i don't do a lot of crane work, but i see all these vids of cranes failing while doing tree work, 9 times out of 10 is it climber or crane operator who is to blame? and if you have a crane go over on your job is you black balled by the other crane companies? it seems like an expensive mistake.
Crane questions
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custom8726
ArboristSite Guru
It's a balance of alot of variables to ensure things like this do not happen. usually its a combination of bad judgment that cause crane's to tip. Being educated in all aspects of the operation is key, from crane set-up, to qualified (TREE) crane operators, to being able to acurately judge weight's from scales and / or experience, etc, etc... Calculated risk's is what it comes down to, the more negative factors you can eliminate the better your chances for long term success will be..
John Paul Sanborn
Above average climber
Quite often it is the crane operator, like the one with no cribbing on aggregate ???
I have seen a few cases where the climber thought he could get away with a bigger chunk then he should have.
Why worry about being black balled? Just work as if you don't want to risk an accident.
In my experiance, you rarely have a pick that would over load a large crane if you are not trying to take half the tree all at once.
Every lift is critical, don't try to max it out.
I have seen a few cases where the climber thought he could get away with a bigger chunk then he should have.
Why worry about being black balled? Just work as if you don't want to risk an accident.
In my experiance, you rarely have a pick that would over load a large crane if you are not trying to take half the tree all at once.
Every lift is critical, don't try to max it out.
tree md
Addicted to ArboristSite
It takes two
It takes two. As mentioned above you need a good operator who is experienced at doing TREES. Trees are a different animal, unlike any other type of crane work. However it also takes a climber who is experienced at aerial lifts as well as log weights. Especially when working in the blind (like when picking logs over a house where operator and climber can not see each other). Whenever I bid a crane job first thing I do is figure out where the crane will set up and how far he is going to have to get out with the boom. I will often pull tape and measure the distance. Then I call the owner of the crane service (I don't have my own crane) and tell him the situation, what the set up looks like, the distance the boom is going to have to get out and ask what he recommends as far as size of crane. Often we will meet and look a job over before we do it to make sure we are on the same page.
I would say that any service that flipped one of his cranes would play hell getting him back out to another job.
It takes two. As mentioned above you need a good operator who is experienced at doing TREES. Trees are a different animal, unlike any other type of crane work. However it also takes a climber who is experienced at aerial lifts as well as log weights. Especially when working in the blind (like when picking logs over a house where operator and climber can not see each other). Whenever I bid a crane job first thing I do is figure out where the crane will set up and how far he is going to have to get out with the boom. I will often pull tape and measure the distance. Then I call the owner of the crane service (I don't have my own crane) and tell him the situation, what the set up looks like, the distance the boom is going to have to get out and ask what he recommends as far as size of crane. Often we will meet and look a job over before we do it to make sure we are on the same page.
I would say that any service that flipped one of his cranes would play hell getting him back out to another job.
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custom8726
ArboristSite Guru
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Texas Traveler
ArboristSite Guru
You know I have spent near a lifetime on cranes but never picked a tree in all my time in the seat.
With that said & the wild pictures I have looked at on this site there is a bit more to it than some think.
#1 rule If it is not on the crane chart don't do it & always set up on firm level ground with crane matts to spread the ground pressure
#2 rule There is a hard fast rule most operators live by, know the weight of the load & the limits of the crane at all times.
#3 rule keep the boom over the load at all times
#4 Talk over all lifts with the crew, every single one so they know what to expect.
# 5 Give yourself & crane a safety factor of at least 25% of allowable load, we used to try for a 1/3.
You can figure the weight of the trees, it may take a little extra but it is worth the trouble to stay out of trouble.
With that said & the wild pictures I have looked at on this site there is a bit more to it than some think.
#1 rule If it is not on the crane chart don't do it & always set up on firm level ground with crane matts to spread the ground pressure
#2 rule There is a hard fast rule most operators live by, know the weight of the load & the limits of the crane at all times.
#3 rule keep the boom over the load at all times
#4 Talk over all lifts with the crew, every single one so they know what to expect.
# 5 Give yourself & crane a safety factor of at least 25% of allowable load, we used to try for a 1/3.
You can figure the weight of the trees, it may take a little extra but it is worth the trouble to stay out of trouble.
John Paul Sanborn
Above average climber
The easy way is to take a few test picks to see if the climbers estimations are close. Unless doing small pics I try to use a crane with a scale, load meter, or whatever it is called, on the line.
causing the alarm to sound is a sign that you are not working in the SWL vs max for current configuration.
Tex used a 66-75% of max rule on known lifts. We are often making a SWAG on our pick weights, so we should be more in a 25-50% of max.
If you have a 8000# max to go over a house, would you try for 6000# of stem, limb and leaf?
Do you know guys who assume the O.E. is fudging his numbers downwards, and acts (in)appropriately?
B-Edwards
Addicted to ArboristSite
I have always let the crane op call the cut,(if I trusted him) we used 2-way radios also. The climber also needs to know what's going on and if he feels it is wrong don't do it. This is one of those times that everyone needs to be qualified on the job, keep the drunks and dope heads away and anyone else who doesn't have both oars in the water.
custom8726
ArboristSite Guru
No likely, but in certain circumstances yes. For instance if your are picking the base log and you can cut it at ground level and there is room to lay the pick down if in fact it ends up being to heavy, then I could see working that close to your max. All 3 cranes we use have scales and I try to comunicate with the C.O. before and after every pick. Generally if we had a 8k max capacity I would try to make the picks around 4k allowing plenty of room for unexpected variables. For instance a strong wind gust after the pick can be a recipe for disaster if you are nearly maxed out and then this 6k top swings another 30' away from the crane and well you can guess the out come from there if you did not properly prepare..
