M816 boom extention

73m819

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Thought DaveP repowered his 819 also, so with with LI one that is six
 

doghead

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Ron, why don't you start a thread with a poll, to try to account for M819 owners?
 

Jersey4x4

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I want something removable. I have a old picture from I guess Korea with a wrecker and a jib installed on the end for use errecting shelters and so on. The guy that drove it has been to see my truck many times telling me stories and such about what they would do in the field. I was even granted a look at the album. There is a picture of the wrecker towing a half track.
Anyway, I thin I am going to build a jib frame about 8' in length that can pin on the inner boom and I will document the build and draw up plans for it also. I just acquired a set of forks for the boom also, which come in real handy around the shop.

I have seen a few where the boom was whacked off just above the extension cylinder pin and another boom was welded to it (the added section was cut 4ft or 5ft below the pin)

Only draw back is now you have 4ft to 5ft more boom all the time - was thinking of making a replaceable extended boom for mine but not quite sure which method I like best yet...

Matt
 

Welder Sam

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Yeah, i think i have to go with the saftey side this time. Cranes are awesome as long as they are used as designed. Modern booms with jibs were designed to be used together.

To those who go ahead, i wish u all the luck in the world. However, please dont work near me. No offense intended.
 
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Yeah, i think i have to go with the saftey side this time. Cranes are awesome as long as they are used as designed. Modern booms with jibs were designed to be used together.

To those who go ahead, i wish u all the luck in the world. However, please dont work near me. No offense intended.
Sam - the more I use the crane truck (wrecker) the more I am tending to agree with you - the reach is pretty decent already and the truck really would need to be bigger and heavier to support a longer stick...

And that doesn't even take into account the structural issues of chopping the exisiting boom off and adding to it - I may pick up and extra inner boom just in case I decide to in the end but for now I am not considering it too seriously...

The other problem is you never know who'll end up at the helm - could get ugly in a hurry!

Matt
 

Welder Sam

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Once ya go to whittling and welding on a boom, ya open up a whole can of worms that most have no clue about. Really, if you need more stick, buy more stick. Theyre out there. In salvage yards even. Theyre in treelines and back of lots. Above all else, be safe. When you have a component fail, you dont have the option of hitting the ditch. It just falls. Right on top of whatever and who ever is near. Frankly, i dont want my wife telling my girls about how daddy wont be there for them because somebody thought they knew what they were doing. Not even if that somebody is me. Im a seasoned welder/fabricator and i have seen alot. Can i repair a boom? Yes. Will i modify one? Well, ya aint got enough $ to talk me into that. When all else fails, remember, GRAVITY WORKS!.

You folks have a nice evenin.
 
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I work on big ships doing heavy engine overhaul and repair - giving me lots of experiance to do a lot of non traditional rigging in tight spaces with heavy loads of delicate (but enormous parts)

When you have to fly a 4000lb part off the end of a rail system, around the corner, over an edge, down one deck, mate it to some more parts and then rig the whole assembly onto the front end of a engine bigger than one of our entire trucks you get an appreciation for unknown rigging points, old gear, and learn to do things in a manner which you stay clear at all times from the fall lines and do your best to minimize risk.

Basically the less we know the more we dare to try...

I agree - it's bit sketch ball

Matt

PS - I wouldn't worry about the ladder within reason ;-) - unless you weigh 300lbs or something!
 

Speedwoble

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The 816, at max. extension (18') is rated to lift 4000lb on outriggers, on rubber 3000lb, 800lb at the boom tip would put 8000lb on the boom tip if it was 10' from the boom tip, and as it gets further from the tip, the worse it gets. Cranes (the 816 has a crane) have roughly a 20% overload STRUCTUAL safety factor (not cable & rigging) tipping is 75 to 80%
of rated load, so you can see with just a few MODS you can get into trouble real easy and as I said above, just because something does not happen during the stress caused by overload, DOES NOT mean things were not stressed or that a event won't happen later even with NO overload
I was thinking about it and I humbly suggest you may have it wrong. The weight the crane is lifting is the same, regardless of the length of the boom. If you are lifting 10000 lbs @ 10 ft(boom retracted, not sure of the exact number, feel free to correct me) the crane frame has 10000lbs additional on it. If you are lifting 4000 lbs @ 18 ft(max extension) you are still only putting 4000lbs at the crane frame.
HOWEVER, the boom affects the leverage. Once again, thinking at the base of the crane, 10000lbs*10ft=100000ftlbs. That is the maximum leverage, torque, or moment the crane frame can handle. At 18 ft, the load is reduced to stay within the torque limit. In our case, 4000lbs*18ft=72000ftlbs. Continuing on, at 28 ft, the max weight would be 100000ftlbs/28ft= 3570lbs. This does not take into account the weight of the boom. The weight of the boom is likely the reason the max permitted moment at 18ft is only 72,000ftlbs.
As you pointed out, the weight of the boom matters, so real load would be less. Probably still not be safe for 800lbs, but certainly not the same as hanging 8000lbs at the tip as you implied.
Not trying to pick a fight, but it is not the weight that matters, but the torque, or the moment in engineering speak.
 
