OT: Ratcheting bearing?

(I'm not sure where this would be on topic)
I need something to help drive a wheel. A bearing will be stuck on a shaft that will be connected to a DC motor. The shaft cannot be
allowed to apply reverse force on the motor. I can explain further if necessary.
What I want is something like a ratcheting wrench uses. Apparently there are ratcheting devices to drive the wheel of a bicycle but what I've seen of those would be too large. It needs to be no more than about 1 inch maximum diameter.
So, is there such a thing as a ratcheting bearing? Something similar?
What I mean by "ratcheting" is that the bearing will turn freely in one direction but won't turn in the other direction.
By the way. I recall a clicking sound made by some geared bicycles when coasting, was that made by a ratcheting device? Just curious.
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On Fri, 17 Aug 2007 05:26:08 +0000, John Doe wrote:

The clicking sound on multi speed bikes is a ratcheting device that uses dogs to engage teeth when pedaled and slip when coasting.
I believe you are looking for a Torrington bearing. These don't use teeth and grip a smooth shaft in one direction and slip when the shaft rotates at a faster speed than the bearing is being turned.
http://www.google.com/search?hl=en&q=torrington+one+directional+bearing&btnG=Google+Search
http://www.runryder.com/helicopter/t55473p1 /
http://www.thomasnet.com/products/oneway-clutches-15521008-1.html
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John Doe wrote:

http://tinyurl.com/2rhn3e
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if
what
similar?
A 'spring clutch' would give you unidirectional gripping
http://www.heli-cal.com/Html/FlxFacts/FFacts60.htm
AWEM
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...

Well that's enlightening.
--
thanks to the replies

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wrote:

Many many spring clutches used in electromechanical type writers such as the old IBM 'golfball'. To acutate all you need is a slight friction drag on the free end of the spring so it tends to 'wind up' and grip the shaft. They could operate as amazing speeds both gripping and releasing.
AWEM
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...

How do you match the shaft with the spring?
Are there matched pairs made of common springs and shafts?
Could you just go with the same inner and outer diameter for the spring and the shaft?
Those are my questions.
If an extension spring can be put on the motor shaft sticking outwards toward the drive shaft, and be longer than the drive shaft it's going to slide onto, there could be a momentary and even flexible application of the one-way drive shaft? It would just have to easily slide onto and off of the drive shaft, and still grip in the forward direction.
The motor is a 36 V DC cordless drill motor. Even applied at about half power, it might produce more torque than the one-way needle bearings I ordered.
The drive shaft will go between a pair of wheels on my in-line skates, for a roller drive. There is a limited amount of space between wheels because that's how in-line skates traverse rough terrain. I would like to make an in-line wheel skateboard too (after figuring out how to steer the thing).
Thanks to the replies. I'm just wallowing in the possibilities presented here in this thread. Wish I'd asked/known about spring clutches and needle bearing clutches many months ago.

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wrote:

slight
up'
The ones I'm familiar with have a spring that is a sliding fit on the shaft. The tension / actuating arm puts friction on the free end, winding the spring and grabbing the shaft, so there is quite a size tolerance over which it should work. Just make sure that the spring is loose enough that the shaft doesn't grab in the unwound state, and that the actuator applies enough drag to wind the spring until it does grab.
AWEM
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On Fri, 17 Aug 2007 07:31:19 +0100, "Andrew Mawson"

it is called a sprague clutch.
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On Fri, 17 Aug 2007 20:33:49 +0800, Stealth Pilot

Sprag is the correct (or at least more common) spelling.
The spring clutches and roller clutches are suitable for light duty, non-critical applications. Sprag clutches are available with much higher torque capacity than either spring or roller clutches.
--
Ned Simmons

