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Patrike
06-12-2008, 10:02 AM
Hi

I need a freewheel sprocket to tie the motor to the Kyoto shaft. I have one for the motor but it is 3 inches and that means I will need a big ass sprocket on the kyoto shaft to help reduce the rpms to useble level.

Any suggestions would be greatly appreciated.

Motor shaft is a keyed 5/8inch and the Kyoto is 3/4inch(as most of you know but for those that don't)

Patrick

AtomicZombie
06-12-2008, 12:23 PM
I wish you luck on that one. I looked for a year for something like that, and came up with one unit worth $900 bucks.

The unit is called a sprague clutch, overrunning clutch, or freewheeling clutch.

A typical cycle freehub will not take the forces of even a 1hp motor.

Best thing I could come up with was to have a belt and idler pulley that could loosen the belt when you wanted human power.

If you find a better part for under $100, do let us know.

Brad



Hi

I need a freewheel sprocket to tie the motor to the Kyoto shaft. I have one for the motor but it is 3 inches and that means I will need a big ass sprocket on the kyoto shaft to help reduce the rpms to useble level.

Any suggestions would be greatly appreciated.

Motor shaft is a keyed 5/8inch and the Kyoto is 3/4inch(as most of you know but for those that don't)

Patrick

Patrike
06-12-2008, 01:25 PM
I found this one rated for mini bikes and scooters?? Price is right, Looks like the standard TP24 thread. I could mount this on the Kyoto shaft and put a small fixed sprocket on the motor. Please sound in as I do not know much about these things.

http://www.partsforscooters.com/Free-Wheel-Hub;jsessionid=0a01054f1f437f1466e553544f678df4f54 ad14c6552.e3eTaxiNaN0Te34Pa38Ta38Lbhn0#

Thanks
Patrick

AtomicZombie
06-12-2008, 07:14 PM
That is a standard freehub with a flange instead of teeth. It may be ok for a very small motor, but anything over a few hundred watts will tear that thing apart.

Those guys that make the Rhodes car tired using BMX freehubs with the 1HP scott motor, and it constantly fails.

Brad

Patrike
06-12-2008, 10:11 PM
Here is the current one I got from someone. I have a 5/8 keyed shaft insert. Not sure of the quality but in the end it is too big:

http://www.dicta.com.tw/lma4.htm (http://www.dicta.com.tw/lma4.htm)

Patrick

Patrike
06-13-2008, 11:48 AM
That is a standard freehub with a flange instead of teeth. It may be ok for a very small motor, but anything over a few hundred watts will tear that thing apart.

Those guys that make the Rhodes car tired using BMX freehubs with the 1HP scott motor, and it constantly fails.

Brad

A case where sell anything and don't care what happens.

I am wondering if somehow 2 could be bounded together to share the load--probably to complicated as they would have to be set to stop at the same position.

Also found these site:

http://www.stieber.net/

Thier sprag freewheels sound interesting and they have nice diags! I emailed them for pricing yesterday -- no answer yet. Looks like they could be adapted.

Later
Patrick

AtomicZombie
06-13-2008, 01:05 PM
Those sprag units (for a 3/4 shaft) are the ones I was quoted $850 on!

As for the multiple freehub idea...

I was going to try that once as well but then realized that no number of freehubs on the same shaft would be stronger than a single freehub.

I know that sounds silly, but...

Freehub pawls click into place after at least 5 degrees or more, so the chances that more than one would click perfectly into place at the exact same time is extremely slim. So if you had 4 freehubs on a shaft joined by either multiple chains or some machined housing, only one at a time would be taking the entire force, creating the same weal link as a single unit. The first would break, and then the others would follow one at a time.

It would be like unwinding a multi-stranded rope and then trying to tow a car with each thin segment tied an inch shorter than the next. One at a time, they would snap, never working as a team (like many governments). So in the end, all weak links do not add up to being any stronger than a single weak link.

Brad








A case where sell anything and don't care what happens.

I am wondering if somehow 2 could be bounded together to share the load--probably to complicated as they would have to be set to stop at the same position.

Also found these site:

http://www.stieber.net/ (http://www.stieber.net/)

Thier sprag freewheels sound interesting and they have nice diags! I emailed them for pricing yesterday -- no answer yet. Looks like they could be adapted.

Later
Patrick

Patrike
06-13-2008, 02:18 PM
Those sprag units (for a 3/4 shaft) are the ones I was quoted $850 on!

As for the multiple freehub idea...

I was going to try that once as well but then realized that no number of freehubs on the same shaft would be stronger than a single freehub.

I know that sounds silly, but...

Freehub pawls click into place after at least 5 degrees or more, so the chances that more than one would click perfectly into place at the exact same time is extremely slim. So if you had 4 freehubs on a shaft joined by either multiple chains or some machined housing, only one at a time would be taking the entire force, creating the same weal link as a single unit. The first would break, and then the others would follow one at a time.

It would be like unwinding a multi-stranded rope and then trying to tow a car with each thin segment tied an inch shorter than the next. One at a time, they would snap, never working as a team (like many governments). So in the end, all weak links do not add up to being any stronger than a single weak link.

Brad

I won't hold my breath for the sprag stuff then - I guess cause they only sell on a week the got to make up for it somehow! -- I can't see manufacturing cost being more then 20$ each.

Thats what I pretty much thought about doubling up!

Patrick

Patrike
06-13-2008, 06:33 PM
What if you put two - one per shaft - linear/ in line -- the one on the motor shaft would lock then spin the chain slightly until the one the wheel shaft caught up to it. When it locks then they are in sink.

In my mind - the motor one has to lock up first because it is driver -- The wheel one is the follower and inverted/reversed to the motor and it will lock after. If that sounds plausible let me know.

Patrick

AtomicZombie
06-14-2008, 12:28 AM
You would still be at the mercy of one freehub for strength plus the added friction of multiple shaft bearings.

Brad

Patrike
06-16-2008, 10:12 AM
Did some reading -- the mountain BMX and trials guys tend to go with this freewheel made by Whites.

The trials is the toughest with 72 points of contact. Suggested retail is 100$ -- some shopping around will be in required.

http://www.whiteind.com/home.html (http://www.whiteind.com/home.html)

Patrick