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looking for some top answers for these crane questions

Dmconstruct

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Hello Im retaking a state exam and am trying to pass it this time around.

Some of the questions that stood out from the last time are

1. What would happen if the boom cylinder line failed while a load was suspended?

2. What are steps to reduce "cabling"?

3. What needs to happen when an air compressor is added to the rear of the crane?


There are no multiple choices with these questions, please help I sit for this test in less then a week
 

gostr8r

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Just my opinion, but #1 should be that a factory installed holding valve is supposed to protect the line bleeding off from causing the boom to lower anymore. #2 What the hell is cabling? IDK. #3 It must be approved by the manufacturer and then follow their recommendations in regards to the additional c/w effect it might have. It might mean a chart amendment or a different chart itself. Might also mean removal of an equal amount of factory c/w ballast to total the correct amount as charted too.
 

coorecat

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The NCCCO test I took for Lattice Boom Crawler had general knowledge,site specific,load charts and a practical test it can't be much different than a state test but the NCCCO is all I've had to take in NC.
 

Hoister

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I second gostr8rs answers. And I too say, what is cabling supposed to mean?
 

Dmconstruct

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The only thing I can think that cabling might mean that multiple parts of line might get tangled? Or maybe the spool of rope is not winding correctly. I specifically remember that question and it has bothered me for the past 6 months
 

cecil89

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cabling is when you are using a multiple part line.What happens in cabling is when you first pick up the load the block spins instead of the hook twisting the load lines. I have also picked up a load an had it get to a certain height an then the load lines twisted up. When it is up high it sucks big time. I had it twist so bad the load did not want to come down. could not boom down all the way because i would have gone out of the chart. :Banghead I believe it is not as common as it use to be. cable being improved upon over the years. Us old people use to out smart this. If we found that it wanted to cable we would lash the block to the hook or the rigging on the hook. have tag lines on the load an keep every thing (block- load) from spinning. I hope you have understood what I have been trying to explain. I believe in bobs rigging handbook there was a page on cabling. It had to do with a mathematical equation. Boom tip height, number of parts of line, an a few other variables.It was to tell you at what height it would start cabling. Never really figured out the equation. (was never known to be an Einstein) Really does it matter at what height. all it takes is being wrong on your height an you done screwed the pooch.All the times that I had cabling problems I was using right regular lay cable. an I have not encountered that problem in quite some time. (you do know about old people an dementia ) Equation solved lash block before picking load:D
 
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Hoister

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Never heard that term for getting a twist. But if that's what that question is referring to, your practice to prevent it would be to pull all of your slack through your block and head section removing any twist in the line before making it over or under each sheave. Even that doesn't always do the trick. The other day I came off of 90k with 300' , four parts and it twisted on me. But after running it back up against the two block and back down it came out.
 

gostr8r

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Bob's Handbook is ok for it's day and I still reread it from time to time to stay focused, but a few other factors are involved besides what he covers. In addition to improper rope or the reeving itself, coming off a heavy load by only booming down to adjust for upward deflection on the rigging, instead of coming down on the load line too, can also cause that to happen too. As well as a sluggish and hard running sheave in the block or head section, and a less than well moving thrust or swivel bearing on the load block. Just my 2 cents worth for what it helps.
 

heavylift

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#3 can't really answer, but the ones I've seen usually have a set of leads hanging off the boom, whether it's power pack or air compressor, They do look a little back heavy until the leads are lifted, the crane still had the same counter weights on it as usual.
 

Hoister

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Bob's Handbook is ok for it's day and I still reread it from time to time to stay focused, but a few other factors are involved besides what he covers. In addition to improper rope or the reeving itself, coming off a heavy load by only booming down to adjust for upward deflection on the rigging, instead of coming down on the load line too, can also cause that to happen too. As well as a sluggish and hard running sheave in the block or head section, and a less than well moving thrust or swivel bearing on the load block. Just my 2 cents worth for what it helps.


×2

I will add. My twist up last week after coming off of 90k happened after we first built the crane, it was really the first lift off of the main and hasn't happened again. So in my case it just settled in.
 

Dmconstruct

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Could one also count the number of twists and drop the ball/block to the becket and counter turn the line the same number of twists??
Also does everyone else agree with the holding valve being the correct answer for number 1?
 

gostr8r

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Well the question as you typed it was 'would' not should, so who knows? We can't predict what a rig 'would do' if we aren't really familiar with that rig. If the intent is 'should' tho then I would go with the inherent and intentional design of the holding valve preventing a boom cylinder from bleeding down.
 

Dmconstruct

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Thanks gostr8r for your input, as far as the "cabling" question, would you consider using rotation resistant rope as a valid answer?
 

gostr8r

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It might be and then it might not. Years ago the rotation resistant rope wasn't recommended on multi part reeving, but now some of the new stuff is very good for that application. So that might not be the most correct step but could be one of them. The thing is that the term rotation resistant in that ropes description doesn't refer to the block rotating, but to the body of rope itself. Since the inner layers go opposite direction to the outer layers [right lay layers over left lay layers] it counteracts the ropes tendency to twist like when you ring out a wet rag, as it slightly elongates under a heavy load. So to try to answer your question Dmconstruct, using that kind of rope might only be one of the steps, and could only be partially correct and not a really a preventive step with older RR ropes. IMO Balanced reeving on the head and block sheaves is more of a positive step, as well as letting the rope uncoil each time before running it thru another sheave. These tests usually also like answers that state that you should 'follow the manufactures recommendations'. So I would make that one of the steps taken too for sure, in regards to the 'choice' of rope type, grade and construction. Hope this helps some more.
 
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