Am I using the right pulley terminology? 3

[KaptainKen]

Gents;

I need to purchase a stock "Overrunning pulley" ... at least that's what I call it. But a tedious string of Google searches have resulted in no good results. Then I can only conclude I'm not using the correct name for this gadget. My application is for a low horsepower machine used in agriculture.

I have posted a cut-away sketch on PhotoBucket.
Link:

http://i99.photobucket.com/albums/l318/Kaptain_Ken/OverRunningPulley.jpg

Refering to the sketch: In normal operation shaft "A" rotates in a clockwise direction (driven from the other end which is not shown) and shaft "B" is stopped. Within the hub of the pulley on shaft "A" are a few rollers which, when shaft "A" is rotating clockwise, rest in a slanted groove or slot.

As shaft "A" rotates clockwise no motion or power is transmitted to the pulley. OK ... mabe some residual motion, but certainly no power.

When shaft "A" is not rotating (not under power) and I want to run shaft "A" in a counter-clockwise direction, I would turn on the electric motor (not shown) with shaft "B" and it's pulley rotating CCW. As the shaft "A" pulley rotates CCW the rollers would run up their little ramps, "jam" against the hub and then rotate shaft "A" in a counter-clockwise direction.

So ... what is the correct name for the big pulley and it's hub?

In the event this gadget is not readily available as a stock, off the shelf gadget (and I know that anything can be custom manufacured with sufficient application of money), I could, I guess put a centrifugal clutch/pully on the motor shaft "B".

I would rather not do this to avoid the constantly running V-belt. And I'm not sure how long a centrifugal clutch would last (being 99% of the time) run in the "wrong", disengaged direction.

Any leads, links or insights regarding this would be appreciated.

Best regards

Ken

 

[BobM3]

Sprague clutch.

 

[alansimpson]

Overrunning clutch.
Don't think it would be easy to source with correct pulley but the clutch comes in a variety of configurations for mounting to pulley. Most bearing manufacturers would have one.

See

http://www.directindustry.com/industrial-manufacturer/overrunning-clutch-75597.html

 

[CanuckMiner]

I've specified backstops on inclined conveyors, which do pretty much the same thing as you're describing.

See

http://pt.rexnord.com/products/backstops/backstops.asp

Cheers,
CanuckMiner

 

[eromlignod]

For larger overrunning applications you would probably use a "sprag" clutch (not Sprague). It has little individual sprags that stop the race with a wedging action in one direction. The name comes from the sprag they used to use to stop wagons from rolling, which was just a hinged prop bar that swung down onto the road, kind of like a bike kick-stand.

Smaller shafts would more likely use a "roller clutch", which looks just like a needle bearing, except it has a little retainer cage that forces the rollers into a bind when rotated in one direction. This type has almost no backlash.

Don
Kansas City

 

[KaptainKen]

Gents;

"Sprag" it is! I used to know this stuff when I was employed in machine design. It's amazing how much you forget in 20 plus years. I remembered the principle, but not the name of the device.

Alan: "Overrunning clutch" was the key. My Google searches were too limiting. I guess it makes more sense for a manufacturer to make a sprag hub (or "roller" hub, eromignod) and then the end user can attach whatever he wants to make an overrunning pulley or an overrunning sprocket or an overrunning ... whatever. When I Googled "overrunning clutch" I got lots of good leads.

Thanks for your help, Gents!

Best regards,

Ken