Bridge Crane build

Aukai said:
I had no brakes on my trailer, every year the rear brakes were completely replaced, except for the caliper because of salt water.
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Ouch, 15,000lbs without trailor brakes. Credit to you for being able to drive that.
 
40-50mph at the most, no freeways, and always looked for an out.
 
Aukai said:
40-50mph at the most, no freeways, and always looked for an out.
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That’s pretty much how I haul hay. I find 11 tons to be about the most I want to put on the trailer.
 
What size beam would be needed for a 25' span to pull automotive engines? I do not want to put a center support between the cars if possible.
I could put in a center beam while in use I suppose also.
 
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Aukai said:
What size beam would be needed for a 25' span to pull automotive engines? I do not want to put a center support between the cars if possible.
I could put in a center beam while in use I suppose also.
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Honestly, I'm really not willing to give out engineering advise on building overhead cranes. My engineering degree is electrical, not mechanical or civil. I spent quite a bit of time with spreadsheets and engineering tables to do mine, and I'm comfortable with it. But casually throwing out a beam size scares me, even if I knew what weight "an engine" implied. Liability is certainly an issue, but I'd also feel guilty if I got it wrong and someone got hurt. Sorry to disappoint, maybe someone else is willing to throw out a number/size?
 
@Aukai There is a lot of missing information in your question. If you want to assess the requirements for one component of a lift like that, there are calculators on the internet that can address the strength of a single beam. However...

I, too, am reluctant to give any specific advice on the building of any lifting equipment. I was trained as an Engineer, and developed a side practice with regards to Rope Rescue, which helped me learn rigging for moving heavy machines. With all that background, I am still over a year and over 50 redesigns on my bridge crane. I still have a "few refinements" to make.

The lift has to be mapped from the load through every component and it's loading all the way to the ground under the load (the place where it would impact if the load suddenly fell).

I know this feels like a cop out. but better to say 'no' than lose a friend.
 
Thank you I understand.
 
Rabler & Dabbler, I totally respect and understand your position on Aukai's question. However, It brings up the question; any advice given here, in many cases could be potentially dangerous if wrong or misinterpreted.
 
Eddyde said:
Rabler & Dabbler, I totally respect and understand your position on Aukai's question. However, It brings up the question; any advice given here, in many cases could be potentially dangerous if wrong or misinterpreted.
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Sure. Those of us who do a lot of lifting are extra squeemish about giving advice on only a small part of the whole system. But that is not quite what the problem is.

For a given I beam, say a steel beam 4" X 4" wide flange I beam, one can calculate the maximum allowable load in the center, for a point load. - But the reverse question has too many variables: is it a fixed beam, or does it have traveling loads, is is supported only at the ends, or does it have other supports, and a myriad of other possibilities, including how heavy the motor is (as @rabler said).

I know that *my* 4" X4" I beam can take 200kg at 15 feet, because I calculated all the stresses - for that beam - then I bought the beam and tested it to see that it was right.

For a hobbyist the best approach is to overbuild, but since I don't know enough about @Aukai question I cannot even begin to answer it. What looks like a simple question might have more behind it than you might think.

I guess that goes for other machining advice, but I think less so.on
 
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