Failed becket??

[Natman]

NOT rigged wrong, in service for 850 hours since new wire rope was installed (9/16", Manitex 101S) total time on machine, and assumed the same on the becket, 13,000 hours. The operator (not me) was lifting a bunk of OSB, got it about 8' high and wham, she let go. No damage or injuries. He had about 100' of stick out, at a very steep angle, and once the ball came loose the wire rope ended up spooling back down the boom, he jumped out of the (open, no cab) seat and got clear of it. I hope it comes through, but if you zoom in close you can see the becket (spelling?) is CRACKED. The new style he replaced it with is slightly different, as this problem apparently has been known to happen with this older style of welded construction. When it cracks it lets the wedge not do it's job. To say my friend who was operating the machine at the time was surprised to see this is a given. He is a conscientious type who takes good care of anything mechanical he owns, and he owns 3 boom trucks, 1 mis my old 101, not the one that failed. He of course realizes he got off real lucky. .

 

[crane operator]

Why didn't the tail clamp catch it? Probably hit it so hard it just popped it off?

Thanks for the pictures, I used to work with a guy who had one fail on him, he thought his was simply worn (I think it wasn't seated fully after installing ball), and he didn't have a tail clamp.

I have never seen a welded becket, everything I've ever been around was one piece. I imagine its cheaper to make two stampings and weld them together (some cost accounting engineer says this would save x-dollars per machine) The factory excuse will be- he should have seen it on his daily inspection. I could see minor shock loading over time causing the crack ( and it does happen all the time). At least no one was hurt.

 

[lantraxco]

Wow... lucky indeed. Give me forgings anyday.

 

[Natman]

Yes indeed, we have enough things that can go wrong without a crucial little detail like the becket giving it up. My friend had to do some fast talking at first to convince me he hadn't screwed up/was at fault. I compared it (we're both pilots) to us flying along, minding our own business, not stressing the airplane with anything unusual, an wham, the wings fold up!

 

[John C.]

Looks like the wedge might have pulled through the piece with the rope. If that was the case tail clamps would not have made any difference.

That crack doesn't appear to be in the weld and that weld is about as crappy a work as I've seen in a long time for something so critical. I doubt any agency that certifies cranes would ever accept that as being safe.

 

[Knepptune]

I thought the crack ran right along the center of the weld. I've never seen a welded becket either tho. Bet that guy is double checking all his beckets now.

I like the ones that the wedge itself clamps to the cable.

 

[td25c]

Looks like the wedge might have pulled through the piece with the rope. If that was the case tail clamps would not have made any difference.

That's what it looks like to me as well John C .
Wonder if the wedge was to small for the becket socket ?

I don't like a wedge that will fall all the way through the socket . I'm talking about without any cable involved , just the bare wedge & becket .

Like crane operator & Knepptune mentioned this welded becket is new to me as well .

 

[old-iron-habit]

I don't think that is a broken weld either. If the weld had spread enough for the wedge to pull thru I think there would be some sprung metal showing. The paint on the top would likely have popped to some extend when the becket spread on the bottom. I think the wedge may have pulled thru. I would like to see a photo of it next to the small end of the becket. I have never before seen a welded becket either.

 

[td25c]

I don't think that is a broken weld either. If the weld had spread enough for the wedge to pull thru I think there would be some sprung metal showing. The paint on the top would likely have popped to some extend when the becket spread on the bottom. I think the wedge may have pulled thru. I would like to see a photo of it next to the small end of the becket. I have never before seen a welded becket either.

Agree old - iron .

That becket should have busted wide open if the wedge pulled through .

Pulled out a 1/2 & 5/8 inch cable becket's this evening . The wedge is to big to fall though it's proper becket .
Then swapped wedges and the 1/2 inch wedge would easily fall through the 5/8 becket .
Not a huge difference in size between them .
Spooky part is that the smaller wedge would work for awhile until she pulls through .

 

[John C.]

Does anyone else see the crack running down the left corner of the broken becket?

At any rate there is a lot of stuff wrong with this failure. Was the load line put in the wrong side of the becket? Was the wedge to proper size for the becket and the rope? Were there tail clamps installed? Look at the dents on the corners of that piece. Kind of shows some pretty rough handling. I don't think I would have used it in any case but maybe it should have gone in the scrap bin a long time ago. It is good to hear no one got hurt.

 

[td25c]

John C , I see some fine " lines " running down the left & right upper side but they don't look like open busted cracks .
More like how it was manufactured .
Don't know ?

 

[Knepptune]

Natman, Is the crack right down the center of the weld on the bottom? That's what it looks like to me.

As for the dents on the top of the becket I've smacked the top corners of beckets a lot when seating the wedge. Looks like that's what the dents are from.

