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  1. #1
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    Default survey question

    I’m gathering data for a paper I’ll be presenting in Nov. Please the complete following:

    Gravity biases carabiner locking sleeve motion in a vibratory environment because ___________ .

    Feel free to elaborate on your answer as necessary. Also, if you choose to participate, please refrain from any discussion beyond your answer, since further discussion might bias the results.

    Your input will remain anonymous and is greatly appreciated.

    If you prefer to not post a reply in public, please send me a private message or email me: davey@cwmr.org

    Thanks.
    Last edited by servantleader; 08-30-2012 at 12:14 PM.


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    To elaborate, I'm looking for physical explanations of the observed locking sleeve motion in terms of the forces, torques etc that act on the locking sleeve.

    Thanks.
    Last edited by servantleader; 08-30-2012 at 12:11 PM.

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    Forum Member FiremanLyman's Avatar
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    Brother, I am still trying to figure out the sentence. Please dumb the wording down for this tailboarder.
    ~Drew
    Firefighter/EMT/Technical Rescue
    USAR TF Rescue Specialist

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    Forum Member Lewiston2FF's Avatar
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    If I am interpreting your question right. What impact does gravity have on the locking sleeve of a caribiner when subjected to vibrations? Is this correct? Basically asking will a caribiner oriented with the locking sleeve upward unlock when subject to vibrations?
    Shawn M. Cecula
    Firefighter
    IACOJ Division of Fire and EMS

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    Hi David,

    Accounting for gravitational unlocking is something I learned as a teen-age rock climber in the 70s. I noticed it when rigging slingshot top rope set-ups. Rather, I noticed it when I'd arrive at the carabiners as I'd finish a climb. Hey, I swear I locked those!

    The slingshot TR set-up has a high directional above the climb, which allows the belayer to operate at the ground level. A standard set-up in the climbing world- 2 carabiners, not a pulley. Minimum of 2 non-lockers with gates opposed. When long slings/rope are involved in the upper anchor legs, more movement at the carabiners is possible, which makes me like having at least one of the carabiners be a locker.
    Back then, the only type of locking carabiner on the market was the manual twist lock (which we are discussing), or a Type 2. [Type 1 being a non-locker, Type 3 being an auto-lock via spring loaded gate, and Type 4 being similar to a Type 3, but also having an additional spring loaded mechanism creating a separate movement required other than turning the locking .collar to an open position (typically an up or down sliding motion of the locking collar).] With Type 3 and 4, the gravity issue goes away.

    So the cause of the gravitational unlocking- Well, it isn't gravity by itself. It's a combination of gravity with a carabiner that has the locking collar exposed to a "downhill" angle, along with another factor such as
    - vibration of the carabiner due to rope friction
    - the tapping/rubbing/striking of the carabiner against the wall/rock/whatever repetitively.
    - the shaking or movement action of the carabiner being repetitively loaded and then unloaded. This is noticeable even along a horizontal axis in rigging, such as a haul system or a back tie of an anchor's interior directional which goes slack during haul reset. Particularly with "D" shaped carabiners, even with a horizontal orientation of the spine, the gate remains at a downward angle with gravity influencing the unlocking action if the spine is downward (another subject of diagonal loading here).

    If you shake a type 2 carabiner, you can typically hear the play within the locking collar.

    Some factors that will determine the likeliness or unlikeliness of gravitational unlocking: design and shape, amount of play in the locking collar, material type, foreign substance with the locking collar (dirt, sand, ice, etc.), and I'm sure many others.

    As long as one keeps the locking collar downhill, the whole concern of gravitational unlocking can be kept to a minimum.

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    Forum Member FiremanLyman's Avatar
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    OK, understand the sentence now...
    Quote Originally Posted by servantleader View Post
    Gravity biases carabiner locking sleeve motion in a vibratory environment because ___________ .
    ...because someone smart said so. I have never had a haul/lower more than 300', have never noticed a biner shaking the lock off.
    ~Drew
    Firefighter/EMT/Technical Rescue
    USAR TF Rescue Specialist

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    Quote Originally Posted by Lewiston2FF View Post
    If I am interpreting your question right. What impact does gravity have on the locking sleeve of a caribiner when subjected to vibrations? Is this correct? Basically asking will a caribiner oriented with the locking sleeve upward unlock when subject to vibrations?
    Correct, and if you believe that type 2 biner locking sleeves should move downward when subject to vibrations, provide some speculation as to why this is so.