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73m819

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I was thinking about it and I humbly suggest you may have it wrong. The weight the crane is lifting is the same, regardless of the length of the boom. If you are lifting 4000 lbs @ 10 ft(boom retracted, not sure of the exact number, feel free to correct me) the crane frame has 4000lbs additional on it. If you are lifting 2000 lbs @ 18 ft(max extension) you are still only putting 2000lbs at the crane frame.
HOWEVER, the boom affects the leverage. Once again, thinking at the base of the crane, 4000lbs*10ft=40000ftlbs. That is the maximum leverage, torque, or moment the crane frame can handle. At 18 ft, the load is reduced to stay within the torque limit. In our case, 2000lbs*18ft=36000ftlbs. Continuing on, at 28 ft, the max weight would be 40000ftlbs/28ft= 1428lbs. This does not take into account the weight of the boom.
As you pointed out, the weight of the boom matters, so real load would be less. Probably still not be safe for 800lbs, but certainly not the same as hanging 8000lbs at the tip as you implied.
Not trying to pick a fight, but it is not the weight that matters, but the torque, or the moment in engineering speak.
You are wrong, weight does matter and where it is, if the 2000 is the max load at 18', with all the safety factors in, the crane thinks it is picking up the safe max at 10'., I have been operating cranes since about 1960, I run into this kind of thinking all the time. A 10' jib x #800 load=8000lbs, if this is PAST the boom tip, the crane would think it has 8000lbs on the tip, it depends what the boom reach is if this would be a overload or not , If you weigh 200lb and stand on a 10' bar to break your lug nuts loose, you are putting 2000lbs on the other end and the lug nuts. In the crane world, there are all kind of charts that cover loads off a jib, boom tips, load/weight transfer, tip extensons DEDUCTIONS ect. A crane boom is designed for a spacific MAX. load, stress, ect. under design conditions, start adding things that CHANGE those loads and stress, and no longer within design conditions, things start to happen, stress, crack, ect. as I said before stress may not cause an event NOW, but in time will bite you in the a$$, could then happen even without much of a load.
DON"T beleive me, ask anybody in the crane industry about adding stuff past the boom tip. EVERYTHING ON OR PAST THE BOOM TIP IS CONSIDERED LOAD ON THE BOOM and hence the crane it self, the ONLy time this CHANGES if the load is off the jib, then anything on or past the jib tip is the load, you would be useing the jib charts. Being that military wreckers DONOT have nor designed for the stresses for OM jibs and the load charts to go with it, in this case ALL weight is OFF the boom tip.

I would be glad to talk to you on the phone anytime abot this
 
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zebedee

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Ok???? Any reason to bump a 3 year old thread with that?
... I'm gonna say "NO", but glad he did - I'd have never have thought to search for this! ... been thinking about it, but assumed it would be shot full of holes by the "safety Police" and therefore not posted.

Commercially - big no no.
... but if a tree falls in the forest - . . . - you can put up your own trusses. (No pics, no calcs, no weld x-rays thus did not happen...)
 

liekos62

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No I didn't even notice that it was 3 years old, but I figured someone looking for a M819 might want to know where one is....

Thanks!
 

73m819

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I have said it before and will say it again, once you realize your in trouble with these military wreckers, it will already be to late to do anything, from the moment the boom is moded, ANYTHING that happens will be on you or the next owner, because once the mod is done, it will be NO LONGER in AS BUILT specs.
 

73m819

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Hey Ron or DH what's the max lift on 819 at 26'?
According to the -10,
on outriggers---4500 lbs.
no outriggers---1700 lbs.

What the -10 DOES NOT say is if this is straight out or max. boom up (45 deg.), what I am fixen to do once things warm up, is to do a work radius chart, wish I had a hanging scale, that way I could do a load radius chart, lay out the load till a bit of lightness then deduct 20% off the weight, that would give a SLL.
 

AMGeneral

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Being a crane operator myself, plus having owned and operated both a M816,and a M62A1 I gotta agree with Ron,

I almost turned my M816 over on level ground,the ONLY thing that saved me was a LARGE tree that the wrecker bed fell against on the way over.

The military wreckers are way overbuilt and can lead you into a somewhat false sense of safety as to what the will handle,they will fail,rather abruptly.

My M62A1 had a 14 foot extension welded to the boom tip when I got it,with a linemans bucket attached to it.

That was the first thing I removed from the wrecker boom and torched it up into pieces before it went to scrap.

It is possible to exchange a M246/M819 inner boom onto a M62 wrecker shipper,just not into a M816 or a M543.

The M246 and M819 used the same type boom design as the M62 wrecker produced by Austin Western.

Just my opinion,I would look for a M819 if you are needing extra reach vs add a jib on the current boom.
 
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