Crane tip-over.

[jomoco]

I've always done a little God forgive me prayer in my head before removing a big healthy tree, regardless of species.

Mess with nature enough and She'll mess with you.

Tree's are the most giving thing on the planet in my opinion!

I guess I must be a druid?

jomoco

 

[Adkpk]

I know this may be a bit idealistic but imo the house should never have been built under a tree like that. It's the towns fault for not for seeing that someone would have an issue with living under a monster such as that beautiful tree. Should of deeded that piece of land a park. People are stupid. If the tree had a say it should have pulled the crane down on top of the house. Oh, right, it did. :greenchainsaw:

 

[John Paul Sanborn]

Some random comments here.

By reading the articles, the comments from the tree worker(s)

the piece broke off suddenly and shocked the crane, the boom was jibbed out and low, the load was heavy. This will cause a fish poling of the boom; it flexes a few feet down causing the load to accelerate, maybe enough for the force of the load to over load the near max capacity. In these situations you want to have some pretension, and the sheave directly over head, and make a snap cut that needs no force to separate, and not so close to max-cap.

By the book this is a critical lift and you should be working around half of capacity, not trying to push the limit.

Another case of people thinking they know what they are doing, and screwing the pooch.

The climber is the luckiest man on sooo ways. The OE should have told them to cut some 500# chunks.

 

[pdqdl]

You're right on the vector mathematics, but you're using an overly simple formula for this example.

T=r*F*sin(a)

T = torque
r = distance
F = force applied
a = angle between the distance (the crane's arm) and the Force (the downward pull of gravity)

When you apply a force perpendicular, the angle = 90 and thus the sin(a) = 1. So T=r*F is true, because it's equivalent to T=r*F*1. That's your basic torque wrench since you apply you're arm's force to the handle at 90º.

...

No, I did not use too simple a formula. You used the formula for calculating torque from the length of the boom and the angle of the boom, essentially the hypotenuse of the vector triangle of any given lifting situation.

I used the true (and simplest) torque formula, as depicted on the lift chart on most cranes: lift capacity at distance from center of the crane. Nowhere on those charts (at least the ones I have seen) is there any chart value for "angle of boom". But maybe some cranes are different.

My formula is essentially the base of the vector triangle where it meets gravity at a 90° angle, a more practical application of vector mathematics, since a tape measure and a known weight will enable a crane operator to know whether it is a safe load. No sine chart needed, no guesswork about what the true angle might be.

Otherwise, your analysis and math are top-notch.

 

[treevet]

I've always done a little God forgive me prayer in my head before removing a big healthy tree, regardless of species.

Mess with nature enough and She'll mess with you.

Tree's are the most giving thing on the planet in my opinion!

I guess I must be a druid?

jomoco

Here is a photo of a tree I rescued (all others wanted to remove it) that was hit with a severe down shear and crushed the south side of the residence. There were 3 other major split co doms that threatened the property. There was a natural canopy half way down the canopy and above there to the 150 foot top there was very little until the lush top.

This tree was increment bored at 480 years old in 1980 by Ohio State University. Some of the cuts appear to be in err by being flat topped but they were left this way as there were laterals on both sides aiding in preventing die back. The ones you see with naked tops are dead and will be removed soon. This was done 8 years ago and there has been only that die back last year and that prob. was a result of 2 years of severe drought the 2 prior to last year.

I had a crane in the road above the drive as the drive has a steep hill next to it. This is a case where the HO's were not afraid of the tree squashing their house and it did but....they were soon to build an addition right where it hit. So everyone (and the tree) wins to some extent.

 

[VA-Sawyer]

Back in post #81 ( I think ) Dalmation90 shows that raising the angle of the boom reduces the tipping torque. That is true, but he doesn't explain that it also reduces the radius from center. In order to maintain the same working radius the boom ( lever length ) has to get longer as the boom is raised. This results the same tipping torque for any given radius. PDQL is dead right on this. The cranes I have been operating don't care how much the boom is extended vs boom angle. All weight limits are based on working radius from pivot center. Note: Only true without Jib.
Rick

 

[jomoco]

Looks like about 8 crane picks to me TV!

Just kidding!

Oak I presume?

jomoco

 

[treevet]

Looks like about 8 crane picks to me TV!

Just kidding!

Oak I presume?

jomoco

Biggest Bur Oak in the state of Ohio prior to its misfortune. 2 blocks from my house on Hillcrest Dr. in Cincinnati. As with any picture, it is much larger than the picture would lead you to think.

 

[Hoister]

Back in post #81 ( I think ) Dalmation90 shows that raising the angle of the boom reduces the tipping torque. That is true, but he doesn't explain that it also reduces the radius from center. In order to maintain the same working radius the boom ( lever length ) has to get longer as the boom is raised. This results the same tipping torque for any given radius. PDQL is dead right on this. The cranes I have been operating don't care how much the boom is extended vs boom angle. All weight limits are based on working radius from pivot center. Note: Only true without Jib.
Rick

No its not ..I can show you structual integrityover tipping ..cranes are not all tipping ..they have a structual aspect as well ..I dont know what youve been running ..a few makes and models with shots of the charts would be nice ..

Most the newer generation cranes are based on structual integrity and have no line on tipping ..in theroy the crane will blow a beam or bust a boom before it tips ..
Torque though a basic prinicipal of to older style Grove crane ..Isnt the way the newer cranes are designed ..load moment, structual strenght ..With that in mind Its also posable to add 28,000lbs to a boom and still increase lifting capacities are an increased radius ..because the boom is now compressed ..versus bent..Its called super lift ..or SSl class of cranes ..