TreeTopKid
ArboristSite Guru
corsair4360
ArboristSite Member
Lifting Wood with a Crane
I worked on helicopter logging analysis in the early 70's. The most challenging part of the whole operation was figuring out what the log density actually was for a turn and therefore the true log weight. Since the helicopter is very expensive in terms of dollars per hour, the challenge was how to load it to the 90% or so of its maximum load and not overload it for each turn. An overweight turn was the cause of a crash wrecking one of the Erickson S-64's years ago.
The relevant part was that the tables for log weights are not suited to estimating the weights accurately for lifting them with things like helicopters or cranes were the lifting device has a hard limit on the weight they can lift.
The reason the weight tables are not good for lifting estimates is they are averages, and the data the tables are created from has high variability for wood, especially standing trees. What this can literally mean is the same sized log can have dramatically different weights. Trees are not like steel or aluminum where the weight of a given shape is quite certain in terms of pounds per lineal or cubic foot. Tree weight for a log or section of a tree is harder to work out since the variables are rotten, sound, species, moisture content, actual wood volume for the proposed lift, etc. Even for a single species the variation is large. The data in wood books are based upon sound kiln dry wood, which is not the case for standing wood.
For crane work, like helicopter work, I would use the heaviest weight per cubic foot you can find as the basis for your estimates. The best you could have is from actual experience in your locale and the particular species in question.
As one poster said the newer cranes have weight measuring equipment, but that is a catch 22 since that only works once you have the section of the tree cut and weight is on the crane. If you underestimated the weight of the tree section, then you have the possibility for breakage, the crane falling over or such.
I worked on helicopter logging analysis in the early 70's. The most challenging part of the whole operation was figuring out what the log density actually was for a turn and therefore the true log weight. Since the helicopter is very expensive in terms of dollars per hour, the challenge was how to load it to the 90% or so of its maximum load and not overload it for each turn. An overweight turn was the cause of a crash wrecking one of the Erickson S-64's years ago.
The relevant part was that the tables for log weights are not suited to estimating the weights accurately for lifting them with things like helicopters or cranes were the lifting device has a hard limit on the weight they can lift.
The reason the weight tables are not good for lifting estimates is they are averages, and the data the tables are created from has high variability for wood, especially standing trees. What this can literally mean is the same sized log can have dramatically different weights. Trees are not like steel or aluminum where the weight of a given shape is quite certain in terms of pounds per lineal or cubic foot. Tree weight for a log or section of a tree is harder to work out since the variables are rotten, sound, species, moisture content, actual wood volume for the proposed lift, etc. Even for a single species the variation is large. The data in wood books are based upon sound kiln dry wood, which is not the case for standing wood.
For crane work, like helicopter work, I would use the heaviest weight per cubic foot you can find as the basis for your estimates. The best you could have is from actual experience in your locale and the particular species in question.
As one poster said the newer cranes have weight measuring equipment, but that is a catch 22 since that only works once you have the section of the tree cut and weight is on the crane. If you underestimated the weight of the tree section, then you have the possibility for breakage, the crane falling over or such.
John Paul Sanborn
Above average climber
So true, we do have some green wood weigh tables available for the past 5-10 years, but as you say they are averages. I will go high on my SWAG, then do a test pick that to see how it works out.
The biggest difference here is that in helo logging, the bird is picking a log. This is much easier to tape the base and estimate. When you are making a multistem pick there is a lot of intuition involved.
Exactly, the only place an experienced worker wants to come close to max is when there are few variables to the critical lift . So many do not understand max load vs SWL.
Now say you are fully boomed out and near 45* (whatever optimal reach is). Will you still work at 50% or will you be even more conservative?
Texas Traveler
ArboristSite Guru
OK this is what or how most crane operators have to do in the real World of comerical & heavy construction.
We are pushed by overeager management out for production. If you are slow, you are replaced. Just the no bull#### facts of life.
All of the US Army COE projects have a 2/3 safety factor that is great for the operators.
We can go home at night without worrying about our lives & for others.
All of the rental crane companies want their cranes returned in the same condition as when they left.
So if you are unsure of your lift please ask them for help, most are experinced from the getgo in rigging & making risky lifts.
There is nothing out there that has more pucker factor than a unknown weight in a unbalanced crane lift. ole Murphs law will kick in every time.
I was forced into a bad crane lift one time by management playing both ends against the middle. I either did the lift or go home.
A year later it was still being brought up in safety meetings company wide.
And they were a nationwide construction company.
The lift & the crane used was thought-up by one stupid foreman on a power trip.
The crane was a 75 ton American mobile rig using 120 ft of boom lifting the max on the chart.
But it comes out they missed the est. weight by 8000 to 10,000 lbs.
I placed the load on the side of the crane as close as possable to the crane. Centered the hook on the load & started lifting.
The boom angle indictor was straight up when the load cleared the truck. At first it would not swing, a mechanic standing by tighten the friction
I had structial failure, the outrigger seals blew. Lifted it again after blocking up, when I looked up the boom. It was bowed up out past the boom pendant lines 10 feet or more.
Management all of a sudden had other places to go.
As I swung around to where I going to set the load about 25 ft. in the air.
I started tipping over, it set down on the caps just 1 foot off from where it needed to be. The rear of the crane was 4 ft. in the air. The foreman that was still on the job shut the job down.
I would have given a hundred bucks for a picture of the boom out past the pendant lines.
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Nice +1 JPS
treeclimber101
UNCLE BUCK
being a crane operator do you think the crane was overloaded or overboomed on saw for hire
treeclimber101
UNCLE BUCK
very windy thurs busy busy
whats the difference? hope the wind storm blew some work your way 101.
nice, i left mid post fer a cat resqvery windy thurs busy busy
treeclimber101
UNCLE BUCK
what i dont understand . did you get my p.m.
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