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There are devices out there that look like roller bearings but the rollers are egg shaped instead of being round. Had an electric starter on a Gravely tractor years ago with this set up. It allows free rotation in one direction but locks up in the other. No ratchet pawls to wear or break, just a series of cam shaped rollers between two smooth surfaces. Don't know the name for them but I bet someone here does
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I do, unfortunately.
Gravely call them "cams" or "roller cams", I can't remember which and I'm too lazy to look it up. What they ought to be called is RCAYBBSDWYSTPs. That is "roller cams and you'd better be sitting down when you see the price". They are about 1/2" long, maybe 1/4" to 5/16" diameter. Not much to them. They wear out primarily because the tit on the sprocket hub that you put the hole in the hand starting strap on looks somewhat like a grease fitting, so a previous owner has often removed it and replaced it with a real grease fitting and then pumped the hub full of grease. The last ones I ordered listed for $28 and change. That's EACH, and there are 21 of them in the clutch. The dealer double checked the price, apologized for it, and then sold me 3 of them at about $20 each. Which was enough to get the clutch to lock up properly, at least for the time being. If it goes again, I'll consider machining the sprocket assembly to take an off-the-shelf sprag clutch.
John Martin
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wrote:

you are right. it just didnt look correct until I stopped.

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Yep,yep ,yep ... I think MSC has them

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Perhaps that's what you want -- but I think what you *need* is a worm gear.
--
Regards,
Doug Miller (alphageek at milmac dot com)
  Click to see the full signature.
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On Aug 17, 1:12 pm, snipped-for-privacy@milmac.com (Doug Miller) wrote:

I dont know strong you need it to be - fishing reels have anti reverse bearings in them to stop the handle reversing. It is usually a self contained bearing unit - If you where near South Africa I could give you a bunch :)
Tim South Africa
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wrote:

http://www.mcmaster.com/ctlg/DisplCtlgPage.aspx?ReqTypTALOG&CtlgPgNbr1092&CtlgEdition=&sesnextrepD3463286979944&ScreenWidth24 &McMMainWidth2
That's all one line. It's page 1092 in the McMaster-Carr catalog.
"one-way locking needle bearings".
LLoyd
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote:

http://www.mcmaster.com/ctlg/DisplCtlgPage.aspx?ReqTypTALOG&CtlgPgNbr92&CtlgEdition=&sesnextrepD3463286979944&ScreenWidth24&McMMainWidth2
Wow, thanks for the link, that was my next question. What I asked for was probably more like what Andrew Mawson first provided, but the one-way bearings (with or without radial load protection) might be even better for my project.
Whatever, it has to be something discussed in this thread. Very useful information, examples, and terminology, thanks.
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote:
...
http://www.mcmaster.com/ctlg/DisplCtlgPage.aspx?ReqTypTALOG&CtlgPgNbr92&CtlgEdition=&sesnextrepD3463286979944&ScreenWidth24&McMMainWidth2

Must the shaft they are stuck onto be very smooth?
If so.
Any suggestions locally (USA) for a short 1" or 2" piece of 1/4" diameter smooth steel rod? I guess it has to be "ground".
Or do I have to order that online too? I was in a hurry (to have the bearings shipped today) and bought them without thinking much about what those bearings might require to be usable. All I have is some ordinary steel rod purchased from Lowe's.
Thanks.

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On Fri, 17 Aug 2007 22:41:13 GMT, John Doe

=======Suggest drill rod or dowel pin.
Local suppliers tend to let drill rod set until the surface is dinged and pitted so you may be better of ordering. 1/4 inch drill rod is cheap in 3 ft lengths. click on http://www.use-enco.com/CGI/INLMK32?PARTPG=INSRAR2 http://www.use-enco.com/CGI/INSRIT?PMAKAP5-0258&PMPXNO4330&PARTPG=INLMK3 Enco has a minimum box [100] order for dowel pins (20 for pull dowel pins) so if you have a local supplier that will sell you onsies-twosies that may be a better bet. for info click on http://www.use-enco.com/CGI/INLMK32?PARTPG=INSRAR2 Be warned that there are several types of "dowel pins" and a 1/4 inch may be on the money, oversized or undersized. Be sure to check, and take your mike as these sometimes get mixed in stock.
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