Come-along vs. Rope mechanical advantage system

[Groundman One]

Been toying with the idea of buying some good pulleys from Sherrill, some rigging tails, and making my own mechanical advantage setup. My climbers says there's no point since we have a come along that seems to do the job and is less expensive and has more pull. We've used the come-along to tension the porta-wrap line and to pull trees.

$50+ for a come-along or $200+ for a rope mechanical advantage setup.

What, if any, are the advantages of the rope system?

 

[Del_]

Maasdam rope puller plus pulleys for M/A.

 

[RajElectric]

+1 on the maasdam and pulley.

 

[Groundman One]

Maasdam rope puller plus pulleys for M/A.

That's what my climber has. He picked it up for about $25 at a yard sale. We used it last week with the porta-wrap and it was fine. Rigged it under the porta-wrap on a whoopie sling and had it pulling on the main line going to the porta with a prussic at the end of the rope line running through the puller. It was great.

Just wondering why some people use or prefer to use a rope system since it's more expensive.

 

[Hoowasat]

Just wondering why some people use or prefer to use a rope system since it's more expensive.

I already had rope, carabiners and know-how to tie a Blakes, so two of the double-sheave pulleys only cost me about $60. Why buy the whole system if you already own most of the components? Besides, the pulleys stow in a much smaller space & they're easier to rig while aloft.

 

[Groundman One]

I already had rope, carabiners and know-how to tie a Blakes, so two of the double-sheave pulleys only cost me about $60. Why buy the whole system if you already own most of the components? Besides, the pulleys stow in a much smaller space & they're easier to rig while aloft.

I hear ya.

I was going to get two pulleys at $60 each and a couple of rigging tails, and maybe one more good carabiner. Nice and clean and new. But the rope puller my climber has works really well. We just the leave the rope end in the puller bare and tie it as a prussic to the line feeding into the porta wrap.

Again, I was curious if there was some clear advantage to the rope system that I was unaware of that made the extra cash outlay worthwhile. Sherrill has a nice 5:1 rope system but with the tax it's nearly $400. but the 10:1 rope puller is maybe $75. I'm sure some people prefer the rope system, was curious why.

 

[Del_]

I already had rope, carabiners and know-how to tie a Blakes, so two of the double-sheave pulleys only cost me about $60. Why buy the whole system if you already own most of the components? Besides, the pulleys stow in a much smaller space & they're easier to rig while aloft.

I've often used two of the SMI double sheave pulleys and the Maasdam rope puller. This gives a 4/1 M/A and multipling the puller's 1,500 rated pull X 4 with a 3/4 rope going into the tree being pulled. I don't use this rig for lowering. If we've got serious lowering and lifting to do the GRCS comes gets used.

 

[Groundman One]

I've often used two of the SMI double sheave pulleys and the Maasdam rope puller. This gives a 4/1 M/A and multipling the puller's 1,500 rated pull X 4 with a 3/4 rope going into the tree being pulled. I don't use this rig for lowering. If we've got serious lowering and lifting to do the GRCS comes gets used.

Are you going over the WLL of your rope and/or connectors when you use a rope puller and double sheave pulleys?

 

[Del_]

Are you going over the WLL of your rope and/or connectors when you use a rope puller and double sheave pulleys?

Not usually. We use galvanized clevis's Vs. carabiners.

http://www.treestuff.com/store/catalog.asp?category_id=231&item=1359

 

[Groundman One]

Not usually. We use galvanized clevis's Vs. carabiners.

http://www.treestuff.com/store/catalog.asp?category_id=231&item=1359

Why kind of rope are you using?

I'm going to grab some 3/4" Dynasorb soon. But even that stuff maxes out at 2300lb WLL.

 

[imagineero]

The main advantage to using pulleys is that a lot of guys already have them. I've got a bunch of pulleys sitting around, none of the double/tripples, but plenty of singles in a bunch of sizes. I don't use them for lifting, but for technical pullovers it's hard to beat the control and gearing you can get. By gearing I mean you can tune the system to get the amount of pull you need.

I'll usually start with a 3:1 using 7/8" with 9 tonne pulleys, and stack another 3:1 behind that. Stacked combinations multiply each other, with a bit of loss, so that gets you somewhere around 8:1. I can then stack another 3:1 behind that, and another 31 behind that if needed, using progressively smaller ropes/pulleys. The ropes at the tail end see less weight that the ropes at the business end. It's pretty easy to achieve 50:1, so one Groundie can pull over a substantial tree. It gives a lot more control than, say, a rope tied to a truck. Like comparing a scalpel to a sledgehammer. It is slow, and you may have to reset the final 3:1 multiple times to achieve the desired pull at the business end. I usually put some progress capture in there too.

Variations on this theme can be useful if you need to climb a partially failed tree to climb it. 2-3 guys ropes can stabilise most trees enough to make them safe to climb.

