# Zip line suggestions (loop runners w/carabiners or trolley using top pulley return)



## Tree Raptor (Jan 1, 2012)

have a 65' bucket but to date have not used zip lines. On occasion we have chipper off bucket truck and on a 4wd 3/4ton pickup and chip into woods. On some of these occasions a zip line to lower branches would be very efficient. Looked at some Youtube clips trying to see what would be best setup. I don't know whether using lots of loop runners with biners is best or rigging up a trolley device on the zip line with a pulley up high for "return" is best. Just don't have any experience using a zip line but know it would save lots of time when rigged. 

If using loop runners on limb then snapping carabiners to zip line, will the weight of the limb cause any damage when the biner rides down (free fall speed) or is it best to use a trolley. 

I would imagine that small limbs the loop runners would be quick and easy while doing large to very large might require a different option. 

I would think that the strongest carabiners purchased would be the best and safest option ...

Are the dynema loop runners better ?


Look forward to hearing suggestions and techniques.


----------



## the Aerialist (Jan 1, 2012)

*Skip the trolley ...*

And get lots of 'biners set up on runners. Faster and more efficient than running the trolley back and forth.


----------



## 2treeornot2tree (Jan 1, 2012)

When you start making zip lines, just remember that you dont want them super tight. If they are too tight, you can end up making your forces on the anchor points double your weight of the limb your zipping down. I know in the fire company, we were taught to leave 10 % dip in the line. example 150' zip line, then you would leave 15' of dip from horizontal anchor points. I dont know if it would be the same when you have one anchor point way up in a tree and the other on the ground. I would just use webbing loops, rope loops and carabiners until i got to big stuff, then i think i would switch to pulleys to reduce the friction on the zip line rope.


----------



## squad143 (Jan 2, 2012)

I work on hilly terrain quite a bit and use zip lines wherever feasible to save time. Mostly for limbs. On very rare occasions will I use them on heavy wood.

I won't get into the dynamics that the stress puts on the tree ( you should know what you're doing when using zip lines, especially on dead trees) however I'll stick to answering the question you asked in your post.

Stick to plain loop runners, forget the dyneema. You should not be submitting a zip line to the forces that would require you to use dyneema. Same thing with the Biners. The Biners attached to the loop runner in this Sherrill kit are suffice for most limbs. Speed Line Kit : SherrillTree Tree Care Equipment

Use 4 foot or longer loop runners. Anything shorter is going to be a pain and you will most likely end up nicking them when cutting the limbs anyways. If there is extra length in your runner, it will hang(hopefully out of your way).

Just using Biners has a little quicker set up time, but Biners alone, with a heavy load is harder on the zip line. (Think friction) However, on a low slope with a light load, I'll use a pulley so that the limb will reach its destination.

One thing I will do, is use a pulley and attach several loop runners (girth hitched to limbs). Once you cut the last limb, all the limbs will travel together to their destination.

One thing you definitely want to avoid is "bounce" in the zip line. The forces that a midline bounce can put on a tree (that usually you are tied to) could be catastrophic. If I'm concerned at the speed, and or, potential bounce when lowering an item on a zip line, I'll use another rope attached to the pulley to control the decent. The decent can be controlled either by the climber, using a small port-a-wrap, in the tree. Or by a groundsman, using a port-a-wrap at the base of the trunk and through a false crotch near the tie off for the zip line.

Hope this helps.


----------



## squad143 (Jan 2, 2012)

Found this other post on zip lines: http://www.arboristsite.com/commercial-tree-care-climbing/114556.htm


----------



## pdqdl (Jan 3, 2012)

Skip the trolley, unless you have a need to travel further with each load than will easily slide down your rope. Almost nothing sucks like getting a branch stuck up in the air where you can't get it down safely.

I use these for heavier loads when I don't want to burn up the rope or my cheap aluminum carabiners: Revolver &mdash; Products &mdash; DMM Climbing
Using this carabiner is MUCH faster than using a pulley setup, and almost as good. I bent my 7500lb rated pulley with what I thought was an easy drop, and I have never hurt any of my DMM Revolver carabiners. At almost $30 each, I don't keep too many of them around, though. If I made more money at this, I would do all my speedlines with them or a complete pulley/trolley. If you decide to use them, you need to make sure that the roller stays on the rope. If it gets upside down, it will hang up and cause problems.