 

[crane operator]

Okay- just so were all talking about the same things here

The crack I'm seeing is circled. I don't see this crack opening up enough to allow a correctly fitting becket (larger than hole) through this hole, without us seeing some obvious permanant distortion. I think it would still be spread if that had happened.



In td's picture of a small wedge with the 5/8' becket- even if there was only a 1/2" cable in there- there's not enough room for the wedge and cable to come through the eye, without some huge distortion of the becket.



This is the way I see it. A small wedge, the front cracks- releasing the tension on the cable, cable comes around the wedge, popping the back cable clamp off. A terminator style crosby wedge- as knepptune mentions, the clamp on the wedge should hold it. A piggyback double clamp, the clamp should have hit on the top of the becket, holding the cable in, even without the becket friction.



If only a single clamp to a tail of cable, the tension disappears from the crack, the cable pulls itself around, then it hits the clamp to the becket hard enough to pop it and the tail, off the top of the becket. Cable comes completely around the becket and out the top.

That's why I was looking for info on what the backside cable clamping assembly is like. It's condition, and the tail of the cable's condition, will tell the story, better than the becket condition.

The other option that crossed my mind was a cable failure at the becket bend or top of becket, or two blocking it hard enough to pull it through, and the operator hiding the evidence from the owner and blaming the becket.

I'm not concerned about the outside corner damage- probably from seating a stiff rotation resistant cable, its only the inside of the becket, and its condition that holds the cable.

I doubt we can know for sure without seeing pictures of everything, but I'm always interested in learning.

 

[crane operator]

Crosby terminator:





Piggyback style clamp:





Those are the only two styles of clamping that I use.

This image shows some other tail styles:

 

[td25c]

Okay- just so were all talking about the same things here

The crack I'm seeing is circled. I don't see this crack opening up enough to allow a correctly fitting becket (larger than hole) through this hole, without us seeing some obvious permanant distortion. I think it would still be spread if that had happened.

View attachment 167652

Yeah crane op , I noticed the line you circled running up the center inside the socket .
To me it looked like a parting like where the two halves were put together & welded on the outside but not on the inside ?

It's got me puzzled ?

 

[John C.]

I blew up the photo and see the line down the left side is something like a pencil line.

 

[old-iron-habit]

Yeah crane op , I noticed the line you circled running up the center inside the socket .
To me it looked like a parting like where the two halves were put together & welded on the outside but not on the inside ?

It's got me puzzled ?

I had also looked at that line in the bottom and had surmised that it was a two piece assembly that had been welded on the outside only. I sure would like to hold it in my hands and roll it around to look it over. I could be convinced that for some reason the cable pulled around the wedge. As said good thing no one got injured and the windows are still in the crane. I've seen cable laying in crane windows before and I was glad to not have been involved.

 

[Scrub Puller]

Yair . . .
I have no experience with such components other than on tractor sheaves but have been around steel a bit and done my share of fixing.

(To me) if that line (which I took to be a parting line) was indeed a "crack" that caused the failure I would expect it to be "sprung" distorted and open by a half inch or more . . . I would rather suspect an issue with the wedge or rope size.

Having said that, that wide puddly weave on the topside would be unacceptable to me on such an application . . . and being a worry wart I probably would have burnt out that parting line with a bit more penetration on the first run . . . even if I did have to get in there with a round-file to do a tidy up.

Just a couple of comments from an old bush mechanic.

Cheers.

 

[Natman]

Well I hate to muddy the waters, and the great discussion here on why it failed, but my friend just told he it had NOT cracked, and he (and the shop he works with) is still clueless as to why it failed, other then it was "wore out" with 13,000 hours on it. I understood him wrong it seems, and we both have been so busy we didn't have a chance to talk earlier.

The big time, for real, major crane shop in the major city near him (keeping it a little vague in order to protect everyone I guess) who had rigged the new line with this becket 850 hrs ago, told him that yes it was a 5/8", but that it was OK for his 9/16" line. And, something about the becket being "old style", and the cause of the failure. Sorry to have such a lack of further details. I sure thought he had said something about a cracked weld, I think that was his initial prognosis, since changed. I have learned a good lesson: with the level of expertise here, I better get my facts straight as possible before posting on a subject! But it seemed important enough to post about for sure despite my lack of details. I just thought of something though.... he and his wife are coming through my area in a few days and I will ask him to BRING IT WITH HIM, details to follow.

 

[Knepptune]

Most beckets will hold two different line sizes. It should have had a 9/16 wedge tho. If the becket and wedge were both for 5/8 line then that's exactly why it failed. The wedge should have the line size stamped on it.