Crane rigging

[NebClimber]

I've been looking at some of the recent picutres of crane removals and keep wondering what you guys use to attach the limb to the crane. What does the rigging from the end of the crane's cable to the limb consists of?

I'm not planning on using a crane anytime soon - just curious.

 

[MasterBlaster]

Slings, straps, or cables.

I prefer slings.

 

[Gord]

Slings are nicest to work with, crane operators seem to prefer to use cable tho. Cables and clevises are what I see used most around here.

 

[TheTreeSpyder]

Cable and clevis here too; synthetic slings should get clevises for sure i think.


In the OSHA lifting/RigginG Manual , the sling discussion starts on pg. 49; and hammering down specifically treated on pg.61 (not jamming choke down to flat against wood).

Also, in the AirForce/ Engineering Crane Certification Manual

Very good manuals on cranes, rigging, lifting, balancing and all the loading that takes place.

 

[MasterBlaster]

Nice links, Ken. I use a clevis with a sling 90% of the time.

 

[rbtree]

Thanks Spidey, informative links.

 

[Gord]

And always make sure that the clevis bolt is against the loop and not the running part. It's a bad thing if it gets unscrewed.

 

[MasterBlaster]

Theres that 'saddling a dead horse' thing again!

 

[TheTreeSpyder]

Speaking of deceased ponies.....Found those 2 links when i was looking for formulae for the angle of leveraged lean that Dave Spencer sent me. Looking for the same math with the tree as a fixed boom, as the pulls on a crane at different angles/ boom extensions. So the spreadsheet at TB for calculation of leveraged lean in trees, would also be the same math, and do like calculations for cranes for leveraged load in foot pounds to be spread out by the leveraged pattern and size of the crane's / outrigger footprint on the ground. Given the leveraged length of the boom, and weight; you can see how quickly the loads climb as the degrees of the boom changes, before motion is even calculated in!

 

[kurtztree]

Do you guys that use slings just use a choker hitch when lifting logs from the tree? Did it ever slip alittle? I am thinking about using a crane for a tree that is close to a house so any info would be helpful. This is going to be the first tree with a crane for me. I will search some more older threads to.

 

[MasterBlaster]

Pretty much, with or without a shackle. I've never had one slip yet. Start your cut on the shackle side, and keep your head below the cut as you finish.

 

[Crofter]

If your sling is long enoough double wrap before you choke. I have heard that on a very smooth stem when the sap is running that there could be some danger of them slipping the bark off.

Frank

 

[rbtree]

I have a lot of pics from the big elm we just craned out..to busy to post them just yet...working 12-14 hour days thanks to our windstorm...

On big wood, we usually use a wire choker or sling. On smaller stuff, a sling is nice and easier to use. If a clevis is used, it's much simpler as you dont have to take the sling off the crane ball to thread it through itself. On lateral branches, it is good to use two slings, to balance it as best possible.

Also, it's good to use two slings, even if attaching them in the same place, for that extra margin of safety.

 

[murphy4trees]

The shackle on the sling allows both eyes to stay clipped to the hook making a basket type hitch, which mazimizes strength. The eye is the weak link...
Richie Knowles is "THE" operator around here... I never saw him do it, but he said when he's taking a large tulip log with spring bark.... he repeatedly slams on the cables to tighten them up and rip off the loose bark if it coming... seems like cutting a little notch would help..

 

[rbtree]

I don't follow, Murph. I'd never use a basket arrangement (even if using two slings) when craning a load that might not stay horizontal. And if both eyes are on the crane ball, what use is the shackle? Am I missing something/

 

[Nickrosis]

Spidie, those are fantastic links - I'm gonna print it out and start making some calculators with the equations like you did.

Come to think of it. I hate you! You're giving me more work to do!

 

[ROLLACOSTA]

i like too use webbing slings..im not keen on wire ..hurts my little hands sometimes

 

[murphy4trees]

RB,
both eyes always stay on the hook... That is the "basket effect"

The shackle is used to choker the sling around the wood. The pin always goes through the bite in the sling so as the sling runs through the shackle it doesn't accidently unscrew the pin..

I thought that was standard operating procedure in crane rigging though it is conspicuously missing from Chisholm's crane video...

 

[rbtree]

I see, Dan. You're doubling up the sling....which might be handy if it's too long, or you want to increase safety margins.

 

[kurtztree]

First crane job I ever did today crane operator was very smooth and it was the first job he ever did with a climber every other time it was only if other tree companys had buckets. It was a 40 ton crane 95' reach without jib. It was fun. Hopefully here are some pics.