 

[RajElectric]

I have these for lighter loads. Was a good place to start for me. Price point was good, quality is OK. They come in handy. It's not the be all end all, I just ordered the individual pulleys elsewhere on the seller's page.

http://www.ebay.com/itm/Twin-sheave...120?pt=LH_DefaultDomain_0&hash=item3f10603110

 

[Del_]

Why kind of rope are you using?

I'm going to grab some 3/4" Dynasorb soon. But even that stuff maxes out at 2300lb WLL.

Sampson 5/8 and 3/4 inch stable braid. I don't know the exact loads I've placed on the pulling system but I doubt it ever exceeds 1,500lbs. My most often used tree pulling over system is 5/8 with a midline tie in to 1/2 three strand running though a block back to the Maasdam. Sometime on easy pulls it's just the 1/2 three strand with the Maasdam doing a straight pull. Got to watch the straight Maasdam pull though as it can get you in trouble.

http://www.treestuff.com/store/catalog.asp?category_id=3&item=1832

 

[Groundman One]

I have these for lighter loads. Was a good place to start for me. Price point was good, quality is OK. They come in handy. It's not the be all end all, I just ordered the individual pulleys elsewhere on the seller's page.

http://www.ebay.com/itm/Twin-sheave...120?pt=LH_DefaultDomain_0&hash=item3f10603110

Nice. And portable as well.

I figured a small setup would fit right in the bag with my porta-wrap and whoopies.

 

[Groundman One]

Sampson 5/8 and 3/4 inch stable braid. I don't know the exact loads I've placed on the pulling system but I doubt it ever exceeds 1,500lbs. My most often used tree pulling over system is 5/8 with a midline tie in to 1/2 three strand running though a block back to the Maasdam. Sometime on easy pulls it's just the 1/2 three strand with the Maasdam doing a straight pull. Got to watch the straight Maasdam pull though as it can get you in trouble.

http://www.treestuff.com/store/catalog.asp?category_id=3&item=1832

What exactly are you getting at there? (Last sentence in bold.)

Nice rope.

This is what I'm getting: http://www.sherrilltree.com/Dynasorb-Energy-Absorbing-Rigging-Line-3-4#.VYn9t2cg85s

Just the Dynasorb!

 

[Del_]

What exactly are you getting at there? (Last sentence in bold.)

Nice rope.

This is what I'm getting: http://www.sherrilltree.com/Dynasorb-Energy-Absorbing-Rigging-Line-3-4#.VYn9t2cg85s

Just the Dynasorb!

What I'm getting at is the Maasdam rope puller using no M/A can get to be hard to crank, meaning it is reaching it's pulling limit. A 2/1 system works so much better as I can toss a throw line high up into the tree, pull the 5/8 rope up and do a base tie above the felling notch. My 5/8 is 150ft long and the 1/2 inch three strand which the Maasdam requires is 120ft. long. Quite often when pulling trees over we'll tie a pulley to the base of another tree and do a redirect to get the Maasdam operator out of the felling area and sometimes even using a tree right next to the one being felled for the Maasdam anchor. I do this often when felling trees solo.

 

[Groundman One]

Del,

Let's say you just want to max out the tension on the line going into the porta-wrap, that being the case, the WWL of the tensioning/pulling hardware can be below or well below the requirements of the main line, connectors, and lowering device obviously, right? It's only a temporary pull, not a retaining line.

The scenario is putting max tension on a securing line coming from a leaner that my climber is in. If I have 100'+ of pull line going from the leaner, bridging in a center tree, and coming back down to ground level in a third tree into the porta-wrap, it's not easy to really put some good English on that line by hand.

The point being that the M/A setup can be very small and portable I would think. Whereas a true pulling line as what you described above has to be in balance with the strength of all your components.

Great post above.

 

[imagineero]

Why kind of rope are you using?

I'm going to grab some 3/4" Dynasorb soon. But even that stuff maxes out at 2300lb WLL.

It's worth noting that wlls are usually 1/5 of breaking strain to account for shock loading and increase the cycles to failure. For the relatively static purpose of lifting/pulling you can safely use a WLL of half the MBS.

There's a thread somewhere on here that breaks down the realities of WLL, shock loading, MBS, CTF etc

 

[Del_]

Thanks Groundman. That was an old drawing I had on my hard drive.

I see now that you are talking about guying a tree that the climber is in. I like to use two guy lines if at all possible. If a limb or piece of trunk were to hit a guy line it can put a large load on the tree being guyed.

 

[Groundman One]

It's worth noting that wlls are usually 1/5 of breaking strain to account for shock loading and increase the cycles to failure. For the relatively static purpose of lifting/pulling you can safely use a WLL of half the MBS.

There's a thread somewhere on here that breaks down the realities of WLL, shock loading, MBS, CTF etc

I'd like to see that.

I try to be conscious of the limits and conditions of all the hardware and ropes in any given setup. I spend a good deal of time securing things for my climber, and when he asks me if things are secured, I like to know everything is as it should be.