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. .
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.
Wow... lucky indeed. Give me forgings anyday.
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!
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.
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.
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 .
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 .
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.
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 ?
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.
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.
Crosby terminator: Piggyback style clamp: Those are the only two styles of clamping that I use. This image shows some other tail styles:
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 blew up the photo and see the line down the left side is something like a pencil line.
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.
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.
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.
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.
Aha!
From gunnebo johnson website: Johnson Open Wedge Sockets Open Wedge Sockets combine positive attachment with optimum versatility. Easy-to-change Gunnebo Johnson Wedge Sockets are a high strength, cast alloy steel. Each socket accepts at least two different ductile iron wedges. This allows the socket to be used with more than one rope size. Together, wedge and body act as a vise which grips the wire rope and locks it into place. The headed attachment pin is standard and has a charpy value of 25 lbs/ft at -4° F. The socket body has a charpy value of 25lbs/ft at -40°F Gunnebo Johnson Wedge Sockets may be used with multiple sizes of wire rope. To switch from an overhaul ball application calling for a 7/8-inch wire rope to a block application calling for a 1-inch rope, it is not necessary to buy a complete wedge socket. A simple change-out of wedges will suffice. Of the 18 models of wedge sockets offered by Gunnebo Johnson, all but one, the FS-26, can be adapted to at least two sizes of wire rope. The WS-5, in fact, will adapt to three: 1/2, 9/16, and 5/8 inches. Be sure that the wedge is correct for the wire rope size. Each socket manufactured by Gunnebo Johnson has a model number and acceptable rope sizes cast into its body. Each wedge has the rope size and particular socket model it will fit. Wedges are also coded by means of color. Red indicates that the wedge is for the largest size of wire rope stated on its socket. Green indicates that the wedge is for the smallest size of rope stated on its socket. Blue indicates that the wedge is for a rope size of 9/16 inches. At the time of shipment each socket assembly is clearly identified by a steel-banded plastic tag stating: WEDGE IN THIS SOCKET IS FOR (SIZE) WIRE ROPE ONLY. When using wedge sockets note that two precautions should be taken. Make sure that a sudden jolt or impact does not dislodge a wedge. When installing wire rope, always pre-load the wedge with wire rope in place. Check frequently to re-tighten or re-position as necessary. Make allowance for the crimping effect common with all types of wedge sockets. Experience shows that it will reduce the working load limit of a line by 20 percent.
Thanks for the rest of the story natman. "Someone" gave out some bad info that the 5/8" wedge was "close enough". Cable compression with a incorrect sized wedge, distortion allowing it to loosen, and a probably not tight enough cable clamp, on the back side. Sounds like most incidents, its not just one thing, its a chain of events. 5/8" wedge good enough (no its not). It doesn't sound like he's removed the becket in the 800 hrs since, so I doubt he's had a wrench on it to check the clamp tension. Big bunk of plywood loading up the single line, instead of just a truss for weight. The becket being "worn out" is a bunch of bu$%&^. The cable doesn't move on the becket- its not a running line in there. Your buddy should have known better than to accept "close enough". I hope he bought a 9/16" wedge for his becket this time around- it could have been someone's life in a manbasket, or if two guys had been trying to land that bunk of plywood, it could have been on their heads. Thank goodness it wasn't. There's all kinds of information, and misinformation out there. A lot of it on the internet. Don't accept someones word that its right, learn for yourself. I posted some pictures in another thread of incorrect becket installations, all done by big "rental" houses. By a mechanic that no one has trained, he just does what looks right and no one else knows. Tell your buddy to start learning- he should be able to look at it and know whether its right or not. Just paying someone else to do it, doesn't get him off the hook. I always tell guys "I don't care what we get done today, as long as we all get to go home today".
