• Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!

What's it weigh??

Natman

Senior Member
Joined
Dec 19, 2016
Messages
972
Location
ID
I couldn't agree more, no arguement here! You have the facts correct. Migating factors overode my after the fact common sense, as in: 1. material bought ($500.00+) and fabbed (my labor and time) for the spreader bars, when the thinking was it weighed much less. 2. Actually being in the op seat at the job site, all set up and rigged, with a waiting trailer to load it on. 3. Knowing the safety margin (not to be used, I get that) in the stated loads the rigging can handle. 4. How easily the 1300 handled it....., no lifting whatsoever of the opposite side pad, no unusual grunts or groans, no issues winching. 5. A POSSIBILTY my LMI reads heavy....., either due to the addition of the 1400 pound counterweight or just general out of calibration. The last time I picked a known weight, a 3,000 pound electric motor, it read 300 pounds heavy (after allowing for rigging etc.), pretty close, but that was 6 years ago, pre counterweight.

A bit different situation than doing the math at a desk after the fact at a remote location in other words, no pressure or incentive to continue with caution there. You missed the 3 part line (good only for 22,500 lbs), I should have been rigged for a 4 part. This whole thing reminds me of pilots telling flying stories, we all have stories that make us think "what was I thinking," when viewed in hindsight, but during the heat of battle, stuff happens and we end up being here to talk about it. Point being I guess, nothing broke or bent, nobody got hurt, and the job got done, so my proceeding with it wasn't too wild and crazy.. Again like flying, I am thankful knowing there is a significant safety margin over the stated limits, and I'm just stating how the job went down, not bragging about it, if nothing else a lesson in how an op can get sucked into exceeding the limits of his equipment. If the 80 ton Terex had been available, I'd have had the option of calling him but that wasn't possible
 

dwightr

Member
Joined
Jun 18, 2020
Messages
15
Location
North Carolina
google "companion to the AISC Steel Construction Manual"
it has charts on the compressive strength of pipe and tubing.
It's just a little math to figure the compressive load on a spreader bar, then look it up in the chart and see if its ok
 

Natman

Senior Member
Joined
Dec 19, 2016
Messages
972
Location
ID
I did eyeball it close while loaded, and 1" off the foundation, no deflection at all, in all three of them. But knowing in advance is the way to go for sure. As an old hang glider pilot, and even now my kitplane uses round spars, round is a pretty good way to distribute compressive forces. BUT, I remember one time when a guy wanted to keep flying with a dent in his hang glider spar, one small dent, but still straight. To illustrate why that wasn't a good idea, the glider company head honcho carefully balanced on a undented empty soda can, no problem, then he had someone barely flick it with their finger, and it collapsed, I never forgot that. Another thing: if sleeving tubing, splicing, 1.5 times the diameter on each side of the sleeve should maintain full strength. We did do that, but added a bit for the wife and kids. Stress relieved the ends also.
 

dwightr

Member
Joined
Jun 18, 2020
Messages
15
Location
North Carolina
Pipe is very predictable up to a certain point.
When the length of it get to around 200 times the radius of gyration the failure modes become much more unpredictable.
Better to stay away from long and skinny spreader bars.
 

Natman

Senior Member
Joined
Dec 19, 2016
Messages
972
Location
ID
"Radius of gyration," I have never heard that term before, but it'll be used the next time I'm telling flying stories with other pilots!
 
Top