need advise on setting up 4 or 5 to 1 pulley for felling trees & possible port-a-wra

[Tree Raptor]

it looks like the video is a 5:1 (check out this)

got some good feedback from everyone, thank you. The article on the double prussik vs Gibbs was excellent and answered my question perfectly. Everyone should check it out.

In the continuing saga (debate) wether the orig video posted initially was a 5:1 or 4:1 as some have expressed, I copied a picture from a link from the "mechanical advantage" website posted by someone else and it shows a picture of a 5:1 which is the exact same setup as in the original video so it is a true 5:1 mechanical advantage system in that video.

and after reviewing comments on prussik slippage and gibb wear on pull line I think I will stick to just making in slip knot (put a bowline in the pull rope midsteam) and just attach the first pulley to it. I just cannot see a better and safer way to connect the first pulley, no damage to the pull line and no slippage and one less piece of equipment to have)


http://www.swe.org/iac/images/plly_081.jpg

 

[2treeornot2tree]

Early on I bought a block and tackle setup but haven't used it in years, now for smaller stuff I have a couple of manual rope pullers that I use with 3 strand rope, but I also have a gas powered capstan winch that I can put on if I want a continuous pull. I also have probably the same 3 ton comealong that you have with about 30' of Amsteel blue. It came with a pulley mounted on a hook which I've never used, but wouldn't that double the force applied? I carry the 3 ton in the dump truck in case I have to pull it out from somewhere.

If you use the More power puller comalong without the pulley and hook, it is only rated at 1.5 ton. To get the full load capacity of the comalong of 3 ton you need to use the pulley and in essence get a 2:1 ratio on the amstel rope. It takes twice as long to pull something over, but it sure is alot less force needed to crank the handle.

 

[2treeornot2tree]

I just watched it again. It is a 4:1 with a direction change. It is a common mistake people make when making haul systems. To make a 5:1 you would need to have 3 pulleys at the tree.

 

[the Aerialist]

If you use the More power puller comalong without the pulley and hook, it is only rated at 1.5 ton. To get the full load capacity of the comalong of 3 ton you need to use the pulley and in essence get a 2:1 ratio on the amstel rope. It takes twice as long to pull something over, but it sure is alot less force needed to crank the handle.

Yes, that's the exact model I use, I guess 3000# of force is all I've ever needed. The end (9:20) of this video shows me using it along with a floor jack to drop a steeply leaning tree:

[video=youtube;MmM98L_hQm0]http://www.youtube.com/watch?v=MmM98L_hQm0[/video]

My bull rope (19,500# tensile) has a spliced eye on the end and I use that to attach the wench, thereby avoiding either prussic or gibbs type device that could damage the rope.

 

[no tree to big]

AA i'm suprised at 9:36 the jack did not get spit out... and I think you ran out of notch too shoulda been a nice wide one

 

[squad143]

2treeornot2tree

Check this site out: http://www.disasterengineer.org/LinkClick.aspx?fileticket=M7QDgdTHWOw=&tabid=57&mid=395

Go to page 13 of 62. There is a box in the right hand side (middle). Title is 5:1 Simple Mechanical Advantage Pulley System

This is the system in the video.

If you have info to show otherwise, I'm always interested in learning.

 

[squad143]

Here is the pic from the link:

 

[squad143]

AA i'm suprised at 9:36 the jack did not get spit out... and I think you ran out of notch too shoulda been a nice wide one

:agree2:

 

[the Aerialist]

Actually that was perfect ...

AA i'm suprised at 9:36 the jack did not get spit out... and I think you ran out of notch too shoulda been a nice wide one

The jack gets spit out when the tree falls and the notch was just right. You've obviously never tried it.

 

[ForTheArborist]

AA, nice vid. How do you guys keep the gear so bright? The cameras can't even pick up that color 100%. So bright that there's a blur around the chirts and head gear.

 

[imagineero]

Try googling 'prusik test load cell' for a whole bunch of pdf's of guys doing load cell rated fail tests on all types and sizes of prusik/rope combinations, knots and mechanical ascenders. The thing that surprises me on a lot of the tests if that as ropes/slings get older, they get a lot weaker. Prusiks are often stronger than mechanical ascenders, but still nowhere near the strength you might think you'd be getting. Many 1/4" prussiks fail at 1500lbs. Less if old. Mechanical ascenders/rop grabs really should not be used for this type of application though in my opinion. I havent yet seen load cell testing of the tenex prusiks that many of the kits come with.

I have a 5:1 fiddle block combo from a large yacht. Cant remember what it's rated too, but quite a lot. It's the main sail adjuster. It has a cam cleat as the lock. I dont use it all that often, but when I do it's handy. I keep it rigged with 150' of 1/2" line.