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    Quote Originally Posted by servantleader View Post
    Correct, and if you believe that type 2 biner locking sleeves should move downward when subject to vibrations, provide some speculation as to why this is so.
    Sir Issac Newton would say gravity yeah? Vibrating up is highly unlikely. The design of the Carabiner tends to promote the locking direction to flow with gravity. We are always told the gate on top. See image.

    Name:  carabiner.gif
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    Quote Originally Posted by MichaelXYZ View Post
    Sir Issac Newton would say gravity yeah? Vibrating up is highly unlikely. The design of the Carabiner tends to promote the locking direction to flow with gravity. We are always told the gate on top. See image.

    Attachment 22319
    Michael, there are essentially one of two things going on in any system you rig. Your rigging will be subject to the movement of loading and unloading (such as an MA for a resettable haul system), or perhaps vibration, or pivoting, or the like. Otherwise, rigging will be fixed into place under tension and remain there, subject to little to no vibration or movement (an MA tensioned as an anchor back-tie comes to mind.

    In the case of the latter, I'm less anal about leaving the type 2 locker exposed to gravitational unlocking, such as in your picture. Regarding your picture (referring to rigging along the horizontal)... If you consider gravity arrow in your image not to be pointing to the left, but instead downward... Your carabiner would be tilted by having the gate oriented flat or horizontal. Whatever you're clipping to the carabiner should ideally be nestled against the spine at the mouth end, which would then instead make the spine oriented flat or horizontal. If this were done, you'll see that the gate would now be at an upward angle, subjecting the locking collar to gravitational unlocking. This stuff does happen. I've lost count how many times I've seen carabiners be rattled into an unlocked position.

    Another point...

    If the horizontal system you rigged is to be loaded and unloaded, and you have your carabiners (of any type, i.e. 1-4) gates upward, you then expose the carabiners to being diagonal loaded. Diagonal loading of a carabiner is yet another one of the abuses of a carabiner, in the camp of triple loading, torsion, levering, etc. You may have begun the initial loading of the carabiner with the rope or webbing against the spine. But when the system is relaxed, the carabiner will "fall" to where the rope/webbing is at the gate side of the carabiner's mouth end. Upon reloading of the system and the carabiner, the line of force thru the carabiner is now more parallel to the gate and not the spine. You'll especially see this in the HMS and "D" carabiners, and more so if the webbing or rope is damp, creating more of a "grip" against the carabiner end.

    Hold a carabiner with cord or webbing on either end on a horizontal plane in front of you. Tension it and relax, and then tension it again. You'll see the diagonal loading trying to take place if the gate is up. If the gate is down, the default position is along the spine side, which is ideal.

    One may not think this is a big deal if you're using 40+KN steel carabiners. Yes, those carabiners will put up with more abuse. But it can be a big deal if your team is using aluminum carabiners. All of this stuff goes back to the point I made in the other thread about delta links taking place of carabiners in 2-way loading systems. The carabiner nuances can be left by the wayside. The end user can be left in the dark about carabiner abuses in order to save instruction time.

    Lighter weight gear requires a greater understanding of the "why", well beyond the "how", in order to be able to maintain an acceptable level of safety.

    That's enough...
    Last edited by EricUlner; 09-02-2012 at 11:22 AM. Reason: clarity

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    A quick note that I hope makes sense. It's difficult to describe without a prop!!

    Like, Eric, I too have seen this happen. Our environment was during industrial course work. One of the areas was subject to vibrations and the screwgate would be unscrewed.

    Think of it this way...a screw is a simple machine (ie MA) to allow you move the screw over the latch. If the carabiner is placed in a position to allow the screw to unthread downwards (either with gravity or vibrations) it allows the unthreading action to take advantage of the MA. Essentially it will unthread "down" easier than it will unthread "up". (I hope all of that makes sense). This is the theory behind out hinge up, latch down protocol in our courses.

