Saturday, March 11, 2017

Telescoping cranes can bend, but they should not break

When the boom of a telescoping crane is extended to its full reach, there is very little metal overlapping at the joints. I have always wondered how they avoid bending. The answer is that they are evidently designed to safely handle some bend. (I'm being vague about where I got some of these on Facebook pictures because there were some comments that were not "family friendly.")

From Facebook

From Facebook

From Facebook
[Actually, I don't see much bend in this one.]
From Facebook
From Facebook
From Facebook
Philippe Dumas posted two photos with the comment: "GMK 6300L lifting Air compressor to the lake ground from the dam 74m main boom + 21m jib was necessary to reach radius."

My reaction was that the air compressor better be rather light with a radius that long.
Larry Winchester Jibs are for height, not radius.
Keith Havard Hope the pic of boom flexed is with load on hook.
Mike Newcomb lot of cable. [I wonder how much weight the cable itself adds to the load at the end of the boom.]
Mark Walker I'm thinking he maybe close to the end of the chart in that second pic looking from the rear

But the operator needs to know the chart and avoid bending too much. It looks like they should have lifted the tower crane boom as two pieces. Note that as soon as the boom broke, the base lost its load, and it straightened right up.

Screenshot 2
Screenshot 1
Terex Cranes posted
Here's a great example of collaboration - Cropac Equipment Inc., C&C Crane, Total Crane Rental, and MTN Forming brought their expertise together on this Ontario waterfront project with Terex SK 315 and SK 415 tower cranes
[It looks like there is a bend in that boom to me. It also looks like the inner segments are only partially extended. I assume they are overlapping more steel at the base of the boom to try to reduce the bend.]
Balaji Mani posted
[Each segment is extended the same amount, but only about 2/3 of its length. I think there is a little bend in the boom.]
Frank Pintaro posted
Just a little boom deflection Gmk 5275
J.P. Duffy posted
Might be short rigging a couple pics tomorrow
[Building a Potain tower crane: "It will be a MDT219 10t 65m jib." There is a long discussion about "line pull." I don't know what they are talking about, and evidently the operator also does not understand either.]
J.P. Duffy posted three photos with the comment: "Just another day under the sun."



Rick Kleuskens posted
Toronto 23/09/17, one of 11 photos posted

This one is interesting because I do not notice a bend in the boom even though it was operating with a rather long radius.
Bay Crane posted
[It looks like there is a little bend in this one.]
Patrick M Harrison posted
Fish on!!
Brandon Leichinger commented on the above posting

John M. Childers commented on the above posting
I can relate!!!!
Devin Parsons posted
Fish on!!! 🎣🎣🎣🎣
Brandon L Grace commented on the above posting
Why yes.
Thomas Dearmond on the above posting
Brandon Owens commented on the above posting
Yes sir.
Jacob Gibson posted four photos with the comment: "Testing the limits of our brand new LTM 1250-5.1."



A group added two photos. I'm surpised the boom broke in the middle of a segment rather than the near the end of the segment where the next segment's insertion ends.

Philippe Dumas posted three photos with the comment: "GMK 5250L"


Phillippe Dumas posted
GMK 5250L
Jim Paris I'm guessing that the charts say it's a good lift, but man that is an ugly looking boom angle!Philippe Dumas 70 + 21m jib at long radius = it seems normalPete Lefebvre With that jib probably lifting roofers styrofoam
Baoualem Kefif posted four pictures with the comment: "GMK6300L." His third photo shows that at a long radius, it looks like the boom bends under its own weight.

Luke Brower posted two photos with the comment: "From JJ Curran's page."
Luke Brower Need to reach from Detroit to Ohio looks like the crane for the job. 336' and no luffer.
Bill McCarthy If it didn't deflect , then I would start to worry .....


James Zampler posted three photos with the comment: "Love me some deflection!"


David Whitehead commented on James' posting
 When I load tested my 5250L.
Neil Frampton posted
Bit of deflection
William Gadbury What's that 20% off set ?Neil Frampton Yes William it’s 20 degrees offset with 5.4 ton at 25.7 metre radius mmmmm

[I wish I understood the "offset" terminology.]
Brady Buckland commented on the above posting
James Zampier posted
Just a little fishing today.
Michael Singleton Nice deflection shot.
Master Britt Lipscomb posted
GMK 5240
Jahanzeb Afzal posted
[Building a tower crane. If the city would have let them block a traffic lane, they could have used a cheaper hydro because it would have been closer to the tower.]
Kevin Mitchell posted
Grove 6300L... lifting 12.5 ton( 27500lb) for you lot over the pond..75m(250ish ft)boom at 30.4 m (102ft ish) radius... the pic really does not do it justice..hoisted load down just to see how much deflection was there and she came back 7.3 m( 24ft)
Bill Sharp That’s normal they are made to do that or the boom would snap
Graham Morris commented on Kevin's posting
Bendy bendy
Dustin McGovney commented on Kevin's posting
Louis DeFazio commented on Kevin's posting, cropped
Brad Young commented on Kevin's posting
Bendy bendy bendy
Anthony Perrotta posted
Tms 9000-2 in syracuse ny
Clint Johnson I love seeing pics that really show boom deflection. I was under the hook of a 250t all out with jib and aux stinger. Thing looked like a fishing pole with a big one on it.
Steve Wilson Nice! Jamesville trash plant?
Anthony Perrotta Yes sir
Anthony commented on his posting
Yeah it's impressive for sure. Here's another -2 with the insert and luffer in it
Walter Hansen shared
Ben Longman Amazing the boom didn’t snap....
It does demonstrate how strong these cranes are when they tip over. Usually the boom and the outriggers remain intact.
Screenshot @ -0:19 (source)

J.P. Duffy posted
Name that banana
Michael Reich Tms9000e-2

Bay Crane posted
Briand Jones The beginning of a crane rainbow.Jonathan Cummings Cranebow, work on your comments.Marco Santoro All that sweet boom deflection without showing us what's on the hook.... so not fair @bay CraneThomas Hagans Jon Shrock stretched outJon Shrock Thats gotta be around 200-225 radius
Chris A Baez commented on Bay Crane's posting
Dale Lanham Damn I didn’t realize they bowed that much!Scott Lozier They bend like a fly rod.Joey Colicchio Normal for a 275/300 long boom with jib...just looks scary
Clayton Chaban posted
Jr Lemasters commented on Clayton's posting
Trevor Crawford commented on Clayton's posting


1, cropped

2, cropped
Posted, cropped
Craig Harry Cameron Derek Manns seen one of these before ?Derek Manns No never broken like that.Garrett Larkin Brian Boudreau I'm not even sure how.Brian Boudreau KATO's new series of knuckle picker.

[It looks like Kato needs to go back to the drawing board 
(actually, the computer screen) and add some steel to the main boom. The problem with computer aided design is that it allows the engineers to build with less steel than they did in the pencil and paper days. That improves the cost of building, but lowers the margin of safety.]
Jeff Funk Looks like rotec failure ouch
[This is the first time I have seen a photo of the attachment of the house to the truck failing. Normally the truck tips over if the load is off the chart.]
The first time I have seen the failure point being a hydraulic ram:

The first 30 seconds of this video is interesting. It shows that the boom needs to be raised as it bends underload. It is selling a computer to do the compensation. All of the comments felt strongly that another computer is not needed because any decent crane operator can "hold radius." (source)

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