Quick release for drop testing?

Interestingly enough, I am having a bit of trouble finding an economical device which can drop a hanging load on cue. I started with a snap shackle like this...

...but quickly found that the device does not open very well when loaded. I have seen this device used for drop testing and it works great...



...but it comes with a very high price tag.

Any suggestions?

Old seat belt buckle?

Visegrips? Drill a hole an put a pin in it, then use an old school climbing hammer tied to the pin?

20 kN wrote:Interestingly enough, I am having a bit of trouble finding an economical device which can drop a hanging load on cue. I started with a snap shackle like this... ...but quickly found that the device does not open very well when loaded. I have seen this device used for drop testing and it works great... ...but it comes with a very high price tag. Any suggestions?

Best option for heavy loads is a parachute 3-Ring Assembly.

Sandy Crimp wrote: Best option for heavy loads is a parachute 3-Ring Assembly.

3 ring release system

Dana Bartlett wrote:I don't know anything abut parachutes, and the little video was very interesting. Why is the 3-ring assembly designed that way? What are the advantages?

It simply is another method of designing a reliable and secure load releasable anchorage.

A good pelican hook is another way.

Quick-release water ski hook.

Jim Titt wrote:Quick-release water ski hook.

I couldent find much info about that on Google. Do you mind providing a link?

seashop.be/product_info.php…
This is the Plastimo one (a huge French yacht equipment company for those not into boating) but there must be someone selling a similar item in the USA.
That´s not what I use though, I made a pneumatic one up from scrap.

one easy way would be to have a pulley with a light piece of cord that re-directs it horizontally to an anchor. then, just cut the horizontal leg of the cord. easy and cheap.

I had trouble with this while doing a project. I had no funds and resorted to tying a tight and well dressed daisy chain in a 7mm line. Took only 3-4 small loops and it actually worked well.

20 kN wrote:Interestingly enough, I am having a bit of trouble finding an economical device which can drop a hanging load on cue. I started with a snap shackle like this... ...but quickly found that the device does not open very well when loaded. I have seen this device used for drop testing and it works great... ...but it comes with a very high price tag. Any suggestions?

Those are both for sailing and they can quick release 1000's of lbs of force easily. If you're having trouble releasing a few hundred pounds then you either have a shitty snap shackle (what they're called in sailing world) or your not pulling the pin in line... I would recommend attaching a lanyard to the pin and puttin some 3 in 1 oil on the pin too.

20 kN wrote:Interestingly enough, I am having a bit of trouble finding an economical device which can drop a hanging load on cue. Any suggestions?

I can pass along the names of a few belayers that fit this description perfectly!

The first device you have shown is the same one as in the Ouray ice screw drop test video. They did use a short lanyard.
How much weight are you dropping?

Depends on the weight you need to drop - up to a couple hundred pounds just pull it up with your hands (have a friend help) and let go of it.

There are some interesting shackles that are used on the Mythbusters TV show. They routinely drop thousands of pounds with them, and some are cable-actuated and they have one that has a wireless servo motor release.

Can't seem to find a good picture of one though...

slim wrote:one easy way would be to have a pulley with a light piece of cord that re-directs it horizontally to an anchor. then, just cut the horizontal leg of the cord. easy and cheap.

too easy...

CaptainMo wrote: Those are both for sailing and they can quick release 1000's of lbs of force easily. If you're having trouble releasing a few hundred pounds then you either have a shitty snap shackle (what they're called in sailing world) or your not pulling the pin in line... I would recommend attaching a lanyard to the pin and puttin some 3 in 1 oil on the pin too.

Interesting. I decided to look up snap shackle on Wikipedia and found this:

Note: When this type of shackle is used to release a significant load, it will work rather poorly (hard to release) and is likely to have the pin assembly or the split ring fail.

en.wikipedia.org/wiki/Shackle

That is exactly what happened to me. I tried to release 500 lbs and ended up breaking the split ring. I was pulling on the rig inline with its axle and I attached rope to the ring for leverage. This is the snap shackle I used:

westmarine.com/webapp/wcs/s…

Peter Franzen wrote:There are some interesting shackles that are used on the Mythbusters TV show. They routinely drop thousands of pounds with them, and some are cable-actuated and they have one that has a wireless servo motor release. Can't seem to find a good picture of one though...

They use this:

sweeney-special-effects.com…

But it costs $350-500 depending on the model.

Bryan Ferguson wrote:The Valdotain-tresse with the addition of a release strand tied around the Valditain will allow for heavy (multiple kilonewton) loads to be suspended and easily and reliably released.

How do you tie the release strand? The site below shows that the user must manually remove a carabiner (or other device) to release the knot. The knot looks like a version of the klemheist knot, which is not easily releasable.

netknots.com/rope_knots/val…

The folks at the Rope Test Lab FB group are quite fond of the 3 ring method, and there was a good discussion on it there a couple months back.

As Slim mentioned, why not just tie it with a cord and cut the cord?

I'm not sure you even need the pulley that Slim mentioned -- I'd just tie a loop in some nylon cord or strap, and then cut it.

Jon Nelson wrote:As Slim mentioned, why not just tie it with a cord and cut the cord? I'm not sure you even need the pulley that Slim mentioned -- I'd just tie a loop in some nylon cord or strap, and then cut it.

Because I have to conduct 30+ drop samples. But more importantly, I am conducting drop tests on a highline, so I will be on the ground and I need to release the load remotely, presumably by pulling on a rope connected to some type of release mechanism. For the most part, I only need to drop 150 lb samples, so maybe some type of quick-release knot would work. The catch is that if I use a knot the knot needs to completely release from the highline so the weight can free fall.