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| At what point would this lifting devise fail? | |||
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| Posted by: blacksmith1956 ® 11/07/2009, 16:28:38 Author Profile eMail author Edit |
I built a spreader bar for a working load limit of 12,000 lbs. It must be proof loaded at 24,000 lbs. At what point would it fail? The assembly consists of 2- 20 foot long 3x8x.500 steel tubes. beteen these tubes are, at the center line is a 1.500 steel plate 30 inches long and 8 inches wide matching the tubes. 5 feet from the bar center each way is another 1.500 plate 24 inches long 8 inches wide the center of these plates are 5 feet from the spreader bar center. At each end of the spreader bar 18 inches from each end is another 1.500 plate 8 inches wide extending to each end. All welds were made with a 3 pass dual shield welding process Thank you in advance for any help you can provide. |
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| : At what point would this lifting devise fail? | |||
| : At what point would this lifting devise fail? -- blacksmith1956 | Post Reply | Top of thread | Engineering Forum |
| Posted by: zekeman ® 11/08/2009, 10:43:37 Author Profile eMail author Edit |
Need a drawing. |
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| : : At what point would this lifting devise fail? -- zekeman | Post Reply | Top of thread | Engineering Forum |
| Posted by: blacksmith1956 ® 11/08/2009, 13:36:08 Author Profile eMail author Edit |
I wish i could post a drawing but I have no way to do so. I just want an idea of the falure point. It is a well known design except for using two lenghts of 20 foot 3x8x.500 structural tubing instead of two c channels. It will lift from the center pick point with the capability to hook the load at the 10 foot and 20 foot points. The lift point will always be at the center of gravity for the load. I hope this helps to visualize the devise. |
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| : : : At what point would this lifting devise fail? -- blacksmith1956 | Post Reply | Top of thread | Engineering Forum |
| Posted by: Marky ® 11/08/2009, 17:00:24 Author Profile eMail author Edit |
Hi and welcome to the forum....this seems to be a pretty complex design...zekeman is right we need some sort of drawing. You may get a few ideas...but they would be guesses. |
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| : : : : At what point would this lifting devise fail? -- Marky | Post Reply | Top of thread | Engineering Forum |
| Posted by: blacksmith1956 ® 11/08/2009, 18:12:53 Author Profile eMail author Edit |
Thank you for the welcome. I will try to post a crude drawing of this project. I do not have a cad program or scanner at the moment so I did the best I could with MS Paint. Sorry But I hope this will help visualize this spreader bar It is not dimensioned or to scale
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| : : : : : At what point would this lifting devise fail? -- blacksmith1956 | Post Reply | Top of thread | Engineering Forum |
| Posted by: blacksmith1956 ® 11/10/2009, 18:03:23 Author Profile eMail author Edit |
FYI The proof test was done today. Pulled 24,000 no problem. Before the test a M.E. ran the numbers 8 to 1 safety factor at 12,000 4 to 1 at 24,000 |
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