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Author Topic: Is there such an animal as a dual range (selectable not auto) gear-head reduct'n  (Read 1428 times)

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Offline honoreTopic starter

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...something built like this....

... with a lever select that would enable switching from 1:1 (locked) to 2:1 or 3:1?

To get an idea of the loads and rpm I'm looking at I'd like to add a "dual range" capability by inserting a gearhead between this motor and its swingarm/driveshaft.   I'm completely rebuilding the rest of the bike using a mountainbike frame.  High/Low is for dual-range only... not selectable/shiftable while running.



I realize this is an extreme long shot since I could not find anything like this in a couple of hours of search using a wide variety of search terms and image searches.  The concept certainly exists in the form of two-speed cordless drill transmissions (high rpm in, low out.. and far too light duty for this job) but I can't seem to find an application that would use what I'm looking for.   

Most of the two speed transmissions I've seen for RC vehicles, e-bikes,  and robotics are automatic shift with integrated clutches.  They also seem to be open gearing and bulky.

Any ideas?   Like I said above...  the two-flange, four bolt pattern,  coaxial reduction head that I imaged above, with a lever actuated 1:1 to 2:1 would seem to be the holy grail since many other threads on boards that I've found seem to be looking for a similar animal.   
« Last Edit: August 09, 2012, 02:28:21 PM by honore »

Offline Soeren

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I realize this is an extreme long shot [...]
More than extreme...


Any ideas?   Like I said above...  the two-flange, four bolt pattern,  coaxial reduction head that I imaged above, with a lever actuated 1:1 to 2:1 would seem to be the holy grail since many other threads on boards that I've found seem to be looking for a similar animal.
I promise you not to go writing about robots on any bike forum you use, if you'll reciprocate it by not writing about building bicycles here (as your first post even - talk about bad form).

Just wonder why you didn't connect the dots from bicycle to gearing yourself - a derailleur would be so much better suited than anything else - and don't go with a double or triple up - that would put too much load on the motor if it's balanced for 1:1.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline honoreTopic starter

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See below.... can posts be "nuked" or delected?


 
« Last Edit: August 11, 2012, 12:57:24 PM by honore »

Offline honoreTopic starter

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Quote
I promise you not to go writing about robots on any bike forum you use, if you'll reciprocate it by not writing about building bicycles here (as your first post even - talk about bad form).

In many years of tinkering and experimentation I've asked various questions about projects not directly associated with, but certainly open to the benefit of shared knowledge with,   the topic on generalized boards and forums for welding, RC, bicycles, mopeds, motorcycles, electronics, automobiles, diy-audio, home theater,  home shop and machinery, gardening, etc, etc..... as well as a few other engineering specific and robotics forums.  This is the first time that any question, even of questions far less obviously related to a forum's specific interest and including first posts, has just been dismissed as bad form.

I'd appreciate it greatly if others here would weigh in on the matter of bad form.  Is Soeren just the first person honest enough to set me straight?  I'm sincerely thrown by this.  I'm not offended... just surprised by the accusation.  Maybe I need to reconsider my online manners a bit.

The type gearbox in question is far more commonly applied to robotics than to motorized bicycles.  I did not register here with any intention to seek advice on building, or discussing, bicycles.  That application was only mentioned tangentially to provide anyone willing to share knowledge on such a gearbox with a very rough estimate of the RPM, load, and torque expected.

Believe me I am sincerely sorry if I've gone this long misapprehending a more broadly understood protocol about such "interdisciplinary" questions (as well as admitting that for  most people, myself included somewhat, applying "discipline" to any group of motorized bicycle tinkerers may be a bit of a joke :)

Quote
I promise you not to go writing about robots on any bike forum you use, if you'll reciprocate it by not writing about building bicycles here (as your first post even - talk about bad form).

Is it a fact that members of a forum such as societyofrobots.com have no interests in common with endless-sphere.com for instance?  That surprises me greatly.  How did I so misapprehend that?

Thanks for any advice, especially on the question of form.
 
« Last Edit: August 11, 2012, 01:08:45 PM by honore »

Offline honoreTopic starter

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Seriously?

Offline Keithh28

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Actually, I'm contemplating construction of a 250-300lb outdoor helper robot (cross between a lawnbot, wheelbarrow and wagon gardeners sometimes use) and was interested in the very same type of gearbox, so I for one can see the crossover potential.  My intention was to use the lower gearing when moving heavy loads up hills, but easily able to keep up with a person walking 3-4 mph when on level ground. 

