Failure of our 15 ton crane

I like this crane rob. One pick, chip it up and go.
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Glad noone and nothing got hurt!

Looks like the jib is what failed?


I would say abuse played a large part, cranes are made to lift static loads, period. If the piece lifted 2 feet, it would seem there was a bit too much pretension. The lifting 2 feet (if caused by the ammount of pretension) means the piece bouced on the boom, which is a dynamic loading, which could overload the boom fairly easily.
 
You gotta be EXTRA CAREFUL when you opt to swing the jib. Your load capability goes WAY DOWN.
 
did the booms actually break and go to the ground? from the pics it seems as though the last stage (#3 on a national 15 ton i think?) was bent and later cut off to get the truck home. maybe a case of "catastrophic boom failure due to past occurences" was deflection a problem prior to the incident? glad to hear everyone was lucky.
 
it was the last stage on the main boom that failed, and no, there was not too much pretention... i had no tention prior to lifting, i had the climber cut all the way through (kind of like a snap cut)before any tention was placed. this will allow for the saw to be stowed and the climber to be in "offence" mode and ready to get out of the way. the piece was completely hallow, and the cut was good.....

i left my camera at work, i will try to have the pics tomarrow.


be carefull out there!!
rob
 
check out the 2nd photo and note the old crack w/ rust inside it (at the bottom of the photo) it appears that the crane/boom had an old shock load or similar event. i,m glad nobody got hurt! i,m also sorry for your crane & financial losses too. (downtime is the worst; bunches of money going out and none going in!) if you get a knuckleboom be careful they are susceptable to damage too!
 
I'm glad to hear no one got hurt.

IMO a 15ton crane is way to small to be doing the type of work you guys do. Not sure if your familiar with this or not but you can have a crane inspector do a "MagnaFlux" on your boom once a year. Up in my neck of the woods it costs around $500 but it reveals any hairline cracks that might be present. The other thing on any crane regardless of stiff or knuckleboom is to remember that the furthest wear pads on the boom tend to wear out the quickest and need more frequent replacing. Many crane failures are a result of boom section rubbing directly on another boom section. A few extensions in and out with steel directly on steel and it doesn't take long before something gives.

The other thing to keep in mind and the cheapest way to maintain your boom is grease. Always grease your boom on a regular basis. You'd be amazed at how many people I've spoken to that could have avoided a whole world of grief if they had just greased their boom on a regular basis.


Just like the circle check you do on your trucks in the morning it's suggested that you do a circle check on your boom as well. I doubt anyone does it everyday but it should be made a point to be done at the very least once a week.
 
Gus,

You make some great points. I do a walk through on our rig everyday it goes out. It's too expensive not to! /forum/images/graemlins/smirk.gif

As for the wear pads, about how long (or how many hrs.) should they be in service for? Or, how do you know when to replace the last few?
 
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everytime that this crane goes out (or did) it was subjected too stresses that it was not designed for( i could name a couple of names ) has anyone ever taken a tree down with a crane without putting some type of stress on the crane that it was not designed for... this crane was designed to set trusses on top of buildings, put airconditioning units into place, and ect. all of these types of work are static..... tree work is not.

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Cranes don't know or care if they are picking trees, trusses, or thing-a-ma-giggies. Proper use, regular maintenance, and routine inspections are just as, or perhaps more, important than what is being lifted. Many long time crane operators could relate stories about accidents and/or near misses in various work sites with various types of material.

I am NOT implying that you, your co-workers, or the company was in any way negligent--I am far too removed from the incident to make any type of judgement. But don't just blame tree work.

In answer to your question:

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has anyone ever taken a tree down with a crane without putting some type of stress on the crane that it was not designed for...

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I can honestly and earnestly say yes. If I had to say no, it would be a complete contradition of everything that many people (Steve Chisholm, TCIA, et al.) have been working for over the past three, five or more years. Cranes CAN be used safely, regularly, and efficiently in the tree industry.
 
Do folks distinguish between boom trucks and cranes? In our area boom trucks 15 -20 ton are pretty useless due to boom length. My first employer had a 15 ton, and tried lots of dumb things with it. IE: asked us to stand on outriggers for counterweight!! Lots of bouceing from chart miscalculation. I quit after 6 months!
I primarily sub cranes/operator from actual crane companies. Smallest crane would be a 22tonAT, largest 70tonAT(130'powerboom) with 50 ton truck crane if there is sufficient space. All of these have one consistent operator. In addition, all are equipped with load calculation computers and LMI. If the computer says 12K I like to keep the load around 5K. This allows for the invetiabvle movement from boom deflection and load shift. When a crane picks something from the ground, all of the deflection happens slow. When a pick from a tree happens your guessing how heavy and if it is balenced. Therfore you will have more dynamic loading.I try to avoid to much pretension to minimize this. These are overkill cranes, but there are very few times when I ask myself if this pick will be close to capacity. Cranes are key to tree removal.
I recieved the arborist news with updated crane rules. I have a question of why would you want to remain tied into the crane under load? Seems risky. There is a pic of you Mark doing this, is there a reason?
 
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