Wnadering Jib Crane Boom

CC · Dec 17, 2020

We have an old floor mounted jib crane that wants to drift.
The column was cemented into the floor many years ago and obviously isn't plumbed vertical.
There is no rotator gearbox. It's rotated by hand.
Anyone ever deal with this issue and find a way to deal with the issue?

Thank you!

kenton · Dec 17, 2020

Shim the column back plumb.

At least that is what my old employer did.

Milland · Dec 17, 2020

kenton said:
Shim the column back plumb.

At least that is what my old employer did.

OP would have to break the column free from whatever is cementing it to the floor.

Frankly I think it's worth doing, just from the safety aspect of not wanting a swinging boom to clobber someone. Re-grout it when shimmed.

Either that, or set up a friction brake, but I think the effort to do that isn't in line with the return.

crossthread · Dec 17, 2020

Can you heat and bend the column slightly? Maybe even cut a kerf in the "long" side, straighten it and then weld up the kerf. If it were me I would rather try that then dig up the column. It may have been plumb when it was installed and has bent slightly over the years. If that is the case, then perhaps you could weld some trunions on the "long" side and a threaded truss rod to draw it back to plumb and help to keep it plumb. Might take a little heat on the other side but maybe not if it just bent from use. Not knowing what the dimensions of the crane are, it is hard to figure out what it might take.

Mike1974 · Dec 17, 2020

What about drilling and tapping for a 1/2-5/8 bolt that you could snug up from the bracing at the top to the column? Could jb weld (or even a small tapped hole in the end) to make a piece of brass so it doesn't dig in as bad? You could use as a brake, and even tighten down enough to keep it out of the way when not in use.

CC · Dec 17, 2020

The column is 30" OD free standing piece of tube cemented directly into the concrete floor.

crossthread · Dec 17, 2020

30 inches!? Well my suggestion is horse shit.

Milland · Dec 17, 2020

Welp, look at where you could set some sort of brake in place. Could be as fancy as a disk and caliper with a line to a valve or master cylinder for pressure, or (as suggested) find a place to mount a bar with a tapped hole that will allow a screw to drag on the boom.

Keep in min that the more weight or longer lever arm you're dealing with, the more friction you'll need to ensure boom stability.

Mtndew · Dec 17, 2020

Tighten up the tension rod/turnbuckle thing that goes from the column to the boom, wouldn't that help straighten it up a little?

Mike1974 · Dec 17, 2020

crossthread said:
30 inches!? Well my suggestion is horse shit.

Haha! I was thinking something like 12-18" tops. :leaving:

Bill D · Dec 17, 2020

Any possibility it is bolted to the foundation and all the bolts were buried flush in concrete? Seems impossible to set a tube that big perfectly vertical in wet cement.
Bill D

Milland · Dec 17, 2020

I'm wondering how much load this guy's dealing with. A mast that stout could indicate a lot of weight, or it was just what they had.

If it's a lot of weight, from a *real* safety standpoint it might be best to jackhammer the tube free and set it properly with a high-strength grout, or whatever a civil engineer suggests.

A swinging boom running a couple tons into someone could cost a heck of a lot more than just doing this right.

Phil in Montana · Dec 17, 2020

Add a brake, or a gearbox and overcome the drift...Phil

bloomautomatic · Dec 17, 2020

Can you put a counterbalance on the other side so it doesn't move as much? Won't help with a load, but would keep it still when empty.

Friction brake would help if you kept slight drag on it.

petersen · Dec 17, 2020

Have had experience flame straightening towers and columns that large and larger.

It can be done. (but it ain't simple)

Can you detect and measure the out of plumb condition with a spirit level?
Or perhaps a transit or laser level to measure hook height at high side and low side.

If the needed correction is slight, a "hot shot" or two might bring it enough.

Is it a familiar design with a top bearing and a roller path on the column?
What are overall dimensions?

If it has a central top bearing, could that bearing be shifted with
an eccentric bushing for correction?

Much more information welcome.

petersen

DDoug · Dec 17, 2020

A few pix of the thing would be helpful (very)
and make sure to include the floor interface.

gbent · Dec 17, 2020

Clean carefully around the base of the pillar. If the crane was done properly it is a sleeve mount. There is clearance between the sleeve and the pillar. After the pillar is plumbed a plate is welded around the pillar, and welded to the top flange on the sleeve. If this is the case the repair should be relatively simple.

If the pillar is truly just poured in concrete it could be flame straightened. However I would choose to put power rotation on the jib.

What is the capacity and arm length?

boslab · Dec 17, 2020

For your own peace of mind I’d clean off the base of the column and use some dye pen at rant crack detection fluid, I did have to do several over the years, there were cracked ones, theses were condemned and replaced, the column has been overloaded at some time, aka bent
Mark

Bill D · Dec 17, 2020

For a column that size I think a powered turning rig is required. Pulling several tons around, uphill, by hand is not a very controllable situation.
Bil lD

Pathogen · Dec 17, 2020

I would have made it off plumb to start with if it was at the load point. Then when you need to lift the load and swing to the load point it will naturally drift there.

Wnadering Jib Crane Boom

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