Gantry questions

[truckasaurus]

Today was a decent day on project Airstream. We got the gantries in place and popped the shell off and settled back down on terra firm without any trouble. But where I'm stressing out a bit is lifting and flipping the chassis.

I ran the chains from the hoists around the frame rails just ahead of the bumper and then at the front I ran chain around the A frames just aft of the jack. It all seemed good but as we lifted the chassis the gantry at the front looked a bit sketchy, as if it is bending both across the top horizontal beam and also the verticals; all 4 x 4 construction. I didn't even get the tires off the grass as we were worried that it would all implode in a cloud of splinters.

The hoists are 2 tons each and I used an eye bolt through the beam to mount them but never having done this before I thought I'd get a bit of opinion before I go and get 4 x 6's and rebuild the gantries. The ground isn't overly level so I can block the gantries to get them set up better but will that be enough? Should I take the wheels off?

[Silver Hawk]

1. Why are you flipping it over?

2. Top lintel should be 4x6 for sure - 4x4 has no more strength than a tube. Uprights should be o'k in compression. Wonder they didn't split with shell weight.

3. Why not take off tires?

4. Are you going to replace axles? Now would be a good time to remove them - reduce weight and easier.

[Mixter]

Mine definitely bowed when I lifted my 27'. Not so much that i worried it would break though.

[truckasaurus]

I'm flipping it now to remove the belly pan etc, then back over to yank the floor off. I need to get down to chassis just to use it as a template for the new chassis. I'll be towing it to a shop for copying hopefully.

So new frame, new axles (I hope from Colin), new floor etc.

I can at this stage just suck it up and work under the chassis but there's no way I'm making new belly pan on a new chassis upside down.

[Mixter]

Flipping it was the way to go for me. Made life alot easier for working on the bottom.

[truckasaurus]

Did you just run chain around the chassis like I did you find a better technique?

[millertimeUS]

My gantry also bent in at the top, and during the flip my verticals even took a little lean with the horizontal forces of flipping the frame. My 25' frame had tires and axles on. It was a new frame no doubt much heavier than original with floors, then belly pan and tanks. I had one chain just behind the front hoist and two hoists in the back one over each rear axle. Just by lifting one side in the rear I could control rotation pretty easily and safely. It was a little scary seeing that 4x4 flex though.


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76 'Airstream Tradewind

[millertimeUS]

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76 'Airstream Tradewind

[Mixter]

Mine didnt bow that much. But I did not have axles on it when I was flipping it around painting it or working on the bottom. I did not wrap chains because I had a brand new coat of por15. Instead I used the purple straps from Harbor Freight as a sling- one around the tongue so the frame could spin, and 1 over each of the main frame rails on the rear. Worked awesome.

[Cncampers]

We used 4x6's across the top of our gantries. We only have a 19'. When flipping the frame we tied off one corner of the bumper to the gantry in order to control the flip.


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[truckasaurus]

I do like the sling idea, I'm going to borrow that :-) And is see 4 x 6's in my near future, thanks all for the tips.

[Colin H]

Originally Posted by truckasaurus

I do like the sling idea, I'm going to borrow that :-) And is see 4 x 6's in my near future, thanks all for the tips.

My gantries are steel, with "I" beams across the top.
Colin

[truckasaurus]

Steel would be awesome but then I'd probably have to admit that I might do a third one sometime soon….

[Colin H]

Originally Posted by truckasaurus

Steel would be awesome but then I'd probably have to admit that I might do a third one sometime soon….

if the shoe fits

[JCPOTTERF]

My first flip was scary so I made a jig for the front and rear out of scrap steel . here's a picture of it. I realize not everyone has the tools to make this but this is what it looks like . I looked everywhere on the web for a photo of one but no luck so i just made what i thought would work. It does do the job I used a spare ball to lock into the hitch and mounted it on to the jig. The rear is two flat plates with 4 bolts that clamp to the rear bumper with the same pipe welded and gusseted to one of the plates a larger pipe acts as a bearing of sorts. It has a controlled flip that's balanced pretty well by shifting the rear plates .
hope it helps ! my gantry is 4x4 it should have been 4x6 but it has worked several times so far . Of course steel I beams or a NASA crane would be ideal.

[truckasaurus]

I like that a lot, I think I'll go this route in the spring. I towed the chassis to a friends farm for winter storage and it was quite illuminating! It did the usual flopping around which made the drive exhausting without WD but I had to stop twice, once for an outrigger that wobbled enough that it came off in my hand and lastly for the rear hold down plate which fell off.