How much weight can safely be suspended from center of 2"x2" square tube 9' long?

[Will S]

How much weight can safely be suspended from center of 2"x2" square tube 9' long?

If a 2" square, 1/8" wall box tube, 9' long, was installed horizontal, and supported only at the ends, how much weight could be safely suspended from it's center? I looked online for structural info on box channel, but could not find the asnwer.

I guess another way to think of it would be how much force applied to the center, would it take to bend that 2x2 box channel, supportedonly at the ends.

Anybody here know about this?

 

[CADplans]

Re: How much weight can safely be suspended from center of 2"x2" square tube 9' long?

There is at least 3 different ways the ends can be supported,
depending on how you support or attach the ends, the carrying capacity will change greatly.

Is the 2X2 setting or 2 sawhorses,,, or welded between two immovable beams??

 

[George2615]

Re: How much weight can safely be suspended from center of 2"x2" square tube 9' long?

Here's a site to estimate deflection of 2x2x1/8" tubing.
If the ends are fixed, a 9' piece of 2x2x.125" would deflect .2004" with a 500 lb. center load.
1/4" thick wall would deflect .1306" with the same weight.
What weight would completely bend the tube to failure is not known.


Deflection Calculator for Square Tubing

 

[Will S]

Re: How much weight can safely be suspended from center of 2"x2" square tube 9' long?

There is at least 3 different ways the ends can be supported,
depending on how you support or attach the ends, the carrying capacity will change greatly.

Is the 2X2 setting or 2 sawhorses,,, or welded between two immovable beams??

In this case, the ends are welded to 2" steel vertical supports, 24" long. Those vertical supports fit into the lift pad receptacles of a hydraulic lift. The weight to be lifted would be suspended by a chain or lifting strap, at the center of the 2x2 channel.

 

[Will S]

Re: How much weight can safely be suspended from center of 2"x2" square tube 9' long?

Thanks for that info. The weight we intend to suspend is actually just under 400 lb, but there may be a time when it would be called upon to lift 750 lb. I realize that there are several ways to atach the the lifting strap, or even attaching 2 straps several feet apart, left and right of center, would probably increase load capacity. I also thought about building a truss beam, or sistering up a second piece of box channel to the main channel, to increase weight capacity, but not needed.

 

[Gary Fowler]

Re: How much weight can safely be suspended from center of 2"x2" square tube 9' long?

A truss design underneath using some 1/2" diameter rod would make it safe to hold 750# or more as long as the rod was properly welded you wouldn't get any sag.

 

[Industrial Toys]

Re: How much weight can safely be suspended from center of 2"x2" square tube 9' long?

1/8" is pretty skinny tubing. Why so light if you are concerned about capacity? Is the weight static? My guess is, 750 lbs is pushing it based on experience. And yes, a little truss makes a HUGE difference.

 

[Will S]

Re: How much weight can safely be suspended from center of 2"x2" square tube 9' long?

I.T The reason I was using 1/8" is that is what I thought I had. Turns out it is 3/16, so that is somewhat better. I plan to make it an inverted truss, if we will lift more than ~400#. I'm fabricating this for a one-time project of lifting an outboard motor a few inches, to replace a tilt-tube. The engine is an '04 Mercury 115hp 4stroke. There just isn't enough room to remove the old tilt-tube with the engine mounted in place. Raising it just enough to pull that tube out, and slide a new SS one in. I need to raise it 2 to maybe 4 inches, for maybe 10 or 15 minutes.

I'd do this with the fork lift tines of my tractor, but the loader has developed a hydraulic leak, and the forks drop a couple feet in about a minute, even with no weight on them. So that's the next project.

 

[Industrial Toys]

Re: How much weight can safely be suspended from center of 2"x2" square tube 9' long?

If you don't value the tube, then just try it. See if it flexes uncomfortably. A simple rib welded onto the bottom of the tube would also add immense strength. Another shorter tube stacked and tacked onto the bottom of the nine footer will also suffice in this situation.

Lots of ways to stiffen up that tube.

You could even string a chain from the ends of the tube or close to it and attach your lifting chain to the centre. Just make sure the chains can't come loose, no way, no how! Then your weight is distributed closer to the ends.

 

[Will S]

Re: How much weight can safely be suspended from center of 2"x2" square tube 9' long?

Good ideas; yep, lots of ways to add strength. I'm not concerned with re-using the materials. I think it might come in handy again.