Then again . Crosby wire clips & loop thimbles still have there place . http://www.thecrosbygroup.com/products/wire-rope-clips/crosby-450-red-u-bolt-wire-rope-clips/ http://www.thecrosbygroup.com/produ...les/crosby-g-411-standard-wire-rope-thimbles/ Pretty tough & reliable set up . We use the becket / wedge socket on the cranes for the ease of switching from single line to multipart block line quickly . No beckets behind the winch trucks or wreckers . They would be torn to pieces in rough work . Wire clips all the way .
Well, the plot thickens! He says the 30 year major crane service company says, and showed him in the book, that the Crosby 5/8" becket should use a 5/8" wedge, EVEN WHEN USING 9/16" ROPE, and that this same "book" says no 9/16" wedge is available for this setup. I should also say that my buddy does a lot of heavy maintenance and repair on his 2 Manitexs and 1 Elliott, and is not blaming the crane company. The only reason he had them change out his winch line was because he had it there anyway doing something real major. It will be 3 weeks or so before he swings through my area, and he'll be bringing the old one. So, while I'm defending his overall mechanical savvy and overall paying of attention to all things mechanical, I will also be the first to jump on board the blame train IF there is something we are not getting right so far on the why it heck it happened! The "worn out" comment was made only after pretty exhaustive searching for another cause, but I agree, and for that matter so does he, that it doesn't make sense.
Man that doesn't sound right at all. What I want to know is how the becket held on the old cable. To pull out 850 hrs into service doesn't make sense. Just to satisfy my curiosity ask him if he switched to a different kind of wire rope. I know that wire rope is different from one manufacture to another. Some just feel softer. I wonder if he had a di-Pac cable on it before and that Cable is enough stiffer and harder that it didn't slide through were a standard cable did. On a di-PAC they start with 5/8 cable and compress it down to 9/16, or 3/4 to 5/8. It's a good cable. Doesn't want to lay right the first time you reel it up but once it's trained it's a good rope. A standard 6x19 is gonna be a lot softer. Just thinking out loud here. Anyhow I'd tell them to take there wore out theory and put it in a place that gets no sunshine. A becket and wedge won't wear out from standard use. You can damage them from overloading but they're not a wear item.
Yair. . . do you folks in the US have any issues with metric substitution/mislabeling? . . . 14mm is not 9/16" Cheers.
I'm in Canada I just put a new rope on a couple months ago it's a 15 mm. All the suppliers I talked to north or south of the border understood the difference. But it wouldn't take much to get it wrong, if you plug it into a metric converter both 14 and 15 will both give you 9/16".
Yair . . . Gotcha Tradesman. That is the very point I was making . . . probably an irrelevant point and I know bugger all about cranes but I thought it couldn't hurt to mention it. I have been caught with the metric conversion thing in other fields . . . tube sizes for instance, a hundred miles from town and the compression fittings don't fit. Cheers.
Even if the becket holds the rope, if you have a grooved drum it's not going to spool properly. I was schooled to be very carful to be sure to match the rope to manufacturers specs.
I had to use the welded becket idea today . We were rigging the Insley for dragline service and replaced bucket cable . We pounded on the wedge for about half hour & gave up . Sliced it down the center and she came loose . http://www.heavytruckforums.com/sho...ufacturing-Company&p=3861&viewfull=1#post3861
I'm certain that nobody will be using this becket for hoisting with people around. Its in the perfect spot on that drag bucket.
Again, though that makes perfect sense, I really doubt the outfit that serviced it last time would make such an area, then again no one is perfect. Maybe they confused or slipped up on the fact that most beckets COULD work with two different size wire ropes, AS LONG AS the proper/specific sized wedge was also used. I think he still has it, I'll check......
My thoughts as well old-iron . Not to worried about using it on the bucket . If it fails I could possibly injure a bullfrog or water moccasin . Then again if it don't fail I could still possibly injure a slithery critter . I better post a two week notice at the pond before I start so those guys can move out before work begins .
According to my friend, the info came right out of the Crosby "book", for 9/16" wire rope you are supposed to use a 5/8" becket AND wedge. And, he was showed this info in the book after the failure. Maybe it was an old book or a new one, but that is for sure what they called for and what they did.