Wrap spring clutch design basics 3

[rudylyon57]

Can anyone direct me toward, or eamil, resources that deal with the design of wrap spring clutches? I designed one about 15 years ago and have misplaced all my reference materials. Thanks.

 

[eromlignod]

Do you mean an overrunning clutch, or a single-revolution clutch?

Don
Kansas City

 

[rudylyon57]

Thanks for your interest. I am referring to an overrunning clutch commonly known as a spring or wrap spring clutch. They are in the same class of friction clutches with roller or sprag types.

 

[unclesyd]

All I've seen about the design of wrap spring clutches has been in textbooks and couple of the how does that work type.

Not a full design treatise but it might be a start.

http://books.google.com/books?id=b6...g=mc0VhlAjgig-vLYzLZ5tXGZli1A&hl=en#PPA305,M1

 

[eromlignod]

I'm confused. You clarify in your second post that you are interested in an overrunning clutch, but then you include a link to an explanation of a single-revolution clutch. They are not the same thing.

An overrunning clutch is, as you say, just like a sprag clutch, or just a one-way bearing.

A single-revolution clutch uses the wrapped-spring concept, but also includes a single-revolution tripping mechanism.

There is a pawl that engages a single stop tooth on the output that is also connected to the release tang of the spring. As long as the pawl bears against the tooth, the spring's engagement with the driving shaft is released and the input motor spins freely with no effect on the output. A solenoid can be pulsed that lifts the pawl out of tooth engagement. Since there is no longer any pressure on the release tang, the spring grips and engages the output to the input. The solenoid is only pulsed, so it is released as soon as the pawl is past the tooth. So the tooth rotates around one revolution and smacks into the pawl again, releasing the input to idle again. The tooth is part of the output shaft, so even though there is some slippage during acceleration, you get exactly one revolution every time with no cumulative error.

Is this the device you are talking about?

Don
Kansas City

 

[rudylyon57]

Hi Don,
Sorry about the confusion. The link I attached was not intended to show how I will use the clutch but just an example of a wrap spring application. The clutch will be used in an overrunning application. With that said, can you direct me to design resources for wrap spring clutches?

 

[israelkk]

http://www.eng-tips.com/viewthread.cfm?qid=134306

 

[unclesyd]

eromlignod,
I wholly agree with your post as I hadn't refreshed my screen to catch the OP's second post prior to posting the link for the single wrap spring devices.
I don't normally equate the aforementioned devices to a wrap spring device.

 

[rudylyon57]

Thanks to all. A special thanks to israelkk! I purchased the book by Arthur Burr and will start the design process once available. Should be an exciting application.

 

[tbuelna]

rudylyon57,

There is an excellent design reference on spring wrap clutches published 30 years ago by the engineering staff at Sikorsky. You can download it free at the DOD STINET website:

http://stinet.dtic.mil/

It's titled "Helicopter Freewheel Unit Design Guide".

 

[rudylyon57]

Hi tbuelna,

Thanks. That report was exactly what I was serching for. I'll need to have a deeper look in that site as needed. Israelkk, looks like our plot was fouled!