    I have never seen this occur in a horizontal plane. We teach to place gates up when used horizontal so the gates aren't smacking the ground, thus increasing the potential for unthreading.

    Jeff

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    When I posted the image, I assumed the load end would be pointing in the downward direction, that's the reason I added the directional arrow. The horizontal image was only used because that is what I found on the net

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    Forum Member Lewiston2FF's Avatar
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    I too was taught and that the gate on a horizontally loaded carabiner is oriented down. When using a carabiner in a vertical orientation it should be oriented so that the gate is away from you and the locking screw is oriented down. "Scratch your belly button, don't pick your nose". I have seen some locks vibrate loose in high vibration situations. What have we done about it? Nothing other than maintain operational discipline to check locks frequently.
    Shawn M. Cecula
    Firefighter
    IACOJ Division of Fire and EMS

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    I have never seen this occur in a horizontal plane. We teach to place gates up when used horizontal so the gates aren't smacking the ground, thus increasing the potential for unthreading.

    Jeff[/QUOTE]

    I have seen carabiners (both manual screw lock and single action auto lock) unlock in a horizontal position. In some cases the carabiner was moving along the ground and unlocked do to friction. In other cases the stationary horizontal carabiner had a moving rope rub across the gate causing it to unlock.

    Because of this and because of OSHA, we use only double action auto locking carabiners. The locking gate has to be slid up under spring tension then rotated under spring tension to get it to open. OSHA says that manual screw lock carabiners do not meet the intent of their standard (fall protection) because someone could forget to lock them properly. They also say that they would find it hard to cite an organization for using manual lock carabiners unless the carabiner caused an accident. Sounds pretty Catch 22 to me.

    Unless you work in industry or are in an OSHA state (there are about 26 OSHA states where fire departments can and have been cited for violations) then the OSHA regs don't apply to you. Before we switched to the double action carabiners we solved the accidental unlocking problem with a small piece of duct tape around the screw.

    Mike

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    Best I could find, The carabiner is referenced in OSHA Std. 1910.66 which states the carabiner must conform to ANSI Z359.12, that is far as I could get as you need to purchase the standard.

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    Quote Originally Posted by MichaelXYZ View Post
    Best I could find, The carabiner is referenced in OSHA Std. 1910.66 which states the carabiner must conform to ANSI Z359.12, that is far as I could get as you need to purchase the standard.
    I wrote the OSHA Region 6 safety office way back in 1997 to ask for a clarification about manual locking carabiners. The following is a follow up phone call I got from Mr. Jose Chapa (a nice guy and long since retired):

    Carabiner/Snap-Hook Follow-Up
    October 3, 1997

    A follow-up call from the OSHA Region VI Safety Office in Dallas, TX at 1300 hours on Friday, October 3, 1997 lead to the following information from Mr. Jose Chapa.

    He said he had called Washington, DC and talked to Jule Jones, the woman who wrote the construction fall protection standard, to get a clarification about our carabiner questions for us. She said that carabiners are not snap hooks and that we should check with the manufacturer of the carabiner to see if they meet the intent of the standard.

    Jose said what OSHA wanted to see in the way of carabiners is self-closing and self-locking but that if a team were using self-closing manual locking carabiners then OSHA would have a hard time citing them for it if it did not lead to or cause an accident during the operation.

    I bought the ANSI standard when it was published in 2007. There is no Z359.12 but here is what it says about carabiners in the definition section of Z359.2.18:

    2.18 Carabiner. A connector generally comprised of a trapezoidal or oval shaped body with a closed gate or similar arrangement that may be opened to attach to another object and, when released, automatically closes to retain the object.

    Under the explanatory information for this definition is states:

    E2.18. In addition, carabiner may also be spelled karabiner. There are generally three types of carabiners: (i) the automatic or self-locking type (required by this standard) with a self-closing, self-locking gate that remains closed and locked until intentionally unlocked and opened for connection or disconnection; (ii) the manual locking type (not permitted by this standard) with a self-closing gate that must be manually locked by the user, and that remains closed and locked until intentionally unlocked and opened by the user for connection or disconnection; or, (iii) the non-locking type (not permitted by this standard) with a self-closing gate that cannot be locked.

    Hope this helps.

    Mike

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