3 Ring Release

[Rigster 0]

Hi Gang,
I'm not a rigger but thought this would be the place to ask the question. How many pounds of pressure are on the loop preventing the 3 rings from releasing? Can anyone elaborate?
Thanks

[FrogNog 1]

In theory the tension on the "white loop" that goes around the cutaway cable should be 1/200th of the tension on that riser, in an original-size ring system. Systems with mini rings will theoretically present much more white loop tension than "regular" size ring systems - the Jumpshack doc below says 6.6 times as much tension (i.e. only a 1/30th lever). The Aerodyne MiniForce system may theoretically present less white loop tension than a mini (round) ring system; I don't know and don't have their technical info at hand.

Some amount of basic 3-ring lever technology is described here:
http://www.jumpshack.com/default.asp?CategoryID=TECH&PageID=3RING&SortBy=DATE_D. Searching the forum was icky because everyone moved their old docs.

-=-=-=-=-
Pull.

[riggermick 6]

Quote

Hi Gang,
I'm not a rigger but thought this would be the place to ask the question. How many pounds of pressure are on the loop preventing the 3 rings from releasing? Can anyone elaborate?
Thanks

Aprox 5 lb under "normal" operating conditions. Anything else is up to the conditions present at the time.


Mick.

[jsconn 0]

I do...

http://www.aerodyne-int.com/download/miniforce.pdf

Jody

[Rigster 0]

This is great but your response spurs another questions. What are not NORMAL operating conditions. Are you referring to accumulated dirt on the system? How do you maintain the loop? How often should you change it?

[billvon 2,395]

>What are not NORMAL operating conditions.

A spinning mal
A hard opening
Other overloads (like a Mr. Bill jump)
Incorrect assembly (white loop around larger 3-ring)

>Are you referring to accumulated dirt on the system?

Dirt on the cables will make it harder to pull the cables through the white loop and thereby cut away, but it should not increase the tension on the white loop itself.

>How do you maintain the loop? How often should you change it?

Generally you change it when you change risers. I don't know of anyone who has replaced just the loop, although I'm sure you could do it if you were determined. The most common cause of damage is dragging the rig on a rough surface during packing; that can abrade the loop and weaken it. The only maintenance I do on it is to inspect it periodically (front and back) and work it a bit when changing risers, which I do with some regularity.

There's also the standard riser and release system maintenance, of course.

[riggermick 6]

Quote

This is great but your response spurs another questions. What are not NORMAL operating conditions. Are you referring to accumulated dirt on the system? How do you maintain the loop? How often should you change it?

Exactly! It will change every day that you do or do not use it.


Follow the MFG's recomendations on maintainence, it's crucial to the the systems operating integrety.

Mick.

[Rigster 0]

Dude,thanks for your reply.
What's the material of the cable going thru the loop. The yellow cable.

[billbooth 10]

The yellow cable is 1/16", 7x7 steel cable, coated to 1/8" with Lolon "F", a special nylon based plastic blend.

[ernokaikkonen 0]

Quote

How many pounds of pressure are on the loop preventing the 3 rings from releasing? Can anyone elaborate?

Here is a chart on 3-ring loads and pull forces that I compiled from information available on the RWS and Aerodyne websites.

In short, the force on the loop depends on the load hanging from the risers and the type of 3-ring release used.

[sundevil777 93]

What I would like to see put over that chart is where the cable will start to get distorted noticably...

The fact that the cable bending like that can occur so much easier with mini rings would surprise most jumpers, I think. Most might know that you can expect a higher release force, but don't realize what is actually happening.

I am amazed at how rare the standard rings are now. I didn't hesitate at all when ordering my new rig to stay oldschool.

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[ernokaikkonen 0]

Quote

What I would like to see put over that chart is where the cable will start to get distorted noticably...

Interesting idea. I was actually thinking of doing some pull tests myself(mainly to see how my results compare to the different numbers Aerodyne and RWS came up with), and an observation on the "cable distortion" would be easy to include.

[JohnGraham 0]

If you take a look at this article by RWS there's a table about 3/4 of the way down detailing riser breaking strain for reversed and non-reversed risers - in the notes for the reversed riser it says that:

Quote

The cable was pulled through the grommet at just over 2000 lbs. for both samples. This malfunction can, and most likely will, prevent a cutaway.

but the non-reversed riser did not malfunction in this way, except in one case where:

Quote

The cable was pulled through the grommet in Sample 1 immediately after riser break due to the riser breaking at the grommet. This does not prevent a cutaway.

Erno - you could also put reversed risers on your chart to compare them with RWS and aerodyne rings.


Oh yeah and in that same article it says "Ask about how the 08/98 spec. [riser] is designed to reduce breaking at grommet."
So, could anyone from RWS tell me how is the 08\98 spec. riser designed to do this? Just more reinforcement or what?

[Unparagoned 0]

Quote

If you take a look at this article by RWS there's a table about 3/4 of the way down detailing riser breaking strain for reversed and non-reversed risers - in the notes for the reversed riser it says that:

Quote

The cable was pulled through the grommet at just over 2000 lbs. for both samples. This malfunction can, and most likely will, prevent a cutaway.

but the non-reversed riser did not malfunction in this way,

That article is 7 years old, does anyone know if the reversed risers pdf now uses has the same problems and the ones tested?

[billbooth 10]

Reversed risers, even "properly made" are simply a bad idea for a whole lot of reasons discussed here many times before. But one basic reason is that no one publishes a diagram of what a properly made reversed 3-ring looks like, so how can you tell if you've got one in the first place. Secondly, they are supposed to be stronger than normal type 17 risers. But, with people dying from hard opening shocks on Micro-lined canopies, do you really want stronger risers? Wouldn't you rather have a riser break before your harness (or you) break(s)?