Note: DMM has a disclaimer in the fine print, stating that this product is not for zip lines, mostly on account of accumulated heat. I presume that is not a problem on the short zip lines used in tree work. I always make sure that I keep mine with a spot of oil to make sure they aren't running hot & dry.

If you are bringing down some serious weight, then put a control line on it to regulate the speed and most of the weight, then let the speedline setup control just the direction. A trolley with even less friction than the revolver 'biner can help here, too, if the run is too long.


----------



## Tree Raptor (Jan 5, 2012)

*Heavy Duty Trolley for Zip line (update info)*

was looking for a heavy duty trolley for a zip line and CMI makes one called "Trolley HD" rated at 22,000 with rope capacity of 3/4".

Trolleys -- CMI Corporation

I called CMI and talked to engineering and they said it was good to use in tree removal applications however you needed to purchase the Aluminum rigging plate which afixes to the trolled by unscrewing the 2 knurled lower knobs on the side and putting the aluminum plate inside and replacing the knobs. This plate is rated at 14,000 and he said that if you wanted even more strength that you could purchase 2 of these aluminum plate as the trolley was designed to fit two of them side by side between the side plates of the trolled and you could double your strength. He did say that you could use the trolley without the rigging plate by just attaching the biner to either of the two lower knurled knob axles but that seems to me to put the load off off center. He also advised that the holes in the center of the trolley were not intended for a biner nor would it fit through them. Nice to know. So looks like the rigging place is a must. 

This is the aluminum rigging plate "Maxi rigging plate"

Aluminum 'Maxi' Rigging Plate -- CMI Corporation

I believe Baileys sells them both. Unless I can find something stronger I might end up going with this one.


----------



## pdqdl (Jan 5, 2012)

The problem with great big, heavy duty speed line equipment is that by the time you really need to use something that strong, you are likely to put such enormous side loads on the tree that you end up killing yourself by pulling the tree down. Most removals are done on failing trees, anyway.

I do not recommend zip lining big pieces of the tree unless you do an awful lot of it and have a lot of experience. But then, I am still a bit new to the technique also.


----------



## Tree Raptor (Jan 6, 2012)

*HD Trolley cont'd*



pdqdl said:


> The problem with great big, heavy duty speed line equipment is that by the time you really need to use something that strong, you are likely to put such enormous side loads on the tree that you end up killing yourself by pulling the tree down. Most removals are done on failing trees, anyway.
> 
> I do not recommend zip lining big pieces of the tree unless you do an awful lot of it and have a lot of experience. But then, I am still a bit new to the technique also.



I hear you pdqdl, if there is one thing that I have learned on this thread is extreme caution on side loads. I have always had a tendency to go over kill on gear to be on the safe side. Just because I have such a heavy duty trolley I probably will never even come close to its capacity. Since this will be a first for me I will start out small and slowly work up to heavier items watching carefully as I do to see the dynamics happening. I for sure till take the advise of (I can't remember who posted it) but to use large block and porty to first hang the larger stuff, then transfer over to zip line, when it is doable and will save time.


----------



## ForTheArborist (Jan 7, 2012)

the Aerialist said:


> And get lots of 'biners set up on runners. Faster and more efficient than running the trolley back and forth.



This is good idea for a lot of light branches. Instead of piling them all on one load, send the down one at a time. I use clips instead of carabiners so I'm not messing with unlocking each one. When I'm running low, the ground crew sends a bunch back up. I do this a lot on Palm Trees that are over the landscaping.


----------



## pdqdl (Jan 7, 2012)

I use these on light stuff: http://www.baileysonline.com/itemdetail.asp?item=21358&catID=19

They are cheap and strong, they have a nice big gate opening, and they are much lighter than the hardware store spring clips that have a very limited gate opening and don't slide on a rope worth a hoot.

These things: Peerless Spring Link  10mm Size | Shackles + Quick Links | Northern Tool + Equipment


----------