Keith

Offline newInRobotics

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Have You guys considered making own CVT?
"Computer games don't affect kids; I mean if Pac-Man affected us as kids, we'd all be running around in darkened rooms, munching magic pills and listening to repetitive electronic music." - Kristian W

Offline Gertlex

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honore, in my opinion, this was a perfectly valid thread.  My opinion is based on the fact that this hobby of mine is not purely robotics, and is more generally tinkering. If some project of mine uses features also found in robotics, I'd post a thread about it, too, when stuck.
I

Offline Keithh28

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Here's a thought, I came across a go cart transmission which only had two gears, forward and reverse, but the reverse was something like 2:1 while forward was 1:1. If your motors are not directionally biased, you could shift into reverse with a servo and then command your drive motor to spin "backwards", resulting in the bot going forward, but much slower. Any thoughts?

Keith

Offline Soeren

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Is it a fact that members of a forum such as societyofrobots.com have no interests in common with endless-sphere.com for instance?  That surprises me greatly.  How did I so misapprehend that?
No, I'm personally building a pedal assist system for a friends cargo bike, but if I had any questions in that department, I'd post them to a bicycle forum (or a general electronics, or mechanics, whatever applies, forum) and for eg. photography related stuff, I use a forum for photography, not a robot forum - solely toget a better response, as eg. bicycle experts are a much higher percentage of the user base at a bicycle forum and chances are higher that someone have already solved it in such a place.

You might like the throw-it-all-in-one-bin-and-let-the-people-responding-worry-over-my-problems-as-I-don't-care-for-order-myself attitude, which is the equivalent to throwing all your screws, nuts, nails and such, of all sizes, in one box and perhaps all your tools in another. This don't really work for most of us, as we don't like to spend most of our time sorting through unneded stuff to get to what we want at a give time.

Most people like their information sorted just as well, while your attitude towards information suggests that we should close all forums but one, which should cater for all questions imaginable, preferably in one long thread.

However, you're not quite honest about it, as you managed to place your question in Mechanics & Construction, rather than eg. Software, which indicates that you have at least a tiny snag of sorting ability ;D


When I have some time available to help others on the net, I prefer not to waste most of it sorting through stuff unrelated to the forums I seek, as the act of sorting is not my goal then.
You may see this as hostility, but I have seen several fora thinned to such extent that people stopped using them and if I didn't care enough about SoR to be "unpleasent" to defend its existense, as I see a need for it, every now and then, It wouldn't be worth my time and I'd just spend the time in other places (like I have done on several occasions, when a forum gets distorted by too many off topic posts).
If you post within a forums topic, or list of topics, you'll have a lot more users willing and able to help you as well, so it's in your own interest as well.


I'm often told that I could just ignore such posts, but ignoring a problem won't make it go away, so I spend precious time, every now and then, trying to keep the dilution at bay.

The reason that you haven't ever heard a thing about it may be, that most people like to express such in a rather "polished" way, that you may have overheard, some people doesn't care for sorting at all and most forums have an advertising revenue that is directly proportional to the number of registered users, which make their owners go "oh, let's just ignore such posts - a user is a user and a dollar is a dollar", ignoring the fact that such attitude may (will) kill a forum sooner or later.

I have no vested interest to protect, so I can afford to be honest about it - had you placed your question on a bike forum, I'd try my best to help (assuming I saw it in one of the places I frequent when I'm in "bicycle mood" :)), and I'd frown about any robot related questions there.


Besides... It seems that you got so caught up being corrected, that you completely ignored my final sentence, which was supposed to suggest a better way of solving your problem.
Don't take life so hard. If you can't handle a little critique without shifting the entire topic of your question towards the critique itself, you really need to grow some hard skin - this is the internet after all :)

And the time I spent on this post goes from trying to help somebody with an on-topic question, as I haven't yet assembled my time machine kit - and I find that unfair to people who do sort their stuff, but necessary to perhaps educate you in a way that helps us both - you to get better answers and me to do my bit to keep this forum alive and hopefully reaching others and help them stay on topic (thereby keeping other fora alive as well), whereever and whatever their questions might be.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline Keithh28

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Soeren, I admire your passion for the forum, it's clear that you take the success or failure of this forum very seriously, and I applaud you for that.

As to the derailleur idea, in my experience derailleurs are very finicky beasts which often require you to push the gear lever a little past where you need it, and then return to "center" the chain, unless you opt for one of those high-end sets which click from gear to gear...that might work.  And come to think of it, I've seen derailleurs that are electronically shifted. Here's one example:

http://www.upgradecycle.com/campagnolo-6018.html?utm_source=googleshopping&utm_medium=cse

Very pricey, but very light weight!


As to my go-cart gearbox idea, I found the website:

http://www.mfgsupply.com/gomini/gominiaxles/gominiaxlesgearbox/218390a.html

It's bigger and more expensive than I remember, and you'd need two if you were doing differential steering, but might work for a very large robot or (Soeren, skip this sentence  ;) ) a large motor-bike. 

Keith

 


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