Man Killed Pulling a Log

   / Man Killed Pulling a Log #21  
rd_macgregor said:
I also agree with the comments about amateurs trying to jerk a tree stump (or whatever) out.
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I've said this before... We don't know WHAT they were doing. They may have been doing everything "the right way" and this was from equipment failure.

rd_macgregor said:
Who knows what kind of chain they were using, too?
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That could be the core of why this happened, or it could be essentially irrelevant.

What I believe we should all be focused on from this are two things:

- This was an unfortunate incident that has prematurely ended someone's life and brought suffering to the lives around them far too early.

- There are right ways and wrong ways of doing things, and we should discuss those separately from what happened in VA. We don't know the actual details and anything we state surrounding the events are nothing more than absolute speculation. We do not have to assume that what happened in VA was the result of incorrect actions (using a strap instead of a chain, putting sudden tension on a chain instead of gradual, etc) in order to discuss ways of pulling stumps, moving trees, etc in ways that are as safe as we can make them.
 
   / Man Killed Pulling a Log #22  
When a chain snaps it has minimal recoil because it's not elastic and it doesn't stretch (much).

However, if attached to the pulling vehicle or tractor by a strap when the chain breaks, then the stretched strap will suddenly recoil and bring the still-attached piece of broken chain with it like a slingshot and that's deadly.

If you have to use a chain with a strap, always attach the chain to the pulling vehicle and not to the object being pulled.
 
   / Man Killed Pulling a Log #23  
When a chain snaps it has minimal recoil because it's not elastic and it doesn't stretch (much).

However, if attached to the pulling vehicle or tractor by a strap when the chain breaks, then the stretched strap will suddenly recoil and bring the still-attached piece of broken chain with it like a slingshot and that's deadly.

If you have to use a chain with a strap, always attach the chain to the pulling vehicle and not to the object being pulled.
 
   / Man Killed Pulling a Log #24  
ARB sells a product touting if used will stop the fling of a cable.

arb001%20041.jpg
 
   / Man Killed Pulling a Log #26  
The problem with tension is stored energy. The more stretch, the more stored energy. Chain has little stretch, and is the best flexible method to pull with. That said, the grade of chain will affect the stretch. Higher grades stretch less than lower grades. Just my observation here but most people buy chain with lower grade, which is cheaper.

I have broken many chains and learned early on that below grade 70 should be used for things like porch swings or anchors. Whenever lifting or pulling, I use nothing but grade 70. I'm sure it can happen, but every grade 70 I have broken practically drops straight down. If you have to get a running start to add momentum force when pulling, you will always risk the whip back when whatever you use breaks.

Cable is convenient and stores easy, but stretches a lot and because it is light (compared to chain) it recoils violently from the stored energy. The new super braids have little stretch compared to steel and is good choice if not using chain. The stretch straps may be light, and let use use momentum, but they are über dangerous. Btw- the tire added to chain or cable was a way to add a little stored energy to them or to reduce the shock load on the system form jerks or sudden changes in the dragged load. These are often referred to as snubbers.

Adding something of mass to a cable is used to create a fulcrum to reduce the length of the whip if it occurs, expending the energy by making the cable change the direction. The longer the pull, the more mass is needed or better yet, add multiple masses spread out across the line. For instance, using the truck mat for a 10' pull mid line is pretty good. For a 20 foot pull, adding another and spacing them to divide the line in thirds is better than putting two in the center.

I'm sure there are some better engineers or physicists here that can explain these things better than I. best advice, always consider where ANY stored energy may go and not be there.
 
   / Man Killed Pulling a Log #28  
I remember reading on here that somebody uses an old piece of firehose on their chains? If the chain does come apart, the hose acts as a dampner...

Now, if I can remember who posted that?? :scratchchin:
 
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   / Man Killed Pulling a Log #29  
Although a mass placed over the chain/cable/strap can work to reduce the amount of energy left in it by the time it hits you in the face, I suspect the real benefit is just putting a bit of downward vector into it, so that the chain/cable/strap hits the ground before it gets to you and your face.

xtn
 
   / Man Killed Pulling a Log #30  
In the body shop, we often used a piece of old carpet to dampen chains on our frame machine.

Hooks, clamps, pieces of chains, and hunks of metal flying across the shop at very high velocity, are par for the course in that kind of work.

It doesn't take long to realize you don't want to be in the line of fire. :tombstone:
 
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