I am looking for a type of clutch similar to a sprag clutch, but one
that allows the inner ring to rotate freely, in EITHER direction, but
engages when the outer ring is moved. Does this kind of clutch exist?
And if so, what is it called?

scritch

"scritch" wrote in message
...
I am looking for a type of clutch similar to a sprag clutch, but one
that allows the inner ring to rotate freely, in EITHER direction, but
engages when the outer ring is moved. Does this kind of clutch
exist? And if so, what is it called?

scritch

A cone clutch. The outer ring moves axially to engage or disengage. If
you want rotation relative to a fixed frame to engage it, you could
use a helical clutch shaft like a Maytag washing machine.

The centrifugal clutch in a chainsaw, snowmobile, go-kart etc might
give you some ideas.

jsw

scritch fired this volley in news:jtkp6o$jpf$1
@speranza.aioe.org:

I am looking for a type of clutch similar to a sprag clutch, but one
that allows the inner ring to rotate freely, in EITHER direction, but
engages when the outer ring is moved. Does this kind of clutch exist?
And if so, what is it called?

When the outer ring moves at all, or when it reaches a certain speed?

If you mean "at all", no. Not unless you provide a separate mechanical
action to cause engagement of the elements.

The traditional "one way clutch" bearings use needle rollers that are
held snug to the shaft and ramps in the outer race with small springs.
When the inner shaft is rotated against the compression of the springs,
they move up into the wider part of the ramp, and disengage from the
shaft. When the inner shaft is rotated in the direction to allow the
springs to extend, the rollers jam between the narrowing ramp and the
shaft, locking the two together.

There are centrifugally-engaged clutches that will engage once the outer
(or inner) race reaches a certain speed.

I can envision a sort of clutch that spring-centered on helical ramps,
but causing it to engage in either direction would require that turning
the outer race also cause some sort of deflection of the outer race along
the axis of the driven shaft. That would be easy enough to do with cam
followers on the outer race ends and a friction-delayed cam on each end
that lagged in rotation. It would require some significant backlash
before driving would occur, and would require reversal back into the
neutral position to disengage.

Here's a patent depicting that kind of method.
http://www.google.com/patents/US6702708

LLoyd

"Jim Wilkins" wrote in message
...

"scritch" wrote in message
...
I am looking for a type of clutch similar to a sprag clutch, but one
that allows the inner ring to rotate freely, in EITHER direction,
but engages when the outer ring is moved. Does this kind of clutch
exist? And if so, what is it called?

scritch

The centrifugal clutch in a chainsaw, snowmobile, go-kart etc might
give you some ideas.
jsw

I had to go out back and look. The reel drive clutch on my 1950's
lawnmower engages outward like a centrifugal clutch when the conical
end of a sliding shift sleeve pushes out a clutch shoe actuating
lever.

jsw

On Wed, 11 Jul 2012 13:54:53 -0700, scritch
wrote:

I am looking for a type of clutch similar to a sprag clutch, but one
that allows the inner ring to rotate freely, in EITHER direction, but
engages when the outer ring is moved. Does this kind of clutch exist?
And if so, what is it called?

scritch

I just happened to be looking for the same thing today for the feed on
a machine tool. I was hoping for a passive device that would allow a
handwheel to override the power feed. The description of the device at
the top of this page is interesting, but there doesn't appear to be
any more info online.
http://www.hilliardcorp.com/drivetrain-clutch.html

I also turned up a few patents with a search for "overrunning
bidirectional clutch" but nothing that looked promisisng and I haven't
waded thru them yet.

Some old GMN literature in my files shows some bidirectional sprags,
but they seem to need some outside intervention to switch. Again, I
haven't studied them carefully yet.

I may be stuck with a dog or face gear clutch actuated manually,
pneumatically or magnetically. If you find something I'd love to see
it.

--
Ned Simmons

On Wed, 11 Jul 2012 13:54:53 -0700, scritch
wrote:

I am looking for a type of clutch similar to a sprag clutch, but one
that allows the inner ring to rotate freely, in EITHER direction, but
engages when the outer ring is moved. Does this kind of clutch exist?
And if so, what is it called?

scritch

If i understand you correctly, you're looking for the system found on
gravely commercial lawn tractors. My units have two clutches. One unit
goes low-neutral-high for speed on the PTO or mower. The other clutch
unit goes forward-nuetral-reverse.

