Pulling Tree Stumps Safely

SPYDERLK · Dec 17, 2007

IslandTractor said:
[[[This is getting more confusing for me. The contradictions seem to be over whether 1) large but not high grade chain (so it breaks but doesn't stretch) or 2) wire rope is best. Why shouldn't polyester towing straps also join the contest for safest? Even if they break, they don't have much mass and assuming the broken side hook stays with the tree side, you would just have a nasty piece of pliable plastic webbing coming back at you rather than heavy steel.]]] It might hurt like the dickens but is unlikely to take your head off.

What I get from this thread so far on chain/wire rope/straps is that one should clearly oversize them but additionally it seems there is a fairly wide range of products that are in use and considered safe. The other point seems to be that any of these can break but are most likely to break when applying a sudden rather than continuous force. The biggest risk then would be when you don't pretension the towing chain/wire/strap before applying towing force with a tractor. Again, the bottom line lesson to me is to get out the backhoe for stumps that are even close to a challenge rather than trying to yank them out.

I know what your saying. There is no simple answer to which is best. All things considered tho, there is no contradiction. Here are a few back and forth points:

The stored energy thing is extremely important. You want to store as little as possible and not release it quickly. Compared to chain, rope and cable store a lot. However, the release of their stored energy is much more wasteful than chain. Visualize all those crisscrossed fibers rubbing against each other as the rope snaps back. Extend the same idea to cable - just not as much. Now, almost unique to cable, is the way it often breaks. Not sudden. Several strands followed by some give followed by more strands etc. Sort of pop pop pop instead of POW. The same energy is released, but a lot is absorbed/dissipated between pops. The speed of the rebound is another thing that sucks E out. Compared to chain, rope and cable are light. They move fast - - but they are moving thru air, and air is exponentially stubborn at speed. Not only must the air be forced out of the way of the recoil motion, it must also re enter between fibers where it was squeezed out by the tension - more losses. What about the form of the recoil? - a cable runs into its stiffness and has to loop around - a bad thing.

Contrast all this with chain.... Less elastic stretch even than cable but release is almost always more sudden. When a link fails some E goes into straightening it, but the force to straighten is comparatively small and the distance very short before the chain is free. There are almost no other unavoidable losses. Elastic recoil of steel is fairly efficient. External rubbing is almost nonexistant until the links slack. Nearly all of the [altho lesser] stored energy is now kinetic. The recoil is 10s of feet per second rather than 100s. But its massive and air isnt slowing it down. Zero speed is good speed to be hit by even a small part of a chain. If there is no recoil velocity off line of pull all is good. That wonderfully supple chain will come crashing into itself and form a puddle a couple feet behind your drawbar. A cable will not do this under any circumstance. If there is up velocity in the chain recoil you may be in trouble, but the likelihood of it reaching you with a chain is less than the others - its moving slow and so has plenty of fall time.

What about comparative care and feeding, handling and storage, versatility in use? If its not chain dont ride it hard and put it away wet or dirty. Small fibers oxidize well and are also quickly compromised by abrasion. Dont think you will have freedom to change the working length at a whim or be able to suffer many physical abuses harmlessly that would kink or snap the others.

No way you can be totally safe. On the average tho, I think you are safer with chain.
larry

Highbeam · Dec 17, 2007

Here's an odd question from an odd engineer. Does it help or hurt to have a longer pulling chain? I like to link together a couple of 20 footers to prevent having the tree or dead limbs falling on me. The angle of pull is more horizontal with more chain so I don't get the rear end of the machine being lifted.

I acquired a spool of 1" nylon rope from a power company. I used it with my bulldozer to pull trees over or to convince them to fall a certain way when I cut them. It had stretch and it broke a few times. I was pulling from the dozer drawbar and the rear brush screen which is designed for this sort of thing took a couple of very signifcant wallops from the broken rope. No rope for me anymore. I am convinced that chain or cable is superior.

Cable and chokers have that nasty tendency to poke through your fingers while handling and are difficult to stow. Chain is my main device, I use the 5/16 stuff since a 3/8 chain gets to be very heavy in the woods.

N80 · Dec 17, 2007

I don't understand any of the physics in regard to this. But I know what I saw. One truck in the mud, one on solid ground. Chain hooked to leaf spring shackle on stuck trunk and bumper of pulling truck. Pulling truck gets a running start and snatches chain (yes, alcohol was involved, and no, I was not....just a spectator). After several snatches chain breaks. Flies back like a lightening bolt. Hits front edge of the hood of the stuck K5, bounces upwards and hits A-pillar, windshield and roof. Hood is wrinkled up (looked like waves in the metal), a-pillar dented in, roof dented, windshiled shattered but chain did not enter the vehicle.