 

[Hoister]

Exactly, I now see it clearly, the operator of the crane was tugging a little to hard when it gave way.
I didn't see this other topic prior to my post on the second one. this now makes much more sense.

Perhaps the two should be merged

I compleatly agree the tree should not have been removed, I saw no danger that outweighed the value of that tree

How was the crane operator tugging to hard ..it shock loaded the crane when it drifted of the trunk ..there wasnt enough pull to lessen the drop ..

probably because the cutters saw was binding in the cut ..no operator in his right mind would pull more than the quoted weight ..

 

[Hoister]

..based on the chart below ..
#1
With 3500lb load whats the maximum radius attainable
110ft main boom ..3500lb load whats my maximum radius ..

With 100 foot main boom ,at a 60 foot radius whats the maximum capacity
With 62ft main boom 54ft jib in service at 60ft radius what's the capacity ..



Just for jeers and chuckles gentilemen ..:jester:

 

[VA-Sawyer]

I did say " on the cranes I have operated " I cerianly don't have enough experience to say "all cranes".

Notice on the chart that in most cases you have a greater lift capacity using a lower boom angle for a given radius. There are exceptions at 55' and 65'.
The chart for the crane I've been using lately looks more like yours inside of 64' boom length. No heavy line for structual limit vs tipping.
They don't have a jib on this one, but the one I ran before did have one and the limits with the jib were screwy. As I recall, you couldn't couldn't boom below 30 degrees at max extension if the jib was extended. You had to retract the boom before you could lower it enough to install or remove the jib. The jib help to gain elevation but not radius if I remember it right.
Rick

 

[ropensaddle]

I've always done a little God forgive me prayer in my head before removing a big healthy tree, regardless of species.

Mess with nature enough and She'll mess with you.

Tree's are the most giving thing on the planet in my opinion!

I guess I must be a druid?

jomoco

Jomo I did not know you were a tree hugger

 

[jomoco]

Jomo I did not know you were a tree hugger

What yu talkin bout Rope?

Only rookies hug trees that take them for rides!

A real pro triangulates and pushes against the tree, moving with it as one.

I'm sure most veteran mass murderers have regrets about what they do!

jomoco

 

[ropensaddle]

What yu talkin bout Rope?

Only rookies hug trees that take them for rides!

A real pro triangulates and pushes against the tree, moving with it as one.

I'm sure most veteran mass murderers have regrets about what they do!

jomoco

Yeah sure they do lol. I have taken down quite a few that likely would still be fine today. I have very few regrets though as it would have been another service if I declined. My family and their living come before me or any tree.

 

[ROOTSXROCKS]

Here, there's at least three craftsman that take urban woods.

These guys are huge

www.urbanhardwoods.com

WOW Im in love these guys are right up my alley, I am making plans to visit there studio in SF in a couple of weeks Thank you for the Link. this will be the star of my trip.
Oh yeah Im a tree hugger too but that cherry was dying I swear

 

[VA-Sawyer]

Hoister,

Here are my answers to your questions:

110' main boom 3500lb load max radius?

at full extension, no jib installed 60' (same if jib stowed)
retract to 94', no jib 65' ( same if jib stowed )

110' (you typed 100' but the chart is for a 110'boom ) main boom @ 60'radius max load?

at full extension, no jib 4000 lbs ( 3750 with jib stowed )
retract to 78' no jib 4900 lbs ( 4550 lbs with jib stowed )
Notice that jib stowed chart lists 76' instead of 78' need to confirm
that it is only a typo.

62' extension on 110' main boom and 54' jib installed working at 60' radius.

116' total boom @ 60' radius is about 57 degrees boom angle.
54' jib at 57 degrees is good for 1300 lbs.

Rick

 

[treevet]

below 30 degrees at max extension if the jib was extended. You had to retract the boom before you could lower it enough to install or remove the jib. The jib help to gain elevation but not radius if I remember it right.
Rick

It appears on his chart you do not drop the boom below 44 degrees if fully extended with the jib on.

With my small truck crane you can actually feel the truck getting tippy if you are not playing by the rules. Probably not the case on these big ones but maybe a buzzer goes off or it stops operating? The chart and the weight of the pick goes out the window when a piece is stuck on the trunk. No way to figure that one under any scenario.

Wonder the outcome of this thang. Do they finish the job with the giant crane? When finished does the client pay the bill likely after their house is fixed?

 

[VA-Sawyer]

TreeVet,

I agree with you about chart numbers going out the window when dealing with wood chunks still on the trunk.
I prefer to keep loads in trees to 50% of chart limit. If I was using the crane hoister posted the chart for, I may lower it to 25-33% of chart limit, if that limit is structual. A chunk doesn't have to fall far to hit with 2 G's. Structual overloads happen instantly in steel. Even if it doesn't fail then, it remembers the overstress and can fail at a lower limit later.

The crane I'm currently running is at a home construction site on a mountain. It is sitting with the front of the truck higher than the rear. ( about 10 degrees ) That throws the chart out the window as well.
Rick

 

[BC WetCoast]

I wouldn't go that far. I'm a big advocate of personal property rights and think the HO absolutely has the final say in that decision and if they wanted to hire me, I'd do it. However, if the HO's were talked into removal with shady tactics and fear mongering that is another thing entirely...

The City of Vancouver has just instituted a maximum $10,000 fine if any tree greater than 8"dbh is cut on private property WITHOUT a permit.

The notion of personal property rights is idyllic at best. It has never truly existed and never will. Regardless of where you live, you can't open a toxic waste dump in your backyard, or build a 37 story skyscraper on your city lot.