Author Topic: One -way sprags  (Read 8243 times)

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Offline floydjer

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One -way sprags
« on: August 17, 2009, 12:11:32 PM »
How about using a sprag in place of the clutch? Lift off the throttle/shift/back on the loud pedal. I`m thinking out-side the box(as usual). Jerry
I`d never advocate drugs,alcohol,violence or insanity to anyone...But they work for me.

Offline RichFox

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Re: One -way sprags
« Reply #1 on: August 17, 2009, 12:25:30 PM »
In the long ago I had a drag bantam with a 241 Dodge and a cast iron torqueflite. Injected. Before stall converts. So I drop shifted it on the start line. Replaced sprags a lot in that thing. Kind of got to the point that I never wanted to see a sprag again.

Offline rebelce

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Re: One -way sprags
« Reply #2 on: August 19, 2009, 08:29:47 AM »
It must have been thought of before, it's OK in the rule book. Trick is finding one.

Offline Ervin

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Re: One -way sprags
« Reply #3 on: August 19, 2009, 08:44:08 AM »
Better question would be,,,,,WHY?

   Ervin

Offline floydjer

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Re: One -way sprags
« Reply #4 on: August 19, 2009, 03:37:50 PM »
Better question would be,,,,,WHY?

   Ervin
So that if( I mean WHEN) the engine locks-up at speed, The drive train would free wheel. :cheers:J.B.
I`d never advocate drugs,alcohol,violence or insanity to anyone...But they work for me.

Offline sheribuchta

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Re: One -way sprags
« Reply #5 on: August 19, 2009, 04:41:06 PM »
had one on a boat   with a prop    and big block olds      willie buchta

Offline manta22

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Re: One -way sprags
« Reply #6 on: August 19, 2009, 05:06:57 PM »
Make sure the sprag (over- running clutch) is a "full- phasing" type. Early on there were helicopter crashes caused by sprag clutch failures; a few individual rollers locked up before the others and this caused the sprag to sieze. By controlling the rollers so they all acted in unison, the problem was solved.

Regards, Neil  Tucson, AZ
Regards, Neil  Tucson, AZ

Offline Dave Cox

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Re: One -way sprags
« Reply #7 on: August 19, 2009, 05:18:44 PM »
Better question would be,,,,,WHY?

   Ervin
So that if( I mean WHEN) the engine locks-up at speed, The drive train would free wheel. :cheers:J.B.

AMEN!


Offline Glen

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Re: One -way sprags
« Reply #8 on: August 19, 2009, 07:36:42 PM »
There are at least two cases where front wheel drives with sprauges on the drive wheels had one side lock up and crash. One free wheeling and the other not makes for a nasty ride.
Glen
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Offline John Burk

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Re: One -way sprags
« Reply #9 on: August 19, 2009, 09:02:25 PM »
On front wheel drive cars the sprag needs to be between the transmission and rear . Drag boats also need overrunning clutches so I ordered one with the Casale V-drive I'm using as an overdrive in my front drive streamliner . Casale calls theirs a Whirlaway . That's where Dan Thomason and Ed Tradup got theirs for Dannyboy . Much stronger than the sprags used in production automatic transmissions .

Offline Rex Schimmer

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Re: One -way sprags
« Reply #10 on: August 20, 2009, 02:05:18 PM »
Look up the company Formsprag on the net. They make any size you want, high quality and good.

Rex
Rex

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Offline hotrod

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Re: One -way sprags
« Reply #11 on: August 20, 2009, 04:13:47 PM »
Throttle lift compression braking, or blown seized engine, or transmission, on a front wheel drive car would get very interesting (ugly) very quick at speed without an over running clutch. Same reason many cars do not run front brakes.

Larry

Offline jl222

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Re: One -way sprags
« Reply #12 on: August 21, 2009, 12:28:32 AM »
Throttle lift compression braking, or blown seized engine, or transmission, on a front wheel drive car would get very interesting (ugly) very quick at speed without an over running clutch. Same reason many cars do not run front brakes.

Larry

   Rear brake lockup= oversteer  Front brake lockup = understeer in the direction headed

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Offline floydjer

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Re: One -way sprags
« Reply #13 on: September 04, 2009, 02:01:13 PM »
O.K. ,I`ve re-thought this. How about a spring loaded face-dog between the trans. and rear differential? :?
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Offline Genuine GM

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Re: One -way sprags
« Reply #14 on: October 20, 2009, 07:49:01 PM »
I have alot of experience with Sprags.  I am the Chief Inspector a company that works on helicopters.  Helicopter component overhaul is what I used to do for a living and they all have freewheeling units to allow them to auto-rotate if the engine lets go. 

To run one, it needs to be between the transmission and the driveshaft or the driveshaft and the rearend.  You could probably get a sprag out of a used helicopter if you called a operator, or a service center and asked nicely.  They have relatively short retirement lives in the aircraft and are removed in great shape and tagged unserviceable.

The problem is the size needed.  A turbine engine puts out a steady state rpm and torque.   To govern the power of the aircraft you change the collective pitch of the blades.  The RPM stays constant. 

A Bell 206 Long Ranger will have around 400 shp and a Bell 407 will have 500+.  Those will be the most common sprags to run across.  If you ask you could probably get the inner and outer shafts as these have very minute damage limits.  I could email the copies of the maintenance manual pages needed. 

The best might be out of a Bell 412EP.  1200SHP out of a Pratt and Whitney PT6T-3DF Twin Pac.  The clutch is in the engine combining gearbox and doesn't have the same retirement life as the other aircraft.  It would be harder to come across.  You would probably need to contact Pratt and Whitney Canada or Standard Aero and see if their overhaul shops have any laying around they could release.

For a smaller unit, contact your local PD, News, or other operator and tell them what you want to do and why.  You will probably have to sign some release form as the FAA has gotten strict on used-unserviceable parts showing up later on installed on an aircraft. 

C. J.
Don’t let the troubles in your head, steal too much time, you’ll soon be dead - so play. You Never Know – DMB