I'm no trauma expert but I think if it hit someone it would have killed them.

AndyMA · Dec 17, 2007

Ever see a log skidder without a lot of protection built in!! Most of our tractors don't offer squat in comparison for protection.

Andy

SPYDERLK · Dec 17, 2007

N80 said:
I don't understand any of the physics in regard to this. But I know what I saw. One truck in the mud, one on solid ground. Chain hooked to leaf spring shackle on stuck trunk and bumper of pulling truck. Pulling truck gets a running start and snatches chain (yes, alcohol was involved, and no, I was not....just a spectator). After several snatches chain breaks. Flies back like a lightening bolt. Hits front edge of the hood of the stuck K5, bounces upwards and hits A-pillar, windshield and roof. Hood is wrinkled up (looked like waves in the metal), a-pillar dented in, roof dented, windshiled shattered but chain did not enter the vehicle.

I'm no trauma expert but I think if it hit someone it would have killed them.

Do you know for a fact that the chain broke? What I see from your [good] description is that the chain was hooked to an excellent energy storage device on the vehicle to which it returned. Im guessing that the chain held the load, but at peak load, where max energy was stored in that spring, the chain hook pulled free of the tow bumper and returned all spring and incidental chain elastic stretch energy to the stuck truck. Also, the loft of the flight was probably caused by the below CG hookup on the tow vehicle combined by the suspension. This would cause a forward rotational flip action at jerk.
Ill give it some more thot while I have another Irish coffee.
larry

mike69440 · Dec 17, 2007

I have wire rope 5/16" and 3/8" and Chaim 5/16 Grade 70 , 3/8" and heavy 1/2" stuff. The chain always goes on the tractor or excavator and the rope around the tree and the weaker hook on the chain to rope joint. If the line fails, the snap back is a short length of chain heading for the drawbar. (So I chip some paint.) or the wire should snap back at the tree. (Bark damage, who cares?)

I hope that is that safest. I don't thake a running start with the L39 or Excavator, my B7200, even weighted to 2500 Lbs., can't break a cable if I tried. The danger there is tractor snapback!

SPYDERLK · Dec 17, 2007

mike69440 said:
I have wire rope 5/16" and 3/8" and Chaim 5/16 Grade 70 , 3/8" and heavy 1/2" stuff. The chain always goes on the tractor or excavator and the rope around the tree and the weaker hook on the chain to rope joint. If the line fails, the snap back is a short length of chain heading for the drawbar. (So I chip some paint.) or the wire should snap back at the tree. (Bark damage, who cares?)

I hope that is that safest. I don't thake a running start with the L39 or Excavator, my B7200, even weighted to 2500 Lbs., can't break a cable if I tried. The danger there is tractor snapback!

Those chains have min breaking strengths of 18K and up - I would guess stronger than your strongest cable and certainly enuf to straighten the hooks. You would want your failure, if any, to happen on the tractor end so that recoil is away from you.
larry

wrangler6831 · Dec 17, 2007

gemini5362 said:
AS a rule I love the Mythbuster program and find it very interesting. However on the cable breaking show I have a tendency to disagree with them. Anyone that spent time on a naval ship or other big ship can probably tell what a breaking cable looks like. There are plenty of documented case of what happens on an Aircraft carrier when a catapult cable breaks or an arresting cable.

They were proving that the cable wouldn't cut a person in half. I think they both agreed that it wil seriosly injur if not kill you but it wouldn't cut you in half.

N80 · Dec 17, 2007

SPYDERLK said:
Do you know for a fact that the chain broke?
larry

Yep, it was my chain.

Again, I deny any participation in the event. I was watching this guy drive his new-to-him used Blazer into a mudhole that I knew he could not make it through. When he buried the front grill under mud and water he asked the local drunk red-neck to pull him out with his 60's era Chevy 2wd pickup. The cab was already filling with water. Well, between these two rocket scientists they had no chain. I gave them mine and moved off a safe distance (I was young and stupid.....but not stupid enough to get anywhere near these two) and watched the festivities.

The chain broke at a link on the end nearest the pulling vehicle. It was 3/8" chain but I have no idea of what quality. And this guy was snatching the heck out of it. Each time it jerked the rear of the pulling vehicle in the air.

Don't get me wrong. I'm not arguing for cables or straps or against chains (I use chains for 95% of my pulling needs) I'm just pointing out that under the right conditions an improperly employed chain can be as lethal, if not more so than, an improperly used strap or cable.