Remember that you can stack your mechanical advantage also. The most common combo I use is a 2:1 behind another 2:1. I tie the main line to the tree, and use a bowline at the end. I attach a high rated bearing pulley to the bowline. I then tie another rope to whatever my anchor is, through the pulley and back. That's your 2:1. I then tie another bowline in this 'pull rope' and attach a progress capture pulley to it. I put the progress capture pulley here because it is under a lot less stress than the first pulley. Another rope from the anchor to the second pulley gives me a 2:1 pulling on a 2:1 for a theoretical 4:1. You dont quite get 4:1 because of losses but it's good.

This is an easy thing because you've often already got a couple pulleys out and ready to go. You can stack all kinds of combinations, like 2:1 behind a 5:1 etc. One thing worth remembering is which parts of the system are getting different loads. Always put the strongest part of your gear closer to the tree in the system ie; put your biggest bull rope from the tree, then your biggest pulley and next biggest rope etc, put the weakest/smallest parts of the system farther away from the tree because they will see a lot less weight. For example, If I was going to stack my 2:1 and 5:1, I would definitely put the 2:1 first. My big pulley is rated to 20,000lbs, and I'd put my 7/8" double esterlon on it. Then I would attach the 5:1 on the pull of the 2:1, because it's rated for a lot less weight and only has half inch rope. With stacked systems, the final 'pull' may only be seeing as little as 1/10 of the load.

Shaun

 

[the Aerialist]

The blur is my halo ...

AA, nice vid. How do you guys keep the gear so bright? The cameras can't even pick up that color 100%. So bright that there's a blur around the chirts and head gear.

Actually I bought the crew new safety green shirts for the job, those shirts aren't quite as bright now.

 

[tree MDS]

Comealongs are so 80's... I mean seriously, I can't imagine a real treeguy going there, just saying. Click, click.. lmao! Some serious porch material right there!

 

[2treeornot2tree]

I thought about getting one of those capstan winches, but what do you do it you have to stop pulling. Shut off the motor? Does anyone have one, and if so how does it work for pulling over trees?

 

[the Aerialist]

I thought about getting one of those capstan winches, but what do you do it you have to stop pulling. Shut off the motor? Does anyone have one, and if so how does it work for pulling over trees?

After you put 2 ~ 3 wraps on the capstan the tale of the rope passes through the fairlead which is just a smooth hook to guide the rope. The amount of tension or "pull" you put on the tail of the rope controls the amount of "pull" that the capstan puts on the tree. You have a fine degree of control here, up to the limit of the winch. If the motor stalls or quits you still have all the holding power of the capstan.

 

[no tree to big]

The jack gets spit out when the tree falls and the notch was just right. You've obviously never tried it.

very obvious how the jack would get kicked out... think physics and just stare a minute and the tree was almost perfectly vertical when the hinge broke yes much better then the start but generally you try to have it leaning a bit in the general direction of the desired fall so no the notch was not just right it was a bit off and your right NO!!! I have never tried that because its just redicuolus to have a floor jack out on a tree job, ok the last job I did I had a floor jack in the back of my pickup but it was because I needed it to change a tire earlier that day...

 

[AT sawyer]

Consider a Griphoist. Pricey new, but you can get them on Ebay for a couple hundred bucks. Unlimited wire rope travel, nearly indestructible, and can straight pull 2000lb. Add blocks to redirect pull or for more power, and the wire rope won't stretch.

View attachment 212968

 

[squad143]

Actually that was perfect...... You've obviously never tried it.

AA, you have seem to have gathered quite a reputation on here. I'm not going to jump in, call you names and such...... But, that was far from perfect. I don't know where you learned your trade, but that face cut was too shallow.

Jacks on trees...... Only heard of them being used on huge trees. Plus, they did not have wheels on them. We're you thinking outside the box? Most likely. Have I ever tried it, No. Never will, not in that configuration. It worked, I'll give you that, but it was far from perfect.

Eventually, if you push the enevlope long enough, you'll end up with a paper cut. There are alot safer ways to remove that tree.

No one has ever called 911 because someone did something smart.

Plus, I have to ask. Why would someone drop their saw on the ground like that? (8:56)

 

[jefflovstrom]

I finally gave in and watched the whole video. I could not turn away, like an accident on the other side of the freeway. Wow, I would be truly feel stupid. Hey Doug, around 3:50 or so, did the guy get hit from the swing? Give that lady a hard hat. Dude, you are insane and I hope you do not kill yourself or your groundie.
Jeff

 

[mattfr12]

Try that stalpen tree jack surprisingly its really really strong when dropping trunks don't have to set to many ropes anymore. cleared a lot with it and didn't have to take the wedges out of my pocket.