally posted by napalm View Post
    Super G- To change gears on the Schlumpf hub the rider hits the shifting button with his/her ankle on the down-stroke of their pedal revolution.
    Ouch! I'm no expert at shifting, but I use the side of the heel of my shoe, not my ankle.

    Judging by the images above, it looks like possibly this shifts the "drive cog" over to the flat-toothed gear and away from the planetary gears to give you the 1:1 gear. Something like that?

    Leave a comment:


  • justtysen
    replied
    Originally posted by MuniOrBust View Post
    Also, is it possible to have a reduction gear using a planetary gear set?
    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.

    Originally posted by MuniOrBust View Post
    This wiki page seems to suggest it:
    If I understand the description correctly this is an specific variation on the planetary gearing system which while ingenious probably only works for very low gear ratios and has an inherent backlash which would only get worse as one increased the ratios.

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  • jaco_flans
    replied
    Originally posted by From the Woods View Post
    Someone could try to build a prototype using Lego Technik

    I am sure it's possible to build a multi-gear hub for unicycles but a lightweight and not too bulky realization will be the biggest problem.
    Haha! I tried last year with Legos but I didn't have the right wheels for it, so I did it with K-nex. It was working properly but I think it was like a 1:10 gear

    Last year I draw a geared hub on paint, I only had one gear though, I dont know how it works for 2 gears. I always wanted to built my own, maybe one day I will

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  • napalm
    replied
    Super G- To change gears on the Schlumpf hub the rider hits the shifting button with his/her ankle on the down-stroke of their pedal revolution. This engages the second gear- to shift back, the rider simply does the same but with their other ankle.
    mark

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  • Super G
    replied
    Great thread. Could someone please explain specifically what a rider does to shift gears?

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  • MuniOrBust
    replied
    How about a Schlumpf with no direct drive at all? Both sides having planetary gear sets. Would there be a demand for such a hub? What would the ratios be?

    It would be even sweeter if you could open it up and swap out gear sets to change your ratios.

    Also, is it possible to have a reduction gear using a planetary gear set?

    This wiki page seems to suggest it:
    Originally posted by Epicyclic Gearing wiki page
    "During World War II, a special variation of epicyclic gearing was developed for portable radar gear, where a very high reduction ratio in a small package was needed. This had two outer annular gears, each half the thickness of the other gears. One of these two annular gears was held fixed and had one fewer teeth than did the other. Therefore, several turns of the "sun" gear made the "planet" gears complete a single revolution, which in turn made the rotating annular gear rotate by a single tooth."

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  • naturequack
    replied
    I also remember seeing a video that showed Florian spinning a Schlumpf hub that was mounted on a board. The hub was a special demonstration model that had a cutaway that allowed you to see inside the hub as the gears spun. I remember this video being on the Schlumpf Innovations website, but I couldn't find it there when I just checked. Maybe you could email Florian and he'd put it back up on the website.
    Geoff

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  • bouin-bouin
    replied
    Originally posted by MuniOrBust View Post
    Cool. Thanks for your summary rob!

    So the middle ring is pushed to the left or right to engage it into either "gear".

    With those two options of "left" or "right", is makes sense that you could only have two gears.

    How could it be changed in the future to have 3 gears?
    Maybe if the 1:1 gear was in the middle and to to the sides were different planetary gear sets. For the 1:1 gear, the middle ring would have to engage in a completely different way than it does now. Instead of engaging with the hub flange, maybe it could engage with the hub body. Then a push to either side would engage it with a planetary gear.
    But having a left, middle, and right position would probably require a bit more dexterity than the average foot possesses. Maybe if the push buttons behaved more like a clickable pen. Each button engages or disengages the planetary gear it is associated with. If neither is engaged, it's 1:1. If both are engaged it explodes.

    It works on paper! Ship it!
    For information the exact Schlumpf ratio is not 1.5 but 1.5625 . Difference between the 2 Schlumpf ratios is very important, much more important than a change of front gear on a MTB !

    An other photo of the Schlumpf hub :


    Last summer, I made a design with exactly such concept with 2 planetary gear sets on both sides and a direct drive in the middle but this has a major concern regarding buttons has their travel will be twice as Schlumpf and will make them very fragile in case of UPD

    My current design is cable control and with just one sliding planetary gear sets and with 3 sliding claws to get all the 3 gears (0.72 / 1 / 1.38)

    Didier

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  • naturequack
    replied
    You want pictures? Here are all of the pictures that I've been able to collect over the last couple of years: I don't pretend to really understand how this works. I'm happy just treating it like a black box that performs miracles. Although these pics sure are cool looking. Hope they help your understanding.
    Geoff
    Attached Files

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  • From the Woods
    replied
    Someone could try to build a prototype using Lego Technik

    I am sure it's possible to build a multi-gear hub for unicycles but a lightweight and not too bulky realization will be the biggest problem.
    Last edited by From the Woods; 2010-01-21, 07:52 PM.

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  • hugo
    replied
    I would prefer that one of the buttons shifts up, and the other shifts down, independent of the number of gears.

    Multiple gears are possible in bicycle hubs, so it must also be possible in a uni hub. Of course, bicycle hubs rotate in only one direction and there are more differences, so I do not know if it is possible at all to design a multi-gear hub for a unicycle, I would just assume it is.

    @rob: your description makes perfect sense
    Last edited by hugo; 2010-01-21, 07:48 PM.

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