The interior design on this is very clever, you're just moving a ring
with tapered surface back and forth to tighten against a mating drive
surface. The clutch is on the outter diameter with the gearing in the
middle.

karl

"Ned Simmons" wrote in message
...
On Wed, 11 Jul 2012 13:54:53 -0700, scritch
wrote:

I am looking for a type of clutch similar to a sprag clutch, but one
that allows the inner ring to rotate freely, in EITHER direction,
but
engages when the outer ring is moved. Does this kind of clutch
exist?
And if so, what is it called?

scritch

I just happened to be looking for the same thing today for the feed
on
a machine tool. I was hoping for a passive device that would allow a
handwheel to override the power feed. ...

I may be stuck with a dog or face gear clutch actuated manually,
pneumatically or magnetically. If you find something I'd love to see
it.
Ned Simmons

I think I remember a manual input clutch that engaged when handwheel
rotation cammed a cone (or dog?) clutch axially. There was a friction
drag on the cam follower's shaft bearing that had to be carefully
adjusted. IIRC the cam resembled a Hirth coupling with the center bolt
loose:
http://en.wikipedia.org/wiki/Hirth_joint

jsw

scritch wrote:
I am looking for a type of clutch similar to a sprag clutch, but one
that allows the inner ring to rotate freely, in EITHER direction, but
engages when the outer ring is moved. Does this kind of clutch exist?
And if so, what is it called?

scritch

Not without some type of mechanical device to assist.

What are you attempting to do? That might help with suggestions.


--
Steve W.

On Wed, 11 Jul 2012 13:54:53 -0700, scritch
wrote:

I am looking for a type of clutch similar to a sprag clutch, but one
that allows the inner ring to rotate freely, in EITHER direction, but
engages when the outer ring is moved. Does this kind of clutch exist?
And if so, what is it called?

scritch
Magic

On 7/11/2012 8:08 PM, wrote:
On Wed, 11 Jul 2012 13:54:53 -0700, scritch
wrote:

I am looking for a type of clutch similar to a sprag clutch, but one
that allows the inner ring to rotate freely, in EITHER direction, but
engages when the outer ring is moved. Does this kind of clutch exist?
And if so, what is it called?

scritch
Magic


Now, that would be telling my secret! Actually, you guys have told me
what I need to know, and I have a idea now based on your comments. Thanks!

Now, about that birth certificate ...

On Wed, 11 Jul 2012 18:48:32 -0400, "Jim Wilkins"
wrote:


"Ned Simmons" wrote in message
.. .
On Wed, 11 Jul 2012 13:54:53 -0700, scritch
wrote:

I am looking for a type of clutch similar to a sprag clutch, but one
that allows the inner ring to rotate freely, in EITHER direction,
but
engages when the outer ring is moved. Does this kind of clutch
exist?
And if so, what is it called?

scritch

I just happened to be looking for the same thing today for the feed
on
a machine tool. I was hoping for a passive device that would allow a
handwheel to override the power feed. ...

I may be stuck with a dog or face gear clutch actuated manually,
pneumatically or magnetically. If you find something I'd love to see
it.
Ned Simmons

I think I remember a manual input clutch that engaged when handwheel
rotation cammed a cone (or dog?) clutch axially. There was a friction
drag on the cam follower's shaft bearing that had to be carefully
adjusted. IIRC the cam resembled a Hirth coupling with the center bolt
loose:
http://en.wikipedia.org/wiki/Hirth_joint

jsw


I was getting nowhere searching for stock "face gears." "Hirth
coupling" turned up a couple leads. Thanks.

I'm afraid the downside may be that Hirth coupling seems to imply a
level of accuracy that I really don't need. I'm waiting on a price
now, hoping it's better than the $600-1200 price for a pneumatic or
magnetic tooth clutch in the capacity I need.

--
Ned Simmons

On Jul 11, 6:48*pm, "Jim Wilkins" wrote:
"Ned Simmons" wrote in message

...









On Wed, 11 Jul 2012 13:54:53 -0700, scritch
wrote:

I am looking for a type of clutch similar to a sprag clutch, but one
that allows the inner ring to rotate freely, in EITHER direction,
but
engages when the outer ring is moved. *Does this kind of clutch
exist?
And if so, what is it called?

scritch

I just happened to be looking for the same thing today for the feed
on
a machine tool. I was hoping for a passive device that would allow a
handwheel to override the power feed. ...

I may be stuck with a dog or face gear clutch actuated manually,
pneumatically or magnetically. If you find something I'd love to see
it.
Ned Simmons

I think I remember a manual input clutch that engaged when handwheel
rotation cammed a cone (or dog?) clutch axially. There was a friction
drag on the cam follower's shaft bearing that had to be carefully
adjusted. IIRC the cam resembled a Hirth coupling with the center bolt
loose:http://en.wikipedia.org/wiki/Hirth_joint

jsw

I've seen them used on an old Snowbird snowblower that I had, but I
never knew that those couplings had a name. Good info!