Safe vs. UnSafe Extractions

[bartonmd]

Sorry James, It was a dynamic recovery with a static strap. I don't have any dynamic straps. I was moving my truck slowly foward to take up slack. You see it tighten and losen for a sec. Then I tightened and gave the signal to go.

My rear receiver D-shackle to his factory tow hook on the right side of his truck.

Well, your recovery was technically a static recovery.

A vehicle-vehicle recovery can be performed dynamically by having speed going into the extraction... or statically by doing exactly what you did (slowly letting the strap get taught and then proceeding forward with engine power).

Dynamic recoveries are especially helpful where you have poor traction - snow/ice/sand/mud - because the dynamic method can generate forces beyond that of your tire traction.

Dynamic straps are handy because they can be used in both static and dynamic vehicle-vehicle recovery, where a static strap can only be used in static recovery.

Exactly... I used my S-10 Blazer to pull lifted Ramcharger out of this (below), backwards... He was sitting on the rear bumper... Hooked my shackle mount and one end of my dynamic strap up to my Blazer, hooked my 3' piece of chain around his frame and through the other end of my dynamic strap... Backed right up to him, made sure we were ready, then went WOT forward in 4-LO...

I stopped pretty quickly, and he popped up in the air, and out he came... My neck muscles were pretty sore the next day...

[bobbyblaze]

Sorry James, It was a dynamic recovery with a static strap. I don't have any dynamic straps. I was moving my truck slowly foward to take up slack. You see it tighten and losen for a sec. Then I tightened and gave the signal to go.

My rear receiver D-shackle to his factory tow hook on the right side of his truck.

Well, your recovery was technically a static recovery.

A vehicle-vehicle recovery can be performed dynamically by having speed going into the extraction... or statically by doing exactly what you did (slowly letting the strap get taught and then proceeding forward with engine power).

Dynamic recoveries are especially helpful where you have poor traction - snow/ice/sand/mud - because the dynamic method can generate forces beyond that of your tire traction.

Dynamic straps are handy because they can be used in both static and dynamic vehicle-vehicle recovery, where a static strap can only be used in static recovery.

I thought what I did was a static recovery and that's why I wrote it in my first post . . .but when you asked why I didn't do a dynamic pull I second guessed myself and I went to the ORTB home, clicked articles then read the differences between static and dynamic recoveries. The static recovery definition talks about winches and HI-lifts not about using two vehicles with a static (tow) strap so I wrote dynamic in my second post.

Gotta' get me a dynamic strap. Looks like fun. Oh yeah, a strap dampener too.

[Trail X]

Sorry for the confusion. I'll try to add in something about that.

Right now, the best way to determine the differences is on the first page of the article:

A static recovery loads the recovering system without any stretching component. The recovery force is derived from a positive displacement element, such as a winch, or hand ratchet. Dynamic elements, such as ‘snatch’ straps, should not be used in a static recovery unless it is a last resort.

A dynamic recovery can be useful for a quick recovery, provided you have a second vehicle present. The recovery force is derived from the other vehicle’s momentum. If a dynamic strap is not used in this type of recovery, extreme damage can result.

A passive recovery does not utilize horizontal forces at all to recover the vehicle. The recovery is performed by simply increasing the wheel traction through various methods.

So just remember... Dynamic = jolting, impulse loads from vehicle momentum... Static = derived from traction/winch/etc without impulse loads.

Most people stay away from Static vehicle-vehicle recoveries because it creates very high loads on the driveline.

[lil_freak_66]

just thought of bringing this up,last weekend when i was at bundy hill(this was not my strap btw)

we had a recovery strap attached to a winch to pull out the TJ out of some deep,thick mud

once there was tension put on the strap,it snapped,it was old.thankfully nobody got hurt and nothing damaged other than the strap.

make sure your straps are in good working order,and dont use a recovery strap and winch (linking them together) unless you absolutely have to!

this is the same tj i pulled out in september btw,but only on the Mud terrains this time

[rgraboske]

I just read this on another forum I post on, and it seemed a good time to post a reminder

This weekend her son was pulling a lawnmower out of the mud with an ATV, and the snap strapped. The buckle hit him on the cheek and in the eye, fracturing his cheek in six places, and slicing his cornea in half. He was in surgery for six hours Friday night/Saturday AM on just his eye - and they really think he's going to lose it. He's seeing another specialist this morning to see if it can be saved, otherwise, when they repair his cheek (with a metal plate), they'll be removing his eye to make sure the other doesn't "sympathize" and lose vision as well. He was sent home Saturday afternoon, which is crazy to me and is in a lot of pain. He's 14.

[KE7WOX]

Definitely. I just see that a lot of people like to use whatever they have availble in their garage to do it. Seems like he used a ratchet strap or similar. But I've seen people use old chains and other dangerous things.

Also, I wouldn't go mudding a lawn mower, just saying.

There is one thing I have present to this day, back when our Blazer broke down in 2001, my dad made sure no one was within range of the flatbed winch cable, just in case it snapped, and he made it clear, cables can snap, and you don't want to be in range where it can decapitate you (I think the Mythbusters proved it's not possible to get decapitated, but it can definitely pulverize your face). It seems that a lot of people don't realize that, because more than once I've had to tell people to move away because if a cable breaks or a strap breaks loose they will be the ones stopping it.

[rgraboske]

I agree with the no mudding on a lawn tractor, but I will admit to getting our lawn tractor stuck a time or two. It definitely wasn't intentional

[glfredrick]

It is always the hook that gets ya... I've seen it a bunch of times off-roading, once when a hook cleared both the windshield and the rear window of a Jeep. Fortunately it went right between the two in the front seats.

We no longer allow things with hooks except winches, and then with a winch weight in place (even if it is an old rug or blanket).

We snapped one winch line during our UCORA event in Missouri. It was so uneventful that it is almost not worth repeating. The extraction was a stretched Jeep on Rockwell axles w/44s, pulling up an almost vertical face that had a 4' rock step. We had to cinch the pull vehicle to a tree to keep it in place, then we used up every ounce of the Warn 9500 winch. We had a blanket on the winch cable, and when it snapped, it just fell to the ground and that was that.

Many of us are now running synthetic winch line. We prefer winchline.com, the real Amstel Blue.

[rgraboske]

Bumping this back up with another story of stupidity when extracting a stuck vehicle

http://www.autoblog.com/2010/12/23/james-may-hospitalized-shooting-top-gear-syria-special/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+weblogsinc%2Fautoblog+%28Autoblog%29&utm_content=FaceBook

[bartonmd]

You know what let's do... Let's stand on a winch line...

[The Roadie]

He could have been straddling it when it went taut.

[Trail X]

They sure make it seem like they have no experience and are alone when they are out there - but I'm certain that their support teams are fairly large wherever they film. Kinda like the storm chaser guys - they each have like 3 support vehicles following them.

[KE7WOX]

They sure make it seem like they have no experience and are alone when they are out there - but I'm certain that their support teams are fairly large wherever they film. Kinda like the storm chaser guys - they each have like 3 support vehicles following them.

Yeah, remember the Polar Special, they busted a shock, fuel tank and driveshaft, but their Icelandic mechanics were able to fix it. They had 2 other trucks following. And in the Bolivian Special they had at least a newish Sequoia with the camera crew.

[rgraboske]

From what I've read, the show is heavily scripted.

When they were in the US testing the Challenger, ZR1, and CTS-V, they had a silver Trailblazer chase vehicle

[KE7WOX]

Same for the first special (you can see a silver TB when they were running away from the Alabamans)

[rgraboske]

That is some nasty mud

I'll never understand why so many people insist on standing next to a winch cable or tow strap that's under load. They broke two, and yet there were still people standing close by. If that hitch had let go

[The Roadie]

And looped over a tow ball instead of a proper clevis mount. You should need to pass a test before a shop would be allowed to sell you extraction gear.

That reminds me, I need to either upgrade to synthetic line, or install the RF winch remote control I bought two years ago, so I don't need to be in the whip radius.

[KE7WOX]

I'll never understand why so many people insist on standing next to a winch cable or tow strap that's under load. They broke two, and yet there were still people standing close by. If that hitch had let go

They are just like those kids who attempted to use a winch as a dynamic strap, but with a funny accent.


Probably one of the things I will always remember was when we had to get our S-10 Blazer towed (trans oil pan blew up at the beginning of a road trip) was that my dad got all of us in a safe spot before they began winching it up the flatbed, as he said, if that cable snaps, it's taking out whoever is on its path.

[Harry Moto]

(I think the Mythbusters proved it's not possible to get decapitated, but it can definitely pulverize your face).

Please remember that 'Mythbusters' is a TV show, with special effects guys making things blow up for your entertainment. None of my engineering friends can bear to watch, as virtually every step is either an assumption or a conclusion arrived at via the process of 'jumping'. Those two guys wouldn't know good science or a valid test if it fell on them. I hate that they are often 'proving' something that is completely incorrect.

How bad can a snapped cable be, anyways... Any aircraft carrier guys out there?

Sorry for freaking out, but 'Mythbusters' strikes a nerve...

[fishsticks]

(I think the Mythbusters proved it's not possible to get decapitated, but it can definitely pulverize your face).

Please remember that 'Mythbusters' is a TV show, with special effects guys making things blow up for your entertainment. None of my engineering friends can bear to watch, as virtually every step is either an assumption or a conclusion arrived at via the process of 'jumping'. Those two guys wouldn't know good science or a valid test if it fell on them. I hate that they are often 'proving' something that is completely incorrect.

How bad can a snapped cable be, anyways... Any aircraft carrier guys out there?

Sorry for freaking out, but 'Mythbusters' strikes a nerve...

I watch Mythbusters for the explosions...not the science.